Conscious sedation and cardiorespiratory safety during colonoscopy

Background: Cardiorespiratory events during colonoscopy are common. The effect of sedative premedication on cardiorespiratory parameters during colonoscopy has not been studied in controlled, prospective trials. Methods: One hundred eighty patients undergoing colonoscopy were divided into 3 groups: (1) sedation with intravenous midazolam (midazolam group); (2) sedation with intravenous saline (placebo group); and (3) no intravenous cannula (control group). Arterial oxygen saturation (SaO(2)), systolic and diastolic blood pressure and continuous electrocardiogram were recorded prior to, during and after the endoscopic procedure. Results: Midazolam produced lower SaO(2) values during colonoscopy compared with placebo or control groups (p < 0.001, repeated measures analysis of variance). Systolic and diastolic blood pressure during colonoscopy were lower in the midazolam group than in the placebo group (p < 0.01 and p < 0.05, respectively), but no difference was found between the midazolam and the control groups. Hypotension (systolic blood pressure less than 100 mm Hg) occurred more frequently in the midazolam group (19%) than in the placebo (3%; p < 0.01) or control groups (7%; p < 0.05). ST-segment depression developed in 7% of patients during the recording with no difference between the groups. In 75% of cases ST-depression appeared prior to the endoscopic procedure. Conclusions: Premedication with midazolam induced a statistically significant decrease in arterial oxygen saturation and increased the risk for hypotension. However, colonoscopy proved to be a safe procedure both with and without sedation.