Effect of Targeting Mean Arterial Pressure During Cardiopulmonary Bypass by Monitoring Cerebral Autoregulation on Postsurgical Delirium Among Older Patients: A Nested Randomized Clinical Trial

Abstract

Importance: Delirium occurs in up to 52% of patients after cardiac surgery and may result from changes in cerebral perfusion. Using intraoperative cerebral autoregulation monitoring to individualize and optimize cerebral perfusion may be a useful strategy to reduce the incidence of delirium after cardiac surgery.

Objective: To determine whether targeting mean arterial pressure during cardiopulmonary bypass (CPB) using cerebral autoregulation monitoring reduces the incidence of delirium compared with usual care.

Design, setting, and participants: This randomized clinical trial nested within a larger trial enrolled patients older than 55 years who underwent nonemergency cardiac surgery at a single US academic medical center between October 11, 2012, and May 10, 2016, and had a high risk for neurologic complications. Patients, physicians, and outcome assessors were masked to the assigned intervention. A total of 2764 patients were screened, and 199 were eligible for analysis in this study.

Intervention: In the intervention group, the patient's lower limit of cerebral autoregulation was identified during surgery before CPB. On CPB, the patient's mean arterial pressure was targeted to be greater than that patient's lower limit of autoregulation. In the control group, mean arterial pressure targets were determined according to institutional practice.

Main outcomes and measures: The main outcome was any incidence of delirium on postoperative days 1 through 4, as adjudicated by a consensus expert panel.

Results: Among the 199 participants in this study, mean (SD) age was 70.3 (7.5) years and 150 (75.4%) were male. One hundred sixty-two (81.4%) were white, 26 (13.1%) were black, and 11 (5.5%) were of other race. Of 103 patients randomized to usual care, 94 were analyzed, and of 102 patients randomized to the intervention 105 were analyzed. Excluding 5 patients with coma, delirium occurred in 48 of the 91 patients (53%) in the usual care group compared with 39 of the 103 patients (38%) in the intervention group (P = .04). The odds of delirium were reduced by 45% in patients randomized to the autoregulation group (odds ratio, 0.55; 95% CI, 0.31-0.97; P = .04).

Conclusions and relevance: The results of this study suggest that optimizing mean arterial pressure to be greater than the individual patient's lower limit of cerebral autoregulation during CPB may reduce the incidence of delirium after cardiac surgery, but further study is needed.

Trial registration: ClinicalTrials.gov identifier: NCT00981474.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Brown reported receiving grants from the National Institutes of Health (NIH) and grants from the International Anesthesia Research Society during the conduct of the study, consulting for and receiving grant funding from Medtronic; in addition, he reported receiving and an offer to participate in an advisory board for Medtronic, which had not been finalized at time of publication. Dr Neufeld reported receiving personal fees from Merck, Inc, and grant funding from Hitachi Inc, and Ornim, Inc, outside the submitted work. Dr Hori reported receiving a Japan Heart Foundation/Bayer Yakuhin Research Grant Abroad during the study period; a 2018 Jichi Medical University Young Investigators Award; and a 2018 KAKENHIII (Grants-in-Aid for Scientific Research) Grant-in-Aid for Young Scientists B. Dr Hogue reported receiving grants and personal fees being a consultant, and providing lectures for Medtronic/Covidien, Inc, being a consultant to Merck, Inc, and receiving grants from NIH outside the submitted work. Dr Conte reported serving on a scientific advisory board for Medtronic. Dr. Gottesman reported being Associate Editor of Neurology. Dr. Kraut reported receiving grants from NIH during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.. Patient Enrollment

Figure 2.. Delirium Incidence by Randomization Group

Mean arterial pressure during cardiopulmonary bypass was managed according to standard care or autoregulation-targeted goals. Delirium incidence by randomization group is shown.