Cardiopulmonary events during primary colonoscopy screening in an average risk population

Background: Large colorectal cancer screening studies using primary colonoscopy have reported a low risk of major complications. Studies on diagnostic and therapeutic colonoscopy have pointed to a frequent occurrence of (minor) cardiopulmonary events, and with the steady increase of colonoscopy screening, it is important to investigate their occurrence in colonoscopy screening. Methods: This study describes the frequency of bradycardia (pulse rate <60 min I), hypotension (systolic blood pressure (SBP) <90 mmHg), hypoxaemia (blood oxygenation, SaO(2) <90%) and ECG changes during colonoscopy screening in an average-risk population (hospital personnel, n=214, mean age 54.0 +/- 3.8, 39.3% male), without significant comorbidity) and aims at identifying subject-related and/or endoscopic factors associated with their occurrence. All data were collected prospectively. During 214 consecutive primary screening colonoscopies under conscious sedation (midazolam and pethidine), on top of pulse rate and SaO(2), blood pressure and a three-channel ECG were recorded every five minutes. Results: No major complications or relevant ECG changes occurred. Hypoxaemia occurred in 119 (55.6%), hypotension in 19 (8.9%) and bradycardia in 12 subjects (5.6%). In multivariate analysis, the sedation level 3 increased the risk of hypoxaemia (OR 4.8, CI 1.7-13.7), and incomplete colonoscopy (OR 5.3, CI 1.6-18.1) was associated with hypotension. Subjects with bradycardia had a longer mean procedure time (38 +/- 12 vs. 29 +/- 12 min, p<0.05), which did not turn out as a risk factor in a multivariate analysis. Conclusions: Mainly procedure-related and not subject-related factors were found to be associated with the occurrence of cardiopulmonary events in primary colonoscopy screening in this relatively healthy screening population.