Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial

Abstract

Importance: The optimal approach to airway management during out-of-hospital cardiac arrest is unknown.

Objective: To determine whether a supraglottic airway device (SGA) is superior to tracheal intubation (TI) as the initial advanced airway management strategy in adults with nontraumatic out-of-hospital cardiac arrest.

Design, setting, and participants: Multicenter, cluster randomized clinical trial of paramedics from 4 ambulance services in England responding to emergencies for approximately 21 million people. Patients aged 18 years or older who had a nontraumatic out-of-hospital cardiac arrest and were treated by a participating paramedic were enrolled automatically under a waiver of consent between June 2015 and August 2017; follow-up ended in February 2018.

Interventions: Paramedics were randomized 1:1 to use TI (764 paramedics) or SGA (759 paramedics) as their initial advanced airway management strategy.

Main outcomes and measures: The primary outcome was modified Rankin Scale score at hospital discharge or 30 days after out-of-hospital cardiac arrest, whichever occurred sooner. Modified Rankin Scale score was divided into 2 ranges: 0-3 (good outcome) or 4-6 (poor outcome; 6 = death). Secondary outcomes included ventilation success, regurgitation, and aspiration.

Results: A total of 9296 patients (4886 in the SGA group and 4410 in the TI group) were enrolled (median age, 73 years; 3373 were women [36.3%]), and the modified Rankin Scale score was known for 9289 patients. In the SGA group, 311 of 4882 patients (6.4%) had a good outcome (modified Rankin Scale score range, 0-3) vs 300 of 4407 patients (6.8%) in the TI group (adjusted risk difference [RD], -0.6% [95% CI, -1.6% to 0.4%]). Initial ventilation was successful in 4255 of 4868 patients (87.4%) in the SGA group compared with 3473 of 4397 patients (79.0%) in the TI group (adjusted RD, 8.3% [95% CI, 6.3% to 10.2%]). However, patients randomized to receive TI were less likely to receive advanced airway management (3419 of 4404 patients [77.6%] vs 4161 of 4883 patients [85.2%] in the SGA group). Two of the secondary outcomes (regurgitation and aspiration) were not significantly different between groups (regurgitation: 1268 of 4865 patients [26.1%] in the SGA group vs 1072 of 4372 patients [24.5%] in the TI group; adjusted RD, 1.4% [95% CI, -0.6% to 3.4%]; aspiration: 729 of 4824 patients [15.1%] vs 647 of 4337 patients [14.9%], respectively; adjusted RD, 0.1% [95% CI, -1.5% to 1.8%]).

Conclusions and relevance: Among patients with out-of-hospital cardiac arrest, randomization to a strategy of advanced airway management with a supraglottic airway device compared with tracheal intubation did not result in a favorable functional outcome at 30 days.

Trial registration: ISRCTN Identifier: 08256118.

Conflict of interest statement

Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Nolan reported being the editor-in-chief of Resuscitation for which he receives honoraria. Dr Reeves reported salary support from grants from the National Institute for Health Research. Dr Rogers reported salary support from a British Heart Foundation grant until March 2017. No other disclosures were reported.

Figures

Figure 1.. Flow of Study Paramedics and Patients

Grouped according to the randomization assignment of the first paramedic on the scene who was participating in the study. aThere were 113 paramedics who withdrew after randomization (58 randomized to tracheal intubation [TI] and 55 randomized to the supraglottic airway device [SGA]). The median number of patients with out-of-hospital cardiac arrest treated by a paramedic who later withdrew is 7 for TI (interquartile range [IQR], 3-12; range, 1-54) and 6 for SGA (IQR, 4-11; range, 1-31). The median number of trial patients treated by a paramedic who later withdrew is 3 for TI (IQR, 1.0-5.5; range, 1-10) and 2 for SGA (IQR, 1-4; range, 1-12). These trial patients were retained and included in the analysis. bPatients can have more than 1 reason.

Figure 2.. Patient Interventions and Outcomes by Trial Randomization Assignment of Study Paramedics

aThere were missing data (see eText in Supplement 2). bHad modified Rankin Scale (mRS) score of 6. cThere were 72 patients (2.1%) in tracheal intubation group treated only with a nontrial supraglottic airway device (SGA; all had mRS score in 4-6 range; 2 had return of spontaneous circulation at paramedic arrival; 71 deaths). dThere were 36 patients (0.9%) in SGA group treated only with a nontrial SGA (all had mRS score in 4-6 range; 35 deaths).

Figure 3.. Forest Plot of Primary and Subgroup Analyses

The area of the squares is proportional to the number of patients included. The odds ratios were estimated from a mixed-effects logistic regression model with stratification factors fitted as fixed effects and study paramedic as a random effect. The Wald test was used for the P value comparisons. Patients are grouped by the randomization assignment of the first study paramedic on the scene. A breakdown of the modified Rankin Scale scores in the form of horizontally stacked bar charts appears in eFigure 2 in Supplement 2. aNo. of patients with a modified Rankin Scale score in the range of 0 to 3 (good outcome). bThere were missing data for 7 patients (3 in the tracheal intubation group and 4 in the supraglottic airway device group). cThe Utstein comparator includes patients with an out-of-hospital cardiac arrest with a likely cardiac cause that is witnessed and has an initial rhythm amenable to defibrillation. For the Utstein comparator and noncomparator analyses, there were missing data for 103 patients (52 in the tracheal intubation group and 51 in the supraglottic airway device group). dIndicates a P value for interaction. eThe not witnessed group includes all arrests not witnessed by a study paramedic. For the witnessed and not witnessed analyses, there were missing data for 7 patients (3 in the tracheal intubation group and 4 in the supraglottic airway device group). fIncludes patients treated by a study paramedic who were not resuscitated. There were missing data for 4 patients (1 in the tracheal intubation group and 3 in the supraglottic airway device group).