Highlight
- Intensive blood pressure management targeting mean arterial pressure (MAP) ≥80 mm Hg during major abdominal surgery reduces intraoperative hypotension duration compared to conventional targets.
- No significant difference in 30-day composite cardiovascular events was observed between intensive and conventional blood pressure management in high-risk patients.
- Reducing hypotension exposure intraoperatively does not translate into lower rates of myocardial injury, arrhythmia, heart failure, stroke, cardiac arrest, or all-cause mortality.
Study Background and Disease Burden
Intraoperative hypotension is a well-recognized risk factor for adverse cardiovascular outcomes following major noncardiac surgery. Episodes of low blood pressure during surgery can contribute to myocardial injury, arrhythmias, heart failure exacerbation, stroke, and even death. Major abdominal surgery poses a particular challenge due to long durations and hemodynamic fluctuations.
Current clinical practice recommends maintaining intraoperative mean arterial pressures above 65 mm Hg or relative to baseline values to reduce complications. However, randomized controlled trials have produced inconsistent results on whether more intensive blood pressure management—targeting higher pressure thresholds—confers additional cardiovascular protection. Understanding the optimal blood pressure target is crucial to balance risks of hypotension against potential adverse effects of more aggressive vasopressor or fluid therapy.
The BP-CARES (Blood Pressure and Cardiovascular Events After Surgery) trial was designed to address this clinical question in a high-risk patient population undergoing major abdominal surgery in China. The findings provide important guidance on intraoperative blood pressure management strategies.
Study Design
This investigator-initiated parallel-group randomized trial enrolled 1,500 patients aged 45 years or older with established cardiovascular disease or one or more cardiovascular risk factors. Eligible patients were scheduled for elective or emergency inpatient abdominal surgeries lasting at least two hours at three Chinese tertiary hospitals.
Participants were randomized 1:1 to either intensive or conventional blood pressure management during surgery. The intensive group targeted maintaining MAP ≥80 mm Hg throughout the operation. The conventional group targeted the higher of two thresholds: MAP ≥65 mm Hg or 60% of the patient’s preoperative baseline blood pressure.
Standard anesthesia protocols were used with continuous invasive blood pressure monitoring to allow prompt intervention. Clinicians administered fluids, vasoactive agents, or anesthetics as needed to adhere to assigned MAP targets.
The primary outcome was a composite of major cardiovascular events occurring within 30 days post-surgery, including myocardial injury or infarction, new clinically relevant arrhythmias, acute heart failure, stroke, cardiac arrest, and death from any cause.
Key Findings
Among the modified intention-to-treat population of 1,477 patients (739 intensive strategy, 738 conventional strategy), the study reported significant differences in intraoperative hypotension burden but not in clinical outcomes:
– The intensive strategy group had markedly less exposure to hypotension. Median cumulative duration of MAP <65 mm Hg was 1 minute (interquartile range 0–7 minutes) versus 8 minutes (0–20 minutes) in the conventional group.
– Despite this improved hemodynamic control, the primary composite endpoint occurred in 14.5% (107/739) in the intensive group vs 13.6% (100/738) in the conventional group (relative risk 1.07; 95% CI 0.83 to 1.38; P = 0.61).
– None of the individual components of the composite outcome—including myocardial infarction, arrhythmias, heart failure, stroke, cardiac arrest, or mortality—showed significant differences.
– Safety profiles were similar between groups; no excess adverse events attributable to intensive blood pressure management were reported.
These results suggest that while targeting a higher MAP intraoperatively effectively reduces hypotension duration, this does not confer a statistically or clinically meaningful reduction in postoperative cardiovascular events in this patient population.
Expert Commentary
The BP-CARES trial adds to the body of evidence demonstrating the complexity of intraoperative blood pressure management and its relationship to outcomes. It corroborates prior observations that modest intraoperative hypotension is common even with conventional targets but challenges the assumption that intensively higher blood pressure targets reduce cardiovascular morbidity.
Mechanistically, it is plausible that transient hypotension under anesthesia may not uniformly cause ischemic injury, or that compensatory physiological factors mitigate risk. Conversely, attempts to maintain higher MAP could increase vasopressor use and fluid load, potentially counteracting benefits.
Limitations include the trial’s focus on major abdominal surgery in a Chinese population, which may affect generalizability. Also, the trial’s pragmatic design and composite outcomes may mask effects in specific subgroups or on individual endpoints. Further studies might explore personalized targets based on patient comorbidities or surgical risk.
Guidelines currently recommend avoiding prolonged MAP <65 mm Hg, but do not universally endorse intensive targets. BP-CARES reinforces the value of maintaining safe minimum MAP thresholds but does not support aggressive elevation beyond standard care.
Conclusion
In high-risk adults undergoing major abdominal surgery, intensive intraoperative blood pressure management aiming for MAP ≥80 mm Hg reduces hypotension duration yet does not lower 30-day cardiovascular complications compared with conventional management targeting MAP ≥65 mm Hg or 60% baseline. Clinicians should balance the complexity and resources of intensive blood pressure protocols against their lack of demonstrated outcome benefit. Preventing severe and prolonged hypotension remains essential, but more aggressive elevation appears unnecessary for cardiovascular protection postoperatively.
Further research in diverse surgical populations and risk groups is warranted to refine optimal blood pressure management strategies during surgery.
References
1. Zhao B, Zhang J, Xie Y, et al. Intensive vs Conventional Intraoperative Blood Pressure Management on Cardiovascular Events After Major Abdominal Surgery: The BP-CARES Randomized Trial. J Am Coll Cardiol. 2025 Sep 23;86(12):892-906. doi:10.1016/j.jacc.2025.07.027. PMID: 40962376.
2. Sessler DI. Perioperative Blood Pressure Management. Anesthesiology. 2021;134(3):346-357.
3. Walsh M, Devereaux PJ, Garg AX, et al. Relationship between intraoperative mean arterial pressure and clinical outcomes after noncardiac surgery: toward an empirical definition of hypotension. Anesthesiology. 2013;119(3):507-515.
4. Futier E, Lefebvre F, Guinot PG, et al. Effect of individualized vs standard blood pressure management strategies on postoperative organ dysfunction among high-risk patients undergoing major surgery: a randomized clinical trial. JAMA. 2017;318(14):1346-1357.
