Fraction of Expired Oxygen as a Measure of Preoxygenation Prior to Rapid Sequence Intubation in the Pediatric Emergency Department



      Pulse oximetry (SpO2) is a flawed measure of adequacy of preoxygenation prior to intubation. The fraction of expired oxygen (FeO2) is a promising but understudied alternative.


      To investigate FeO2 as a measure of preoxygenation prior to intubation in a pediatric emergency department.


      We conducted a prospective, observational study of patients 18 and younger. We collected data using video review, and FeO2 was measured via inline sampling. The main outcomes were FeO2 and SpO2 at the start of preoxygenation, end of preoxygenation/start of intubation attempt, and the end of intubation attempt. We compared FeO2 and SpO2 at the end of preoxygenation for patients with and without oxyhemoglobin desaturation.


      We enrolled 85 of 88 eligible patients during the 14-month study period. FeO2 data were available at the start of preoxygenation for 53 of 85 patients (62%), and for the end of preoxygenation for 59 of 85 patients (69%). Median FeO2 at the start and end of preoxygenation was 90% (interquartile range [IQR] 88, 92) and 90% (IQR 88, 92). Median SpO2 at the start and end of preoxygenation was 100% (IQR 100, 100). There were 11 episodes of desaturation, with median FeO2 at the start of intubation attempt of 89.5 (IQR 54.5, 91.5) and median SpO2 of 100 (IQR 99, 100). Patients who did not have a desaturation event had a median FeO2 of 90.0 (IQR 88.0, 92.0).


      Measuring FeO2 during rapid sequence intubation is challenging with feasibility limitations, but may be a more discriminatory metric of adequate preoxygenation.


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