Effect of stimulation of the P6 antiemetic point on postoperative nausea and vomiting.

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.

Comparison of nalbuphine, pethidine and placebo as premedication for minor gynaecological surgery.

In a randomized double-blind placebo-controlled trial involving 80 patients nalbuphine 10 mg and 20 mg were compared with pethidine 100 mg and a placebo given i.m. at least 90 min before minor gynaecological surgery. Nalbuphine proved a suitable alternative to pethidine, producing beneficial sedation which was maximum at 60 min after injection. Both nalbuphine and pethidine reduced the excitatory sequelae of methohexitone induction. Increasing the dose of nalbuphine from 10 mg to 20 mg produced no significant additional sedation or intraoperative benefit. Short-lived pain at the injection site was a feature of the use of nalbuphine in either dose. The main disadvantage of nalbuphine was nausea and vomiting of delayed onset, the frequency of which was similar after either dose.

Traditional Chinese acupuncture: a potentially useful antiemetic?

Two consecutive studies were undertaken to evaluate the effectiveness of acupuncture as an antiemetic used in addition to premedication with opioids in patients undergoing minor gynaecological operations. In the first study 25 of the 50 patients underwent acupuncture immediately after premedication with 100 mg meptazinol, the rest receiving the drug alone, and in the second 75 patients were allocated randomly to one of three groups: a group receiving 10 mg nalbuphine and acupuncture, a group receiving premedication and dummy acupuncture, and a group receiving premedication alone. Manual needling for five minutes at the P6 acupuncture point (Neiguan) resulted in a significant reduction in perioperative nausea and vomiting in the 50 patients who underwent acupuncture compared with the 75 patients who received no acupuncture. These findings cannot be explained, but it is recommended that the use of acupuncture as an antiemetic should be explored further.

The influence of cyclizine and perphenazine on the emetic effect of meptazinol.

The effectiveness of 50 mg cyclizine and 2.5 mg perphenazine against the emetic sequelae of 100 mg meptazinol were studied in a randomized double-blind placebo-controlled trial. Three groups of 40 women received the opioid, together with an anti-emetic by i.m. injection, as premedication prior to minor gynaecological surgery. Beneficial or noxious effects were noted at standard time intervals and anaesthesia standardized as incremental methohexitone with nitrous oxide/oxygen. In the placebo group, 33 out of 40 subjects experienced either nausea or vomiting at some time after the opioid. Cyclizine, 50 mg, provided significant reduction of emetic tendency in both pre-operative and post-operative phases of the study with 22 out of 40 subjects experiencing nausea or vomiting overall. Perphenazine, 2.5 mg, showed no useful anti-emetic effect. Both anti-emetics increased the soporific effect of premedication at the 90-min interval. Subjects receiving perphenazine experienced significantly more dizziness than those of other groups.

Failure of magnesium sulphate to prevent suxamethonium induced muscle pains.

In fit unpremedicated patients undergoing minor operations and who were ambulant on the afternoon of the operations, pretreatment with magnesium sulphate given intravenously did not reduce the incidence of suxamethonium induced myalgia below that in a similar series who received no prophylactic therapy. The injection of magnesium in conscious patients is followed by unpleasant side effects.

Failure of two benzodiazepines to prevent suxamethonium-induced muscle pain.

In a randomised double-blind trial carried out on fit, unpremedicated patients undergoing standard minor operations with early postoperative mobility, using a standard form of anaesthesia, pretreatment with diazepam 0.15 mg/kg or midazolam 0.1 mg/kg failed to reduce significantly the incidence of postoperative muscle pains following suxamethonium 1 mg/kg. By contrast, tubocurarine 0.05 mg/kg proved to be effective as a pretreatment. Neither benzodiazepine influenced the incidence or severity of fasciculations seen with suxamethonium or the duration of neuromuscular block. Tubocurarine virtually abolished visible fasciculation and, in the dose used, reduced the intensity and duration of the neuromuscular block. There were no clinically significant changes in serum potassium, creatinine phosphokinase or aldolase after suxamethonium, although 5 out of 47 showed an atypical rise in creatinine phosphokinase.