The effect of personalized perioperative blood pressure management on intraoperative cerebral oxygen saturation, burst suppression ratio and postoperative neurological outcomes in patients having major non-cardiac surgery: an observational substudy of the IMPROVE-pilot randomized controlled trial.

It is not clear whether adopting personalized intraoperative blood pressure management could lead to better intraoperative regional cerebral saturation (rSO2), lower burst suppression ratio (BSR) or better neurological outcomes. Therefore, we performed this prespecified exploratory substudy of the IMPROVE-pilot trial to investigate the effects of personalized compared to routine intraoperative blood pressure management on the intraoperative rSO2. We also explored the effect of personalized intraoperative blood pressure management on BSR and the incidence of postoperative delirium (POD) and delayed neurocognitive recovery (dNCR). We included patients aged ≥ 45 years with American Society of Anesthesiologists (ASA) physical status II-IV who were scheduled for elective major surgery. Preoperative automated nighttime blood pressure measurements were performed. Patients were randomized to personalized blood pressure management maintaining intraoperative mean arterial pressure (MAP) at least at the preoperative mean nighttime MAP or to routine blood pressure management with a lower MAP intervention threshold of 65 mmHg. Intraoperative measurements of MAP, rSO2 on both hemispheres, and BSR were performed. POD was assessed daily on the first 3 postoperative days using the 3D-confusion assessment method or the confusion assessment method for the intensive care unit. We screened for dNCR using the telephone-Montreal Cognitive Assessment on postoperative days 3, 7, and 30. We enrolled 55 patients and randomized 50 patients. 49 patients were included in the final analysis. The median areas under the baseline rSO2 and BSR were similar between the two groups. One patient assigned to personalized blood pressure management and none of the patients assigned to routine blood pressure management had POD. There was no meaningful difference in the incidence of dNCR between the groups. In this substudy of the IMPROVE-pilot trial, we observed no evidence of difference in intraoperative area under baseline rSO2 between patients who received personalized compared to routine perioperative blood pressure management.

trial registrationThis substudy was registered at the German Clinical Trials Register (Deutsches Register Klinischer Studien DRKS00025762, on December 3, 2021).