MIdazolam has been shown to interact synergistically with propofol during "co.induction" of anaesthesia. I However, it is uncertain whether mldazolam affects propofol requirements during, and recovery times following, total Intravenous anaesthesia (TIVA) In Day Care patients. A double-blind study was therefore designed to determine these effects. Here, we deacdbe unexpected cases of awareness with recall In our study population. METHODS: Ninety unpremedlcated ASA Class I and II adult Day Care patients, 'scheduled to undergo either knee erthreacepy or laparoscoplc procedures, gave written consent to the protocol approved by the hospital REB. Patients received, in a random fashion, either placebo (Group PLAC) or midazolam at a dose of 0.015 ms-ks "~ (Group MID-15), 0.030 mg.kg "~ (Group MID.30) or 0.045 rag.ks "~ (Group MID-45) prior to Induction of anaesthesia. Anaesthesia was then Induced with propofol 0.8-1.5 rag.ks "1 an.d alfantanil 20 Fg.kg "l, and alracurlum 0.5 mg.kg "1 to facilitate tracheal Intubatlon. Anaesthesia was malntalnad with a continuous Infusion of propofol beginning at 100 p.g.kg't.min "t, titrated as required to maintain HR and SBP within =2.0% of the patient's normal values, or in response to patient movement, while atfentanll was Infused st 0.5 Fg.kg'l.mln "~ (constant). Times to awakening ware compared postoperatively. In addition, a follow-up questionnaire, designed to evaluate the overall quality of the anaesthetic experience, was completed for each patient on the first post-operative day. Data were analyzed using the Chlsquare statistic and Flscher's Exact test where appropriate, with significance assumed when P<0.05 RESULTS: Propofol Infusion requirements varied significantly from one patient to another (range 80-280 ug.kg't.min'l), but cumulative requirements were not different between groups~ Rapid awakening was observed in all four groups (5=3, 4=2, 6==3 and 6• rain for groups PLAC, M-15, M-30 andM-45, respaotively). Unexpectedly, however, six patients experienced awareness with recall using this technique (4 of 23 patients in the PLAC group compared with 2 of 67 patients in the mldezolam treatment groups, P<0.02, Table). Five of the 6 patients experienced mild or moderate pain with their re(all, but no patient described any psychologlcat distress or anxiety, In fact, despite their ~perlence of awareness, 3 of the 6 patients related the quality of this anaesthetic to heve been superior to their last anasst hotic, For ethical reasons, the study was stopped. DISCUSSION: Despite the high quality of recovery, TIVA was associated with an unacceptably high incidence of awareness with recall In this study. This may have been due, In part, to the relatively low initial infusion rate of propofoL We unexpectedly found that low dose mldazolam (0.015-0,045 rag.ks "t) reduces the likelihood of intraoperative awareness, without prolonging recovery times REFERENCE:
