Systemic and cerebral hemodynamic changes during craniotomy under mild hypothermia

Systemic and cerebral hemodynamics were evaluated through pulmonary artery and jugular bulb catheters in 31 patients with cerebral aneurysms. The temperature of the pulmonary artery was lowered to 33 - 34°C during surgeries. Systemic circulation deteriorated during mild hypothermia, but cerebral circulation showed a little improvement. Cardiac function recovered by rewarming, but the balance between systemic oxygen supply and demand did not always improve. Therefore, a strict monitoring of systemic circulation is necessary even when the hypothermia is only mild and vasodilator or inotropics would be indicated. Rapid rewarming should be avoided, especially when surgical retraction of the brain is strong or temporary occlusion is prolonged.