Effect of supplemental gases on end-tidal CO2 and oxygen saturation in patients undergoing fentanyl and midazolam outpatient sedation.

Forty-six American Society of Anesthesiologists Class I and II adults were randomly assigned to one to two study groups. Each subject received 0.7 microgram/kg of fentanyl and a titrated dose of midazolam. One group received 100% supplemental oxygen (O2) while another group received 50% nitrous oxide (N2O) and 50% O2. End-tidal carbon dioxide (EtCO2) and O2 saturation (SpO2) were measured at 5-min intervals throughout the procedure. We conclude that there was no significant difference in EtCO2 or O2 saturation between the two groups.