Individualized blood pressure regulation and acute kidney injury in older patients having major abdominal surgery: a pilot randomized trial

Background:Acute kidney injury (AKI) is a common postoperative complication, and hypotension may contribute. We therefore tested the primary hypothesis that individualized intraoperative blood pressure regulation reduces postoperative AKI in older surgical patients. Methods:We enrolled patients >= 60 years old scheduled for elective major abdominal surgery with invasive arterial pressure monitoring. All had goal-directed fluid management based on stroke volume variation cardiac output, and administration of a starch. Participants were randomly assigned to: (1) individualized blood pressure management targeting a systolic blood pressure (SBP) within -20% and +10% if baseline SBP was >= 130 mmHg or diastolic blood pressure was >= 80 mmHg, or otherwise, to target SBP within +/- 10% of the baseline value; (2) maintenance of SBP >= 90 mmHg and MAP >= 65 mmHg. Metaraminol was used to achieve the blood pressure target. AKI incidence was assessed by Kidney Disease Improving Global Outcomes criteria during the initial 7 postoperative days. Results:192 patients were assigned to individualized (n = 96) or routine (n = 96) pressure management. 179 patients were included in the intention-to-treat analysis. Age averaged 68 +/- 5 (SD) years and 64% were male. Randomization to the individualized management reduced the area under MAP <65 mmHg (median difference: -37 [-47 to -25] mmHg-minute, P < 0.001]. The incidence of the AKI was 11% in patients assigned to individualized management vs. 16 % in those assigned to routine management: relative risk 0.72 (95% confidence interval, 0.34-1.54), P = 0.396. Patients assigned to individualized pressure management had more urine output, a shorter postoperative mechanical ventilation duration, and faster recovery of bowel function. Conclusion:Individualized blood pressure management markedly reduced hypotension. As expected in a pilot trial, the 28% reduction in AKI was not statistically significant. However, the reduction was clinically meaningful and suggests that a full trial is warranted.