Nonpharmacologic circulatory support in the brain-dead animal

A nonpharmacologic technique for providing an artificial peripheral resistance enabled the canine heart to pump blood for 12 hours in a brain-dead (spinal) animal model. The artificial peripheral resistance was provided by binding the body with elastic bandage. The only other support provided was artificial respiration. Following the 12-hour preservation period, the hearts were challenged to pump by the intravenous infusion of saline. Aortic pressure, cardiac output (CO), oxygen uptake, body temperature, arterial Na+, K+, pH, and HCO3-, and transchest ECG were monitored in all five animals studied during the control and 12-hour preservation periods. Mean blood pressure fell to 50-60 mmHg following cervical cord transection, rising to above 100 mmHg when the body was bound with elastic bandage that restored the peripheral resistance. During the 12-hour preservation period the average mean blood pressure fell from 118 to 60 mmHg, at which point the average normalized CO was 34 mL/min/kg. Following the saline challenge, the average CO increased to 1.89 times the value at the end of the preservation period, representing an average normalized value of 64.3 mL/min/kg (a typical value for the normal resting dog is 70 mL/min/kg). Body temperature decreased slightly in four animals and increased slightly in one. Na+ was virtually unchanged throughout the control and preservation periods, but K+ increased slightly in all animals, exceeding 5 mEq/L in one animal after 8.5 hours and in another after 10 hours. HCO3- was almost constant in all animals, as was pH. However, the pH was elevated during the preservation period due to slight overventilation to assure a high oxygen saturation.(ABSTRACT TRUNCATED AT 250 WORDS)