Hypotension Prediction Index for Blood Pressure Management

STUDY RATIONALE Even when clinicians try to prevent intraoperative hypotension, they often fail because it is difficult to predict which patients will become hypotensive, much less when. A risk score for predicting minute-by-minute intraoperative hypotension is not currently available. Yet it seems likely that ability to identify when a patient is likely to become hypotensive, and the pathophysiology of the event, will improve hemodynamic management and perhaps patient outcome. Acumen HPI appears to be a reliable predictor of intraoperative hypotension, and should thus help clinicians anticipate and avoid hypotension. Furthermore, the secondary guidance provided by the Acumen HPI may help clinicians optimally manage fluids and thus prevent future episodes in the same patient.

AIMS To determine whether use of Acumen HPI software to guide intraoperative hemodynamic management in the non-cardiac surgery reduces the duration and severity of hypotension.

PRIMARY HYPOTHESIS Our primary hypothesis is that use of the Acumen HPI software guidance reduces TWA intraoperative hypotension below a threshold of 65 mmHg.

Specifically, we will compare the amount of intraoperative hypotension below mean-arterial pressure (MAP) threshold of 65 mmHg, in patients randomized to invasive arterial pressure monitoring vs. invasive arterial pressure monitoring with Acumen Hypotension Prediction Index software. In both cases, clinicians will strive to keep MAP above 65 mmHg to the extent practical.

Inclusion criteria

• Written informed consent
• Age ≥45 years
• ASA Physical Status 3 or 4
• Moderate- or high-risk surgery (for example, orthopedic, spine, urology, and general surgery)
• Planned invasive blood pressure monitoring
• General anesthesia
• Surgery duration expected to last >2 hours
• Planned overnight hospitalization

Exclusion criteria

• Contraindication to the invasive blood pressure monitoring
• Pregnancy
• Emergency surgery
• Known clinically important intracardiac shunts
• Known aortic stenosis with valve area ≤ 1.5 cm2
• Known moderate to severe aortic regurgitation
• Known moderate to severe mitral regurgitation
• Known moderate to severe mitral stenosis
• Patient or surgical procedure type known as an SVV limitation16 (e.g. tidal volume <8mL/kg of theoretical ideal weight, spontaneous ventilation, persistent cardiac arrhythmia, known atrial fibrillation, open chest surgery, Heart Rate/Respiratory Rate (HR/RR) ratio <3.6)
• Current persistent atrial fibrillation
• Congestive heart failure with ejection fraction <35%
• Neurosurgery
• Emergent or cardiovascular surgical procedure
• Patient who is confirmed to be pregnant
• Refusal of patient or authorized representative to sign consent