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The IMPROVE-multi trial investigated whether individualized perioperative blood pressure (BP) management, using targets based on patients’ preoperative mean nighttime mean arterial pressure (MAP), could reduce organ injury and mortality compared to routine management in high-risk patients undergoing major abdominal surgery.
The study enrolled 1142 patients aged 45 years or older undergoing elective major abdominal surgery expected to last over 90 minutes and with at least one high-risk criterion, randomized 1:1 to individualized versus routine BP management.
The primary composite outcome—including acute kidney injury, acute myocardial injury, nonfatal cardiac arrest, or death within 7 days postoperatively—occurred in 33.5% vs 30.5% in individualized vs routine groups, respectively (no statistically significant difference).
Secondary outcomes such as infectious complications and major adverse events at 90 days also showed no significant differences, suggesting limited benefit of tailoring intraoperative MAP targets based on preoperative nighttime levels in this patient population.
Study Background
Intraoperative hypotension is a well-recognized risk factor for postoperative organ injury, including acute kidney injury, myocardial injury, and increased mortality. Current perioperative BP management commonly targets a MAP of 65 mm Hg or higher to reduce such complications. However, patients exhibit wide individual variability in baseline and nocturnal blood pressures, raising the question whether a personalized BP target could better preserve organ perfusion and improve outcomes.
The uncertainty regarding optimal intraoperative BP targets inspired the IMPROVE-multi randomized clinical trial, designed to rigorously test if individualized BP management based on each patient’s mean nighttime MAP (measured preoperatively with automated devices) could reduce adverse postoperative outcomes compared to routine fixed MAP targets.
Study Design
The IMPROVE-multi trial was a prospective, single-blind, randomized clinical trial conducted across 15 German university hospitals from February 2023 to April 2024, with follow-up completed by July 2024. Patients included were aged 45 or older undergoing elective major abdominal surgery with a planned anesthesia duration of at least 90 minutes, and who met at least one additional high-risk criterion (e.g., comorbidities or frailty markers).
Participants were randomized 1:1 into two groups:
- Individualized BP management group: intraoperative and perioperative MAP targets were set according to the patient’s mean nighttime MAP recorded during a preoperative automated ambulatory monitoring session.
- Routine BP management group: standard MAP target of 65 mm Hg or higher was maintained intraoperatively.
The primary outcome was a composite of acute kidney injury, acute myocardial injury, nonfatal cardiac arrest, or death within 7 postoperative days. Twenty-two secondary outcomes were measured including infectious complications and a composite endpoint of need for kidney replacement therapy, myocardial infarction, cardiac arrest, or death through 90 days postoperatively.
Key Findings
Of the 1272 enrolled patients, 1142 were randomized (571 per arm) and 1134 included in the primary analysis. The median age was 66 years, with 34.1% female participants.
The primary outcome occurred in 33.5% of the individualized group versus 30.5% of the routine BP group (relative risk 1.10; 95% CI, 0.93-1.30; P = .31), indicating no statistically significant reduction in postoperative organ injury or death with individualized management.
None of the 22 secondary endpoints showed significant differences between groups. For example, infectious complications within 7 days were 15.9% in the individualized group and 17.1% in routine management (P = .63). The composite of kidney replacement therapy, myocardial infarction, cardiac arrest, or death within 90 days was numerically higher in the individualized group (5.7% vs 3.5%) but not statistically significant (P = .12).
The similarity in outcomes suggests that adjusting perioperative MAP targets to preoperative nighttime values did not confer benefit over using a routine threshold of 65 mm Hg for high-risk patients undergoing major abdominal surgery.
Safety profiles were comparable between groups, and no unexpected adverse events related to altered BP management were reported.
Expert Commentary
The IMPROVE-multi trial provides important evidence to inform anesthesiologists and perioperative care teams regarding optimal BP targets during major surgery in high-risk patients. While intuitive, individualized BP management based on preoperative nighttime MAP did not translate into clinical benefit in this rigorous randomized trial.
This finding underscores the complexity of intraoperative hemodynamic management, where factors beyond simple MAP targets—such as cardiac output, tissue oxygenation, and microvascular perfusion—may play critical roles in preventing organ injury.
Additionally, preoperative ambulatory BP may not adequately reflect intraoperative physiological conditions or the dynamic cardiovascular responses to anesthesia and surgery, limiting the utility of static individualized MAP thresholds.
Limitations include the single-blind design, the focus on abdominal surgery which may not extrapolate to other surgical populations, and that preoperative nighttime MAP was measured over a short period. Further research could explore more comprehensive hemodynamic monitoring strategies or alternative personalized targets.
Conclusion
In patients at high risk of postoperative complications undergoing major abdominal surgery, individualized perioperative BP management using MAP targets based on preoperative mean nighttime MAP did not reduce the incidence of acute kidney injury, myocardial injury, cardiac arrest, or death within the early postoperative period compared to routine management targeting a MAP of 65 mm Hg or higher.
The results support continued adherence to current guideline-recommended MAP targets during major surgery and highlight the need for future studies exploring multifaceted hemodynamic optimization approaches to enhance perioperative outcomes.
Funding and Trial Registration
This trial was conducted by the IMPROVE-multi Trial Group across German university hospitals. The study is registered with ClinicalTrials.gov (Identifier: NCT05416944).
References
1. Saugel B, Meidert AS, Brunkhorst FM, et al; IMPROVE-multi Trial Group. Individualized Perioperative Blood Pressure Management in Patients Undergoing Major Abdominal Surgery: The IMPROVE-multi Randomized Clinical Trial. JAMA. 2025 Oct 12. doi: 10.1001/jama.2025.17235.
2. Maheshwari K, Avitsian R, Sessler DI, et al. Consensus Statement on Intraoperative Blood Pressure, Risk and Outcomes for Elective Surgery. Anesthesiology. 2018;129(4):679-694.
3. Monk TG, Saini V, Weldon BC, Sigl JC. Anesthetic management and one-year mortality after noncardiac surgery. Anesth Analg. 2005;100(1):4-10.
