Non-invasive carbon dioxide monitoring during moderate sedation at different oxygen flow rates in patients undergoing endoscopic retrograde cholangio-pancreatography

Abstract

Background: All patients receiving sedation to facilitate endoscopic procedures should have monitoring of cardiorespiratory parameters before, during, and after administration of sedation/analgesia. We evaluated the effects of different O2 flow rates on the non-invasive CO2 monitoring (EtCO2) in adult patients that were breathing spontaneously under moderate sedation during ERCP. Methods: This prospective randomized double-blind study was conducted on 120 patients assigned randomly to one of the three equal groups (n = 40) (Group I; 2 L/min oxygen flow rate, Group II; 4 L/min oxygen flow rate, and Group III; 6 L/min oxygen flow rate). Primary outcome was EtCO2 at the end of procedure. Secondary outcomes included peripheral O2 saturation, hemodynamics, time to recovery, total propofol dose, patients’ satisfaction, sedation score, and complications. Results: EtCO2 increased significantly between the studied groups at pre-intervention, induction, 5, 10, 20, and 30 min but without any clinical significance (p-value ˂ 0.05). The HR changes were statistically significant at 10 and 20 min after induction of anesthesia. While SpO2, MBP, and RR differences were statistically not significant between groups throughout the whole study periods (p-value >0.05). Arterial blood gas analysis showed PCO2 was significantly different between the study groups but still within the normal range of readings, while pH and HCO3 showed statistically insignificant differences between the three groups. Conclusion: The study demonstrated that different O2 flow rates did not affect the non-invasive EtCO2 measurements by the Dual-Guard device during moderate sedation in patients undergoing ERCP. Non-invasive EtCO2 monitoring can provide an early warning sign of hypoventilation during moderate sedation.