Beneficial effects of endotracheal extubation on ventricular performance. Implications for early extubation after cardiac operations

Abstract

Early endotracheal extubation has been shown to be a safe postoperative management option in patients having cardiac operations. However, few objective data exist on the response of ventricular performance to early termination of controlled ventilation. Seven patients undergoing routine elective coronary artery bypass grafting or adult repair of atrial septal defect were studied after intraoperative placement of left ventricular micromanometers, left ventricular minor axis dimension crystals, and left atrial and intrapleural pressure catheters. Physiologic data were recorded intraoperatively, during controlled mandatory ventilation in the intensive care unit, and during spontaneous respiration immediately after extubation. Extubation to spontaneous breathing was associated with a significant decline in intrapleural pressure and significant increases in left ventricular end-diastolic diameter, ejection diameter shortening, stroke work, and cardiac output. The augmented left ventricular diastolic filling seemed to result from the fall in intrapleural pressure and perhaps from normalization of right ventricular afterload. The preload recruitable stroke work relationship showed that myocardial contractility remained constant after extubation, and ventricular function improved primarily because of increased preload associated with shifting of the capacitance blood volume toward the chest. Thus endotracheal extubation enhances cardiac performance after uncomplicated cardiac surgical procedures, and by this mechanism early extubation may be clinically beneficial as a routine adjunct to postoperative care.