Effect of deep hypothermia under total spinal anesthesia on blood flow distribution of cardiac output in dogs

The systemic blood flow distribution of cardiac output of adult dogs, the brain temperature of which was kept at 24℃ by a simple hypothermia method under total spinal anesthesia was investigated. The systemic blood distribution was measured using a redioactive tracer microsphere (51Cr, 85Sr, 125I : 15±5μ in diameter) before total spinal anesthesia, after total spinal anesthesia and under deep hypothermia. Cardiac output was reduced to 83% of the control after total spinal anesthesia and to 38% of the control under hypothermia. The systemic blood re-distribution to each organ determined from the gamma-ray value of trapped redioactive microspheres tended, to be higher than the control value after the total spinal anesthesia in the brain, the heart and the kidney, but to be lower in the gastrointestinal tract. The systemic blood re-distribution to each organ except the liver decreased equally under hypothemia. That is, marked blood re-distribution accompanied by low cardiac output was not recognized. This method could be a safe and useful means for determining blood distribution during open heart surgery.