[Trials of controlled hypotension with sodium nitroprusside in ORL surgery. Resistance and tachyphylaxis].

Sodium nitropusside has been used to lower blood pressure during surgical operations on the ear, nose and throat when an operative field without bleeding was desired, e.g. surgery of the inner ear under microscope in particular. In our experience, with the preparation used, sodium nitropusside proved to be a powerful hypotensive agent, the effect of which comes on early but it is difficult to use owing to frequent tachyphylaxis, the possible causes of which are considered. No undesirable side-effects were noted on the main functions. From this limited personal experience, the efficacy of this technique of per-operative hypotension did not appear greater in the surgical field under consideration to those of the anaesthetic techniques used commonly, e.g. neuroleptanalgesia under artificial ventilation, which proved sufficient for reduction in operative bleeding and which had already caused the authors to abandon, some time ago, the use of hypotensive ganglioplegic drugs.