Conscious sedation and cardiorespiratory safety during colonoscopy

Background: Cardiorespiratory events during colonoscopy are common. The eff ect of sedative premedication on cardiorespiratory parameters during colono scopy has not been studied in controlled, prospective trials. Methods: One hundred eighty patients undergoing colonoscopy were divided in to 3 groups: (1) sedation with intravenous midazolam (midazolam group); (2) sedation with intravenous saline (placebo group); and (3) no intravenous c annula (control group). Arterial oxygen saturation (SaO(2)), systolic and d iastolic blood pressure and continuous electrocardiogram were recorded prio r 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 v ariance). Systolic and diastolic blood pressure during colonoscopy were low er 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 c ontrol groups. Hypotension (systolic blood pressure less than 100 mm Hg) oc curred 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 develop ed in 7% of patients during the recording with no difference between the gr oups. In 75% of cases ST-depression appeared prior to the endoscopic proced ure. Conclusions: Premedication with midazolam induced a statistically significa nt decrease in arterial oxygen saturation and increased the risk for hypote nsion. However, colonoscopy proved to be a safe procedure both with and wit hout sedation.