Staten Island Corner: Pre-Hospital Endotracheal Intubation?

Welcome to this month’s edition of Staten Island Corner.  I was recently on EMS rotation so the inspiration for this month’s edition comes from an EMS topic.  I decided to look into the debate of whether endotracheal intubation is the best way to manage an airway in the pre-hospital setting.

It is no surprise that airway management is the number one priority for EMS providers as well as EM physicians.  It is also no surprise that the best way to definitely manage an airway is with an endotracheal tube via endotracheal intubation (ETI).  However, there has been debate recently in the literature as to whether ETI should be performed in the pre-hospital setting by non-physician EMS providers.  In North America, the majority of pre-hospital ETIs are performed by non-physicians  [1].  ETI is a dangerous procedure with a lot of inherent risks.  Some of the complications of an unsuccessful or poorly conducted ETI are esophageal intubation, hypoxemia, post-intubation cardiac arrest, or aggravation/creation of traumatic injuries  [1].

A recent study by Lossius et al. looked at the literature to see if there was a difference in ETI success rates between physician and non-physician manned EMS systems.  They also looked at whether there was a difference in the groups using drug assistance as well as paralytics.  The overall median of success rates for physicians vs. non-physicians was 0.991 vs. 0.849.  All of the physician manned groups had drugs available and used standard RSI, while only 73% of the non-physician group had drugs available and only a subset of those had paralytics available.  However, when comparing physicians to non-physicians who used paralytics, there was still a significant difference in median success rates favoring physicians (0.991 vs, 0.955).  This means that 5 in every 100 patients are now apneic and paralyzed without a definitive airway.  There are also reports of ETI failure rates of up to 15% in non-physician systems using paralytics  [1].  For obvious reasons, this is very dangerous and these numbers are unacceptable on an overall system basis.  The results of this article suggest that in non-physician EMS systems, the focus should possibly shift towards excellent basic airway management and other airway devices rather than ETI.  This article also brings to light the issue of whether or not medications should be used in pre-hospital ETI.  In the ED, RSI is the standard of care, but RSI has inherent risks with the worst risk of having a paralyzed patient that you cannot intubate and cannot ventilate.  With that being said, there is no denying that RSI medications facilitate ETI.  In one study of pre-hospital ETI, the overall success rate for non-arrest patients receiving ETI without medication use vs. with sedation facilitated ETI vs standard RSI was 73.7%, 77%, and 96.3% respectively  [2].

The benefits of pre-hospital ETI have also been called into question.  A recent Cochrane review looked at emergency ETI for acutely ill and injured patients  [3].  One of the studies written by Gausche et al. that was in the review compared paramedic ETI vs. paramedic bag valve mask and ED physician ETI of children  [4].  The study found no survival or good neurological outcome advantage in children in the paramedic ETI group.  There was also no difference in hospital length of stay between the two groups  [3].  Another study that was looked at in the review was a study written by Goldenberg et al. that compared paramedic ETI vs. paramedic esophageal gastric tube airway (EGTA) in adults with out of hospital non-traumatic cardiac arrest  [5].  The results of this study found a small non-significant advantage in the EGTA group in survival to hospital discharge  [3].  The third study that was looked at in the review was a study written by Rabitsch et al. that compared physician ETI vs. combi-tube placement in adults with out-of-hospital non-traumatic cardiac arrest  [6].  The results showed a 3% survival in the ETI group vs. a 6% survival in the combi-tube group  [3].  In another study by Ehrlich that looked at the effectiveness of field ETI in rural pediatric trauma patients, it was found that bag valve mask was adequate to maintain oxygenation and ventilation in up to 90% of the patients  [7].  Bag valve mask offers two distinct advantages over ETI in the field.  It allows for faster transport time because ETI procedure takes time to perform and it also allows you to avoid some of the complications associated with failed ETI.  A failed ETI attempt seems to lead to multiple failed attempts and ETI complications seemed more frequent when the ETI attempt was performed in the field  [7].

Another area that has been researched on this topic is the issue of the proper training to perform ETI.  It is well known that multiple attempts during emergency ETI are associated with complications  [2].  A study by Wang et al. looked to characterize the number of attempts that were needed to accomplish pre-hospital ETI.  The overall success rate of ETI was 87.1% with more than 30% of patients receiving more than one ETI attempt  [2].  There is concern that some pre-hospital providers also do not have enough ongoing training or experience in the field due to a lack of opportunities for ETI.  In a study by Wang et al., it was found that greater than 39% of rescuers did not perform any ETIs in one year and greater than 67% performed two more fewer ETIs in one year  [8].  Also, according to Wang et al., paramedic students in the US are required to perform only five ETIs prior to graduation which is significantly less than Emergency Medicine, Anesthesiology, and Nurse Anesthetists  [8].

ETI is not the only option for airway management.  There are multiple “rescue airway” devices that can be used in the pre-hospital setting that many believe can be used for primary airway management.  One particular area where this has gotten attention is in the setting of CPR.  A supraglottic airway rescue device can reduce time to ventilation and decrease the amount of time of no compressions  [9].  In a manikin study by Reutzler et al., ETI was compared with six supraglottic airway devices looking at time to ventilation and usability.  The success rate for ETI was 78% compared with 100 % in five of the six devices  [9].  Also, the time to ventilation was significantly shorter in five of the six supraglottic devices compared to ETI  [9].

Given that pre-hospital ETI is a difficult and emergent procedure that can be affected by a variety of situational variables, it is difficult to standardize and therefore difficult to study.  Lossius et el. looked at this issue in a recent systematic review  [10].  According to this review, there is insufficient reporting of airway core variables in the available EMS literature.  There is a wide variety in operator experience, patient case mix, and technique as well as little documentation of the other factors involved before, during, and after the procedure  [10].  This makes it difficult to compare various studies and generalize the results to other EMS systems.  There is a need for a standardized format for documenting and reporting pre-hospital ETI in order to produce better studies on the topic.

The issue of pre-hospital airway management is a complex one with many variables and many opinions.  There is some literature supporting the notion that ETI has an unacceptably high pre-hospital failure/complication rate which has caused some people to suggest the use of other airway devices and basic airway management instead of ETI.  It is very important that further standardized research is done on this topic in order to determine what the best method is for securing an airway in a safe and efficient manner in the pre-hospital setting.

References:

1)      Lossius HM, Roislien J, Lockey DJ.  Patient safety in pre-hospital emergency tracheal intubation: a comprehensive meta-analysis of the intubation success rates of EMS providers.  Crit Care.  2012 Feb 11;16(1):R24.

2)      Wang HE, Yealy DM.  How many attempts are required to accomplish out-of-hospital endotracheal intubation?  Acad Emerg Med 2006, 13:372-377.

3)      Lecky F, Bryden D, Little R, Tong N, Moulton C.  Emergency intubation for acutely ill and injured patients.   Cochrane Database Syst Rev 2008, 16:CD001429.

4)      Gausche M, Lewis RJ, Stratton SJ, Haynes BE, Gunter CS, Goodrich SM, Poore PD, McCollough MD, Henderson DP, Pratt FD, Seidel JS.  Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: a controlled clinical trial. JAMA 2000;9(283):783–90.

5)      Goldenberg IF, Campion BC, Siebold CM, McBride JW, Long LA.  Esophageal gastric tube airway vs endotracheal tube in prehospital cardiopulmonary arrest. Chest 1986;90(1):90–6.

6)      Rabitsch W, Schellongowski P, Staudinger T, Hofbauer R, Dufek V, Eder B, Raab H, Thell R, Schuster E, Frass M.  Comparison of a conventional tracheal airway with the Combitube in an urban emergency medical services system run by physicians. Resuscitation 2003;57(1):27–32.

7)      Ehrlich PF, Seidman PS, Atallah O, Haque A, Helmkamp J.  Endotracheal intubations in rural pediatric trauma patients.  J Pediatr Surg.  2004 Sep;39(9):1376-80.

8)      Wang HE, Kupas DF, Hostler D, Cooney R, Yealy D, Lave JR.  Procedural experience with out-of-hospital endotracheal intubation. Crit Care Med. 2005;33:1718–1721.

9)      Ruetzler K, Roessler B, Potura L, Priemayr A, Robak O, Schuster E, Frass M.  Performance and skill retention of intubation by paramedics using seven different airway devices – A manikin study. Resuscitation. 2011;82:593–597.

10)  Lossius HM, Sollid SJ, Rehn M, Lockey DJ. Revisiting the value of pre-hospital tracheal intubation: an all time systematic literature review extracting the Utstein airway core variables.  Crit Care 2011, 15:R26.

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