To Tube or Not To Tube?

When endotracheal intubation (ETI) was first introduced to EMS in the mid 1980s, it became a core procedure of ALS. ETI delineated the basic first responder from the paramedic and helped create the “doctor”-like image of paramedics on television. As EMS evolved, the benefits of prehospital ETI were questioned as evidence-based medicine became the driving force behind procedure adoption. No longer could an intervention be thought of as effective without evidence to support its use. The remainder of this article will cover various areas of ETI, such as efficacy, ETI success rates and recommendations.

How Did Prehospital ETI Become the “Gold Standard?”

 In 1983, Stewart et al. performed a study to measure the feasibility of paramedics performing ETI. While the study confirmed paramedics could perform ETI, it actually illustrated they could perform ETI in deeply comatose or cardiac-arrested patients with a success rate of 90.3%. Children, semi-conscious and trauma patients were not included, which resulted in an artificially high success rate. The Stewart study received notoriety when it was published in November 1984.¹ Stewart continued to author voluminous articles and books endorsing the ability of paramedics to perform prehospital ETI, and the rest, as they say, is history.

Paramedic Prehospital Success Rates of Field ETI

When reviewing prehospital ETI success rate studies, care must be taken to eliminate studies that produce non-generalizable results for prehospital populations. With the aforementioned in mind, the requirements for inclusion in this document are as follows: 1) The study must include a reputable means of measuring success, usually done by an emergency department physician in the clinical setting; 2) confirmation must include correct placement of the tube’s depth and location and; 3) the study must not exclude large segments of the population i.e., patients in c-spine or non-arrested subsets.

One study by Deakin et al. that met these criteria found a success rate of 71.2% out of 52 participants.² A more comprehensive study by Deakin’s group revealed a success rate of 83.8% out of 439 participants.³ Katz and Falk constructed a similar study with a 75% success rate in 108 participants.⁴⁵ Lastly, Wang et al. performed a study that demonstrated a success rate of 78% out of 1,953 participants. Thus, the weighted mean success rate for this document is 78.6%.

Do Any Studies Show High Prehospital ETI Success Rates?

Yes…when it is performed by medical school residents and anesthesiologists. One such study by Albrecht et al. exposed a success rate of 98.2% performed by residents with over 20 supervised ETIs before enrolling in the study.⁶ Another study by Sollid et al. described an ETI success rate of 99.2% performed by anesthesiologists in an air ambulance system.⁷

While both of these studies are well constructed and include numerous patients over many years, the positive results do not translate to paramedics in the field. Moreover, there are no reliable studies with success rates similar to the aforementioned averages when ETI is performed by prehospital paramedics.

Does ETI Decrease Morbidity and Mortality?

One of the basic concepts taught in EMS is “first, do no harm.” Davis et al. set out to see if prehospital ETI diverges from this principle, excluding cofactors that would normally corrupt a meaningful study to show correlation, or lack of, between ETI, mortality and morbidity. The design of the study was as follows: Logistic regression was used to explore the impact of prehospital intubation on outcome, controlling for age, gender, mechanism, Glasgow Coma Scale score, head/neck AIS score, Injury Severity Score and hypotension. Neural network analysis was performed to identify patients predicted to benefit from prehospital intubation. Davis found that prehospital ETI “was associated with a decrease in survival among patients with moderate-to-severe TBI [traumatic brain injury]” yet those with extensive trauma may benefit from ETI. Furthermore, those who received ETI sustained an increased mortality rate of 6% compared to those without, even while taking into account the aforementioned co-factors.⁸

In addition to the Davis study, the 2005 Ontario Prehospital Advanced Life Support (OPALS) study by Ian G. Stiell had similar findings. The OPALS study was the largest multi-region clinical trial ever conducted in the prehospital setting. Constructed in three phases similar to the American Heart Association’s chain of survival, Stiell sought to measure the benefit of basic CPR, defibrillation and ALS. The study showed a great benefit with the first two chains, CPR and early defibrillation. The ALS phase, including medications and ETI, showed no benefit. As Stiell made clear, “[T]he study intervention variable, advanced life support in Phase III, was not associated with a change in survival (odds ratio 1.1; 95% CI, 0.8-1).”⁹

Lastly, a study conducted by Cobas et al. demonstrated no measurable benefit of prehospital ETI over BLS airway management with a poor ETI success rate of 69%. Furthermore, Cobas surmised that a possible correlation may exist between ETI, hypoxia and increased scene times.¹⁰  

Are Paramedics Adequately Trained to Perform ETI?

ETI training for paramedics is a topic often cited in industry research journals as being problematic. Most paramedic training programs require five to 10 ETIs before one is able to perform the skill unsupervised. While this may appear to be enough practice for a few confident paramedics, it is not enough to gain true proficiency. Deakin et al. cited a study of anesthesia residents that illustrated a 90% success rate with ETI would require approximately 57 attempts.¹¹ Wang and Yealy also illustrated a large difference in the number of ETIs a paramedic must perform compared to an emergency medicine or anesthesiology resident. The national paramedic curriculum required only five successful ETIs, where the number for residents is 35 to 200 successful intubations before being able to practice the skill unsupervised.¹²

As for skill fade, the prognosis is no better. Deakin referred to evidence that the average paramedic in a large rural/urban system performs ETI only one to two times per year.¹³ A study of Pennsylvania paramedics exposed an average of one ETI per year, with 40% of the paramedics not performing ETI at all. Moreover, Wang and Yealy state evidence that shows a direct correlation between the number of ETIs a paramedic performs and the success rate as, “Error rates were lower for EMS services that performed more intubations annually (more than 50 per year).”¹⁴

Is ETI the Only Definitive Airway?

The term definitive is commonly known as “most reliable” or “complete,” and is often used to define ETI. The argument usually takes a form that “ETI is the only definitive airway,” which implicitly says that no other airway is suitable. To evaluate this statement, relevant benefits of the airway need to be reviewed.

Inability to adequately oxygenate with a mask: While ETI will suffice, a supraglottic airway device (SAD) or laryngeal mask airway (LMA) will as well. All of these devices direct oxygen to the lungs more effectively than using a mask alone.

Prevents aspiration of vomitus or other substances: Once again, ETI will suffice, but many SADs or LMAs will also restrict foreign objects from entering the trachea during ventilation.

Airway compromise, i.e. inhalation injury or airway obstruction: In this instance, ETI may be the only appropriate airway introduced through the endotracheal cavity. A surgical airway or trans-tracheal jet insufflation procedure may suffice for the short term, but is typically only used in the most dire circumstances.

Medication administration via ETI: Alternative airways are inserted in the esophagus and do not pass into the trachea; thus, medication administration via an alternative airway is not possible. Despite losing the ability to administer medications with alternative airways, the efficacy of ET-administered medications is questionable.^15–17 Intraosseous (IO) may be a better route for administering medication than via the ET tube.

Tracheal suctioning: The only acceptable method for suctioning the trachea is via an ET tube, thus there is no alternative for this procedure.¹⁸ This being said, the benefit and frequency of suctioning via the ET tube in the prehospital setting must be evaluated and valued accordingly.

Addressing the Drawbacks of ETI

While no airway intervention can be performed correctly 100% of the time, the evidence-supported suggestions listed below ought to be considered when attempting to reduce complications related to ETI:

• Create a tiered 9-1-1 system. Create a tiered system that includes Basic Life Support, and calls that would otherwise receive an ALS unit would receive a BLS unit if appropriate. By keeping ALS units available for higher acuity patients, a smaller number of paramedics would receive an increase in acute patients, giving them more experience with infrequently used skills and helping prevent skill fade. Davis highlighted this type of system in his research as a means to improve ETI success, while Wang and Yealy believe a tiered structure may not affect the ETI success rate.^19,20  Additional research is required before implementing this type of change if the impetus is increasing ETI success rates.
• Increase training and ETI attempts. The minimum number of successful ETIs must be increased for initial paramedic training. This can only be done if the programs are lengthened and the clinical requirements increased. Paramedics who have not achieved the minimum number of successful ETIs per a specified time period would have to spend operating room time to regain proficiency. While this is possible, it would become a time-consuming and overwhelming process in an EMS region with a high number of paramedics and relatively few ETI possibilities.
• Prohibit prehospital ETI. Prohibiting ETI in the prehospital setting would be feasible due to the availability of alternative rescue airways. While some of these devices are rather nascent, there is voluminous research that supports these airways can be inserted more quickly and lead to higher success rates than the standard ET tube.^21–24

Conclusion

Option 1 and 2 attempt to lessen the problem but not correct it. Allowing a high degree of ETI failure must demand considerable positive outcomes for times when it is done correctly, yet this is not the case. Furthermore, the idea that a procedure like ETI successfully performed in a controlled, well-lit setting by a physician can be executed equally as well by less well trained personnel in a less than ideal environment is deeply problematic.

Consequently, the value of ETI prehospital suctioning and medication administration must be analyzed to support the justification for the airway’s use or abandonment. Once we are able to look past ETI as the “gold standard,” we can see it for what it is: a procedure that has numerous drawbacks when performed by paramedics in the prehospital setting.

References

1. Stewart RD, Pans PM, Pelton GH, Garretson D. Effect of varied training techniques on field endotracheal intubation success rates. Ann Emerg Med 13(11):1032-1036, 1984.

2. Deakin CD, King P, Thompson F. Prehospital advance airway management by ambulance technicians and paramedics: Is clinical practice sufficient to maintain skills? Emerg Med J 26:888-891, 2009.

3. Deakin CD, Peters R, Tomlinson P, Cassidy M. Securing the prehospital airway: A comparison of laryngeal mask insertion and endotracheal intubation by UK paramedics. Emerg Med J 22:64-67, 2005.

4. Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med 37(1):32-37, 2001.

5. Wang HE, Yealy DM. Out-of-hospital endotracheal intubation: Where are we?" Ann Emerg Med 47(6):532-541, 2006.

6. Albrecht E, Yersin B, Spahn DR, et al. Success rate of airway management by residents in a pre-hospital emergency setting: A retrospective study. Eur J Trauma 32(6):516-522, 2006.

7. Sollid S, Lossius HM, Soreide E. Pre-hospital intubation by anaesthesiologists [sic] in patients with severe trauma: An audit of a Norwegian helicopter emergency medical service. J Trauma, Resusc Emerg Med 18(30):1-6, 2010. https://www.sjtrem.com/content/18/1/30 (accessed August 11, 2010).

8. Davis D P, Peay J, Sise MJ, et al. The impact of prehospital endotracheal intubation on outcome in moderate to severe traumatic brain injury. J Trauma Inj, Infection, Crit Care 58(5):933-939, 2005.

9. Canadian Health Services Research Foundation. Ontario Pre-hospital Advanced Life Support (OPALS) Study, by Ian G. Stiell, MD. Ontario: Canadian Health Services Research Foundation, 2005. https://www.chsrf.ca/final_research/ogc/pdf/stiell_e.pdf (accessed July 10, 2010).

10. Cobas, MA, Alejandra De la Pena M, Manning R, et al. Prehospital intubations and mortality: A Level 1 trauma center perspective. Crit Care Trauma 109(2):489-493, Aug 2009.

11. Deakin C, Clarke T, Nolan J, et al. A critical reassessment of ambulance service airway management in pre-hospital care. Joint Royal Colleges, June 2008.

12. Wang HE, Yealy DM. Out-of-hospital endotracheal intubation: Where are we? Ann Emerg Med 47(6):532-541, 2006.

13. Deakin et al. A critical reassessment of ambulance service airway management in pre-hospital care. Joint Royal Colleges, June 2008.

14. Wang HE, Yealy DM. Out-of-hospital endotracheal intubation: Where are we? Ann Emerg Med 47(6):532-541, 2006.

15. Powers DR, Donowitz D, Leigh G. Endotracheal administration of emergency medications. South Med J 77(3):340-342, 1984.

16. Barber AC, Wyckoff C, Myra H. Use and efficacy of endotracheal versus intravenous epinephrine during neonatal cardiopulmonary resuscitation in the delivery room. Amer Acad Peds https://www.pediatrics.org/cgi/content/full/118/3/1028 (accessed July 28, 2010).

17. Dittrich K. ACLS update: A new role for medications. Nursing2007, pp. 56-58, Dec 2007.

18. Deakin et al. A critical reassessment of ambulance service airway management in pre-hospital care." Joint Royal Colleges, June 2008.

19. Davis DP, Peay J, Sise MJ. The impact of prehospital endotracheal intubation on outcome in moderate to severe traumatic brain injury. J Trauma Inj, Infection, Crit Care 58(5):933-939, 2005.

20. Wang HE, Yealy DM. Out-of-hospital endotracheal intubation: Where are we? Ann Emerg Med 47(6):532-541, 2006.

21. Russi CS, Buresh CT, Hartley MJ. A pilot study of the King LT supralaryngeal airway use in a rural Iowa EMS system. Emerg Med 1:135-138, 2008.

22. Bledsoe B. The disappearing endotracheal tube. https://www.bryanbledsoe.com. https://www.bryanbledsoe.com/data/pdf/handouts/PowerPoint/Future%20of%20Intubation.pptx(accessed July 12, 2010).

23. Fowler R. King LT-D to the rescue. JEMS, pp. 90-92, Jul 2005.

24. Russi CS, Wilcox CL, House HR. The laryngeal tube device: A simple and timely adjunct to airway management. Am J Emerg Med 25: pp. 263-267, 2007.

Christopher Ferbrache, MBA, EMT, has16 years of medical experience in the public and private sector. He is the operations supervisor for a small non-profit ambulance service. He can be contacted at chrisferb@gmail.com.