Risk factors associated with vasovagal reactions during colonoscopy.

To define the syndrome of vasovagal reactions that occur during colonoscopy and to identify those risk factors associated with this development, we prospectively evaluated patients undergoing colonoscopy with monitored sedation. A total of 223 consecutive patients were evaluated during the 60-day study period. A vasovagal reaction was defined as the occurrence of one or more of the following: diaphoresis, sustained bradycardia of less than 60 beats/min or a decrease in heart rate of 10%, or hypotension (systolic blood pressure less than 90 mm Hg, diastolic blood pressure less than 60 mm Hg, or a reduction in blood pressure of more than 10% below a baseline measurement before colonoscopy and after sedation). Thirty-seven (16.5%) of the 223 patients experienced a vasovagal reaction by our criteria. The remaining 186 patients did not; 100 of these patients were randomly selected by computer to form a control group. No statistically significant differences were observed between the vasovagal and control groups with regard to demographics, cardiopulmonary disease, cardiac medications, procedure success, the endoscopist, patient procedure tolerance, colon preparation, or procedure difficulty. A significant difference was seen in the mean dose of midazolam used in the vasovagal group as compared with that used in the control group (4.6 mg versus 3.9 mg, p < 0.04), and moderate to severe diverticulosis was more commonly seen in the vasovagal group as compared with the control group (43% versus 16%, p < 0.02). Thirteen (35%) of the 37 patients who had a vasovagal reaction required medical intervention (5.8% of the 223 patients).(ABSTRACT TRUNCATED AT 250 WORDS)