An analgesic strategy for tympanoplasties

UNLABELLED: After induction with vecuronium, etomidate and then isoflurane or enflurane, nitrous oxide, useful at the beginning of tympanoplasty is washed out before the end of operation. So barotrauma on the graft is avoided. In the expectation of analgesia insufficiency, alfentanil is infused intravenously all over the operation period following two modes: constant flow mode (1.25 micrograms.kg-1.min-1) after a bolus (25 micrograms.kg-1): 33 patients; decreasing hyperbolic flow mode (H): cumulative dose = 10.8 x t0.5 (where t = minutes of infusion) = 47 patients. In this mode, plasma concentration is measured by 12 patients. RESULTS: the mean plasmatic level of alfentanil is steady during the 120 minutes duration of anaesthesia: standard deviation is higher than 30%. After high quality anaesthesia in both technics, recovery time was shorter with H mode than with constant flow one (extubation time = 46 +/- 31 min. versus 92 +/- 54 min). H. mode seems to be safer. Though, individual reactivity, drug interaction and genetic polymorphism must make us cautious! Two patients presented apnea 20 and 60 minutes after an efficient awakening.