The general principles of postoperative care applicable to patients having coronary artery bypass are identical to those for any major surgical procedure and will not be reviewed here. The special considerations regarding circulatory support using intra-aortic balloon counterpulsation and those regarding mechanical ventilation are reviewed elsewhere in this symposium. Dr. Richard O. Russell, Jr. will emphasize hemodynamic monitoring and principles of cardiovascular management in this section of the program.
I shall review two topics of controversy in postoperative management: (1) the use of vasodilator therapy (problem of postoperative hypertension), and (2) the use of anticoagulants.
Hypertension occurring early in the postoperative period has been reported in approximately one third of patients following coronary artery bypass. This incidence is significantly higher than that in patients undergoing cardiac valve replacement or major noncardiac surgery. Hypertension is usually observed during the first 6 hours postoperatively and is defined as blood pressures exceeding 90 to 100 mm Hg diastolic and/or 140 to 160 mm Hg systolic.
The cause of this phenomenon is unknown. We showed that hypertension in this context is due to increased peripheral vascular resistance and not to increased cardiac output. Our preliminary studies indicate no consistent elevation of serum catecholamines during the hypertensive period compared to resting levels. Others have suggested increased plasma catecholamines or angiotensin II as contributory factors. Hypertension in the early postoperative period does not appear to be related to (1) preoperative blood pressure, (2) preoperative circulatory indices measured during cardiac catheterization, such as blood pressure, . . .