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(789) The FeO2 as a Measure of Preoxygenation Before Rapid Sequence Intubation in the Pediatric Emergency Department


Sara Constand – Medical Student, University of Cincinnati College of Medicine

Katherine J. Edmunds – Physician, Cincinnati Children’s Hospital Medical Center

Benjamin T. Kerrey – Associate Professor, Division of Emergency Medicine, Cincinnati Children's Hospital Medical Center

Sara Constand – Medical Student, University of Cincinnati College of Medicine


Background and Objectives: Preoxygenation prior to Rapid Sequence Intubation (RSI) creates an oxygen reservoir to prolong the safe apnea time and prevent oxyhemoglobin desaturation. Safe apnea is particularly important in children, who desaturate faster and have greater risk of hypoxemia. Adequate preoxygenation is typically defined as pulse oximetry (SpO2) of 100% after 3 minutes of supplemental oxygen with high FiO2. SpO2, however, this is an indirect measure of the oxygen reservoir. The fraction of expired oxygen (FeO2) is a promising alternative to measure the effectiveness of preoxygenation, but FeO2 has never been studied in critically ill children. This study aims to characterize FeO2 values during preoxygenation for patients undergoing RSI in a pediatric emergency department (PED). We sought to determine whether FeO2 is associated with the occurrence, depth, or duration of oxyhemoglobin desaturation.

Methods: This is an observational, prospective, video-based study of patients undergoing RSI in the PED of an urban pediatric institution. Patients were eligible if they were 18 years or younger and underwent RSI in the PED. Data was collected by structured review of the electronic record and video recordings, captured with an audiovisual system that records continuously in each resuscitation bay; the patient monitor is included in the video recording. FeO2 was collected from the patient monitor before, during, and after preoxygenation and after attempts at tracheal intubation.

Results: During the 5-month study period (Aug-Dec 2019), 47 eligible patients underwent RSI. For 17 patients, FeO2, SpO2, or both were missing. Our final sample size for the main analysis was 30 subjects (63%). Median age was 1.2 years [interquartile range (IQR) 0.1, 3.3]. 10 patients (33%) were trauma patients. Median FeO2 and SpO2 at the start of preoxygenation were 90% (IQR 87.3, 93.3%) and 100% (IQR 100, 100%), respectively. Median FeO2 and SpO2 at the end of preoxygenation were 92% (IQR 90, 94%) and 100% (IQR 100%, 100%). Three patients experienced oxyhemoglobin desaturation during RSI (SpO2 dropping to <90%). The median FeO2 at the end of preoxygenation for the patients who desaturated was 60% (IQR 19-81%).

Conclusion: FeO2 appears to be a more discriminating measure of preoxygenation for critically ill children undergoing RSI, in particular in patients who experience oxyhemoglobin desaturation. We will complete enrollment in the summer 2020.

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