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Br J Anaesth. 2014 Dec;113(6):1009-17. doi: 10.1093/bja/aeu319. Epub 2014 Sep 25.

Arterial pressure above the upper cerebral autoregulation limit during cardiopulmonary bypass is associated with postoperative delirium.

Author information

1
Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins Hospital, 1800 Orleans Ave, Zayed 6208B, Baltimore, MD 21287, USA.
2
Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Hospital, 1800 Orleans Ave, Zayed 6208B, Baltimore, MD 21287, USA.
3
Department of Psychiatry, The Johns Hopkins Hospital, 1800 Orleans Ave, Zayed 6208B, Baltimore, MD 21287, USA.
4
Department of Neurology, The Johns Hopkins University School of Medicine, The Johns Hopkins Hospital, 1800 Orleans Ave, Zayed 6208B, Baltimore, MD 21287, USA.
5
Department of Cardiovascular Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
6
Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Hospital, 1800 Orleans Ave, Zayed 6208B, Baltimore, MD 21287, USA chogue2@jhmi.edu.

Abstract

BACKGROUND:

Mean arterial pressure (MAP) below the lower limit of cerebral autoregulation during cardiopulmonary bypass (CPB) is associated with complications after cardiac surgery. However, simply raising empiric MAP targets during CPB might result in MAP above the upper limit of autoregulation (ULA), causing cerebral hyperperfusion in some patients and predisposing them to cerebral dysfunction after surgery. We hypothesized that MAP above an ULA during CPB is associated with postoperative delirium.

METHODS:

Autoregulation during CPB was monitored continuously in 491 patients with the cerebral oximetry index (COx) in this prospective observational study. COx represents Pearson's correlation coefficient between low-frequency changes in regional cerebral oxygen saturation (measured with near-infrared spectroscopy) and MAP. Delirium was defined throughout the postoperative hospitalization based on clinical detection with prospectively defined methods.

RESULTS:

Delirium was observed in 45 (9.2%) patients. Mechanical ventilation for >48 h [odds ratio (OR), 3.94; 95% confidence interval (CI), 1.72-9.03], preoperative antidepressant use (OR, 3.0; 95% CI, 1.29-6.96), prior stroke (OR, 2.79; 95% CI, 1.12-6.96), congestive heart failure (OR, 2.68; 95% CI, 1.28-5.62), the product of the magnitude and duration of MAP above an ULA (mm Hg h; OR, 1.09; 95% CI, 1.03-1.15), and age (per year of age; OR, 1.01; 95% CI, 1.01-1.07) were independently associated with postoperative delirium.

CONCLUSIONS:

Excursions of MAP above the upper limit of cerebral autoregulation during CPB are associated with risk for delirium. Optimizing MAP during CPB to remain within the cerebral autoregulation range might reduce risk of delirium.

CLINICAL TRIAL REGISTRATION:

clinicaltrials.gov NCT00769691 and NCT00981474.

KEYWORDS:

cardiac surgery; cardiopulmonary bypass; cerebral autoregulation; delirium

PMID:
25256545
PMCID:
PMC4235573
DOI:
10.1093/bja/aeu319
[Indexed for MEDLINE]
Free PMC Article

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