44 Impact of End-Tidal Oxygen Monitoring on the Efficacy of Preoxygenation During Rapid Sequence Intubation in the Emergency Department

Abstract

Preoxygenation is a vital step of rapid sequence intubation (RSI) which is performed to maximize oxygen stores in the body so that the longest possible safe apnea time is achieved. End-tidal oxygen (ETO2) monitoring is not routinely performed in emergency departments (ED), and little is known about the efficacy of current preoxygenation strategies during emergency airway management. The objective of this investigation is to determine the impact of ETO2 monitoring on the efficacy of preoxygenation during RSI in the ED. This ethically approved observational study was conducted at two academic EDs in Sydney, Australia and New York City, United States. Using an oxygen analyzer, patients undergoing RSI had ETO2 measured during the preoxygenation process. In Phase 1, emergency physicians were blinded to the ETO2 values during preoxygenation; and in Phase 2, they were un-blinded to the ETO2 values. Intubating operators were free to choose the method of preoxygenation, which was with a bag-valve-mask (BVM) or a non-rebreather (NRB) mask. The primary outcome was the highest ETO2 achieved at induction of anesthesia. An ETO2>85% was considered to be indicative of maximal preoxygenation, as recommended by the Difficult Airway Society management guidelines for the critically ill. One hundred patients were enrolled in the study during Phase 1 and 78 patients in Phase 2 over a 14-month period. The median ETO2 achieved at induction was 78% (IQR 64 to 86) in Phase 1 was and 90% (IQR 81 to 91) in Phase 2 (Figure). An ETO2 of >85% was achieved in 26% of patients in Phase 1 and in 70% of patients in Phase 2. The mean difference between achieving an ETO2 of >85% in Phase I and Phase 2 was 44% (95% CI 29.6 to 55.8). The use of ETO2 monitoring during RSI in the ED allowed the maximal preoxygenation in 44% more patients. Maximal preoxygenation via the use of ETO2 monitoring during ED RSI may extend the safe apneic period. Further research is required to determine if this improvement in preoxygenation results in clinical benefits for patients undergoing emergent intubation.