Endocrine changes during anesthesia and cardiopulmonary bypass
Adel A. El-Etr, M.D.
Silas N. Glisson, Ph.D.
Kanteerava Balasaraswathi, M.D.
Patients who are subjected to anesthesia and surgical stress generally undergo several endocrine changes in response to stress. The endocrine changes may vary according to the physical status of the patient, severity of the surgical procedure, type of anesthetic used, level of anesthesia, and other factors. In patients undergoing cardiac operations, the typical endocrine response may be further modified by the use of cardiopulmonary bypass and the simultaneous effect of hemodilution produced by the bypass. Also during extracorporeal circulation, patients are perfused with a low mean arterial pressure and in most cases this perfusion is of a nonpulsatile nature. Because of the multiplicity and interaction of these endocrine systems, investigations into the endocrine changes associated with anesthesia and surgery have been difficult. Most investigators have attempted to study endocrine responses by measuring circulating hormonal levels at different times during operative procedures. These studies have focused primarily on the responsiveness of the pituitary, adrenocortical, and adrenal medullary endocrine systems during anesthesia and surgery. Some of these studies have attempted to correlate changes in blood pressure with hormonal changes, particularly during and after cardiopulmonary bypass. As a result of these investigations, we are beginning to understand the precipitating causes of hypertension that frequently occur after cardiopulmonary bypass.
The antidiuretic hormone (ADH) has been studied probably more than any other endocrine hormone during anesthesia and cardiopulmonary bypass. A major portion of this research has been done by Philbin et al.1 In their early studies, ADH secretion was found to be influenced