Controling Mean Arterial Pressure Using a Closed-Loop System for Vasopressor Titration

Postoperative Hypotension Management With Computer-guided Vasopressor Titration in High-Risk Patients After Cardiac Surgery: A Randomized Controlled Trial

The investigators have developed an automated vasopressor controller to improve the titration of vasopressor in order to maintain mean arterial pressure (MAP) within a narrow range and have recently shown the controller was effective in both the operating room and intensive care unit. The controller has been used recently in a case series of three patients undergoing cardiac surgery and in five patients after cardiac surgery.

The investigators want to compare now a manual to a closed-loop titration of vasopressor infusion in patients admitted in the Intensive Care unit after cardiac surgery

Perioperative hypotension and arterial pressure variability have been shown to negatively impact patient outcomes, increasing risk of stroke, kidney injury, and myocardial injury among others.

Vasopressors are usually used to rapidly correct hypotension. Vasopressor infusions are typically administered by standard infusion pump with the rate adjusted by anesthesiologists 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 infeasible for human providers to pay constant attention and make second-to-second changes, management is often suboptimal (i.e. large amounts of time are spent in hypotension below the target, or well above the target with the vasopressor drip still running).

The investigators have developed an automated closed-loop vasopressor (CLV) controller to improve the titration of vasopressor (e.g:noradrenaline) in order to maintain MAP within a narrow range in the perioperative setting. The investigators have published engineering, animal and most recently, pilot,studies or case series with promising results.

In this randomized controlled trial, the investigators will compare time spent in hypotension defined as a mean arterial pressure < 65 mmHg. They tested the hypothesis that the automated system will allow patients to spent less time during the postoperative period with a MAP < 65 mmHg. This is thus a superiority study over a two hours study period

Inclusion Criteria:

• Adult patient
• Elective cardiac surgery
• French speaking patient

Exclusion Criteria:

• Uncontrolled hypertension
• Renal insufficiency (estimated glomerular filtration rate < 30mL/min/1,73m²)
• Left ejection fraction < 40%
• Emergency surgery
• Preoperative infection
• Preoperative cardiac arrythmia
• Pregnant women