[Controlled hypotension with sodium nitroprosside in patients placed in the sitting position during intracranial operations (author's transl)].

Sodium nitroprusside was used to induce hypotension during continuous neuroleptanalgesia in 11 neurosurgical patients aged between 13 and 53 years placed in the sitting position. No patient had cardiovascular disease. 14 patients aged between 18 and 72 years without induced hypotension were used as controls to compare the action of our standardized method of anaesthesia on the same parameters that were also monitored during blood pressure lowering. Cerebral perfusion of these 14 patients with highly elevated intracranial pressure with or without cardiovascular disease already seemed to be threatened by the upright position. Therefore, induced hypotension was not performed. The average dosage of sodium nitroprusside was 2.08 mcg/kg/min. The initial medium arterial pressure was lowered by a mean of 32.4%, associated with an average increase in pulse rate of 38.9%. The values of arterial PO2 never fell below 100 mmHg and the PCO2 remained between 25 and 35 mm Hg, indicating adequate cardiovascular function and gas exchange. Careful monitoring of the patients during and after blood pressure lowering with sodium nitroprusside made it possible to take advantage of the induced hypotension also in strictly-selected neurosurgical patients who have to be operated on in upright position.