Lorazepam has been studied as preanaesthetic medication given by mouth, i.m. and i.v. Sediation and side-effects and the incidence of anterograde amnesia in patients having a standard operation under methohexitone-nitrous oxide-oxygen anaesthesia were assessed. In a preliminary study of three i.m. (2-, 4- and 8-mg) and six oral (1-,2-,2.5-,4-,5- and 8-mg) doses, the optimum dose was found to be 4 mg for patients with an average weight of 60 kg. This dose was studied in detail when given by all three routes and compared with the commercially available 2.5- and 5-mg tablets. Even when given i.v., there was a delay of 30-40 min in the onset of maximum sedative effect and drowsiness persisted for at least 4 h. Although the onset of action by i.m. injection was slightly faster than when the drug was given by mouth this advantage was more than offset by the high frequencies of pain at the site of injection and restlessness which persisted for 20-40 min. Oral lorazepam in doses of 2.5-5.0 mg was a reliable, effective sedative which could be recommended for routine preanaesthetic medication, provided rapid recovery was not essential. Its soporific effect was accompanied by an appreciable incidence of anterograde amnesia.

Emergence excitement or delirium and unpleasant postoperative dreams are the most undesirable sequelae of ketamine. Their occurrence has made it an unacceptable form of anaesthesia in adults, except when there is a specific indication for its use. Psychic sequelae occur more commonly in women than in men' and their incidence is related to the nature and duration of the and of the patient. A number of drugs have been given before, during or after anaesthesia to help reduce undesirable s e q~e I a e ,~* '~~ but it is difficult to compare their efficacy because of the varying types of operations and differing methods of interpretation of data. This paper reports a study in which ten drugs were given, alone or in combination, as intravenous premedication to a standard patient population anaesthet ised with ketamine alone and subjected to a standard follow-up. MethodPatients were undergoing morning minor gynaecological operations in one of two hospital units. The contraindications to the inclusion of a patient in the study were hypertension, a history of a cerebral vascular accident or psychiatric upset.Anaesthesia was induced with 2 mg/kg ketamine and maintained with intermittent doses in the region of 0.25 mg/kg as required. Arterial pressure and heart rate were measured at frequent intervals throughout and observations made during anaesthesia were standardised according to the scheme described by Dundee, Moore & Nich01l.~ Only the incidence of 'unacceptable' anaesthesia is presented here and this is defined as: 'Anaesthetic conditions making surgery difficult or impossible (hypertonus, involuntary movement, etc). or a sustained rise in systolic or diastolic pressure of 30+mmHg, or heart rate above 120 bpm.' These did not preclude the successful completion of the operation as operating conditions were often transformed by the use of nitrous oxide-oxygen with or without halothane or trichloroethylene.Patients were observed closely at the end of operation and the occurrence and severity of emergency delirium noted. This was classed as mild or severe, the latter implying screaming which would upset other patients or attendants. In all instances this was rapidly terminated by the intravenous injection of diazepam, droperidol or physostigmine.At a visit made 6 or 24 h after operation patients were questioned about the occurrence of 'dreams' which were classed as unpleasant or pleasant according to their content. At this visit patients were asked if, in the event of their

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