Abstract
We evaluated the effect of trimetaphan induced hypotension on arterial blood-gases in patients undergoing mastectomy. Fifty patients studied were divided into five groups of 10 patients each according to the anesthetic agents used: halothane, enflurane, isoflurane, sevoflurane and ketamine. Nitrous oxide and oxygen were used in all groups. Mean arterial pressure during induced hypotension was maintained at 70% of that before hypotension. Significant reduction in PaO2 was observed during induced hypoten-sion in all groups. There was no difference between the five groups in the degree of PaO2 decrease.These findings suggest that induced hypotension may impair pulmonary gas exchange, regardless of the anesthetic agent used, by changing the ventilation-perfusion ratio. Therefore, pulseoxymetry or continuous arterial blood-gas monitoring should be used under these conditions.
