Use of End Tidal Oxygen Monitoring to Assess Preoxygenation During Rapid Sequence Intubation in the Emergency Department

From the Annals of EM:

Study objective

Preoxygenation is important to prevent oxygen desaturation during emergency airway management. The purpose of this study is to describe the use of end tidal oxygen (eto2) during rapid sequence intubation in the emergency department.


This study was carried out in 2 academic centers in Sydney, Australia, and New York City. We included patients undergoing rapid sequence intubation in the emergency department. A standard gas analyzer was used to measure eto2. Preoxygenation methods included nonrebreather mask and bag-valve-mask ventilation. We measured eto2 before preoxygenation and at administration of rapid sequence intubation medications. We also characterized peri-intubation SpO2, identifying instances of SpO2 less than 90%.


We included 100 patients during a 6-month period. Median eto2 level before and after preoxygenation was 53% (interquartile range [IQR] 43% to 65%) and 78% (IQR 64% to 86%), respectively. One fourth of patients achieved an eto2 level greater than 85%. Median eto2 level achieved varied with preoxygenation method, ranging from 80% (IQR 60% to 87%) for the nonrebreather mask group to 77% (IQR 65% to 86%) for the bag-valve-mask group. The method with the highest median eto2 level was nonrebreather mask at flush rate (86%; IQR 80% to 90%) and the lowest median eto2 level was nonrebreather mask at 15 L/min (57%; IQR 53% to 60%). Eighteen patients (18%) experienced oxygen desaturation (SpO2 <90%); of these, 14 (78%) did not reach an eto2 level greater than 85% at induction.


ETO2 varied with different preoxygenation techniques employed in the emergency department. Most patients undergoing rapid sequence intubation did not achieve maximal preoxygenation. Measuring ETO2 in the emergency department may be a valuable adjunct for optimizing preoxygenation during emergency airway management.

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