EFFECTS OF THIOPENTAL AND KETAMINE ON CARDIAC-FUNCTION DURING MODERATE HEMORRHAGE IN CHRONICALLY INSTRUMENTED RATS

This study was designed to assess the effects of thiopental and ketami ne on cardiac function after a blood loss of 2 ml/100 g of body weight . In nine Sprague-Dawley rats, a catheter was placed in the abdominal aorta, a pulsed Doppler probe was positioned around the thoracic aorta , and a wall-thickness probe was sutured onto the left ventricle. On t hree occasions, all rats were studied awake, during thiopental anesthe sia, and during ketamine anesthesia. In awake rats, a 30% blood loss r esulted in an immediate, transient hypotension (49%) and a prolonged d ecrease in cardiac output (39%) and stroke volume (28%). No significan t changes were observed in the wall-thickening fraction, which is an i ndex of cardiac contractility, and in the heart rate. The effect of th iopental on cardiovascular responses to moderate hemorrhage was minima l. Although ketamine did not affect the hypotensive response to modera te hemorrhage, it did accentuate systemic vasoconstriction and cardiac depression as indicated by a decrease in cardiac output (57%), stroke volume (49%), and wall thickness (47%).