[Dosage-problems in controlled sodium nitroprusside hypotension in oto-rhino-laryngological surgery (author's...

During a study of 130 patients undergoing hypotensive anaesthesia for oto-rhino-laryngological surgery the most important dose problems with sodium nitroprusside (S.N.P.) were characterized. In 14% of the cases more than 15 mcg/kg body weight/min S.N.P. were required. Our data show, that the smallest S.N.P. consumption occurs during neuroleptanalgesia in combination with 0.3--0.8 Vol-% enflurane. On the other hand, during neuroleptanalgesia alone, in several cases toxic amounts of S.N.P. would have been necessary to produce adequate hypotension. In such cases about 0.5 mg/kg body weight dihydralazine must be employed as a supporting agent for hypotension. The influence of this drug on the manoeuvrability of the low pressure state and on the administration of S.N.P. was investigated. Although, the equivalent amount of sodium thiosulfate (S.T.) did not increase the S.N.P. sensibility, its routine use is reconviended, since the combination of S.Th, and even higher doses of S.N.P. were tolerated without metabolic acidosis. As an alternative substance after long-term use of S.N.P. nitroglycerine should be used.