Manual vs Closed-loop Control of Mean Arterial Pressure
Condition: Hypotension
MeSH terms: Hypotension
Study type: Interventional

Summary: 
      Intraoperative hypotension can impact patient outcome. Vasopressors are usually used to
      correct hypotension and ensure adequate organ perfusion.

      The investigators have recently developed an automated system (closed-loop system) to titrate
      vasopressor agents in surgical and intensive care patients.

      The purpose of this study is to compare two strategies to correct hypotension based on an
      individual definition of hypotension (therefore, the target MAP used to define hypotension
      will differ for each patient (individualized approach):

        1. Control group = standard practice ( manually adjusted norepinephrine infusion to correct
           hypotension and keep MAP within 90% of patient's baseline MAP

        2. Intervention group = closed-loop (automated) vasopressor administration system will
           deliver norepinephrine using feedback from standard operating room hemodynamic monitor
           (EV1000 Monitor-Flotrac, Edwards Lifesciences, IRVINE, USA) to correct hypotension and
           keep MAP within 90% of patient's baseline MAP
    

Detailed description: 
      In order to prevent the known postoperative complications of intraoperative hypotension,
      vasopressor agents are occasionally used to ensure adequate perfusion. These vasopressors are
      usually administered as manually adjusted infusions, but this practice requires considerable
      time and attention.

      To overcome this issue, the investigators have developed a closed-loop vasopressor (CLV)
      controller to potentially correct hypotension more efficiently. After completing extensive
      in-silico, in-vivo studies and a pilot human trial in a small cohort of 20 patients, the
      investigators aimed to conduct now a randomized control trial comparing manual vasopressor
      adjustment versus closed-loop vasopressor adjustment in high risk patients undergoing major
      abdominal surgeries in order to correct hypotension during surgery

      The primary outcome will be the incidence of hypotension (defined as a reduction of > 10%
      from patient's MAP target, or a allowed tolerance of 10% reduction from patient's baseline
      MAP). This has been chosen based on the recent study of Emmanuel Futier and colleagues
      (Effect of Individualized vs Standard Blood Pressure Management Strategies on Postoperative
      Organ Dysfunction Among High-Risk Patients Undergoing Major Surgery: A Randomized Clinical
      Trial. JAMA. 2017 Oct 10;318(14):1346-1357), even if it was originally done with systolic
      blood pressure

      Participants in both groups will receive standard patient care in that in no way will their
      anesthetic or surgical procedure will be altered as part of the study, with the exception of
      vasopressor administration.

      Fluids will be standardized in both groups and will be given as a continuous baseline
      infusion of 3 ml/kg/h (balanced crystalloid solution) and additional fluid boluses (mini
      fluid challenges of 100 ml) as a goal directed fluid therapy strategy to maintain stroke
      volume variation < 13%. The only difference is the way norepinephrine is delivered to the
      patient (manual versus closed-loop assisted)
    

Intervention name(s): closed-loop system; Manual adjustment
Intervention type(s): Device; Device
Intervention description(s): Hypotension will be corrected by an automated system for vasopressor administration.
Fluids will be given using a goal directed strategy (EV1000 Monitor, Edwards Lifesciences, Irvine, CA, USA); Vasopressor agents will be manually adjusted (standard practice).
Fluids will be given using a goal directed strategy (EV1000 Monitor, Edwards Lifesciences, Irvine, CA, USA)
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Single center prospective randomized controlled trial
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment