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

To our knowledge, no study has assessed the correlation of fraction of inspired oxygen (FiO₂) and end-tidal oxygen (EtO₂) values obtained from a gas analyzer during the preoxygenation period of rapid sequence intubation (RSI) to predict partial pressure of oxygen (PaO₂) among patients requiring intubation in the emergency department (ED).

The purpose of this study was to determine whether a simple equation using EtO₂ and FiO₂ at time of induction could reliably estimate minimal PaO₂ in ED patients undergoing RSI.

We conducted an observational pilot study performed in an adult ED utilizing a gas analyzer to obtain EtO₂ and FiO₂ values in ED patients undergoing RSI from data collectors blinded to our objective. The Pearson correlation coefficient was calculated between the equation's predicted PaO₂ and the PaO₂ drawn from an arterial blood gas shortly after intubation. A Bland-Altman plot analysis was performed to identify any additional bias.

Seventy-five patients were enrolled. The equation's mean predicted minimal PaO₂ and mean PaO₂ 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 PaO₂ and post-intubation PaO₂ demonstrated a strong correlation (r² = 0.89). The Bland-Altman plot indicated no bias affecting the correlation between the predicted and actual PaO₂.

Among ED patients undergoing RSI, the use of a gas analyzer to measure EtO₂ and FiO₂ can provide a reliable measure of the minimal PaO₂ at the time of induction during the RSI phase of preoxygenation.