TECHNIQUES FOR SUCCESSFUL CARDIOPULMONARY BYPASS IN CALF

The calf is an excellent experimental animal, but problems in the care and management of these animals, particularly during thoracotomy and cardiopulmonary bypass, have led to a high morbidity and mortality. Pulmonary complications have been most common and have been thought to be due in part to intrinsic problems or immaturity of the lungs and pulmonary circulation of the calf. The results of this study suggest that the pulmonary problems are due primarily to unsatisfactory ventilation. High-pressure (25-30 cm. H2O), large-tidal-volume ventilation before and after bypass, with the lungs inflated but not ventilated during bypass, eliminated the pulmonary complications associated with cardiopulmonary bypass in the calf. Methods were developed to prevent other complications in the calf during cardiopulmonary bypass, including foaming of blood in the extracorporeal system, cardiac irritability, ventricular fibrillation, rumen distension, patent ductus arteriosus, and transition from the extracorporeal circuit. These and other techniques have allowed prolonged intrathoracic procedures and cardiopulmonary bypass in the calf with excellent survival and little postoperative morbidity. © 1969.