[Effects of deep halothane and isoflurane anesthesia on cerebral as well as coronary metabolism]

Mongrel dogs were subjected to halothane or isoflurane to examine the relationship between systolic blood pressure and cerebral as well as myocardial metabolism. The oxygen and hydrogen ion balances in the brain were not disturbed in either group to the systolic blood pressure level of 70 mmHg and were well maintained in the isoflurane group below this level. The myocardial oxygen balance was not aggravated in either group, whereas, the myocardial hydrogen ion balance was disturbed in the halothane group at the systolic blood pressure level between 70 mmHg and 50 mmHg though it was preserved in the isoflurane group. These findings demonstrate that the systolic blood pressure not disturbing oxygen and hydrogen ion balances in the brain and myocardium is 70 mmHg during halothane or isoflurane anesthesia, while isoflurane anesthesia becomes advantageous at the systolic blood pressures below this level. While the myocardial metabolism is less affected by lowering of blood pressures than the cerebral metabolism, it seems important to secure cardiac functions to maintain metabolism in both organs.