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

Abstract

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 and 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) yr and 64% were male. Randomization to the individualized management reduced the area under MAP <65 mmHg [median difference: - 37 (-47 to -25) mmHg-min, P < 0.001]. The incidence of the AKI was 11% in patients assigned to individualized management versus 16 % in those assigned to routine management: relative risk 0.72 [95% CI 0.34 to 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.