Midazolam is a short-acting water-soluble benzodiazepine (at pH less than 4), a member of a new class of imidazobenzodiazepine derivatives. At physiological pH the drug becomes much more lipid soluble. Water solubility minimises pain on injection and venous thrombosis compared with diazepam administered in organic solvent. Midazolam is a hypnotic-sedative drug with anxiolytic and marked amnestic properties. To date it has been used mostly by the intravenous route, for sedation in dentistry and endoscopic procedures and as an adjunct to local anaesthetic techniques. It has proved less reliable than thiopentone, but preferable to diazepam, as an intravenous induction agent and is unlikely to replace the other well established drugs. However, due to the cardiorespiratory stability following its administration, midazolam is useful for anaesthetic induction in poor-risk, elderly and cardiac patients. The short elimination half-life (1.5-3.5h) and the absence of clinically important long acting metabolites make midazolam suitable for long term infusion as a sedative and amnestic for intensive care, but clinical trials have yet to be completed. Thus, a combination of properties make midazolam a useful addition to the benzodiazepine group.

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The antiemetic action of stimulation of the P6 (Neiguan) acupuncture (ACP) point has been studied in women, premedicated with nalbuphine 10 mg, undergoing minor gynaecological operations under methohexitone-nitrous oxide-oxygen anaesthesia. Invasive ACP--manual or electrical at 10 Hz--applied for 5 min at the time of administration of the premedication markedly reduced the incidence of vomiting and nausea in the first 6 h after operation, compared with untreated controls. This did not occur with stimulation of a "dummy" ACP point outside the recognized ACP meridians. Non-invasive methods (stimulation via a conducting stud or by pressure) were equally as effective as invasive ACP during the early postoperative period. However, both these non-invasive approaches were less effective than invasive ACP in the 1-6 h postoperative period, although each was as effective as two standard antiemetics (cyclizine 50 mg, metoclopramide 10 mg). In view of the total absence of any side effects in more than 500 ACP procedures, the clinical applications of this finding are worthy of further study.

SummaryThe induction characteristics of thiopentone, etomidate and methohexitone have been compared to those of propofol(2,6 di-isopropyl phenol) in unpremedicated patients. Propofo12.5 mglkg caused significantly more hypotension, excitatory side effects and pain on injection at the dorsum of hand than thiopentone 5 mglkg. However, with regard to the latter two sequelae. etomidate 0.3 mglkg andmethohexitone I .5 mglkg caused similar or more frequent upset. Propofol2.0 mglkg was equipotent with thiopentone 4.0 mglkg in terms of successful induction of anaesthesia. Hypotension may contraindicate the use of propofol in the hypovolaemic or unfit patient.

In a multi-facet study we evaluated the efficacy of P6 electroacupuncture (10 Hz applied for 5 min) as an antiemetic in patients receiving a variety of cancer chemotherapy drugs. The study involved 130 (15 in an open pilot study, 10 in a randomized placebo controlled crossover study and 105 in a definitive study) patients who had a history of distressing sickness after previous treatment, and who, on the basis of a previous survey, would be expected to have a 96% chance of this with subsequent therapy. Sickness was either completely absent or reduced considerably in 97% of patients and no side effects were encountered. The limited crossover study, using a ‘dummy’ acupuncture (ACP) point showed that the beneficial effects were limited to the P6 point. Logistic and ethical considerations excluded the possibility of carrying out a larger placebo-controlled study. While in our hands P6 ACP was an effective antiemetic in patients having cancer chemotherapy, because of the time involved and the brevity of the action (8 h) an alternative approach to electro-ACP is required before this technique is adopted clinically.