RESUMO
In 9 patients who were expected to have the dental orthognatic surgery under the general anesthesia, Na Nitroprusside was administered to induce and maintain the hypotension. The following results were obtained during operation 1) Mean arterial pressure was 58mrnHg during controlled hypotension. 2) There were no significant changes in heart rates and central venous pressure during operation. 3) There were no significant changes in arterial pH and arterial contents of oxygen and carbon dioxide during operation. 4) Hemoglobin concentration and hematocrit were significantly decreased 90 minutes after administration of Na Nitroprusside and 30 minutes after discontinuing intravenous infusion of Na Nitroprusside. 5) There were no significant changes in the blood concentration of K, Na, and Cl. 6) The average amount of blood loss during operation was estimoted by 380 cc.