Deliberate hypotension for middle ear microsurgery.

Abstract

By means of groups of one hundred patients undergoing middle ear microsurgery, we compared two hypotensive anesthesia techniques combining halothane, a non-depolarising myorelaxant and a beta adrenoreceptor blocking agent. Practolol, a beta 1 receptor blocker was administered to the patients of group A while those of group B received labetalol, a more recently introduced alpha and beta receptor blocker. The duration of microsurgery for each type of pathology was identical in both groups but the operation conditions (mostly the amount of bleeding) were better in group B (statistically significant). Moreover, the mean delivered halothane concentration could be reduced by 20% (from 0.85% to 0.68%). Thirty patients undergoing tympanoplasty were followed up for several months to determine the the importance of peroperative conditions in relation to the functional result of these operations. Excessive bleeding hinders the surgeon and the positioning of the implant and also, as confirmed by this study, makes the success of the tympanoplasty uncertain. Two factors likely to predispose the patient to bleeding (and able to be brought under control preoperatively) have been highlighted: these are overweight (obese status about 80 kg) and a systolic arterial blood pressure at rest above 140 torr. The various agents which were used and the reasons for their choice are discussed.