Original Article

A Perfluorocarbon Emulsion Prime Additive Improves the Electroencephalogram and Cerebral Blood Flow at the Initiation of Cardiopulmonary Bypass

¹ Divisions of Cardiothoracic Surgery, Departments of Surgery and Anesthesiology, School of Medicine, University of Washington Seattle, Washington
² Cardiac Anesthesiology, Departments of Surgery and Anesthesiology, School of Medicine, University of Washington Seattle, Washington

^* Address correspondence to: Craig Vocelka, CCP, Cardiothoracic Surgery SA-25, University of Washington, 1959 NE Pacific St., Seattle, WA 98195

Abstract

Depression in electroencephalogram (EEG) has been documented clinically and is reproducible in swine at the initiation of cardiopulmonary bypass (CPB) utilizing a crystalloid prime. The physiological cause of this transient alteration in electrical brain activity appears to be associated with the transient drop in arterial pressure. The etiology is unknown but may be attributable to the bolus of the crystalloid prime or micro emboli, either air or fibrin-platelet.

Thirteen swine (17-26 kg) were anesthetized and received 4 mg/kg dexamethasone, and following a tracheotomy were ventilated with halothane in 100% O₂. Surgical preparation included: sternotomy and preparation for right atrial- aortic CPB. The CPB circuit consisted of a hollow fiber membrane oxygenator, a hard-shell venous reservoir, a roller pump, and PVC tubing. The circuit was randomly primed with either 1200 ml Plasmalyte-A or 10 ml/kg perfluorocarbon emulsion (PFE) and Plasmalyte-A to total 1200 ml. The animals were monitored continuously for systemic hemodynamics and electrocardiogram, and cerebral monitoring included blood flow and bitemporal EEG. Arterial blood gases were measured and PaCO₂ was kept between 30-45 mmHg both before and during CPB. Cerebral blood flow (CBF) was measured pre-CPB and at 10 minutes after initiation of CPB. Bitemporal computerized EEG was analyzed every 60 seconds. Total power of each hemisphere, power in frequency bands, and spectral edge were recorded.

All animals demonstrated a relative decrease in EEG total power at the onset of CPB. Animals that received PFE demonstrated a more stable arterial blood pressure, an increased CBF, and a lesser decrease and an earlier recovery of the EEG power. The differences in hemodynamics and EEG in the PFE prime group may be beneficial in decreasing the neuro-psychological changes associated with CPB and needs further investigation.