Closed-Loop Control of Vasopressor Administration in Patients Undergoing Cardiac Revascularization Surgery

INTRAOPERATIVE hypotension and arterial pressure variability have been shown to affect patient outcomes negatively, increasing the risk of stroke, kidney injury, and myocardical injury, among other conditions. Vasopressors normally are used to correct hypotension rapidly. Vasopressor infusions typically are administered by standard infusion pump, with the rate adjusted by bedside providers to reach a predefined target mean arterial pressure (MAP); this requires frequent changes in the infusion rate because of the almost constantly changing hemodynamic status of such patients. Because it is unfeasible for human providers to pay constant attention and make second-to-second changes, management is often suboptimal (ie, large amounts of time are spent in hypotension below the target or well above the target with the vasopressor drip still running). Indeed, it has been shown that patients under continuous vasopressor infusion in both the operating room and intensive care unit spend about 50% of treatment time outside a reasonable MAP target when on vasopressors. The authors of the present article developed an automated closed-loop vasopressor (CLV) controller to improve the titration of vasopressor (eg, norepinephrine) in order to maintain MAP within a narrow range (§5 mmHg of the chosen target) in the perioperative setting.