Resus: When to Intubate? Airway Management in the Chain of Survival
Adequate oxygenation and ventilation is critical to achieving return of spontaneous circulation (ROSC) in non-traumatic outside-of-hospital cardiac arrests (OHCA), however the most effective method of airway management strategy is not well defined. Initial airway management options deployed by emergency medical services (EMS) providers include the use of a bag-valve-mask (BVM), or placement of advanced airways including supraglottic airways (SGA) or endotracheal intubation (ETI). Historically, ETI is considered the first-line approach for airway management in the prehospital setting with prior studies suggesting superior outcomes (1). However, in 2018 the authors of the AIRWAYS-2 trial suggested ETI offered no advantage to SGA placement in the prehospital setting (2). Overall patient survival to 30-days or discharge with favorable neurological outcome (modified rankin score <3) of 6.8% in ETI arm (n=4407) and 6.4% in the SGA arm (OR=0.92 95% CI=0.77-1.09, p=0.33, n=4407 and 4882 respectively). As a secondary outcome they found earlier success requiring < 2 attempts of airway placement with 87.4% and 79.0% in the SGA and ETI groups respectively (OR=1.92, 95% CI=1.66-2.22, p<0.001). However, they did find an increased unintentional loss of the established airway in the SGA group. Interestingly, the authors of the PART trial, a cluster-crossover randomized trial of 3004 adults with OHCA had an increased 72-hour survival with SGA when compared to ETI in the prehospital setting (18.3% for SGA, 15.4% for ETI) which achieved statistical significance (3). Together, these studies suggest SGA placement is non-inferior to, and may offer benefit over ETI in the prehospital setting requiring fewer attempts for successful placement but may less stable once established.
After presentation to the Emergency Department (ED), When should we transition from an SGA to placement of an ETT? The results of the AIRWAY-2 and PART trials were illuminating, but do not address continued usage of SGA versus ETI upon presentation in ED with the presence of providers with increased ETI experience and resources. To the best of my knowledge, there is no multi-institutional randomized control trial addressing this issue. This represents an important gap in critical care literature which warrants further investigation. Here we will discuss factors and current evidence influencing the decision to intubate during resuscitative efforts in the ED.
During management of cardiac arrest, earliest possible defibrillation and high quality compressions have proven reduction in mortality during resuscitation (4, 5). Minimizing interruptions to compressions and maintaining a goal chest compression fraction >60% is intended to maximize coronary perfusion and increase likelihood of obtaining ROSC. Placement of an ETT represents a significant source of compression interruption (6). In a prospective observational study 206 in-hospital and OHCAs were video recorded and all compression interruptions were assessed. The authors found 623 compression interruptions >10 seconds with 794 actions performed. Placement of an ETI represented the fourth most frequent cause of interruption to chest compressions occurring 6.2% of interruptions (Fig 1). Interestingly, actions related to assessing or modifying quality compressions represented the top three most frequent interruptions including pulse checks and adjustments to compression devices or compression provider switching.
Figure 1.
In the prehospital setting usage of an SGA may offer decreased mortality compared to ETI with newer evidence suggesting timing of advanced airway placement is associated with improved rates of ROSC in certain populations (7). However, the decision to intubate in non-traumatic OHCAs by ED providers is based upon clinical judgment, and the impact of early ETI prior to ROSC remains largely unexplored. In a multi-institution observational study, the authors of Anderson et al 2018 assessed the impact of ETI timing during in-hospital cardiac arrest (IHCA) on 30-day survival, ROSC and functional outcomes. They found early ETI, defined as <15 minutes from arrest, reduces 30-day survival with worse functional outcomes (Fig. 2) (8). Although these findings may not generalize to OHCA, a multi-institution trial assessing time to ETI of OHCA patients who received an SGA with no ETI attempts prior to ED presentation is warranted. To the best of my knowledge such a study has not been performed.
FIgure 2.
If the decision to intubate is made prior to sustained ROSC, to minimize compression interruption, the resuscitation team must maximize success rate of first attempt ETI. Airway difficulty and availability of video assisted ETI equipment are predictors of first attempt success rate.
Video assisted approaches to ETI offer decreased compression interruption and increased first attempt rates in patients with difficult airways. A small single-institution prospective randomized control trial assessing the use of video-assisted laryngoscopy (VL) versus direct laryngoscopy (DL) in physicians with varying ETI experience was performed (9). Their findings suggest VL offered a decreased rate of compression interruptions with an average time of 4.0s for DL (range 1.0–11.0s, n=69) compared with 0.0s in the VL arm (range 0.0–1.0s, n=71). Compression interruptions >10 seconds occurred frequently in 26.1% (18/69) of attempts in the DL arm. These longer compression interruptions were not observed in the VL arm (0/71, p < 0.001). In the surgical setting, a small prospective randomized control trial assessing 200 patients undergoing general anesthesia, were randomized to for ETI using DL (n=100) or VL (n=100) and time to complete intubation was stratified by airway difficulty as measured by Cormack and Lehane classification (10). The authors found, VL to offer decreased ETI time for all Cormack and Lehane classifications which is most pronounced in more difficult class III-IV airways (Fig. 3).
Figure 3.
Prehospital attempts at advanced airway placement in non-traumatic OHCA, SGA is non-inferior to ETI in 30-day patient survival. Upon presentation to the ED, the decision to intubate prior to sustained ROSC should be made with caution as minimizing interruption of high-quality compressions is paramount. Taking into account patient anatomy, presence of experienced providers, and usage of video assisted devices improves success rate of first attempts and minimizes compression interruption during ETI. If any of these factors are unfavorable continued use of the established advance airway placed by EMS, or placement of an SGA should be considered until sustained ROSC is achieved.
POST BY: OTIS PINKARD, MS4
FACULTY EDITING BY: COLIN MCCLOSKEY, MD
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