The Edge: Laryngeal Tube Insertion or Endotracheal Intubation?

The Edge is a new monthly column from FlightBridgeED that will feature top providers sharing current trends in critical care and prehospital medicine. In this installment FlightBridgeED's Ashley and Eric Bauer analyze the Pragmatic Airway Resuscitation Trial (PART). 

Intubating patients can be exciting and fun. However, it is often debated whether placing an endotracheal tube (ET) or a supraglottic airway (SGA) is the best option for patients in cardiac arrest. There are great arguments on both sides. 

Endotracheal intubation (ETI) is looked at as the gold standard and definitive airway choice throughout the world. SGAs are widely used in many facets, most commonly as backup airways. However, there are protocols that have adopted the SGA as the first choice for all unresponsive patients without a gag reflex who require airway management. Often medical direction, training, and provider level dictate this approach. 

What is the best strategy for your patient? To answer this question it is imperative to use an evidence-based systematic approach, beginning with gathering and critically analyzing multiple studies on the topic. To begin we will analyze one of those studies, the Pragmatic Airway Resuscitation Trial (PART).

Question—The clinical question posed by the study was, “What is the effect of an initial airway management strategy using laryngeal tube (LT) insertion, compared with endotracheal intubation, on survival among adults with out-of-hospital cardiac arrest?”¹

Design—The PART study was designed as a multicenter, pragmatic, cluster-crossover, randomized controlled trial. The trial was designed to group 27 U.S. EMS agencies from the Resuscitation Outcomes Consortium into 13 randomized clusters.¹

Patients—A total of 3,004 adult patients were included in the trial. Patients had to experience nontraumatic out-of-hospital cardiac arrest (OHCA) that required ventilatory support or advanced airway insertion.

Intervention—Each randomized cluster was assigned an initial airway management strategy with insertion or orotracheal ETI. The study only used the Ambu King LTS-D, as it is the most commonly utilized SGA device in the United States.

Comparison—Crossover to the alternative strategy occurred within 3–5-month intervals.

Outcome—The primary outcome was 72-hour survival. Secondary outcomes included return of spontaneous circulation (ROSC), survival to hospital discharge, favorable neurological outcome upon hospital discharge (determined by a Modified Rankin Scale score of 3 or less), and key adverse events.

Validity

The researchers attempted to ensure internal validity through randomization techniques. The initial 27 EMS agencies were grouped into 13 randomized clusters, with each cluster selecting an a priori crossover interval of either three or five months. A detailed randomization plan was then completed to achieve an overall balance at the end of the study. Treatment assignment intervals were computer-randomized within each cluster to ensure a balance for both airway groups and reduce systematic bias. The study also included the use of a protocol in an attempt for all participants to do things the same way. Primary and secondary outcomes were analyzed on an intention-to-treat basis to decrease bias.

There were also threats to the internal validity of the study. The protocol used did not limit the number of initial LT or ETI insertion attempts. EMS agencies had to follow their local protocols for airway placement confirmation and management of OHCA patients, possibly introducing confounding factors. The trial also could not control the care received by the patient once they were delivered to the receiving facility. This included whether the initial EMS airway was used or replaced, targeted temperature management, PCI utilization, or when life-sustaining therapies were stopped. The overall training and experience of each EMS provider could also be considered a confounding factor. 

Crossover notifications were provided to each cluster at least one month prior to the crossover date. However, EMS agencies were allowed to align those dates with their training schedules, avoid weekend crossovers, and avoid crossovers during the last month of the trial, which could cause the findings to be questioned as well. 

Two crossover adjustments had to be made to achieve a balanced enrollment between all groups. Enrollment within one of the cluster groups exceeded projections, so to improve external validity that cluster was instructed to perform an additional crossover. One EMS agency ended its participation prior to completion of the study, so to compensate another cluster was instructed to defer its final crossover. This reprocessing was made without knowledge of outcome data and occurred by randomization cluster as well. 

Comorbidities of patients, as well as their location within the United States, impacted the overall generalizability of the study as well.

Concerns/Limitations

After adjustment analysis, the difference in 72-hour survival between the LT and ETI groups was no longer statistically significant (p=0.11). The post hoc adjustment accounted for age, sex, response time, initial cardiac rhythm, whether the incident was witnessed, and bystander chest compressions. Unsuccessful first-pass insertion was higher for ETI at 44.1% compared to the LT group at 11.8%.¹ Could the level of training within the EMS system affect these percentage rates? Would a higher-performing agency have different results? Would higher first-pass success elicit better survival? 

A team led by Texas emergency physician Jason Lesnick, MD, performed a secondary analysis utilizing the PART data in an attempt to determine the effects of LT and ETI first-pass success on adult OHCA outcomes.² They reported first-pass success is associated with ROSC and 72-hour survival but not necessarily hospital survivability or hospital survival with intact neurological function. This is a significant finding and further depicts how training and overall agency performance within the realm of ETI and first-pass success factored into the initial outcome data. Further research should focus on compression quality and continuity and how this may influence 72-hour survival.

Other limitations included the disparity of training among the different EMS agencies as well as the type of quality improvement monitoring that occurred. The study would likely have benefited from a much larger sample size, as well as the inclusion of more EMS agencies. Unfortunately, it only focused on the LT and did not consider other SGA devices.

Conclusion

According to the PART, LT insertion in initial airway management should be considered for patients with OHCA. However, as mentioned above, there are several limitations that must be considered. Based on this, U.S. EMS agencies should adopt the best protocol based on overall performance that is driven by high-quality training and medical director interaction with the EMS system. Further research is needed to provide a more evidence-based answer.   

References

1. Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Tube Insertion on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA, 2018 Aug 28; 320(8): 769–78.

2. Lesnick J, Zhang Y, Moore JX, et al. Effect of Airway Insertion First-Pass Success Upon Patient Outcomes in the Pragmatic Airway Resuscitation Trial. Circulation, 2019 Nov; 140: A02.

Ashley Bauer, MBA, MSN, APRN, NP-C, CFRN, C-NPT, is vice president of business operations for FlightBridgeED. She is an advanced practice RN in the ED. She began as an ER nurse, transitioned to flight nurse, and is currently a nurse practitioner.

Eric Bauer, MBA, FP-C, CCP-C, C-NPT, EMT-P, is the president and cofounder of FlightBridgeED. He has worked in the EMS field for 29 years, the past 17 in the HEMS industry. He is an internationally recognized best-selling author, speaker, and educator and holds a bachelor’s degree in healthcare administration and a Master of Business Administration. Eric received the 2018 John Jordan Award for Excellence in Transport Medicine Journalism from the Air & Surface Transport Nurses Association.