Hypotension Prediction Index versus Mean Arterial Pressure Alarm for Preventing Intraoperative Hypotension in Elective Noncardiac Surgery: A Randomized Controlled Trial

BACKGROUND: Intraoperative hypotension is common during surgery and has been retrospectively associated with acute kidney injury, myocardial injury, and increased mortality. The Hypotension Prediction Index was developed to support proactive blood pressure management but shows a strong correlation with mean arterial pressure. Observational data suggest that a mean arterial pressure alarm set at 72 mmHg may perform similarly to the default Hypotension Prediction Index alarm (greater than 85). The authors hypothesized that a 72 mmHg mean arterial pressure alarm is noninferior to the Hypotension Prediction Index in preventing intraoperative hypotension. METHODS: In this single-center, blinded, randomized controlled trial, adults undergoing moderate- or high-risk elective noncardiac surgery with continuous arterial pressure monitoring were assigned to either a mean arterial pressure alarm (less than 72 mmHg) or a Hypotension Prediction Index alarm (greater than 85). The primary outcome was the area under the threshold for mean arterial pressure less than 65 mmHg. Secondary outcomes included the incidence and severity of hypo- and hypertension, duration of active alarms, incidence of acute kidney and myocardial injury, 30-day mortality, hospital length of stay, and cumulative dosages of vasoactive medication and fluids. RESULTS: A total of 143 participants were included in the final analysis. The median [IQR] area under the hypotension threshold was 3.75 [0.00 to 22.62] mmHg ⋅ min in the mean arterial pressure group and 4.00 [0.00 to 19.00] mmHg ⋅ min in the Hypotension Prediction Index group. After log-transformation, the mean difference was 0.03 (95% CI, -0.24 to 0.29), with the lower bound remaining above the predefined noninferiority margin (-0.4). No differences were observed in secondary hemodynamic metrics, alarm characteristics, patient outcomes, or administered medications and fluids. CONCLUSION: A mean arterial pressure alarm of 72 mmHg is noninferior to the Hypotension Prediction Index greater than 85 in preventing intraoperative hypotension. Given its simplicity and broad availability, a mean arterial pressure alarm of 72 mmHg represents a pragmatic and cost-effective alternative for proactive blood pressure management.