Tight Postoperative Control of Mean Arterial Pressure Using a Closed-loop System for Norepinephrine Administration: A Randomized Controlled Trial in Patients Admitted to the Intensive Care Unit After a Major Surgery.

Although the correction of hypotension during the perioperative period should be a key goal, approximately 40% of overall mortality is still closely linked to the presence of perioperative hypotension which is responsible for significant morbidity particularly in patients undergoing major surgery. Indeed, inadequate management of perioperative hypotension remains an undeniable risk factor for morbidity and mortality. However, management of perioperative mean arterial pressure (MAP) is still suboptimal today. Indeed, the analysis of our database demonstrates that, on average, patient spends only 50-60 % of the treatment time within the predetermined MAP target. In about 10% of the treatment time, the patient is under-treated (hypotension) and 30% of the time, the patient is over-treated (hypertension).

The correction of hypotension is achieved using vasopressor drugs (mainly norepinephrine infusion). In 2017 a study published in the JAMA shows that patients with tightly controlled arterial pressure have fewer organ dysfunctions than those with standard blood pressure management. However, maintaining MAP within a narrow range involves regular manual adjustments of norepinephrine infusion doses by intensive care unit nurses. When a hypotension occurs, there is usually two main possible treatments (fluid or vasopressors). In the operating room, for patients undergoing major surgery, we usually optimize fluid and vasopressor titration using an advanced hemodynamic monitoring device "EV1000 monitor" (Edwards Lifesciences, Irvine USA).This monitoring device can also be connected to a computer that controls a norepinephrine infusion pump in order to tightly adjust the infusion of norepinephrine to the target MAP predetermined by the clinician in charge of the patients. We have recently demonstrated that the use of such system resulted in less intraoperative time in hypotension compared to manual management. However, in the postoperative period, in patients admitted in the intensive care unit after a major surgery and requiring tight control of MAP, such demonstration is still lacking.

Therefore, the objective of this randomized controlled superiority study is to demonstrate that, in patients admitted to intensive care unit or post-anesthesia care unit after a major surgery, tight control of MAP using a closed-loop system for vasopressor administration will result in MAP being more often within a predetermined MAP range of 80-90 mmHg compared to the same management without this automated closed-loop system (nurse adjustment of vasopressor administration).