Significant hypercapnia either in CO 2-insufflated or air-insufflated colonoscopy under deep sedation

Abstract

Background Previous reports showed that CO 2-insufflated colonoscopy is safe and less discomfortable. However, hypercapnia remains a vital concernment if deep sedation is necessary for difficult colonoscopy with prolonged CO 2 insufflation. This observational study is to measure bodily CO 2 subjected to colonoscopy facilitated by CO 2- and air- or air-insufflation in conscious-sedation, deep-sedation and awake patients. Objective To investigate if CO 2-insufflated colonoscopy could increase the risk of hypercapnia in awake, conscious-sedation and deep-sedation patients. Methods 104 patients in our health center undergoing sequential esophagogastroscopy and colonoscopy screening were included. At patients’ request, incremental intravenous sedatives were given in order that the air-insufflated esophagogastroscopy could be carried out without the molestation of gag and cough reflexes. The sedation levels were re-evaluated before proceeding colonoscopy and the patients were divided into conscious-sedation (respond purposefully to verbal commands) and deep-sedation groups and randomly allocated for air or CO 2 insufflation. Transcutaneous capnography (TcCO 2) was recorded every minute throughout the colonoscopy procedure. Results The baseline TcCO 2 in the air- (50.9 ± 5.7 mmHg) and CO 2-insufflated (53.1 ± 6.5 mmHg) groups under deep sedation was significantly higher than the groups under conscious-sedation and the awake groups ( p < 0.01). In both air- and CO 2-insufflation groups there were also a statistically significant ( p < 0.01) correlation in TcCO 2 between the start, the peak and the end of colonoscopy. TcCO 2 did not significantly change throughout the colonoscopy in awake and conscious-sedation groups, either with air or CO 2 insufflation. With deep sedation, TcCO 2 significantly increased and peaked around the time when the scope touching the cecum, and then returned to original state with suction and withdrawl of the colonoscope without significant interaction of CO 2 insufflation and deep sedation. Conclusion The TcCO 2 during colonoscopy was correlated to the data before inserting colonoscope but significantly different within awake, conscious-sedation and deep-sedation groups. TcCO 2 did not change significantly either with CO 2 insufflation or air insufflations in awake and conscious-sedation groups. However, in deep-sedation groups with significantly higher baseline TcCO 2, further increase of TcCO 2 were significant without interaction with CO 2 insufflation. We concluded that when patients need deep sedation for colonoscopic procedures facilitated by gas insufflation, hypercapnia is still considerably present, not only with CO 2 insufflation but also with air insufflation colonoscopy.