Hypotension Prediction Index for Blood Pressure Management (HPI)

The Role of Acumen Hypotension Prediction Index Software in Hypotension Management During Moderate to High-Risk Noncardiac Surgery: A Pilot Randomized Control Trial

Design: Single-center randomized comparison of invasive arterial pressure monitoring vs. arterial pressure monitoring combined with Acumen Hypotension Prediction Index (HPI) software guidance on intraoperative hypotension duration and severity. Aim: To determine whether use of Acumen HPI software guidance to guide intraoperative hemodynamic management in the non-cardiac surgery reduces the duration and severity of hypotension. Primary hypothesis: Our primary hypothesis is that adding Acumen HPI software guidance to the information provided by the invasive arterial pressure monitoring during moderate- to high-risk noncardiac surgery reduces time-weighted average (TWA) intraoperative hypotension below a threshold of 65 mmHg.

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.

Single-center randomized comparison of invasive arterial pressure monitoring vs. arterial pressure monitoring combined with Acumen Hypotension Prediction Index (HPI) software guidance on intraoperative hypotension duration and severity.

MAP stands for mean arterial pressure. Time-weighted average MAP below 65 mmHg threshold for each patient was derived by dividing AUC-MAP by the time interval between the first and the last MAP measurements.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure; Calculation of a specific area started when MAP was less than 65 mmHg and ended when MAP was greater than 65 mmHg; Hypotension severity (AUC-MAP) below the threshold of 65 mmHg was calculated as the cumulative sum of the areas below the given threshold for a patient using the trapezoid rule and measured in units of mmHg times minutes.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery) .

MAP stands for mean arterial pressure; Duration is the total amount of time (in minutes) that the MAP under a threshold of 65 mmHg

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure. Time-weighted average MAP below 60 mmHg threshold for each patient was derived by dividing AUC-MAP by the time interval between the first and the last MAP measurements.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure. Time-weighted average MAP below 55 mmHg threshold for each patient was derived by dividing AUC-MAP by the time interval between the first and the last MAP measurements.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure; Calculation of a specific area started when MAP was less than 60 mmHg and ended when MAP was greater than 60 mmHg. Hypotension severity (AUC-MAP) below the threshold of 60 mmHg was calculated as the cumulative sum of the areas below the given threshold for a patient using the trapezoid rule and measured in units of mmHg times minutes.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure; Calculation of a specific area started when MAP was less than 55 mmHg and ended when MAP was greater than 55 mmHg. Hypotension severity (AUC-MAP) below the threshold of 55 mmHg was calculated as the cumulative sum of the areas below the given threshold for a patient using the trapezoid rule and measured in units of mmHg times minutes.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure; Duration is the total amount of time (in minutes) that the MAP under a threshold of 60 mmHg

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

MAP stands for mean arterial pressure; Duration is the total amount of time (in minutes) that the MAP under a threshold of 55 mmHg.

MAP measurements were recorded every 20 s by the EV1000 system from induction (start anesthesia) to leaving Operation room (end of surgery).

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

Maheshwari K, Shimada T, Fang J, Ince I, Mascha EJ, Turan A, Kurz A, Sessler DI. Hypotension Prediction Index software for management of hypotension during moderate- to high-risk noncardiac surgery: protocol for a randomized trial. Trials. 2019 May 3;20(1):255. doi: 10.1186/s13063-019-3329-0.