tag:blogger.com,1999:blog-64548107652581329002024-03-13T14:20:01.877-06:00A Medic's MedicineAnonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-6454810765258132900.post-66224752283549821632015-03-19T19:26:00.002-06:002015-03-19T19:26:27.768-06:00Prehospital Furosemide<h2>
Furosemide use in Prehospital acute decompensated heart failure</h2>
<div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUGuOnJLWI2RQ97kafCaQiNM4UBeOV0UeDUwaQOZZ94a8ESy-ErGftIhV46Sj1RjZhlMRgQoasgSHTb1TVl40zNogA1mQ0GSwbwTssWsf1lNy78WhHcEtnS1aFPtiH_jwsxKSZWb9AiOU/s1600/002407+Furosemide,+10mg+per+mL,+SDV,+10mL+Vial+McGuffMedical.com.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUGuOnJLWI2RQ97kafCaQiNM4UBeOV0UeDUwaQOZZ94a8ESy-ErGftIhV46Sj1RjZhlMRgQoasgSHTb1TVl40zNogA1mQ0GSwbwTssWsf1lNy78WhHcEtnS1aFPtiH_jwsxKSZWb9AiOU/s1600/002407+Furosemide,+10mg+per+mL,+SDV,+10mL+Vial+McGuffMedical.com.jpg" height="320" width="320" /></a></div>
<br /></div>
<h2>
A Case...</h2>
<div>
You are the paramedic on shift today with an AEMT partner running out of the downtown ambulance station. Just before heading off for company training the pager crackles to life. You are headed to a nearby SNF for a 91 year old male with difficulty breathing. Upon your arrival you find the BLS engine crew getting vital signs. The patient is sitting at a lunch table with a bowl of soup, tripoding in severe respiratory distress. He has a nearly continuous cough that sounds "wet". The CNA hands you a stack of paperwork which she claims contains "everything" about the patient's medical history. Another staff member states that the patient has had a "junky" cough worsening for a few days. They are also trying to arrange a swallow study for the patient due to recent minor choking episodes. While the crew is placing the patient on the gurney and attaching monitoring, you note that the patient has a PMHx of CAD, HTN and CHF for which he takes Losartan, Furosemide, Triamterine and ASA. The paperwork states that the pt has NKDA. Once in the med your team establishes IV access and obtains a 12 lead ECG with does not show signs of STEMI or hyperkalemia. Vitals are as follows</div>
<div>
<ul>
<li>NIBP 193/97</li>
<li>Sinus tach @125bpm</li>
<li>RR-38 with ronchi audible without stethoscope </li>
<li>SpO2 68% on NRB@15LPM</li>
<li>Temporal temperature- 99.8 F</li>
</ul>
You decide that the patient needs more respiratory support and initiate CPAP while your partner prepares to drive. You know that having a PMHx of CHF increases the likelihood that the patient is experiencing ADHF. You also know that giving Furosemide to patients who are not in HF could cause harm. You reach into the med bag, wishing that you knew more about the evidence behind Furosemide use in the ambulance...<br />
<br />
<h2>
The Impetus...</h2>
</div>
<div>
Just this year Pan et al published a study in the <i style="font-weight: bold;">Emergency Medicine Journal </i>looking at this very topic. <a href="http://emj.bmj.com/content/32/1/36.short" target="_blank">The abstract can be found here</a> This article is another important piece of data concerning the prehospital use of Furosemide but it is not the whole story. As the cliché goes, "to know where you're going you have to know where you've been". With that in mind we shall take a chronological look at the studies behind Furosemide use on your ambulance. As we peruse the extant data it is important to consider two main questions. Can paramedics accurately diagnose ADHF from undifferentiated respiratory distress? Does Furosemide improve patient oriented outcomes in the population of those patients recieving the drug given the paramedic diagnostic accuracy.<br />
<br />
In the end it is more important that we understand the literature that is pertinent to our ambulance based paramedic practice rather than find "an answer".<br />
<h2>
Early Data</h2>
</div>
<div>
The earliest data on paramedic Furosemide is a case series published by Tresch et al published in 1983 in the <b><i>Annals of Emergency Medicine</i></b>. They looked at a 62 patient case series of ADHF patients. They compared the Paramedic's diagnosis to the final ED diagnosis to asses the diagnostic accuracy of the field crews. Overall they found that the Paramedic diagnostic accuracy was 89% when compared to the final ED diagnosis. They also observed the patients with ADHF that recieved Furosemide in the ambulance for a change in vital signs between the ambulance and the ED. Of the 55 correctly diagnosed ADHF patients, 47 had improvements in their vital signs upon arrival to the ED.<br />
<br />
Next, in 1987 Hoffman et al published a semi-randomized comparison of four different treatment options for ADHF in <b style="font-style: italic;">Chest. </b>They compared Morphine+Furosemide, NTG+Furosemide, NTG+Morphine+Furosemide and NTG+Morphine in the treatment of suspected ADHF. Thay also compared the paramedic diagnosis of ADHF to the final ED diagnosis. The study population only consisted of 57 patients and the groups exhibited major imbalances at baseline. The small n combined with the imbalanced groups makes it impossible to make reliable quantitative comparisons between the groups. Qualitatively, the NTG groups did better, the morphine groups did worse and 29% of the patients who recieved prehospital Furosemide required IV rehydration in the ED. Only 77% of the patients enrolled in the study (ie pateints thought by the paramedics to be in ADHF) carried a final ED diagnosis of ADHF. The group that fared the worst was the Morphine+Furosemide group. <br />
<br />
<h2>
Finally, a bigger study...</h2>
</div>
<div>
After the two above small case series there clearly still existed quite a lot of scientific uncertainty. In a valiant attempt to fill this void, Wuerz et al published a much larger chart review of 493 patients in <b><i>Annals of Emergency Medicine-1992</i></b>. They had a mean age of 74.5 years old and a 10.9% overall mortality rate. Their population has a few baseline imbalances as can be seen in Table 1. <span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">They divided their cohort into critically ill and non-critically ill patients and compared the effects of prehospital ADHF treatments on mortality. </span><br />
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIGnV1WcpHfRhiRwXsqbdWaSHMdz5qIDmcZg_JI5Szy6M8HPeJARKccGDp2tSgcZcX8e3ugLGQ3haHoy9KX9W_swmwLw023CMx7Xz4JQ6fl9ij11f2Uv1jNOYWsDUNp-A5kkKvD4FWEvs/s640/blogger-image--65146565.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIGnV1WcpHfRhiRwXsqbdWaSHMdz5qIDmcZg_JI5Szy6M8HPeJARKccGDp2tSgcZcX8e3ugLGQ3haHoy9KX9W_swmwLw023CMx7Xz4JQ6fl9ij11f2Uv1jNOYWsDUNp-A5kkKvD4FWEvs/s640/blogger-image--65146565.jpg" /></a></span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">They identified 493 cases of ADHF listed at final hospital diagnosis between 1987 and 1989. 51% of these patients had recieved prehospital phamacologic treatments for ADHF as defined as morphine, furosemide, nitroglycerine. Because these groups were not randomized to treatment vs no treatment, there were several factor that appear to influence the likelihoof of paramedics to tread for ADHF. Patients considered "critical" by treating paramedics were more likely to be treated 17% vs 10%. Systolic blood pressure also strongly correlated (pearson 0.96 correlation coefficient) with likelihood of treatment for pressures from 80-280mmHg. Approx 10% of untreated patients did not have successful IV placement in the field. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">The authors excluded patients presenting with hypotension as the ADHF medications (morphine, furosemide, nitroglycerine) are contraindicated. The overal mortality stats are reported in Table 2.</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjox8ms6e5ujkg4K28sg2G9tssHAwPbRsZmdJLNdMHkWbINTcbNaNVmZr5HCl2TXwrvLDtN_rB1Bh-t5dG5FJtAZqqBYPlUd4-1x6Jce8DwnKxx9SNGnG-eBJsQbeB9gogqeUeVmlxTswo/s640/blogger-image--1822833088.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjox8ms6e5ujkg4K28sg2G9tssHAwPbRsZmdJLNdMHkWbINTcbNaNVmZr5HCl2TXwrvLDtN_rB1Bh-t5dG5FJtAZqqBYPlUd4-1x6Jce8DwnKxx9SNGnG-eBJsQbeB9gogqeUeVmlxTswo/s640/blogger-image--1822833088.jpg" /></a></span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Concerning the non-critical patients, the authors put it best. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjILkTGvVoBXTJc-vbDpae5EysGcfa3EmEJvfUsaj_ARcb3EPWEsiDhgUoUJbWRzylVBTjeCi35-nu6MVaKlHmxS35e9s0hcHJaCJ-3hJpc0nzSeVKEggvHm_DvUiBArfToMPHls_1EAUg/s640/blogger-image--2140605382.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjILkTGvVoBXTJc-vbDpae5EysGcfa3EmEJvfUsaj_ARcb3EPWEsiDhgUoUJbWRzylVBTjeCi35-nu6MVaKlHmxS35e9s0hcHJaCJ-3hJpc0nzSeVKEggvHm_DvUiBArfToMPHls_1EAUg/s640/blogger-image--2140605382.jpg" /></a></span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Generally, the authors found that more aggressive prehospital care benefitted ADHF patients but harmed dyspnea patients (asthma, COPD, pneumonia) mistaken for ADHF in the field. The overall accuray of EMS ADHF diagnosis was 87% for critically ill patients but only 69% in the noncritically ill. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-yEhfFKaCgzn3D0abjsfd4Gahn1180628a6rxz17zjWvqUh8AJ16x77a8XvyAABu0_Y-0mjDBPHsdWCoNl5qU8SZ-TnqWC6_m_5BnHpRjziF0CFYvprT10nwIQIHea-rTbvMn1CcuvK4/s640/blogger-image-669937468.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-yEhfFKaCgzn3D0abjsfd4Gahn1180628a6rxz17zjWvqUh8AJ16x77a8XvyAABu0_Y-0mjDBPHsdWCoNl5qU8SZ-TnqWC6_m_5BnHpRjziF0CFYvprT10nwIQIHea-rTbvMn1CcuvK4/s640/blogger-image-669937468.jpg" /></a></span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Prehospital treatment for ADHF decreased the time from 911 call to first ADHF treatement substantially but also increased prehospital treatment to hospital arrival time by 2 minutes.</span></div>
<div class="separator" style="clear: both;">
</div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcOpCyZPBAcZyAkswHx4EfMr-uxiPB9LN6Xi5bSggepTJze1ArqTx5_6TEHWh5tl6b6YT14eP4BI-KLb5mNuDA3I2EtKm1bF7rJQhAwg7e_p9t2zmOBkm9qf7oih5ueHVSqJ6_x_4-9O4/s640/blogger-image-1542781893.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcOpCyZPBAcZyAkswHx4EfMr-uxiPB9LN6Xi5bSggepTJze1ArqTx5_6TEHWh5tl6b6YT14eP4BI-KLb5mNuDA3I2EtKm1bF7rJQhAwg7e_p9t2zmOBkm9qf7oih5ueHVSqJ6_x_4-9O4/s640/blogger-image-1542781893.jpg" /></a></span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Overall, Wuerz et al showed that prehospital treatment of ADHF <i>can</i> be beneficial to critically ill patients. The article also illustrates the controversial points of low prehospital diagnostic accuracy and resulting harm to misdiagnosed patients. As a retrospective chart review, all these differences can be explained, at least in part, by confounding factors. Wuerz et al sets a good foundation upon which a high quality RCT could build upon. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">(and yes, medic's medicine did dig a hardcopy out of the stacks...)</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<h2>
Are there any RCTs on the topic?</h2>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">The best (and only) RCT for evaluating prehospital furosemide use was Holzer-Richling et al published in the <b><i>European Journal of Clinical Investigations-2011</i></b>. They used a physician based ambulance service to study usual care (Oxygen + Morphine +Nitrates) with or without furosemide boluses for dyspneic patients presenting with hypertension > 180mmHg SBP and signs of pulmonary edema. Patients presenting to the ambulance with suspected hypertensive pulmonary edema we placed on O2 at 6 LPM, given 5mg Morphine SC, 5mg Morphine IV and boluses of IV Urapidil (an IV nitrate not used in the US) until SBP was less than 160. At that point they were randomized to 80mg Furosemide IV or placebo. All providers were blinded to to treatement allocation. Treating physicians at the hospital were likewise blinded but they were allowed to give 40mg Furosemide boluses at their own discretion. Groups were well balanced at randomization. The primary outcome was patient reported dyspnea on a 1-10 modified BORG scale 1 hour after randomization. Secondary outcomes included BORG dyspnea scores at 2, 3 and 6 hours in addition to various ABG values. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnGkayqCHgzy-1h8y5puGD7ZFwHjcDp7Ya-3VuSEMakjfcodj6_nz3r7UPWn5fNq1cN2HZ2fQaiJcHTrH_fXSqQjLekvomr0SpmoolDYwJMRGfr6q8Opk5SWnUpQ3g3m6yFWNctnUhw10/s640/blogger-image--204199724.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnGkayqCHgzy-1h8y5puGD7ZFwHjcDp7Ya-3VuSEMakjfcodj6_nz3r7UPWn5fNq1cN2HZ2fQaiJcHTrH_fXSqQjLekvomr0SpmoolDYwJMRGfr6q8Opk5SWnUpQ3g3m6yFWNctnUhw10/s640/blogger-image--204199724.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">They found no differences in dyspnea.</td></tr>
</tbody></table>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"></span></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
Unsurprisingly, the authors also found negative fluid balance in the patients who did receive furosemide and an increase in nitrate administration in those who did not receive furosemide. No other clinically important differences were found among the other secondary endpoints. </div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
In this decent quality RCT the investigators could not demonstrate a difference in a clinical patient oriented outcome when patients were treated with Furosemide in the prehospital setting. It does however suffer from small sample size. The authors note that the trial only had 90% power to detect a difference. It did not evaluate mortality as this would have required much larger sample sizes. Further, due to the physician staffing model and heavy use of IV nitrates, the study has limited external validity to most US EMS services. They also did not evaluate adverse events or misdiagnosis rates. </div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
Finally we reach the study that made this background literature review topical. In January 2015, Pan et al published another retrospective chart review of Furosemide use by the Ottowa Paramedic Service Advanced Care Paramedics for ADHF. They matched ED and EMS charts for Furosemide administration or final ED diagnosis of HF. They organized these charts into three groups: ADHF patients that received furosemide from paramedics, ADHF patients who did not receive Furosemide from paramedics and non-ADHF patients who recieved Furosemide from paramedics. </div>
<div class="separator" style="clear: both;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9jhSXja6d0am-PuXa2Ze2MzjkN_ZuSicQwPsU9oqakBaJ0jOLPaXd_Jk1OUnRfvRuUnQmnl4ivttJSgHRPRoG4d3yWg1eTNFv_gHAeHWU5aJek1thUppackKWBtAZYRtJBFHwBytchxE/s640/blogger-image-568225198.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9jhSXja6d0am-PuXa2Ze2MzjkN_ZuSicQwPsU9oqakBaJ0jOLPaXd_Jk1OUnRfvRuUnQmnl4ivttJSgHRPRoG4d3yWg1eTNFv_gHAeHWU5aJek1thUppackKWBtAZYRtJBFHwBytchxE/s640/blogger-image-568225198.jpg" /></a></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
Their primary outcome measures were safety oriented rather than effectiveness. They measured Serious Adverse Events (SAE) within 2 hours of ER arrival including death, acute kidney injury or failure, need for vasopressors and need for intubation. Secondary outcomes included hypotension, administration of fluid boluses, electrolyte abnormalities or changes in tropinin levels within two hours. The groups were well matched for most prognostic factors but the imbalances are instructive concerning the difficulty of prehospital ADHF diagnosis.</div>
<div class="separator" style="clear: both;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_hIRotqL2t-KyN622PsfdTpQgVVZbbiDYFbR5tUTXA1ygXMLDapuFUkVle56-aH1eNlS43M2NtAvvFwGNO_x3IpFsT6zAaz5Dr3tgmckBVY1DpKGKBWaQXyvJSSFyt_LpSFxojEVkW7Y/s640/blogger-image--343237209.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_hIRotqL2t-KyN622PsfdTpQgVVZbbiDYFbR5tUTXA1ygXMLDapuFUkVle56-aH1eNlS43M2NtAvvFwGNO_x3IpFsT6zAaz5Dr3tgmckBVY1DpKGKBWaQXyvJSSFyt_LpSFxojEVkW7Y/s640/blogger-image--343237209.jpg" width="626" /></a></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
It is clear that patients already carrying a diagnosis of HF are more likely to be correctly identified by paramedics when they have episodes of ADHF. Patients incorrectly treated by paramedics with Furosemide were mostly pneumonia or COPD with a few ACS patients thrown in. </div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
This graph compares the prehospital vital signs recorded by the paramedics across the three groups.</div>
<div class="separator" style="clear: both;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhabePsAoHKjoUXaqWFRuIB0d9Ln9bXWRf9UBMkr_lUqvJJ7zSODAFD5A_B3EfQVL2nLuteHqm-JMi6nKpsldBtoYie4fTvFJCMqqlHUxbzxw3f_TJaqnRZiwzPJhLMbm2CmlngCfbNy-s/s640/blogger-image-465269432.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhabePsAoHKjoUXaqWFRuIB0d9Ln9bXWRf9UBMkr_lUqvJJ7zSODAFD5A_B3EfQVL2nLuteHqm-JMi6nKpsldBtoYie4fTvFJCMqqlHUxbzxw3f_TJaqnRZiwzPJhLMbm2CmlngCfbNy-s/s640/blogger-image-465269432.jpg" /></a></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">It is clear from this graph that the clinical ADHF treated by paramedics on the ambulance is a distinct entity from the ADHF diagnosed in the ED. The patients treated in the ambulance had much higher heart rates and lower SpO2. This makes comparing paramedic and ED diagnosis more challenging. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">The authors ultimately found no statistically significant differences in the SAE rates though the point estimate for SAE in the furosemide-HF group was higher than either other group. Given the worse initial presentation of this group, it is impossible to know whether this is correlation or causation. After correcting for confounders they generated odds ratios for SAEs of 0.62 (95%CI 0.33-1.43) for Furosemide-HF patients and 1.14 (95%CI 0.58-2.23) for furosemide-noHF patients. They did find a worrisome 34.5% rate of paramedic furosemide administration in patients that ultimately did not receive a diagnosis of HF. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<h2>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">A study about diagnosis</span></h2>
<div>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">The last bit of data we will consider is Jaronik et al published in <i style="font-weight: bold;">Prehospital Emergency Care-2006</i>. These authors reviewed all cases of paramedic furosemide administration for a year in a large urban US EMS system. They categorized the usages into appropriate, inappropriate or potentially harmful. Furosemide administration was deemed potentially harmful when the patients carried a final diagnosis of sepsis, dehydration or pneumonia. They found 144 cases of furosemide use. 42% of patients did not receive a primary or secondary diagnosis of CHF. 23% of patients required IV rehydration. Furosemide administration was deemed potentially harmful in 17% of patients. although the study was not powered to asses mortality, the authors report it for our edification. There were nine deaths in the study. Seven of these occurred in patients inappropriately administered furosemide. </span></div>
<div>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<h2>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Final thoughts...</span></h2>
<div>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">The data concerning use of furosemide for ADHF by paramedics are heterogeneous. Some case studies hinted at benefit. On the other hand, the rate of misdiagnosis and misadministration is worryingly high. In reality, the extant data on the topic of prehospital furosemide use does not support a strong stance in either direction, pro or con. It is hard to believe that a mainstay of both inpatient treatment of ADHF and chronic outpatient care of CHF could be detrimental just because it is given in the prehospital setting. On the other hand, the data make it very clear that between one in three and one in four patients we give furosemide to do not have ADHF. While Wuerz showed that diagnostic accuracy increased as the patients were more critical, it also stands to reason that critical patients not suffering from ADHF need timely diagnosis just as badly. Perhaps the most rational actions in light of these data would center around improving paramedic education concerning ADHF or increasing diagnostic accuracy through access to point of care testing. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<h2>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Case Conclusion</span></h2>
<div>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">They patient seems to improve on CPAP. His SpO2 increased to the high 80. You decide to wait on the furosemide for now unless he deteriorates. After the next call the ER doc calls you over to see the patient's chest X ray. She explains that the pt has opacities in the right lung fields but normal left lung. She states that the BNP was normal. She suspects that the pt may have aspirated some of the soup he had been eating. </span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<h2>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;">Further Reading</span></h2>
<div>
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="http://circ.ahajournals.org/content/122/3/265.long" target="_blank">An interesting study concerning another potential effect of furosemide</a></span></div>
<div>
<br /></div>
<div>
<a href="http://emcrit.org/podcasts/scape/" target="_blank">Emcrit #1 (yep the first one) on crashing pulmonary edema patients.</a></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><br />
</span></div>
<div class="separator" style="clear: both;">
<span style="font-family: 'Helvetica Neue Light', HelveticaNeue-Light, helvetica, arial, sans-serif;"><a href="http://foamcast.org/2014/07/07/episode-7-heart-failure/" target="_blank">There's a FOAMcast for everything!</a></span></div>
<div class="separator" style="clear: both;">
<br /></div>
<div class="separator" style="clear: both;">
<br /></div>
</div>
<div>
</div>
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com1tag:blogger.com,1999:blog-6454810765258132900.post-14799635355293718842015-02-16T14:50:00.001-07:002015-02-19T21:26:33.617-07:00Intro to Evidence Based Medicine for ParamedicsThe main purpose of A Medic's Medicine is to create and distribute high quality, user friendly systematic reviews of literature to inform clinical questions in prehospital emergency care. In order help readers fully understand the systematic reviews posted here at A Medic's Medicine, I have endeavored to outline some general tenets of EBM. While I do not have the formal training of others, I am passionate about the topic. I distilled my understanding of basic EBM concepts for this lecture presented to my service's EMS committee. While it is neither exhaustive nor without flaw, I hope that it might serve as a starting point for those interested in understanding the science behind the care we provide on the ambulance.<br />
<br />
<br />
<iframe allowfullscreen="" frameborder="0" height="400" mozallowfullscreen="" src="http://prezi.com/embed/4vmqfornnn6c/?bgcolor=ffffff&lock_to_path=1&autoplay=0&autohide_ctrls=0#" webkitallowfullscreen="" width="550"></iframe><br />
<br />
<br />
<h2>Further Reading </h2><div><a href="http://www.thennt.com/" target="_blank">The NNT is a great website discussing and compiling EBM specific to emergency medicine</a></div><div><br />
</div><div><a href="http://thesgem.com/" target="_blank">The SGEM podcast is an example of high quality EBM and critical appraisal</a></div><div><br />
</div><div><a href="http://www.emlitofnote.com/" target="_blank">While EM Lit of Note is not prehospital specific, it is perhaps the superlative critical appraisal blog today.</a></div><br />
<a href="http://emnerd.com/" target="_blank">Well written EBM discussions of minimalism in EM can be found here at EM Nerd</a><br />
<br />
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com0tag:blogger.com,1999:blog-6454810765258132900.post-35091364170348100012015-02-13T23:03:00.000-07:002015-02-19T21:27:09.232-07:00Minor Head Injury-What to do, What to do?<h2>A Case</h2><div>You arrive on scene to a local ice rink to find an 19 year old male complaining of a headache. He states that, while playing hockey, he fell backwards and struck his head on the ice. His father adds that your patient was slow to get up and "groggy" for several minutes after the fall. Since the ice rink is part of a local municipal recreation facility, they walked across the hall to ask the lifeguards what to do. After about 45 minutes the lifeguards decided to call 911. </div><div><br />
</div><div>Your initial assessment reveals an alert and oriented young man with a patent airway, non labored respirations, strong regular radial pulse and a GCS of 15. He states that he has asthma for which his doctor prescribes albuterol. He denies other medications or allergies. He states that his most recent meal was a cheeseburger for lunch and denies any alcohol intake today. His physical exam is unremarkable. He states that he still has a headache but you are unable to appreciate any swelling, tenderness or hematoma on his head. He does state that he was wearing his helmet. </div><div><br />
</div><div>Your partner lists his vitals for you:</div><div><ul><li>HR-78 </li>
<li>BP- 145/74 mmHg</li>
<li>RR-14</li>
<li>SpO2-94%</li>
<li>BGL-88 mg/dL</li>
</ul><div>What does this patient need? Backboard, C-Collar, Tx to ER for CT scan? Go home with dad after signed refusal? Something in-between? </div></div><div></div><h3>What is a Minor Head Injury?</h3><div>According to Tintinalli's, 7th Ed, </div><blockquote class="tr_bq">"Mild Traumatic Brain Injury (TBI) is defined by a GCS of 14-15. It accounts for approximately 80% of head injuries in the U.S." ..."Minor TBI, often called a 'concussion', is characterized by a neurologic or neurophysiologic dysfunction of varying duration without overt hemorrhages or gross lesions."...."Mild TBI may represent a predominantly metabolic insult as opposed to a structural one."</blockquote><br />
Other, more informal definitions, revolve around a brief loss of consciousness after a blow to the head with a return to GCS 14-15. <br />
<br />
<h3>Why do I care about Minor Head Injuries? </h3>Prehospital providers tend to see quite a few complaints of "concussion", "knocked out" and "out of it". It behooves us to have a solid understanding of what minor head injury is, the potential complications and possible treatments. Through this knowledge we can better triage the patients into low-risk and non low-risk categories and provide each with the appropriate care and disposition.<br />
<div><br />
</div><h3>Risk? Risk of what?</h3><div>The big risk in the GCS 15 patent after a head injury is that they have a bleed in their brain that needs to be addressed by a neurosurgeon before it results in increased ICP, herniation, airway compromise and death. <a href="http://emergencymedicineireland.com/2012/03/anatomy-for-emergency-medicine-9-brain-herniation/">An excellent video overview of brain herniation can be found here</a> This is also a concern for patients and their families. I am sure most of us have been asked whether it is necessary to keep the patient awake for the ensuing 8 hours to ensure they are still OK. Further, decompensation after Minor Head Injury is a major medico-legal concern for many EMTs and paramedics. The challenge of Minor Head Injury is to identify which patients are at such a low risk of later decompensation that they do not require any imaging to look for bleeding in the brain. Such patients could be safely referred to see their primary doctor about Minor Head Injury follow up and return to work/sports advice. How then are we to find these low risk "needles" in the "haystack" of all Minor Head Injury patients?</div><h2>With a Magnet!</h2><div>In this case our "magnet", which allows us to quickly identify low risk Minor Head Injury patients, relies on what are known as "Clinical Decision Tools" (CDTs). We will discuss the most popular and useful clinical decision tool for identifying low risk Minor Head Injuries; the Canadian CT Head Rule (CCTHR). Before we dive right into the literature however, I think we should take a brief moment to talk about what CDTs are and where they come from.<br />
CDTs are a set of criteria that identify a group of patients who have a desired characteristic. EMTs and Paramedics are most familiar with this concept when we determine who needs a cervical collar after trauma. If the patient is GCS 15, not intoxicated, has a normal neuro exam, has no tenderness to palpation of the spine and has no distracting injuries, they do not need a c-collar. This set of criteria are known more formally as the NEXUS criteria. NEXUS is a CDT that identifies a group of patients whose risk of unstable spinal injury is so low that they do not require further medical intervention or testing. The criteria of a CDT can be demographic (such as a patients' age, sex or weight), clinical (such as tenderness or other exam findings), based on medical or personal history (recent surgery or IV drug use) or test results (lab values or imaging). <br />
So where do these rules come from and how do we know that they work? CDTs are created via a two step process called derivation and validation. We shall explore both of these steps as we learn about the CCTHR.</div><h2>Derivation</h2><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZa5LLlE5Fc6repepDWACxNitcXeTs6gqegE4sUN7J2iGu_hFWcIsKN83nv0503Vq4THQ3Y0wZtadJx1Kr10PmWqVsQHmg_w3SfI0poLGuPygljutelFwtN3uw_FlmRNHfqHJ3sm478vk/s1600/Screen+Shot+2014-12-31+at+1.18.20+PM.png" imageanchor="1" style="clear: left; display: inline !important; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZa5LLlE5Fc6repepDWACxNitcXeTs6gqegE4sUN7J2iGu_hFWcIsKN83nv0503Vq4THQ3Y0wZtadJx1Kr10PmWqVsQHmg_w3SfI0poLGuPygljutelFwtN3uw_FlmRNHfqHJ3sm478vk/s1600/Screen+Shot+2014-12-31+at+1.18.20+PM.png" height="288" width="640" /></a></div>This is the abstract from the study in which Ian Stiell et al derived the CCTHR. Lets break this study down. The authors start by identifying a group of patients to observe. They chose to follow all adult patients who presented to ten Canadian EDs with a GCS of 13-15 after head trauma. They then performed a systematic assessment of each of these patients and recorded the results of more than 20 signs, symptoms and exam findings. After recording this data, some patients received a CT scan, others were followed up two weeks later to see how they were doing. After the results of the CT scan, or after the patient was discharged from the hospital, the authors used statistical modeling to chose a set of 4 criteria from the systematic assessment that identified all the patients who needed a medical intervention for their head injury. The four criteria of the CCTHR are as follows<br />
<br />
<ol><li>Failure to reach GCS 15 within 2 hours of the impact</li>
<li>Any sign of skull fracture (open or basilar)</li>
<li>Age greater than 65 </li>
<li>More than 2 episodes of vomitting</li>
</ol>I remember these four criteria with the mnemonic from Dr. David Newman of SMARTEM.org (see further reading) "<b>C</b>anadians <b>G</b>et <b>S</b>loppy <b>A</b>nd <b>V</b>omit" which stands for <b>CCTHR, GCS, Skull fracture, Age, Vomitting </b><br />
<div><ol></ol><div>This is the derivation of the CCTHR. This set of criteria have been shown to pick out all the patients in the derivation study with a desired characteristic; those that required a medical intervention after minor head injury. Next this rule must be proven to work equally well in similar patient populations when used by other clinicians. This is termed validation. </div><div><br />
</div><h2>Validation</h2><div>There are severals studies published that have validated the CCTHR. The first was<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj19X6qnWkyoOPutjzdkCotj_6dugkRqa9JWDELkaV9S46aZRePeUAHpwNTFO5f_sTkzUrcX7eii5kLTGXuxAyznM4Bt3GmOhTu1vKmsg2lB2cXZyMmp54L-5rWvOLDokJeZ9NZXSjA5QY/s1600/Screen+Shot+2015-01-05+at+6.13.26+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj19X6qnWkyoOPutjzdkCotj_6dugkRqa9JWDELkaV9S46aZRePeUAHpwNTFO5f_sTkzUrcX7eii5kLTGXuxAyznM4Bt3GmOhTu1vKmsg2lB2cXZyMmp54L-5rWvOLDokJeZ9NZXSjA5QY/s1600/Screen+Shot+2015-01-05+at+6.13.26+PM.png" height="420" width="640" /></a></div><div class="separator" style="clear: both; text-align: left;">This study is an internal clinical validation i.e. it is a study conducted in the same clinical setting by the same authors that created the original rule. The authors enrolled a 2707 adult patients with minor head injury and applied the CCTHR to them. The authors then looked at the results of CT scans or two week follow up interviews to determine the sensitivity and specificity of the CCTHR. </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhGZc9oDlh3t2VHJ8yRGfM-v90lnOL9Pt_JzcCavLskvDCLlyr3W7l0dGEzsL32bi4DgSFQ_yU1yOtOU0DVVQqBg8kBz9SF_3rDJ012mjWTrekt7H_h_mYBkAN_BwLYeG3TZSbbgdTdk0/s1600/Screen+Shot+2015-01-05+at+6.25.10+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhGZc9oDlh3t2VHJ8yRGfM-v90lnOL9Pt_JzcCavLskvDCLlyr3W7l0dGEzsL32bi4DgSFQ_yU1yOtOU0DVVQqBg8kBz9SF_3rDJ012mjWTrekt7H_h_mYBkAN_BwLYeG3TZSbbgdTdk0/s1600/Screen+Shot+2015-01-05+at+6.25.10+PM.png" height="320" width="281" /></a></div><div class="separator" style="clear: both; text-align: left;">As we can see here the CCTHR did not miss any patients requiring neurosurgical intervention. The authors also found that when all the 2707 charts were reviews by a second investigator there was a 4% rate of misinterpretation of the rule, specifically, discharging a patient that the rule did not characterize as low risk. None of these 4% of patients had a bad outcome at two week follow up or required intervention. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">The next validation was an external validation published in the same issue of JAMA. External clinical validations are application of a CDT in a clinical setting by authors who had no involvement in creating the rule and who practice in centers other than where the rule was created. </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0JYggWPflOhBlJWsTVU2lVpCvwerHvurd4TKSWJxXa_VuAY5J1cn6_oGjFtUZF3VzbjJQ7zaWnQVKouEmT8Hu-FmX0T1Z7SSwz3OZrYuLsOJaZjsfT-3wLCLvqVI3R5Ce4Hriznyd1uQ/s1600/Screen+Shot+2015-01-05+at+6.39.04+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0JYggWPflOhBlJWsTVU2lVpCvwerHvurd4TKSWJxXa_VuAY5J1cn6_oGjFtUZF3VzbjJQ7zaWnQVKouEmT8Hu-FmX0T1Z7SSwz3OZrYuLsOJaZjsfT-3wLCLvqVI3R5Ce4Hriznyd1uQ/s1600/Screen+Shot+2015-01-05+at+6.39.04+PM.png" height="364" width="640" /></a></div><div class="separator" style="clear: both; text-align: left;">These authors looked at 3181 patients that presented with signs of Minor Head Injury to 4 different Dutch academic hospitals. These patients were similar to the patients in the previous studies except that the inclusion criteria for Minor Head Injury were slightly broader and that more patients presented with clinical intoxication (43%). They found that the CCTHR was 100% sensitive for all neurological interventions even in this broader group of Minor Head Injury patients. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">The next validation came from Ro et al in <i>Academic Emergency Medicine-2001. </i>They studied a cohort of 696 patients eligible for the CCTHR. Their primary outcome was evidence of injury on CT scan rather than the need for neurosurgical intervention. They did note that the CCTHR was still 100% sensitive for neurosurgical intervention as one of their secondary outcomes. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">The final validation was a semi-external validation in 2012. </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhs53hU2-XxDFBWR7f19Qs_BZ2ntiYKVc9lbo5JM2h00HIeasGoZHhvAazJhyphenhypheniIQ6z94J0H3xKJISarkqgKfdKuLJP9nD01WkJHybr1gqvTK1uoVqThgC-7AO0w65GTsDCBBWZVBUTmtOg/s1600/Screen+Shot+2015-01-05+at+7.13.22+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhs53hU2-XxDFBWR7f19Qs_BZ2ntiYKVc9lbo5JM2h00HIeasGoZHhvAazJhyphenhypheniIQ6z94J0H3xKJISarkqgKfdKuLJP9nD01WkJHybr1gqvTK1uoVqThgC-7AO0w65GTsDCBBWZVBUTmtOg/s1600/Screen+Shot+2015-01-05+at+7.13.22+PM.png" height="388" width="640" /></a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">This is the first validation of the CCTHR in a US setting (read: insane medical-legal fear). They likewise found 100% sensitivity for neurosurgical intervention. </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMQT2QombfqDKncQ297GeNmYd6I0Qe_wEcuo_SiEbMKE5Fv3ku7azyjNdFcvhw4f-lmQ88tgTcEV7F_IzyZ5-QuJm8tBhd_jbV9dQs7Qt49oh4IuZnMW4WJdmxGvOVezLfPMra6zkiIak/s1600/Screen+Shot+2015-01-05+at+7.27.07+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMQT2QombfqDKncQ297GeNmYd6I0Qe_wEcuo_SiEbMKE5Fv3ku7azyjNdFcvhw4f-lmQ88tgTcEV7F_IzyZ5-QuJm8tBhd_jbV9dQs7Qt49oh4IuZnMW4WJdmxGvOVezLfPMra6zkiIak/s1600/Screen+Shot+2015-01-05+at+7.27.07+PM.png" height="194" width="640" /></a></div>In all these validation cohorts total 7,015 patients (not counting the derivation cohort) with an average 1% neurosurgical intervention rate. In this total group of 7,015 patients, no patient that received a neurosurgical intervention was missed by the CTTHR.<br />
<h2>So now what?</h2><div>How are we to translate our newfound medical knowledge into practice? First of all, you should not blindly take my word for it. Please read these studies and any others you find to have a more complete grasp of the literature. Next, find a mentor or trusted advisor and talk to them about what you have learned. After doing these things a rational approach to minor head injury might be as follows:</div><div><ol><li>Asses patients complaining of head trauma for signs/symptoms of minor head injury such as </li>
<ol><li>Loss of consciousness </li>
<li>Disorientation </li>
<li>Amnesia </li>
</ol><li>Asses Minor Head Injury patients for reasons why the CCTHR might not apply to their case such as </li>
<ol><li>Age less than 16</li>
<li>Penetrating injury </li>
<li>Unstable vitals or Major trauma</li>
<li>Focal neuro deficits</li>
<li>Bleeding disorder or on Coumadin</li>
</ol><li>Apply the CCTHR to all applicable Minor Head Injury patients. </li>
<ol><li>Achieve GCS 15 before 2 hours after impact</li>
<li>No signs of Basilar Skull Fracture </li>
<ol><li>Racoon eyes, Battle's sign, Oto/Rhinorrhea of CSF</li>
</ol><li>Age < 65</li>
<li>Vomitting < 2 episodes</li>
</ol><li>Encourage any patient that does not meet these four criteria to be transported to the ER under your medical supervision.</li>
<ol><li>Any patient that does meet the above criteria should be encouraged to follow up with their primary physician ASAP for return to work/sport advice and post-concussion follow-up.</li>
</ol></ol><h3>Fine Print</h3><div>It is yet unknown if the CCTHR can be applied in patients on newer oral anticoagulant agents such as rivaroxaban or dabigatran. Also since the above studies explicitly excluded patients on coumadin but did not mention aspirin, the CCTHR could theoretically be applied to patients on a daily ASA regimen. It should be said, however, that to do so would be pushing the envelope of the rule. It would be advisable to speak to a medical control physician before doing so. On that note, it is important to have buy in from your organization and medical director before incorporating the CCTHR into your practice. This is one instance where it is better to ask permission than to seek forgiveness.<br />
It is also critical to think long and hard about what matters to you and your patents concerning Minor Head Injury. I firmly believe that unless the patient needs an acute medical intervention which they can only receive in a hospital setting there is no point in them being treated at a hospital. This is very important because, while the CCTHR has not missed a patient in need of a medical intervention, it does not exclude the possibility of a positive CT scan. It is imperative to encourage the patient to see their primary care physician before returning to work/sports and for potential neurology follow up. </div><div><br />
</div><h2>Case Conclusion</h2><div>You advise the patient and his father that he has had a Minor Head Injury, otherwise known as a concussion. You tell them that there is always a risk that his injuries could cause bleeding in his brain and that this is very serious. You also explain that since he is GCS 15, has no signs of skull fracture, is younger than 65 and has not vomitted, his risk of bleeding that requires an intervention is extremely low. You advise the son and father to call 911 again if the patient's signs or symptoms worsen and remind them to see the patient's primary care doctor before going back to school or playing sports. </div><div><br />
</div><h2>Further information</h2><div><a href="http://www.smartem.org/podcasts/minor-head-injury-who-has-badness">An amazing summary of evidence based Minor Head Injury management for both adults and pediatric patients can be found here at SMARTEM.org</a></div></div><div><a href="http://shortcoatsinem.blogspot.com/2013/10/tools-in-ed.html">A great overview of CDTs from the amazing blog of Lauren Westafer</a></div><div><br />
</div><div><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div></div></div><br />
<br />
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com1tag:blogger.com,1999:blog-6454810765258132900.post-13206524686988363952015-02-05T16:53:00.000-07:002015-02-19T21:28:48.343-07:00Is RIC working on your ambulance today?<div class="separator" style="clear: both; text-align: center;"><br />
</div><h2>STEMI! ... now what?</h2><div>Your chest pain call just took a serious turn when the monitor spits out this 12 lead ECG...<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGndZVAEP9n4gydnWv1TdvYuX3Jkqb7pcBImKx00yJGCq0WbTh5YuWrUQFaW-PVCqMVd6UMXgdq8G4ITrS1WNDLfjIE9Z4Vj7CUcWlzp0VHr-I85JAZOr_bko-3h9kE4p1zAbUxSKv6K4/s1600/inf3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGndZVAEP9n4gydnWv1TdvYuX3Jkqb7pcBImKx00yJGCq0WbTh5YuWrUQFaW-PVCqMVd6UMXgdq8G4ITrS1WNDLfjIE9Z4Vj7CUcWlzp0VHr-I85JAZOr_bko-3h9kE4p1zAbUxSKv6K4/s1600/inf3.jpg" height="275" width="640" /></a></div></div><div class="separator" style="clear: both; text-align: left;">Your patient is a 62 y/o M with a known history of CAD. You initiate rapid transport to a PCI center, administer 324 of ASA and establish an IV but do not administer NTG due to recent PDE-5 inhibitor use. You provide early STEMI notification and transmit a copy of the ECG. The patient's pain persists after the ASA and IV opiates. You are still 15 minutes away from the PCI center. You look down at the patient wondering whether there is anything else you can do to improve your patient's prognosis...</div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div><h2>Who is RIC?</h2><div class="separator" style="clear: both; text-align: center;"><br />
</div><div>As it turns out, RIC is an abbreviation that stands for <b><i>Remote Ischemic Conditioning</i></b> and while RIC is not a person, the question still remains "Is RIC working on your ambulance today?" </div><div><br />
</div><div>Remote Ischemic Conditioning refers to occluding arterial flow to an extremity around the time of reperfusion of another ischemic tissue. In more specific detail, RIC involves using a BP cuff to occlude an arm or leg just before and during reperfusion of a STEMI. The arterial flow to the limb is occluded for 4-5 minutes then reinstated for 4-5 minutes. This alternating limb perfusion is repeated 4-5 times. </div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje7-tDm8xaGQccWqSAZ42dKsodzP6I1RDcU3Xc5u5nfSq70QCvV-ET-IAprGijxL1k9sh3pIGQx0ZhnZQyupKb_Ai0OjbfqAo-24XyJPfFqgyD8mkHC4lSbuz_sws-iVw4zmvsTlFYvUs/s1600/Ensure-correct-placement-of-the-cuff.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje7-tDm8xaGQccWqSAZ42dKsodzP6I1RDcU3Xc5u5nfSq70QCvV-ET-IAprGijxL1k9sh3pIGQx0ZhnZQyupKb_Ai0OjbfqAo-24XyJPfFqgyD8mkHC4lSbuz_sws-iVw4zmvsTlFYvUs/s1600/Ensure-correct-placement-of-the-cuff.jpg" height="213" width="320" /></a></div><br />
</div><h2>And just why would we do this?</h2><div>Well as it turns out RIC has been shown in randomized controlled trials to decrease infarction size, peak troponin values and, most importantly, decrease Major Adverse Cardiovascular and Cerebrovascular Events (MACCE) up to three years after a STEMI. </div><div><br />
</div><h2>OK, that just sounds like voodoo!</h2><div>At first, it sure does. It was not until a study by Li et al published in <i>Basic Research in Cardiology-July 2014</i> that the likely mechanism was elucidated.<i> </i> Li et al used a mouse model of cardiac infarction and applied four 5-minute episodes of limb ischemia. The found that the circulating amount of a microRNA substance named miR-144 was more than doubled in the RIC mice and that these mice had greatly decreased infarct size. They then showed that application of synthetic miR-144 to mice with an infarction reduced infarction size without RIC. To top it off, they also showed that if they administered a microRNA molecule that would deactivate miR-144, RIC did not decrease infarct size. Other studies have suggested the mechanism of miR-144's protective effects. miR-144 serves as a repressive transcription factor that binds to the 3' side of certain mRNA and prevents that mRNA from being transcribed into proteins by the ribosomes. The proteins that the now deactivated mRNA would have created are largely responsible for the cell damage that occurs in response to sudden reperfusion of ischemic tissues. </div><div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmHeyrq9mSxOWwgBTG7IHo5uviIKsvcGrupki_0reWUsW1xmadam_dL6vXlcWXRA8kHv7y8qZ1yQJQ40jtREzKMj3ZGEehCMgWkODTXkf1tKf9iqWye6-o8MWJ4WHBo8g1yVeKZ3qDQG8/s1600/img235.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmHeyrq9mSxOWwgBTG7IHo5uviIKsvcGrupki_0reWUsW1xmadam_dL6vXlcWXRA8kHv7y8qZ1yQJQ40jtREzKMj3ZGEehCMgWkODTXkf1tKf9iqWye6-o8MWJ4WHBo8g1yVeKZ3qDQG8/s1600/img235.jpg" height="305" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adam, <i>JYI-2005</i></td></tr>
</tbody></table><br />
</div><h2>Yeah, but I treat very few mouse STEMIs on my ambulance...</h2><div>Luckily RIC as been being studied in human patients for several years now. We shall focus on the studies that are most applicable to ambulance practice, i.e. STEMI patients undergoing percutaneous coronary interventions (PCI). These are unique patients with regard to RIC because they have an occluded coronary artery that is (hopefully) going to be stented open within the next hour. We have the opportunity to intervene in the time before reperfusion injury can occur. The hypothesis of these studies is that, by applying RIC, we can increase the circulating miR-144 concentration before any reperfusion injury can occur. That way, once the artery is reopened in the cath lab, the miR-144 can decrease reperfusion injury by preventing protein-mediated cell damage.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuna285jxFffHk5SpMq94UScBg-w7lArFPLR7P7QWz6gYl1CiZoo153ie3NSDECNiDa4pMS8WQeQOnhNWybmV38t04kiaYkak5SNIeA0PzKi8hMtPG6mFWZqaHyUnzDXTigLx8VVlo3dg/s1600/RIC.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuna285jxFffHk5SpMq94UScBg-w7lArFPLR7P7QWz6gYl1CiZoo153ie3NSDECNiDa4pMS8WQeQOnhNWybmV38t04kiaYkak5SNIeA0PzKi8hMtPG6mFWZqaHyUnzDXTigLx8VVlo3dg/s1600/RIC.png" height="444" width="640" /></a></div><br />
<h2>But does it work?</h2></div><div>The first study to examine is Rentoukas et al published in <i>JACC: Cardiovascular Interventions-2010</i><br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRHsSBtHVzKkWEXKtOgLTfPoPIanC88KBqm5ssmKpzN3Dnfz4qcWxYZ-9LHy-Ze3FccXLbat4R5bz588MmeRxGrCGIL-SnoqAa2lQlD-2AhAuGuzlQtWgivT3qGAlO7vT683oYmIfmqe8/s1600/Screen+Shot+2015-01-06+at+7.16.31+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRHsSBtHVzKkWEXKtOgLTfPoPIanC88KBqm5ssmKpzN3Dnfz4qcWxYZ-9LHy-Ze3FccXLbat4R5bz588MmeRxGrCGIL-SnoqAa2lQlD-2AhAuGuzlQtWgivT3qGAlO7vT683oYmIfmqe8/s1600/Screen+Shot+2015-01-06+at+7.16.31+PM.png" height="640" width="483" /></a></div><div class="separator" style="clear: both; text-align: left;">These authors took 96 patients with STEMI, aged 35-75, symptom onset within 6 hours and who did not have renal failure. They randomly assigned three groups, one who got RIC before and during PCI, one that got RIC before and during PCI plus morphine infusion and a control group who received standard care per the institution. This study is unique in that it is a blinded trial. The investigators put cuffs on the non RIC patients but inflated them to 20mmHg below arterial pressure whereas the intervention group got cuffs inflated 20mmHg above arterial flow. Table 1 shows a well balanced cohort that did not differ in presenting prognostic factors or in-hospital treatment. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Table 2 here shows the primary outcome: the number of patients who had >80% resolution of ST elevation 30 minutes after PCI.</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizDGCJ3rEqklNU5ab7kUyIIyQ_hwxjilE_JSoz6J2CD59qn2KjVLENGcDvgmzi6eOSSR-I1qpbqnJnJhGflihdWA0y2C1QpMP10XOCQZ2HvXMZcuEixP9aq2BYhnu6fFhy5XYYrnQtDOg/s1600/Screen+Shot+2015-01-06+at+8.06.12+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizDGCJ3rEqklNU5ab7kUyIIyQ_hwxjilE_JSoz6J2CD59qn2KjVLENGcDvgmzi6eOSSR-I1qpbqnJnJhGflihdWA0y2C1QpMP10XOCQZ2HvXMZcuEixP9aq2BYhnu6fFhy5XYYrnQtDOg/s1600/Screen+Shot+2015-01-06+at+8.06.12+PM.png" height="400" width="310" /></a></div><div class="separator" style="clear: both; text-align: left;">These authors also measured differences in peak troponin concentration. Average peak troponins were 255.5 ng/ml in control group, 166.0 ng/ml in the RIC group and 103.3 ng/ml in the RIC + Morphine group. While both peak troponin concentration and ST elevation resolution after PCI have been associated with better outcomes after MI, this study did not focus on any patient oriented outcomes. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Botker et al in <i>Lancet 2010</i> used advanced myocardial imaging to asses the area of myocardium at risk from a current STEMI and randomized these patients to RIC starting in the ambulance or usual care. The cohorts were well balanced except for more patients with hypertension in the RIC group. They found the RIC, started in the ambulance, increased the amount of at risk myocardial salvaged by the PCI. Their results also correlated with the hypothetical mechanism, as they found no benefit of the RIC in patients found without a full coronary artery occlusion. Their study suffered from small numbers of patients enrolled as they excluded more than half of the patients initially enrolled in the trial. Overall, this trial was underwhelming but it did offer a glimpse of RIC benefit. It also demonstrates the feasibility of applying RIC to STEMI patients in the ambulance. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Finally, we come to Sloth et al from <i>European Heart Journal 2013</i> who finally addressed both ambulance based RIC and patient oriented outcomes. Sloth et al randomized 333 STEMI patients to ambulance initiated RIC or standard care. They not only measured outcomes from the acute event but also observed the patients for Major Adverse Cardiovascular and Cerebrovascular Events (MACCE) for up to three years after their STEMI. They included all-cause mortality, readmission for heart failure, and ischemic stroke/TIA as MACCE. They found a decrease in MACCE and all cause mortality at 3.4 years. In the per-protocol analysis MACCE decreased from 25.6% in the control group to 13.5% in the RIC group. This result (thankfully) remained statistically significant in the intention-to-treat analysis. </div><br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgF_PRO61uYxNdQR74ylcyEH4njPOBCYPlPVpVij06_lFdcLKKWSzQgDQ8INGDhzoUEs0I3fkcWLp5wvAsr1QTfAlDP-9VhvtV9m6qx1SDNwdzveccOq51g9-QBG9DyBKMi_kjDT0QYHEg/s1600/photo.PNG-11.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgF_PRO61uYxNdQR74ylcyEH4njPOBCYPlPVpVij06_lFdcLKKWSzQgDQ8INGDhzoUEs0I3fkcWLp5wvAsr1QTfAlDP-9VhvtV9m6qx1SDNwdzveccOq51g9-QBG9DyBKMi_kjDT0QYHEg/s1600/photo.PNG-11.jpeg" height="315" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6Gk1K9wpUNYLvmw4K-iBzkyrCauFRDA6rJxlzFh8Lrbi28PAQSoRyhpAOyeNn620pLDPuk8iEF3o_UR2-uLKq9WhAonmdDqjKvmK8VtPfyPIRcYOikEFkbLndZst_J-X7UvhLjIU_UlE/s1600/photo.PNG-10.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6Gk1K9wpUNYLvmw4K-iBzkyrCauFRDA6rJxlzFh8Lrbi28PAQSoRyhpAOyeNn620pLDPuk8iEF3o_UR2-uLKq9WhAonmdDqjKvmK8VtPfyPIRcYOikEFkbLndZst_J-X7UvhLjIU_UlE/s1600/photo.PNG-10.jpeg" height="572" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Further, the cumulative incidence curves remained significantly separated until the end of the follow up period. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><h2>So what now?</h2></div><div>Well, it bears repeating that these studies are generally small. They cannot be said to be conclusive proof that RIC is undoubtedly beneficial. It is however important to consider the balance of cost, benefit and harm when considering adopting an intervention into clinical practice. To that end there is significant data to support the idea that RIC could be profoundly beneficial to STEMI patients when applied in the ambulance before PCI. It also bears mention that there have been no reports of any adverse events related to application of this therapy. Further since neither cost nor technical difficulty stand in the way of applying RIC to the next STEMI patient on the ambulance, it seems to me unethical to deprive that patient a therapy which may potentially extend their life and increase their health. After all if you could have less MACCE years after your STEMI just by having a BP cuff inflated a couple times on your arm wouldn't you want RIC?</div><h2>Next steps...</h2><div>It is always important to have organizational buy-in before incorporating a new intervention into practice. This not only allows an intervention to benefit all patients the organization treats but also allows the outcomes of the intervention to be measured and documented. Read through the data and if RIC seems like it could benefit your patients consider bringing it to you medical director. </div><div><br />
</div><h3>Finally...</h3><div>Huge thanks to Graham Nichol (@grahamnichol) and the EDECMO podcast guys (@EDECMO) for introducing me to this topic. </div><div>They have an excellent discussion of applying RIC to other ischemic conditions including cardiac arrest that can be found <a href="http://edecmo.org/edecmo-xx-limiting-post-arrest-ischemia-reperfusion-injury-graham-nichol/">Here</a>. Hopefully larger trials that are currently underway will support expanding the indications of RIC into these areas. </div><div><br />
</div><h2>Further Reading...</h2><div><a href="http://eurheartj.oxfordjournals.org/content/35/3/138">Editorial discussing Sloth et al</a></div><div><br />
</div><div><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CC8QFjAB&url=http%3A%2F%2Fwww.nihstrokenet.org%2Fdocs%2Fdefault-source%2Fpresentations%2Fpicasso_121014_final.pptx%3Fsfvrsn%3D2&ei=hZWtVLnqCIufyQTPj4DACA&usg=AFQjCNGPEaXpVhWPUl75KTJbgs9vEZTq5Q&sig2=q-wWtr2yfYHZQsHIB_TFhw&bvm=bv.83134100,d.aWw">PPt discussing trial of RIC in stroke</a></div><div><br />
</div><div><a href="http://www.jems.com/article/patient-care/remote-ischemic-conditioning-during-myoc">JEMS article discussing RIC</a></div><div><br />
</div><div><a href="https://www.clinicaltrials.gov/ct2/show/NCT01857414">Largest efficacy trial to date underway in Denmark</a></div><div><br />
</div><br />
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com4tag:blogger.com,1999:blog-6454810765258132900.post-88059911152995812222015-01-25T12:04:00.000-07:002015-02-19T21:28:18.000-07:00Airway Management during Cardiac Arrest<div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><br />
</div>Recently, whatever small corner of the #FOAMems twitter-vers that I inhabit has been ablaze concerning OHCA airway issues and data interpretation.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrBxzb7hGsP66I8GimYv1TBanqloR8uTWDdNpjt4b9ATSk-fKzhSD3r2Rr-ZqbW7Qv7CSHXwH2pZFEBFGxAZRUIiHMhajtGteJmqAai8X0V6YV_O0gGRij7suedNmDP9J6QS6pmCRFp4M/s1600/photo.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrBxzb7hGsP66I8GimYv1TBanqloR8uTWDdNpjt4b9ATSk-fKzhSD3r2Rr-ZqbW7Qv7CSHXwH2pZFEBFGxAZRUIiHMhajtGteJmqAai8X0V6YV_O0gGRij7suedNmDP9J6QS6pmCRFp4M/s1600/photo.PNG" height="400" width="300" /></a></div>As I had been meaning to do a post on the topic for some time, I moved up the posting schedule here at <i><b>A Medic's Medicine</b></i> to hopefully inform the debate a bit and provide a venue for discourse in greater than 140 characters.<br />
<h2>Airway Management during Out of Hospital Cardiac Arrest</h2><div class="separator" style="clear: both; text-align: center;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhbdQvYCeA4Y_L5oWNjh-l0iMsGAA8Z87R3G0st84CG_8kS6iQzF3GUvZ7QovjMo_5GDqZw8TUX6FSPoWdihnxjthh3_Pt6dUk4SkAtz-9_3FEchyphenhyphenzPleYJ_CDfRJ5wfOZVfydJUam_vw/s1600/what+would+you+do.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhbdQvYCeA4Y_L5oWNjh-l0iMsGAA8Z87R3G0st84CG_8kS6iQzF3GUvZ7QovjMo_5GDqZw8TUX6FSPoWdihnxjthh3_Pt6dUk4SkAtz-9_3FEchyphenhyphenzPleYJ_CDfRJ5wfOZVfydJUam_vw/s1600/what+would+you+do.jpg" height="252" width="400" /></a></div><br />
<br />
Strategies for managing the airway during an out of hospital cardiac arrest (OHCA) vary between country, agency, even paramedic. In the US, endotracheal intubation (ETI) has been the standard approach to most patients in need of advanced airway management since the 1970s. Since the early 1980s however, the popularity of supraglottic airways (SGAs) has increased in prehospital care as "rescue airways" to be used in the event of unsuccessful intubation attempts. Eventually, some providers and some agencies started using supraglottic airways as a primary means of airway control in cardiac arrest. As the popularity of supraglottic airways increased, researchers started trying to determine whether one strategy was superior to the other. During these studies some investigators noticed that OHCA patients treated with ventilations from BVM without advanced airway devices seemed to have better outcomes than either intubation or supraglottic airways. This observation has caused some assertions that BLS airway techniques are superior to SGA or ETI for OHCA. This in turn fueled popular opinions among paramedics that blind insertion of SGAs was a better strategy than ETI during OHCA. We shall discuss a handful of the largest trials concerning these three airway strategies to determine if they can inform our practice. By critiquing each study in chronological order we can understand the overall direction of the literature and make informed decisions concerning our care.<br />
<span style="font-size: x-small;">*We will not be discussing Cady et al because they compared ETI specifically to the now obsolete Combitube (they found no difference), nor will we be discussing Rabitsch et al because they studied a european physician led ambulance system (also found no difference)</span><br />
<div><h3>Before we begin...</h3><div>Before looking at the human studies I would encourage everyone to look both at this study from <i>Resuscitation 2012, </i>and the following podcast from <i>Emergency Medicine Ireland.</i><br />
<div class="separator" style="clear: both; font-style: italic; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghuTJE62i618jvO5wroACvL04oL4q4FB5NuDPBJGxITPU-VHC6CvfG3D7rs3yhNY8BTx6rpqDZ1fHKjP70aSlefgiltv4pDREU9-_pTe8oCASNURirauz8s_oq-_ldY47tVFrcxwXr4-M/s1600/Screen+Shot+2015-01-25+at+11.16.31+AM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghuTJE62i618jvO5wroACvL04oL4q4FB5NuDPBJGxITPU-VHC6CvfG3D7rs3yhNY8BTx6rpqDZ1fHKjP70aSlefgiltv4pDREU9-_pTe8oCASNURirauz8s_oq-_ldY47tVFrcxwXr4-M/s1600/Screen+Shot+2015-01-25+at+11.16.31+AM.png" height="298" width="640" /></a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Segal et al demonstrate why there is reason to hypothesize that SGAs might cause issues concerning cerebral blood flow during OHCA. They generated many worrisome graphs such as this. </div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZxnoDcesGyFUH4AXEzfIqjpuSswnQ4dZ4KGsjelDt5ZHuzBsDsY1IbyGRX9oDQYY9E0VGvfzuSQhC_aDQtdkUzbJO4lI3P4atIT-UaAGDRV54DqEmsKpiVeL1LMnESJ7dyOEd0n6iEM8/s1600/0.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZxnoDcesGyFUH4AXEzfIqjpuSswnQ4dZ4KGsjelDt5ZHuzBsDsY1IbyGRX9oDQYY9E0VGvfzuSQhC_aDQtdkUzbJO4lI3P4atIT-UaAGDRV54DqEmsKpiVeL1LMnESJ7dyOEd0n6iEM8/s1600/0.jpeg" height="472" width="640" /></a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div><div class="separator" style="clear: both; text-align: left;">Dr. Andy Neil put together an excellent Vodcast counterpoint that can be accessed <a href="http://emergencymedicineireland.com/2012/05/anatomy-for-emergency-medicine-16-the-lma-as-a-murder-weapon/" target="_blank">Here</a></div><div class="separator" style="clear: both; text-align: left;">Now that we have contemplated the basic science foundations of the debate we can move forward. </div></div><h2>On to the studies!</h2></div><div>In 2011 Shin et al<i> </i>published a propensity matched observational cohort study in <i>Resuscitation </i>that utilized the Korean national EMS database. Before describing the results of the study it is vital to understand the nature of the Korean EMS system. In Korea, OHCA is managed by a single tier system consisting of Level 1 and Level 2 providers. Level 2 providers are similar to EMT-Bs in our system whereas Level 1 providers seem to be paramedic equivalent. Despite the similarities in training levels, these providers have much less autonomy with regards to the management of OHCA than most American paramedics. Korean providers are not permitted to pronounce death in the field or to terminate rescuscitation efforts before transport to an ED. This means that the Korean system is predicated upon the idea that, sooner or later, every OHCA patient must be transported with ongoing rescuscitative efforts unless they achieve ROSC. They included both adult and pediatric patients and compared the outcomes of those treated with ETI, SGA or BVM. They specifically excluded patients with a non cardiac etiology of arrest. They also excluded patients who were not treated by Level 1 providers (i.e. treated by providers without ETI skills) and patients where no resuscitation was attempted upon arrival to ED (presumably obvious deaths for whom the Korean system prevented field termination). They tracked survival to ER admission (ROSC) and survival to hospital discharge. They did not evaluate the neurologic status of these survivors.<br />
<br />
They studied a final cohort of 5,278 patients. The vast majority (87.9%) were managed with BVM alone. 7.4% had an LMA placed and 4.7% underwent ETI. The overall survival to ER rate was 20.2% and their survival to discharge rate was 6.9%. ETI outperformed LMA in unadjusted ROSC (22.0% vs 20.5%), unadjusted survival to discharge (8% vs 5.6%), propensity score matched ROSC (22.2% vs 20.5%) and propensity score matched survival to discharge (8.1% vs 5.7%). Shin et al also compared BVM alone to ETI and BVM alone to LMA. In short there was no statistical difference in unadjusted or propensity matched outcomes for BVM vs ETI (though all point estimates favored ETI). In the BVM vs LMA comparisons, ROSC was less likely for LMA groups in both the unadjusted and propensity cohorts (unadjusted OR= 0.72 95%CI 0.54-0.95, propensity OR=0.72 95%CI 0.5-1.02) Survival to discharge was statistically significantly less in both adjusted and propensity LMA vs BVM cohorts (unadjusted OR=0.52 95%CI 0.32-0.85, propensity OR=0.45 95%CI 0.25-0.82). Shin et al did not directly compare ETI vs LMA and as such the line of reasoning was ETI=BVM, BVM>LMA therefore ETI>LMA? This lack of a direct comparison is certainly a weakness.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8e0no7NCdm7xq4I9x9jkj5RdzVX2SjVq6QpZRvn0QjTbEmUDPtaoJJEOIjiMSFS5lXg_aw4SYcKk1jYhC0aqQCX3XMM_2fJza3XKXnuEhJueSAxpAoOAMc-NK-Y2hm9HQsXQZl7NRKII/s1600/photo.PNG-13.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8e0no7NCdm7xq4I9x9jkj5RdzVX2SjVq6QpZRvn0QjTbEmUDPtaoJJEOIjiMSFS5lXg_aw4SYcKk1jYhC0aqQCX3XMM_2fJza3XKXnuEhJueSAxpAoOAMc-NK-Y2hm9HQsXQZl7NRKII/s1600/photo.PNG-13.jpeg" height="640" width="483" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tables 2 and 3 from Shin et al. </td></tr>
</tbody></table><br />
Next in 2011, Kajino et al<i> </i>published in <i>Critical Care</i> the first of three large Japanese observational cohort studies. They compared ETI vs LMA in all adult, <u>witnessed</u>, non-traumatic OHCA in Osaka from 1/1/2005 until 12/31/2008. In Japan SGAs have been used since 1991 but ETI was only introduced to a select few paramedic level prehospital providers in 2004. The primary outcome was Odds Ratio for Cerebral Performance Category 1-2 at 1 month after OHCA in ETI vs SGA airway management groups. <a href="http://www.fda.gov/ohrms/dockets/ac/05/briefing/2005-4100b1_03_CPC%20Scale.pdf" target="_blank">CPC explanation</a> They also subdivided patients into groups with <10mins or >10mins from collapse to airway placement and compared outcomes. During the study period 5,377 adult witnessed non-traumatic OHCA patients were treated with ETI or SGA. This group had a few important baseline imbalances. First, the ETI group was much more likely to receive Epinephrine than the SGA group (27% vs 6%). The ETI group was 2 years older (mean age for entire cohort was 72.5 years old). The SGA group had shorter collapse to airway placement times (2 mins faster) and collapse to hospital arrival times (3 mins faster). They found increased rates of prehospital ROSC and ROSC in the ED for ETI (16.6% vs 10.1% and 47.8% vs 44.4%, respectively) They found no difference between rates of CPC 1-2 at 1 month after OHCA (3.6% in both groups).<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNM8_u9diedQEUFfRcX8e8_mwBp7C4Q4HdDuZjNvcWUZSJCQGVJ7K62MvY5_Zj22FFRGsr02oC09ysBFfxjOQy95q2-S0eGinrN628MHlKxwnFXkVPADeIpA0-PWMd66KOfLM_jD1DAgY/s1600/photo.PNG-14.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNM8_u9diedQEUFfRcX8e8_mwBp7C4Q4HdDuZjNvcWUZSJCQGVJ7K62MvY5_Zj22FFRGsr02oC09ysBFfxjOQy95q2-S0eGinrN628MHlKxwnFXkVPADeIpA0-PWMd66KOfLM_jD1DAgY/s1600/photo.PNG-14.jpeg" height="177" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Unadjusted outcomes from Kajino et al</td></tr>
</tbody></table><br />
Next, Wang et al in <i>Resuscitation 2012</i> published a secondary analysis of airway management from a prehospital RCT of impedance threshold devices. This was not a RCT of ETI vs LMA because the choice of airway management device was left to paramedic judgement but it does represent a high quality cohort in an practice setting representative of progressive EMS services in America. They included adult, non-traumatic cardiac arrest patients that received ETI or SGA (King Laryngeal Tube, LMA or Combitube). Their primary outcome was survival to hospital discharge with Modified Rankin Scale 3 or less. More on the mRS can be found <a href="http://www.strokecenter.org/wp-content/uploads/2011/08/modified_rankin.pdf" target="_blank">here</a> but, in short, a mRS of three is "moderate disability but able to walk without assistance". The included 24 hour survival and ROSC as secondary outcomes. They found 10,455 adult OHCA patients that received advanced airway management. 81.2% received ETI and 18.8% received SGA. Of the SGA insertions 63% were King LT, 20% were combitubes and 17% were LMAs. The average age of the cohort was 63.3 years old. Survival to discharge with mRS less than three was 4.7% in the ETI group and 3.9% in the SGA group. This was statistically significant with an OR of 1.40 for the ETI group (95%CI 1.04-1.89. The ORs for 24 hour survival and ROSC were also better for ETI at 1.74 and 1.78 respectively. They found no difference in airway or pulmonary complication rates between ETI and SGA groups.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyFXwCbZTMn4_UYTKZFIXbInz4l8dBLhD5tzzYju3yiqeW0iFp2609ZhnqLFFxMNwRBgONNAllSkDUSNgOAASoY2nS12KSHoEBmm4Q3bwJEesVmBHG3VeAuUxa8H3kxRMLwnMbquyj6rg/s1600/photo.PNG-15.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyFXwCbZTMn4_UYTKZFIXbInz4l8dBLhD5tzzYju3yiqeW0iFp2609ZhnqLFFxMNwRBgONNAllSkDUSNgOAASoY2nS12KSHoEBmm4Q3bwJEesVmBHG3VeAuUxa8H3kxRMLwnMbquyj6rg/s1600/photo.PNG-15.jpeg" height="378" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">In a cohort of patients treated by high performing US EMS agencies, ETI significantly outperformed SGA.</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"><br />
</div><br />
In 2013 Tanabe et al published a nationwide OHCA registry study in <i>Journal of Emergency Medicine</i>. Their population included all patients age >15 that presented in cardiac arrest in Japan between 1/1/2005 and 12/31/2007. They compared the rates of survival with CPC 1-2 at one month between ETI, LMA and Esophageal Obturator Airway groups. (They included as "EOAs" any device that occluded the esophagus including the combitube, King Laryngeal Tube and the now obsolete original EOA) They also included rates of prehospital ROSC and survival at 1 month as secondary outcomes. Their Table 1 illustrates some important baseline imbalances within the groups. First, the ETI group was much more likely to receive Epi. The ETI group was also less likely to have suffered an arrest deemed to be primarily cardiac in nature and more likely to have arrest secondary to "exogenous causes" such as trauma, toxicologic causes, etc. The overall age of the cohort was similar to Kajino et al at 72.3 years old.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoEOoV7ZfwO9IB2ncEliS9uXm3pYXXBk69Ntwt6l4V_uIDBudCw8_at2zHo2q4ehYgQzFTQbqm2u0VPwdetpAdU4Lpm67FK-SgRM1sCIQwXy5uhPuzOjx1VDNAgurxL5G9BLNIXz9iCxU/s1600/photo.PNG-17.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoEOoV7ZfwO9IB2ncEliS9uXm3pYXXBk69Ntwt6l4V_uIDBudCw8_at2zHo2q4ehYgQzFTQbqm2u0VPwdetpAdU4Lpm67FK-SgRM1sCIQwXy5uhPuzOjx1VDNAgurxL5G9BLNIXz9iCxU/s1600/photo.PNG-17.jpeg" height="379" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">There are many baseline differences in Tanabe et al.</td></tr>
</tbody></table>Before adjustments the CPC 1-2 survival in the ETI, LMA and EOA groups were similar at 1.14%, 0.98% and 1.04% respectively. After adjusting for confounders they found significantly increased CPC 1-2 survival at 1 month in the ETI group. The adjusted ORs for the LMA and EOA groups were 0.77 and 0.81. Neither 95% CI crossed one. The odds ratios for survival at one month and prehospital ROSC were significantly decreased in the LMA and EOA groups in both adjusted and unadjusted cohorts.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhg56yabzvzDTUdU7JGMh2HLHHwTsRId7cqDc9hrXXaUP1WyIxioD4JMqCsbvlzz1pIYJ4mlDpy937YKZYecXIaceC1VkD61anLMuusupRp0evJhrfIysgt9a5A4pOghK-lWSbT0OgMABU/s1600/photo.PNG-16.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhg56yabzvzDTUdU7JGMh2HLHHwTsRId7cqDc9hrXXaUP1WyIxioD4JMqCsbvlzz1pIYJ4mlDpy937YKZYecXIaceC1VkD61anLMuusupRp0evJhrfIysgt9a5A4pOghK-lWSbT0OgMABU/s1600/photo.PNG-16.jpeg" height="257" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Resulting Odds Ratios from Tanabe et al</td></tr>
</tbody></table><br />
Also in 2013, Hasegawa et al published a further nationwide Japanese cohort in<b> </b><i>JAMA</i>. Their cohort included all OHCA patients aged >18 from 2005 to 2010. Like Tanabe they included all cardiac arrest etiologies including trauma, tox, respiratory, malignancies etc. They compared rates of CPC 1-2 survival at one month between groups that received no advanced airway management, ETI or SGA. Their final cohort was truly huge at 649,359 patients. 56.7% had BVM airway management alone. 6.5% had ETI and 36.9% had SGA placement. They found a 2.9% rate of CPC 1-2 at one month for BVM alone patients, 1.0% for ETI and 1.1% in the SGA placement group. The rates of ROSC and one month survival were better for ETI than LMA in both adjusted and unadjusted analyses.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiip6vlFh9ejhl5rkVLgEO6MwZK2kiul5jdc5ArxyFsjG-96lYM0nwAsUhZPItTTZQIcWZ1NhlKTAhGbEIykw4QbfQZdVJrnpxdhsTd_RmqnGi_AWcw7wgRQ0834LAgnHly2ZsAF40v2Qo/s1600/photo.PNG-18.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiip6vlFh9ejhl5rkVLgEO6MwZK2kiul5jdc5ArxyFsjG-96lYM0nwAsUhZPItTTZQIcWZ1NhlKTAhGbEIykw4QbfQZdVJrnpxdhsTd_RmqnGi_AWcw7wgRQ0834LAgnHly2ZsAF40v2Qo/s1600/photo.PNG-18.jpeg" height="520" width="640" /></a></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><br />
Finally, McMullan et al published results of airway management during cardiac arrest from the ongoing CARES registry in <i>Resuscitation 2014</i>. They compared all OHCA patients age >18 who received BVM only, ETI or SGA. Their primary outcome was CPC 1-2 survival at hospital discharge. They also reported rates of ROSC, survival to admission and survival to discharge. They obtained a cohort of 10,691 patients. 52% received ETI, 29% received SGA (25.8% of which was the King LT) and 18% received BVM alone. The average age was 65 years old.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTMm4Bdjm-qsOQWpEA6GBQHtCtkd3SAwoMz-8QUkAS7q5E5yxid-WLQ-i4Q__n1GhsbUowr7lHaQTsPc56k3iBnLYD5xRv2ch5pM7M7j6y1NhVxIwW7Ekyvm-LMDIsj80hyphenhyphenyzlzDUN6j0/s1600/photo+1.PNG.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTMm4Bdjm-qsOQWpEA6GBQHtCtkd3SAwoMz-8QUkAS7q5E5yxid-WLQ-i4Q__n1GhsbUowr7lHaQTsPc56k3iBnLYD5xRv2ch5pM7M7j6y1NhVxIwW7Ekyvm-LMDIsj80hyphenhyphenyzlzDUN6j0/s1600/photo+1.PNG.jpeg" height="578" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">While the BLS vs ALS airway groups are grossly imbalanced, this is a rather nicely balanced comparison of ETI vs SGA.</td></tr>
</tbody></table>Like Hasegawa et al, these authors found that patients receiving BVM alone were much more likely to have favorable outcomes. Unadjusted CPC 1-2 at discharge was 5.4% for ETI and 5.2% for SGA. The ORs for ETI were consistently better than for SGA across ROSC, survival to admission, survival to discharge and survival with CPC 1-2.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4NTEUlQUAmJajWbFjIMaEzF1oGHH1fAZor2HE_8RBZfbJg4fZutLoWv7dRCoeKnTL2G-1ZwI0d1OWSe3rCoepuILKEcFIZrl3xMT28QhwPPms53wCBKb3vntT8TKYW4S27A3lUhd3_BY/s1600/photo+2.PNG.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4NTEUlQUAmJajWbFjIMaEzF1oGHH1fAZor2HE_8RBZfbJg4fZutLoWv7dRCoeKnTL2G-1ZwI0d1OWSe3rCoepuILKEcFIZrl3xMT28QhwPPms53wCBKb3vntT8TKYW4S27A3lUhd3_BY/s1600/photo+2.PNG.jpeg" height="116" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Unadjusted outcome percentages</td></tr>
</tbody></table><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3ahCvwoOKj4Fn9licyh3AQCkg4SSzu0FFW10gkWbl3f_UQ-sENctyIX4JEYN7KS0evcCky1wNGdyGKpe_Fhrld1EFwqpW7PhyM-2gLP4DU0bWNittzi5Nifk0RFgf9AC04r9oNkzFdMI/s1600/photo.PNG-19.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3ahCvwoOKj4Fn9licyh3AQCkg4SSzu0FFW10gkWbl3f_UQ-sENctyIX4JEYN7KS0evcCky1wNGdyGKpe_Fhrld1EFwqpW7PhyM-2gLP4DU0bWNittzi5Nifk0RFgf9AC04r9oNkzFdMI/s1600/photo.PNG-19.jpeg" height="460" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Odds Ratios for outcomes comparing ETI to SGA</td></tr>
</tbody></table><br />
<h2>What does it all mean?</h2><div>Overall we have looked at seven observational studies that compared ETI to SGA. The results have favored ETI or been neutral in all 7. No study has found significant results indicating that SGAs are better than ETI for adult OHCA. The studies described here are all observational in nature and as such cannot definitively ascribe causation between an intervention and an outcome. That said there are several correlations that have proven consistent throughout. First, US cohorts correlated to supporting ETI vs SGA. This is important because the US cohorts are most externally valid to practice in the US (sorry international readers). The Japanese system differs from the US system in greater average OHCA age and in very low overall rates of neurologically favorable survival. Second, increased overall rates of neurolgically intact survival correlated to supporting ETI vs SGA. This makes both clinical and statistical sense. The cohorts with the highest survival likely had the highest quality EMS care and thus ETI was likely performed with excellent BLS resuscitation ongoing. Statistically, the cohorts with the greatest percentages of neuro intact survival had the greatest statistical power to observe any differenced between ETI and SGAs.<br />
<br />
<h2> Lets recap by looking at some graphs...</h2></div><div class="separator" style="clear: both; text-align: center;"><br />
</div><br />
Here we can see that the unadjusted percentage rates of ROSC as higher for ETI in each study that reported this measure. While it can be argued that ROSC is not a patient centered outcome, it can also be argued that since it is the most common of the outcome variables it inherently has the greatest statistical power to differentiate between ETI and SGA.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_Be6sdmErRiZUfD6vOvYYUDKyUwuMjtNN27rz6hJDjXyOE2JDeacFL4fTb-OlXz6H8oSefEluamwDZ00qJjQl6wqS7cM3KypVoK7Bvm0EcqQgLD9-uBE3o5nNCrnppIbjTxgkAr_BHOY/s1600/ROSC+percent.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_Be6sdmErRiZUfD6vOvYYUDKyUwuMjtNN27rz6hJDjXyOE2JDeacFL4fTb-OlXz6H8oSefEluamwDZ00qJjQl6wqS7cM3KypVoK7Bvm0EcqQgLD9-uBE3o5nNCrnppIbjTxgkAr_BHOY/s1600/ROSC+percent.png" height="374" width="640" /></a></td></tr>
<tr><td class="tr-caption">Unadjusted percentage of patients achieving ROSC<br />
<br />
</td></tr>
</tbody></table>Here we can see the unadjusted rates of neurologically intact survival. This is undoubtedly a patient oriented outcome. The differences shown in McMullan and Wang are both statistically significant.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXqEyK9tc1WeU7BGcxSaRf8mPbjsJcvnvumYNnT2odRInxxo-U2wUFV-W2PwXQmlJ1d7uhWjGioLc1JOSTQ48GSoj0TbbXNoVmSf9-MzI3x24dc82Zjd3rTiv0WDKBVpmpHKI62-juUHA/s1600/Neuro+percents.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXqEyK9tc1WeU7BGcxSaRf8mPbjsJcvnvumYNnT2odRInxxo-U2wUFV-W2PwXQmlJ1d7uhWjGioLc1JOSTQ48GSoj0TbbXNoVmSf9-MzI3x24dc82Zjd3rTiv0WDKBVpmpHKI62-juUHA/s1600/Neuro+percents.png" height="372" width="640" /></a></div><div style="text-align: left;"><br />
</div><div style="text-align: left;"><br />
</div><div style="text-align: left;">Finally here we can see the adjusted and propensity matched analyses for both ROSC and neurologically intact survival. These are expressed as odds ratios compared to 1. As is evident, all the analyses favor ETI except for Kajino which was a nonsignificant difference. The differences in favor of ETI in Wang and McMullan were significant. </div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9MD3eab39CE5MsvQY1pO-qYLr7dRjjMAscudIAQut-1fx3fvF6bQgMkbxE_auLuTRjySo4A8WrP0Z6Fs2GcZGs17wodkACow4WACZMX92d4rrPi6CXs-vHC4bDttmn7pI6NT8wttf1-c/s1600/Adjusted+ORs.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9MD3eab39CE5MsvQY1pO-qYLr7dRjjMAscudIAQut-1fx3fvF6bQgMkbxE_auLuTRjySo4A8WrP0Z6Fs2GcZGs17wodkACow4WACZMX92d4rrPi6CXs-vHC4bDttmn7pI6NT8wttf1-c/s1600/Adjusted+ORs.png" height="368" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adjusted odds ratios for ROSC and neurologically favorable survival. When both ratios are below 1 the study used BVM only as the comparator. *The Tanabe and Kajino differences here are non-significant.</td></tr>
</tbody></table><br />
<br />
<h2>So what about BLS airway?</h2>Many have pointed out the remarkably increased rates of favorable outcomes experienced by those patients treated with BVM alone. It is imperative to understand that these are not randomized control trials and as such cannot ascribe causation, only correlation. As such, because there must have been some reason why some patients received BLS only rather than ALS interventions, the skeptical mind enquires. We can see here from Hasegawa the likely explanation.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhStpE9uS5pP8FWh3fRogIyuPrt-lvkKVGUx9snIVmBjCoYzlqptLZPfP9Z5Mr1XDOUlqD2BOxnkNdZTPUiBtaS2mlWEz5qDyVEBUc0msqiUczoJeoyLCATqk3ANg2fthAD3LN540fjNAo/s1600/photo.PNG-12.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhStpE9uS5pP8FWh3fRogIyuPrt-lvkKVGUx9snIVmBjCoYzlqptLZPfP9Z5Mr1XDOUlqD2BOxnkNdZTPUiBtaS2mlWEz5qDyVEBUc0msqiUczoJeoyLCATqk3ANg2fthAD3LN540fjNAo/s1600/photo.PNG-12.jpeg" height="640" width="411" /></a></div><br />
If the advanced airway group that eventually achieves ROSC has a no flow+low flow time of 8+14 minutes (22 minutes) and the BVM group has a no flow+low flow time of 9+6 minutes (15 mins), who would you think did better? The odds ratios in favor of BVM only reflect the fact that the average patient in the BLS airway arm<b> <i>spent seven less minutes</i></b><i> </i><b><i>DEAD</i> </b>than the ALS airway arm. Here we see the weaknesses of observational trials and the need for a well conducted RCT. BVM only airway management is a <i style="font-weight: bold;">Prognostic factor!</i> None of the studies above that conducted adjustments or propensity scores mention balancing the collapse to ROSC time. Receiving BLS airway only means that the patient had some reason why the paramedic chose not to intubate them or place an SGA. This could be that the patient achieved ROSC before intubation. It could also mean that the patient still had brainstem reflexes impeding laryngoscopy. Whatever the reason it is impossible to adequately adjust a cohort or assign propensity scores to compare an outcome which in itself is a powerful prognostic factor. <br />
Imagine if you compared the outcomes between trauma patients that get a trauma alert called from EMS and trauma patients that did not get a trauma alert. Obviously, the trauma alert patients would look worse than the no alert patients because there was some serious sign or symptom that prompted EMS to declare a trauma alert in the first place. No matter how well you balance age, comorbidities, obesity, etc in a propensity model, the fact remains that your initial comparator has already implicitly stratified the observational cohort into sicker vs less sick patients.<br />
<br />
<h2>The Bottom Line</h2><div>We lack the necessary RCT to determine causal relationships between outcomes and airway management strategies in OHCA. There has been a theoretical concern voiced that the challenges of intubation can lead to decreased compression fraction and other CPR quality measures we know to be predictive of better outcomes. The data presented here illustrate that, regardless of CPR quality measures, ETI was consistently <i>correlated</i> with better outcomes than SGA. In modern US prehospital care, if you prioritize quality chest compressions, intubate during continuous CPR and use techniques such as those listed <a href="http://emcrit.org/podcasts/rich-levitan-airway-lecture/" target="_blank">here</a> to optimize first pass success, there is <i><b>no scientific data</b></i> to say that your patient would be better off with an SGA. <b><i>There is data</i></b> to suggest that your patient may be more likely to survive neurologically intact if you perform ETI in addition to high quality CPR. </div><div>In the end, EBM cannot make our decisions for us, nor should we expect it to. EBM exists to guide and inform our foundational leanings concerning the strengths and weaknesses of our treatments. There are circumstances where OHCA patients should receive SGA or BVM or ETI. EBM summaries, such as the preceding, exist to help us better assimilate the available evidence into the best possible treatment decisions for our patients. </div><h2>Further Reading</h2><div><a href="http://www.ems12lead.com/2014/06/20/pit-crew-cpr-the-explicit-details/" target="_blank">Pit Crew CPR from Tom at EMS 12Lead</a></div><div><br />
</div><div><a href="http://emcrit.org/podcasts/new-intra-arrest/" target="_blank">The one and only Scott Weingart on Intra-arrest management</a></div><div><br />
</div><div><a href="http://lifeinthefastlane.com/ccc/cardiac-arrest-literature-summaries/" target="_blank">Some other Cardiac Arrest lit summaries from LITFL</a></div><div><br />
</div><div><a href="http://shortcoatsinem.blogspot.com/2013/06/house-of-gods-law-3-revised.html" target="_blank">Pulse checks during CPR from ShortcoatsinEM</a></div><div><br />
</div><div><a href="http://vimeo.com/111483585" target="_blank">Own The Airway! R Levitan from SMACCGOLD</a></div><div><br />
</div><div><br />
</div><br />
</div><script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com0tag:blogger.com,1999:blog-6454810765258132900.post-55892668056923517602015-01-20T19:26:00.000-07:002015-02-19T21:27:33.964-07:00LMA shopping<h2>Comparison of two common laryngeal mask airways</h2><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhbMhndVhyphenhyphenuIOKxVB61D8Z1K_UF7_MhUSL8pnJkR6HvZOHkcOykokEpTWUIgVgCBE1rBTEtP6svIH8FSSyQLnCxYS9k3yCxBRwY3UM_T9jHlQtlzIGVypiEDAzA2BTa4LU1kfeUEBPd7o/s1600/2.15b-(LMA-supreme)_sm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhbMhndVhyphenhyphenuIOKxVB61D8Z1K_UF7_MhUSL8pnJkR6HvZOHkcOykokEpTWUIgVgCBE1rBTEtP6svIH8FSSyQLnCxYS9k3yCxBRwY3UM_T9jHlQtlzIGVypiEDAzA2BTa4LU1kfeUEBPd7o/s1600/2.15b-(LMA-supreme)_sm.jpg" height="266" width="400" /></a></div><h2 style="text-align: center;">VS </h2><div><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR7lOMeB6BU4Rbdk-dDNbVdDoRXLItuFDsiI9ZXRASnB9R7EhyphenhyphenE8b2VQIRW2jqRY1BEXuF7Nopup5IC_nfPkjFG_y1KPbUzGgM_0Ap4ffT8RFa3JLs_SHCYNGxXYejIR0eCSYPvy5lG3g/s1600/igel.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR7lOMeB6BU4Rbdk-dDNbVdDoRXLItuFDsiI9ZXRASnB9R7EhyphenhyphenE8b2VQIRW2jqRY1BEXuF7Nopup5IC_nfPkjFG_y1KPbUzGgM_0Ap4ffT8RFa3JLs_SHCYNGxXYejIR0eCSYPvy5lG3g/s1600/igel.jpg" height="240" width="400" /></a></div><h2 style="text-align: left;"></h2><h2 style="text-align: left;">The Impetus...</h2><div>Recently our service experienced a certain supply chain issue regarding our smallest sized rescue airway, the LMA unique. The issues was quickly resolved but it spurred us to take a fresh look at our airway devices. This review was especially timely as the state of New Mexico EMS bureau (in their infinite wisdom) removed intubation from all prehospital care for patients less than 12 years old. Thus, our "rescue airway" had just become our only advanced airway option. It seems important to carefully evaluate such an important part of our airway toolkit. </div><div>* This will not be an exhaustive review of all extra/supraglottic airway devices. Further, it will not address the myriad simulation and manequin studies that have been published. It will focus on direct comparisons of two specific laryngeal mask type airways. </div><div><br />
</div><h2>Background</h2><div><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:Zoom>0</w:Zoom> <w:TrackMoves>false</w:TrackMoves> <w:TrackFormatting/> <w:PunctuationKerning/> <w:DrawingGridHorizontalSpacing>18 pt</w:DrawingGridHorizontalSpacing> <w:DrawingGridVerticalSpacing>18 pt</w:DrawingGridVerticalSpacing> <w:DisplayHorizontalDrawingGridEvery>0</w:DisplayHorizontalDrawingGridEvery> <w:DisplayVerticalDrawingGridEvery>0</w:DisplayVerticalDrawingGridEvery> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:DontGrowAutofit/> <w:DontAutofitConstrainedTables/> <w:DontVertAlignInTxbx/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="276"> </w:LatentStyles> </xml><![endif]--> <!--[if gte mso 10]> <style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin:0in;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:"Times New Roman";
mso-ascii-font-family:Helvetica;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:"Times New Roman";
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Helvetica;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
</style> <![endif]--> <!--StartFragment--> <br />
<div class="Body"><span style="font-family: inherit;">Extraglottic airways in many forms have been widely used, first in the anesthesias setting, and later in prehospital emergency care since the late 1970s. Originally the Esophageal Obturator Airway was marketed to prehospital providers as a way to improve BVM ventilations. The Esophageal Obturator airway decreased gastric insufflation by combining a standard BVM mask with an esophageal balloon. The EOA was gradually replaced by the combitube and then the LMA because they negated the need for the operator to maintain a mask seal. The first LMA insertion in a live patient was performed by the device's inventor, Dr. Archie Brain, in 1981. Since that time the LMA has become a mainstay of prehospital airway management both as a main airway tool for EMT level providers and as a "rescue" airway for providers with more advanced airway skills. </span></div><div class="Body"><span style="font-family: inherit;">The LMA can be thought of as a tube with a distal mask that seals, not to the mouth and nose, but to the glottic structures. The initial shape of the LMA-Classic (LMA-c) was based on plaster casts made by Dr. Brain on cadavers. Dr. Brain was reportedly required to compromise his desired shape for the LMA-c due to materials and production constraints. Nonetheless, the LMA-c rapidly became common in anesthesia practice. The LMA-c is still used in the setting of short operations, supine patient positioning, normal glottic anatomy, non-morbid obesity and absent lung pathology. </span></div><div class="Body"><span style="font-family: inherit;">These uses influence the way the LMA has been tested and measured. Most studies evaluating LMAs are done in elective anesthesia patients who have been screened for potential conditions or situations where an LMA may be less effective. EMS usage is generally in unselected patients that are often obese, unfasted and who must be moved several times during the course of their prehospital care. This key difference in patient population is an important consideration when evaluating the external validity of anesthesia studies to the prehospital setting. A device that is well suited to OR practice may not perform as well for patients in the prehospital environment.</span><br />
<span style="font-family: inherit;">The LMA literature is complicated by a few quirks of nomenclature that we will here resolve before continuing. The first versions of the LMA were reusable and there are even second generation reusable LMAs. The original LMA created by Dr. Brain for reuse in the OR setting is known as the LMA-Classic. The LMA-Classic has a disposable counterpart known as the LMA-Unique. The second generation LMA created for reuse in the OR setting is called the LMA-Proseal. Its disposable counterpart is called the LMA-Supreme. While the Proseal and the Supreme do differ in materials, their design and specifications are extremely similar allowing extrapolation of LMA-Proseal data to practice with the LMA-Supreme. Following suit, other companies have begun manufacturing other "second generation" LMA type devices that seem to offer increased functionality over the LMA-Classic/Unique such as the I-Gel laryngeal mask airway.</span></div><div class="Body"><span style="font-family: inherit;"><span style="mso-spacerun: yes;"> The second generation LMA type devices (the LMA-Proseal, I-Gel and the LMA-Supreme) do differ significantly from the LMA-Classic/Unique. </span> These devices typically have a larger cuff that has a deeper cup shape, a thicker stem tube that better resists torsion and an integrated tube that permits gastric decompression. </span></div><span style="font-family: inherit;"> </span><span style="font-family: inherit;"> </span><span style="font-family: inherit;"> </span><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: center;"><tbody>
<tr><td style="text-align: center;"><span style="font-family: inherit;"></span><br />
</td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: inherit; font-size: small;"></span><br />
</td></tr>
</tbody></table><div class="Body"><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:Zoom>0</w:Zoom> <w:TrackMoves>false</w:TrackMoves> <w:TrackFormatting/> <w:PunctuationKerning/> <w:DrawingGridHorizontalSpacing>18 pt</w:DrawingGridHorizontalSpacing> <w:DrawingGridVerticalSpacing>18 pt</w:DrawingGridVerticalSpacing> <w:DisplayHorizontalDrawingGridEvery>0</w:DisplayHorizontalDrawingGridEvery> <w:DisplayVerticalDrawingGridEvery>0</w:DisplayVerticalDrawingGridEvery> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:DontGrowAutofit/> <w:DontAutofitConstrainedTables/> <w:DontVertAlignInTxbx/> </w:Compatibility> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="276"> </w:LatentStyles> </xml><![endif]--><span style="font-family: inherit;"> <!--[if gte mso 10]> <style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin:0in;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:"Times New Roman";
mso-ascii-font-family:Helvetica;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:"Times New Roman";
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Helvetica;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;}
</style> <![endif]--> <!--StartFragment--> The two second generation laryngeal mask devices that have been most robustly studied are the LMA-Supreme (LMA-S) and the I-Gel(IG). Both have oval stem tubes with integrated bite blocks and a gastric decompression port. The LMA-S has a reinforced leading tip that resists the tip-folding the LMA-C often suffered. The LMA-S cuff is also larger volume and raised on the proximal side to better seal the airway. </span></div><div class="Body"><span style="font-family: inherit;">The I-Gel has a thermal elastomer cuff that does not require inflation. It also has a raised proximal side that increases seal pressure and decreases down-folding of the epiglottis. Like the LMA-S, the I-Gel has a decompression port.</span></div><div class="Body"><span style="font-family: Times, 'Times New Roman', serif;"><br />
</span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="font-family: Times, "Times New Roman", serif; margin-left: 1em; margin-right: 1em; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ7a5uIxXG2sivAnd14GlVpU6e6wHHtFBUzsBbM5OOHK778PsK2cjyHkd90s-8Pq-Y0NVjAdAPw4FS-lBHsam_8YhY6j7834ZxzkiHPOiZyM3VweredA_Ju_TThhaWRXARWk3FVNKIXfE/s1600/AM910-700x700.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ7a5uIxXG2sivAnd14GlVpU6e6wHHtFBUzsBbM5OOHK778PsK2cjyHkd90s-8Pq-Y0NVjAdAPw4FS-lBHsam_8YhY6j7834ZxzkiHPOiZyM3VweredA_Ju_TThhaWRXARWk3FVNKIXfE/s1600/AM910-700x700.jpg" height="320" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;">LMA-C (Unique) Note the tip is part of the balloon. This creates a propensity for folding during placement and subsequent malpositioning. </td></tr>
</tbody></table><div class="Body"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR7lOMeB6BU4Rbdk-dDNbVdDoRXLItuFDsiI9ZXRASnB9R7EhyphenhyphenE8b2VQIRW2jqRY1BEXuF7Nopup5IC_nfPkjFG_y1KPbUzGgM_0Ap4ffT8RFa3JLs_SHCYNGxXYejIR0eCSYPvy5lG3g/s1600/igel.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR7lOMeB6BU4Rbdk-dDNbVdDoRXLItuFDsiI9ZXRASnB9R7EhyphenhyphenE8b2VQIRW2jqRY1BEXuF7Nopup5IC_nfPkjFG_y1KPbUzGgM_0Ap4ffT8RFa3JLs_SHCYNGxXYejIR0eCSYPvy5lG3g/s1600/igel.jpg" height="192" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The I-Gel has a bite block, suction tube and soft gel cuff.</td></tr>
</tbody></table><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW2N-seH1H2urHndVlqrAtpSNqLS2pXxBocnP2Z0_VxVd3TTJQgpMF7maMeMEXOaGYcNgSxUWLnjeWlWeBI7ncf5Mdx_Z9gsxJXiJHLcdquREphjOO5gFbuL0BgaXznTCVSVe56zjiNOc/s1600/LMA+North+America_LMA+Supreme_2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW2N-seH1H2urHndVlqrAtpSNqLS2pXxBocnP2Z0_VxVd3TTJQgpMF7maMeMEXOaGYcNgSxUWLnjeWlWeBI7ncf5Mdx_Z9gsxJXiJHLcdquREphjOO5gFbuL0BgaXznTCVSVe56zjiNOc/s1600/LMA+North+America_LMA+Supreme_2.jpg" height="295" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The LMA-Supreme. The tip is reinforced to prevent folding, there is an integrated bite block and a gastric decompression tube.</td></tr>
</tbody></table></span></span></div><div class="separator" style="clear: both; text-align: center;"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;"><br />
</span></span></div><h2 style="text-align: left;"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;">LMA-S vs I-Gel comparison papers</span></span></h2><div style="text-align: left;"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;">The first paper consider on our LMA vs I-Gel journey is Chen et al from <i>PLoS-1</i> in 2013 titled</span></span></div><div style="text-align: left;"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;"><br />
</span></span> <br />
<div class="separator" style="clear: both; text-align: center;"><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7HHB9r14CIdJwcb2FBVOrfIjGgavW3dNnxO2Xk2GUAQ2Rhsg1Ga4d_sA8gmlYK_4Lbljk5ZMFHkEGvzKPISucdN4fQzfhPBuuzp0V4U03E7kYxAeVLEKcLKMILAkOtMuJQj8DVgKZ4iI/s1600/Screen+Shot+2015-01-07+at+9.04.45+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7HHB9r14CIdJwcb2FBVOrfIjGgavW3dNnxO2Xk2GUAQ2Rhsg1Ga4d_sA8gmlYK_4Lbljk5ZMFHkEGvzKPISucdN4fQzfhPBuuzp0V4U03E7kYxAeVLEKcLKMILAkOtMuJQj8DVgKZ4iI/s1600/Screen+Shot+2015-01-07+at+9.04.45+PM.png" height="99" width="640" /></a></span></span></div><span style="font-family: Times, Times New Roman, serif;"><span style="font-size: small;"> </span></span></div><br />
This paper was a reasonably well conducted systematic review/meta-analysis. They utilized a broad search strategy and validated systems to asses the quality of the included studies. They Identified ten RCTs that compared the LMA-S and the I-Gel in adult anesthesia settings. </div><div style="clear: both;">Patients were paralyzed in two of the ten studies. The authors evaluated 7 comparator variables listed here.</div><div style="clear: both;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGf9T3ab4wyQmEwl0_UuFrdvbh3UIEbOieUW3_HLubN20PCjtTM-SbxD2nAgFUr3GkexfixWz4FWo4gpHrB4o8KKdxrMs3zHoPBI5XWCLlYN7sqQufJPSpr0ESK0bq_K2bmBpW3fihyPs/s640/blogger-image-460802584.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGf9T3ab4wyQmEwl0_UuFrdvbh3UIEbOieUW3_HLubN20PCjtTM-SbxD2nAgFUr3GkexfixWz4FWo4gpHrB4o8KKdxrMs3zHoPBI5XWCLlYN7sqQufJPSpr0ESK0bq_K2bmBpW3fihyPs/s640/blogger-image-460802584.jpg" /></a></div>As is evident from the I-squared statistic, 4 of the 7 variables had significant heterogeneity. Heterogeneity refers to the degree of variation in the results found in the individual trials before meta-analysis. The greater the variation, the less reliable the conclusions of the meta-analysis may be. The I-squared statistic is a way to quantify this degree of variation. As the heterogeneity increases, the value of I-squared increases. </div>For the unfamiliar, a summary of the I-squared measure of heterogeneity can be found <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC192859/" target="_blank">here</a>. <br />
<br />
The authors found no significant differences in leak pressures, insertion time, first attempt success rates, fiber optic view or blood on device after removal. They did find that passage of a gastric tube was easier with the LMA-S and that post op sore throat was less common with the I-Gel.<br />
<br />
Their funnel plot did not show evidence of publication bias. This is very reassuring given the industry sponsorship in several of these trials. <a href="http://en.wikipedia.org/wiki/Funnel_plot" target="_blank">More on Funnel Plots</a> <br />
<br />
In the end, Chen et al seems to indicate that in the controlled setting of the OR, in which the patients are carefully selected for management with a supraglottic airway, the differences between the LMA-S and I-Gel are likely small and confined to less important characteristics. <br />
<br />
Since Chen et al there have been two comparison studies published. The first was Joly et al in <em>Canadian Journal of Anesthesia-2013.</em> They randomized 100 ASA class I-III paralyzed anesthesia patients to I-Gel of LMA-S. They did exclude patients with risk factors for supraglottic airway failure such as GERD, unfasted, glottic distortion or BMI >35. In general agreement with Chen et al, they found an 92% overall success rate for both devices and no difference in leak pressures. Insertion of the LMA-S was on average 8 seconds faster than the I-Gel. <br />
<br />
The second study was Middleton et al from <em>Resuscitation-2014.</em> Middleton et al is both the best of times and the worst of times as they nearly ask the question we are most interested in but they were unable to recruit adequate numbers to power their study. They performed an unblinded RCT of the I-Gel vs a first generation LMA for out of hospital cardiac arrest. The devices were placed by Australian Paramedics (who seem to compare most closely to an EMT/AEMT in our system). The service was able to use their own internal airway registry to determine that, before the study, they had a 64% baseline LMA-c success rate. They planned a trial n=100 but in the end they could only recruit 51 patients. Despite this, they found a 57% success rate for the LMA and a 90% success rate for the I-Gel. The paramedics (EMTs) reported greater ease of insertion with the I-Gel. While this study does not compare the LMA-S to the I-Gel, it does teach us two things. First, it is likely that either second generation LMA device (LMA-S or I-Gel) is superior to the first generation devices. Second, in unselected patients undergoing CPR and possible transport in a prehospital environment, the overall success of even the second generation devices is likely only 9/10 or 90%. <br />
<br />
<h2>What about Pediatrics?</h2>The best RCT of the I-Gel vs the LMA-S in a pediatric setting was published a couple months ago by Kim et al in<em> Korean Journal of Anesthesiology-2014.</em><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKMt41SFLtwfzreQBdNbhbp-MsO4ZtL4_NiuL-xIburmVfUmXf_rRThZrN9kOOLdUY4dYmVb3b1xX242xP-NplelRm14P_5xZJ8sbxpHMZzJ4vauM3pp7QruJkZEcUhAC60d49OVaj1Sc/s1600/Screen+Shot+2015-01-10+at+9.14.38+AM.png" imageanchor="1" style="clear: left; display: inline !important; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKMt41SFLtwfzreQBdNbhbp-MsO4ZtL4_NiuL-xIburmVfUmXf_rRThZrN9kOOLdUY4dYmVb3b1xX242xP-NplelRm14P_5xZJ8sbxpHMZzJ4vauM3pp7QruJkZEcUhAC60d49OVaj1Sc/s1600/Screen+Shot+2015-01-10+at+9.14.38+AM.png" height="284" width="640" /></a><br />
This was a well done RCT comparing the two second generation airways in paralyzed children. The same caveats that we discussed regarding patient selection for trials in adult trials apply to an even greater extent in pediatric trials. These patients are highly selected and do not have critical illness or severe co-morbidities (ASA I-II). Similar to adult studies, Kim et al found no difference between the insertion success rates. While they did find statistically significant differences in leak pressure and time to insertion (I-gel was slower but higher leak pressure), these differences were not clinically significant. They did find a potentially important difference in the number of manipulations of the device required to maintain a seal during anesthesia. They found that the I-Gel required many more manipulations during use but nearly all of these manipulations were simply reseating the device back into the oropharynx.<br />
<br />
Before Kim et al, Saran et al and Lopez-Gil et al published these studies that seem to corroborate what we have already said about the I-Gel- vs LMA-S. Here are the abstracts for those interested.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2ouQg4ou8qBKlE3rS0bHv8-W7npthgXgDJIyZvefWeXmEc1ZxtkKpYgsBptGoWtaLLHhgKhCSFN6Lwuz-y1nr9KO9S0XZpQ50Pcdah8z3hAkZY-wtal4__rZ0d_9fsf6PZzErcPQmSq8/s1600/Screen+Shot+2015-01-10+at+9.12.33+AM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2ouQg4ou8qBKlE3rS0bHv8-W7npthgXgDJIyZvefWeXmEc1ZxtkKpYgsBptGoWtaLLHhgKhCSFN6Lwuz-y1nr9KO9S0XZpQ50Pcdah8z3hAkZY-wtal4__rZ0d_9fsf6PZzErcPQmSq8/s1600/Screen+Shot+2015-01-10+at+9.12.33+AM.png" height="262" width="640" /></a></div><h2><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjukReLPt_xQAtmR9AWbrcz7z1t16W2UviLp_eItkdYotEYH-DGpDmyIqino3ZZzqcAoj7GPoBW1245sH1mH0xMId1DEjgwoYZZKLx73aft24wlrWVOysniPBI1CNm8KFWfO97KutaH-mw/s1600/Screen+Shot+2015-01-10+at+9.10.26+AM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjukReLPt_xQAtmR9AWbrcz7z1t16W2UviLp_eItkdYotEYH-DGpDmyIqino3ZZzqcAoj7GPoBW1245sH1mH0xMId1DEjgwoYZZKLx73aft24wlrWVOysniPBI1CNm8KFWfO97KutaH-mw/s1600/Screen+Shot+2015-01-10+at+9.10.26+AM.png" height="322" width="640" /></a></div><br />
<br />
So now what?</h2>It would seem that the comparison of the I-Gel vs the LMA-S is one of those situations in Evidence Based Medicine where there is equipoise between the two alternatives. The extant literature does not indicate that there are important differences between the two devices. The choice between the two can be made according to organizational preference and cost. Each device has advantages and disadvantages and should be chosen, taught and trained with accordingly.<br />
<br />
<h2>Further Reading</h2><a href="http://www.tamingthesru.com/blog/ic-cordes/extraglotticdevices?rq=LMA" target="_blank">Here is a broader review of extra/supraglottic airways from the stellar folks at Taming the SRU</a><br />
<br />
<a href="http://www.i-gel.com/evidences" target="_blank">While clearly biased, this is the evidence page from the I-Gel manufacturer</a><br />
<br />
<a href="http://www.lmana.com/pwpcontrol.php?pwpID=6347" target="_blank">LMA-Supreme website</a><br />
<br />
<a href="http://www.scancrit.com/2012/04/27/supraglottic-airway-devices-cerebral-bloodflow/" target="_blank">Scancrit article concerning a controversy regarding LMA use in cardiac arrest</a><br />
<br />
<a href="http://emergencymedicineireland.com/2012/05/anatomy-for-emergency-medicine-16-the-lma-as-a-murder-weapon/" target="_blank">Andy Neil's well-presented reply to the controversy</a><br />
<br />
<br />
<h2> </h2><h2><!--EndFragment--></h2><div></div><script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-59917741-1', 'auto');
ga('send', 'pageview');
</script>Anonymoushttp://www.blogger.com/profile/05638300401004812309noreply@blogger.com0