AUTHOR=Shi Yubo , Jin Ying , Song Jianli , Shi Jingfeng , Liu Xiaoying , Zhao Guoqing , Su Zhenbo 

TITLE=A quasi-experimental study of fresh oxygen flow on patients’ oxygen reserve during mask-assisted ventilation under general anesthesia induction

JOURNAL=Frontiers in Medicine

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2023.1261177

DOI=10.3389/fmed.2023.1261177

ISSN=2296-858X

ABSTRACT=<sec id="sec1"><title>Background</title><p>To compare the effect of different amounts of fresh oxygen flow on oxygen reserve in patients undergoing general anesthesia.</p></sec><sec id="sec2"><title>Methods</title><p>Seventy-two patients were enrolled in this quasi-experimental study. Patients were randomly divided into experimental groups with a fresh oxygen flow of 1 L/min, 2 L/min, 4 L/min, and 8 L/min (denoted as G1, G2, G3, and G4, respectively) for 2 min of mask-assisted ventilation. Safe apnea time (SAT) was the primary endpoint; SAT was defined as the time from the cessation of ventilation to the time the patient’s pulse oxygen saturation (SpO<sub>2</sub>) decreased to 90%. Ventilation indicators such as end-tidal oxygen concentration (EtO<sub>2</sub>), end-tidal carbon dioxide partial pressure (EtCO<sub>2</sub>), SpO<sub>2,</sub> and carbon dioxide (CO<sub>2</sub>) elimination amount, during mask-assisted ventilation, were the secondary endpoints.</p></sec><sec id="sec3"><title>Results</title><p>The SAT of G1, G2, G3, and G4 were 305.1 ± 97.0 s, 315 ± 112.5 s, 381.3 ± 118.6 s, and 359 ± 104.4 s, respectively (<italic>p</italic> &gt; 0.05). The EtO<sub>2</sub> after 2 min of mask-assisted ventilation in groups G1, G2, G3, and G4 were 69.7 ± 8.8%, 75.2 ± 5.0%, 82.5 ± 3.3%, and 86.8 ± 1.5%, respectively (<italic>p</italic> &lt; 0.05). Also, there was a moderate positive correlation between the fresh oxygen flow and EtO<sub>2</sub> (correlation coefficient r = 0.52, 95% CI 0.31–0.67, <italic>p</italic> &lt; 0.0001). The CO<sub>2</sub> elimination in the G1 and G2 groups was greater than that in the G4 group (<italic>p</italic> &lt; 0.05). There was no significant difference in other indicators among the groups (all <italic>p</italic> &gt; 0.05).</p></sec><sec id="sec4"><title>Conclusion</title><p>The amount of fresh oxygen flow during mask-assisted ventilation was positively correlated with EtO<sub>2</sub>. Also, even though there was no significant difference, the patients’ oxygen reserves increased with the increase in fresh oxygen flow.</p></sec>