Deliberate arterial hypotension in plastic surgery for the reduction of hypertrophic breast: a critical appraisal of surgical ischaemia and haemodynamic changes during sodium nitroprusside infusion.

Deliberate hypotension was used to attain surgical haemostasis in thirteen patients undergoing plastic and reconstructive surgery on breast, with an 0.01% sodium nitroprusside (SNP) infusion and concomitant deep neuroleptanaesthesia. The mean surgical haemorrhage was 217 ml in the hypotensive group and when compared with a group of 13 normotensive patients, in whom the average blood loss was 688 ml, the difference was highly significant. A continuous monitoring of the changes in the circulatory dynamics, by electrical impedance plethysmography which was sustained before, during and after the application of SNP, revealed considerable enhancement in the cardiac output as well as the peripheral blood flow of all patients investigated. There was a moderate increase in the stroke volume of a majority of patients. The total systemic resistance was greatly diminished in all the patients submitted to hypotensive anaesthesia with nitroprusside. The clinical criteria were also compared with another group of fourteen patients where arfonad (trimetaphan) was employed to induce hypotension. The difference in bleeding between the two hypotensive groups was insignificant. Neither sodium nitroprusside nor arfonad induced hypotension necessitated any blood transfusion, during or after the surgery.