Myocardial Ischemia During Weaning From Mechanical Ventilation

Coronary artery disease (CAD) affects more than 11 million Americans and is the leading cause of death in the United States. Both CAD and critical illness occur more frequently in older patients. However, the contri-bution of myocardial ischemia to morbidity and mortal-ity in critically ill patients has not been well studied. Weaning from mechanical ventilation is expected to be a period of significant cardiopulmonary stress during recovery from critical illness. However, few studies have examined the epidemiology of and clinical risk factors for weaning-related myocardial ischemia. In this review, the pathophysiology of myocardial ischemia during weaning is outlined, the studies examining this entity are analyzed, and a systematic approach to diagnosis and management is suggested. Copyright © 1998 by W. B. Saunders Company. The effects of mechanical ventilation on the circulation have been outlined in several concise reviews. 1.2 The principal effects of positive-pressure ventilation (PPV) are to (1) Reduce right and left ventricular preloadi-7 and (2) Reduce left ventricular afterload. 1,8-1