While controlled intraoperative hypotension significantly reduces blood loss, existing trials are not adequately powered to investigate safety, particularly myocardial and renal injury.

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• Leah Dauterman, Nabia Khan, Connor Tebbe, Jiangqiong Li, Yanhua Sun, David Gunderman, Ziyue Liu, David C Adams, Daniel I Sessler, and Lingzhong Meng.
• Indiana University School of Medicine, Indiana University, Indianapolis, IN, USA.
• Br J Anaesth. 2024 Nov 1; 133 (5): 940954940-954.

BackgroundIntraoperative controlled hypotension improves surgical field visibility by reducing blood loss (efficacy) but poses potential risks linked to organ hypoperfusion (safety). The use of controlled hypotension persists despite increasing evidence of associations between intraoperative inadvertent hypotension and adverse outcomes. Therefore, we tested the hypothesis that the focus and results of intraoperative controlled hypertension research differ across anaesthesia and surgery investigators because of differing priorities.MethodsWe systematically reviewed randomised trials comparing controlled hypotension with usual care with trials categorised by investigators' affiliation.ResultsWe identified 48 eligible trials, of which 37 were conducted by anaesthesia investigators and 11 by surgery investigators. For the primary outcome, 54% of the anaesthesia-led trials focused on safety, whereas all (100%) surgery-led trials focused on efficacy (P=0.004). Compared with usual care, mean arterial pressure in controlled hypotension was 23% (95% confidence interval [CI] 17-29%) lower in anaesthesia trials and 30% (95% CI 14-37%) lower in surgery trials; estimated blood loss was 44% (95% CI 30-55%) less in anaesthesia trials and 38% (95% CI 30-49%) less in surgery trials. Overall, blood loss was reduced by 43% (95% CI 32-53%), and trial sequential analysis supported an efficacy conclusion. Mean arterial pressure and estimated blood loss reductions were associated (R2=0.41, P=0.002). All trials were underpowered for safety outcomes, and none adequately evaluated myocardial or renal injury.ConclusionsAnaesthesia researchers prioritised safety outcomes, whereas surgery researchers emphasised efficacy in controlled hypotension trials. Controlled hypotension significantly reduces blood loss. In contrast, safety outcomes were poorly studied. Given increasing observational evidence linking inadvertent hypotension to myocardial and renal injury, the safety of controlled hypotension remains to be addressed.Systematic Review ProtocolPROSPERO (CRD42023450397).Copyright © 2024 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

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