Physiologic changes during colonoscopy

We prospectrvely evaluated multiple physiologic parameters in 104 consecutive unselected patients undergoing elective colonoscopy. Changes observed during colonoscopy were then correlated with the type of anesthesia and level of sedation, position of the endoscope and presence of looping, existence of comorbid medical conditions, concomitant medication usage, and the occurrence of endoscopy induced pain. Clinically important changes in O₂ saturation (54%) and in blood pressure (44%) were most frequently noted. Less frequent were changes in pulse (15%) or respiratory rate (4%). These clinically significant changes were associated with induction of anesthesia or endoscope looping and pain in 58 to 62% of the patients. In the remainder of patients, no obvious factor was associated with the observed alterations in physiologic parameters. There was no correlation with presence of comorbid medical conditions, use of concurrent medication, dose of anesthesia, level of sedation, and/or colon segment reached by the endoscope. Although there was no apparent morbidity associated with the induced changes in physiologic parameters, these data suggest that certain patients may be at increased risk of procedure-related morbidity and support the need for physiologic monitoring in high-risk patients.