Novel Use of a Gas Analyzer Can Reliably Predict the Arterial Oxygen among Emergency Department Patients Undergoing Rapid Sequence Intubation.

Background: To our knowledge, no study has assessed the correlation of fraction of inspired oxygen (FiO) and end-tidal oxygen (EtO) values obtained from a gas analyzer during the preoxygenation period of rapid sequence intubation (RSI) to predict partial pressure of oxygen (PaO) among patients requiring intubation in the emergency department (ED).

Objective: The purpose of this study was to determine whether a simple equation using EtO and FiO at time of induction could reliably estimate minimal PaO in ED patients undergoing RSI.

Methods: We conducted an observational pilot study performed in an adult ED utilizing a gas analyzer to obtain EtO and FiO values in ED patients undergoing RSI from data collectors blinded to our objective. The Pearson correlation coefficient was calculated between the equation's predicted PaO and the PaO drawn from an arterial blood gas shortly after intubation. A Bland-Altman plot analysis was performed to identify any additional bias.

Results: Seventy-five patients were enrolled. The equation's mean predicted minimal PaO and mean PaO from an arterial blood gas within 3 min after intubation was 178 mm Hg (95% confidence interval [CI] 145-211 mm Hg) and 209 mm Hg (95% CI 170-258 mm Hg), respectively. The Pearson correlation coefficient between the predicted minimal PaO and post-intubation PaO demonstrated a strong correlation (r = 0.89). The Bland-Altman plot indicated no bias affecting the correlation between the predicted and actual PaO.

Conclusions: Among ED patients undergoing RSI, the use of a gas analyzer to measure EtO and FiO can provide a reliable measure of the minimal PaO at the time of induction during the RSI phase of preoxygenation.