Advanced Monitoring to Inform and Guide Perioperative Hemodynamic Optimization 1 (AMIGO-1) Study

A Single Centre Feasibility Randomized Controlled Trial of Advanced Minimally Invasive Monitoring to Optimize Hemodynamic Management in Major Noncardiac Surgery

Serious complications occur in about 16% of major surgeries. Episode of hypotension during surgery may be a leading cause of these complications. Even though hypotension occurs frequently during surgery, choosing the correct treatment remains difficult in clinical practice. Physicians are often uncertain as to whether low blood pressure should be treated with intravenous fluid or vasoactive drugs. The first treatment of choice typically involves administering more intravenous fluid; however, excessive fluid administration during surgery has been shown to be deleterious. New minimally invasive hemodynamic monitors now offer a potential solution by guiding physicians with respect to the choice of appropriate intervention (i.e., fluid versus vasoactive drugs). The Investigators will conduct a single-center feasibility randomized control trial (RCT) at the Toronto General Hospital (Toronto, ON, Canada) of an algorithm to manage hypotension during surgery based on the information captured by a minimally invasive monitor. Sixty participants who are aged 40 years or older and scheduled to undergo an abdominal, pelvic or vascular surgery will be randomized to have the intraoperative hypotension managed by either the new algorithm (guided by the monitor) or usual care. Participants will be recruited over 12 to 18 months, and followed for 30 days to describe differences in clinical care, hemodynamics, complications, and death. The feasibility of a future multicenter RCT will be assessed based on this present study demonstrating that (1) the algorithm can be practically implemented in a clinical setting where hemodynamic monitors are not typically used; (2) initial descriptive data suggest differences in care between groups; (3) there are no obvious major harms from the protocol; and (4) there is an acceptable participation rate among eligible patients. These data will inform any required changes to the algorithm and protocol to allow for its application in a future study.

Inclusion Criteria:

• Age ≥40 years

• Abdominal, retroperitoneal, pelvic or vascular surgery requiring general anesthesia and planned postoperative stay of ≥48 hours for medical reasons

• Elevated perioperative cardiovascular risk based on at least one of the following:

  • cardiovascular comorbidities: coronary artery disease, heart failure, cerebrovascular disease, or peripheral arterial disease
  • elevated age (≥70 y),
  • smoker,
  • hypertension,
  • diabetes mellitus,
  • or preoperative estimated glomerular filtration rate ≤60mL/min/1.73m2

• Planned placement of invasive arterial line for clinical care

Exclusion Criteria:

• Preoperative dialysis dependence
• Minimally invasive procedures (i.e., laparoscopic or endovascular approach)
• Intra-thoracic procedures
• Non-sinus rhythm
• Liver resection surgery