Influence of long-term anesthesia on regional blood flow distribution and hemodynamics in the dog.

The effects of 8 h sodium pentobarbital anesthesia on the cardiovascular function and blood flow distribution have been studied on dogs under controlled ventilation. A myocardial depressant action was registered in heart rate, cardiac output and left ventricular work, compensated by an increased peripheral resistance. Blood flow distribution judged by 15 mum carbonized microspheres revealed reduction of the fraction of the blood distributed to the brain. Simultaneously infused microspheres of 15 and 50 mum showed arteriovenous shunting of the smaller spheres compared to the larger through the heart, kidneys, stomach, small and large intestine and the brain. Correspondingly increased fractions of the smaller microspheres were found in the lungs and the liver. The preportal arteriovenous shunting to the liver was larger after 8 h of pentobarbital anesthesia than after 20 min or in conscious dogs.