The Cardiac Output in Response to Surgical Trauma

To the surgeon, contemplating the performance of a major operation, the physiological mechanisms by which man recovers from trauma become important. Although much is known of the respiratory, 3,13,17 metabolic, 16,20 and endocrine 11,12 responses to surgery, the system which most obviously fails is the circulation. Usually this is secondary to inadequacy of blood volume, respiration, or other parts of the mechanism. But little is known of the pattern of cardiac output or peripheral resistance during recovery. It has been appreciated for some time that an improvement must be made in the function of the heart if a patient is to survive a cardiac operation. Recently Boyd et al. 1 and we ourselves 4 pointed out that those patients usually died who failed to increase the cardiac output postoperatively and who continued in a state of relative tissue hypoxia and metabolic acidosis. It is the purpose of this paper to