[Recovery from unconsciousness following severe hemodilution and hypotension caused by intraoperative massive hemorrhage: a case report].

A 75-year-old female with a history of cerebral infarction fell into sudden hypotension (mean blood pressure of around 46 mmHg) and severe anemia (hematocrit < or = 10%; minimum hemoglobin concentration of 2.0 g.dl-1) of approximately one hour due to massive hemorrhage during surgical removal of pheochromocytoma originated in the right adrenal gland. Nevertheless, she recovered from the unconsciousness after over 9 hours postoperatively. It is suggested that major reasons for her escaping from the brain damage, in spite of the low cerebral perfusion pressure, might be the decreased cerebral oxygen consumption due to the intraoperative mild hypothermia (31.5 degrees C) and the avoidance due to hemodilution of the extremely low cerebral blood flow.