The Effects of Preoperative Resting Blood Pressure and Nighttime Blood Pressure on the Associations between Perioperative Blood Pressures and Postoperative Complications: A Prospective, Observational Study in Vascular Surgery Patients

OBJECTIVES: To describe the associations between perioperative blood pressures and clinical postoperative outcomes, and to investigate if these associations depend on the preoperative resting and nadir nighttime blood pressures. DESIGN: A prospective, observational study. SETTING: A single-center study. PARTICIPANTS: 200 patients undergoing vascular surgery under general anesthesia. INTERVENTIONS: Preoperative (resting- and nighttime), intraoperative, and postoperative blood pressure measurements were performed. MEASUREMENTS AND MAIN RESULTS: Intraoperative and postoperative hypotension were defined as time with mean arterial pressure (MAP) < 65 mmHg and the area from the MAP curve up to MAP 65 mmHg (mmHg × min). The burden of postoperative complications was quantified using the Comprehensive Complication Index 30 days after surgery. A hurdle statistical model was used due to the zero-inflated outcome data. In multivariable analyses every minute with MAP < 65 mmHg during anesthesia and in the postanesthesia care unit was associated with a 0.15- and 0.09-point increase in Comprehensive Complication Index at 30 days, respectively. Preoperative resting- and nighttime blood pressures did not significantly modify the associations between intra- or postoperative hypotension and postoperative complications. CONCLUSIONS: Intraoperative and postoperative hypotension were significantly associated with postoperative complications in vascular surgery patients. There were no statistically significant interactions between these associations and preoperative nighttime blood pressure, or ambulatory resting blood pressure.