Failure of intramuscularly administered lorazepam and scopolamine-morphine premedication to produce amnesic effects to supplement conduction anaesthesia.

Patients undergoing surgery under regional anaesthesia often prefer to be sedated and do not later want to recall the procedure. One hundred and twenty-one patients scheduled for various surgical procedures under epidural, spinal, sacral, or brachial plexus blockades received 1 mg/kg of pethidine, 0.007 mg/kg of scopolamine, plus 0.14 mg/kg of morphine, or 0.03 mg/kg or 0.06 mg/kg or lorazepam intramuscularly as preanaesthetic medication before the operation. The patients's self-assessments of degree of fatigue and apprehension were similar after each premedication when assessed before operation. Postoperative anxiety and confusion as well as need for postoperative care and supervision were greatest after 0.06mg/kg of lorazepam. Significantly (P smaller than 0.05 to P smaller than 0.01) fewer patients given 0.06 mg/kg or lorazepam remembered different events and procedures carried out on them before and after operation than those given other premedications, but no significant differences were noted in patients' ability to recall the performance of operation when asked on the following day. Seventy-seven, 63, and 57% of patients receiving 0.06 mg/kg of lorazepam remembered the start of blockade, performance of operation, and stay in recovery room, respectively. Intravenous sedation should be preferred to these intramuscularly administered premedications if drug-induced amnesia is sought to supplement local anaesthetic techniques.