M.D. Vickers

Tramadol: pain relief by an opioid without depression of respiration

Two independent clinical trials were conducted simultaneously. In one, tramadol and pethidine were compared in 30 patients by patient‐controlled analgesia during the first 24 h following abdominal surgery. The mean 24 h consumption of tramadol and pethidine was 642 mg and 606 mg respectively, giving a potency estimate of tramadol relative to pethidine of 0.94 (95% confidence interval 0.72–1.17). In the second trial, the effect on respiration of three doses of tramadol (0.5, 1.0, and 2.0 mg.kg−1) was compared with that of morphine sulphate (0.143 mg.kg−1) by intravenous injection during stable halothane anaesthesia. At approximately 1.5 times the equipotent dose, as estimated from the first trial, tramadol transiently depressed the rate of respiration but had no effect on end‐tidal carbon dioxide tension. Morphine caused apnoea or considerable depression of ventilation. The results suggest that mechanisms other than opioid receptor activity play a significant role in the analgesia produced by tramadol.

Self-administered nalbuphine, morphine and pethidine. Comparison, by intravenous route, following cholecystectomy.

In a double‐blind clinical trial of 48 patients, nalbuphine, morphine, and pethidine were compared by on‐demand intravenous analgesia during the first 24 hours after cholecystectomy. Overall pain relief (visual analogue score) was recorded by the patients as 50 (SEM 4) for nalbuphine, 44 (SEM 4) for morphine and 53 (SEM 5) for pethidine. These scores were not significantly dfferent. The mean demand for each drug over the 24‐hour period was 70 (SEM 12) mg for nalbuphine, 46 (SEM 6) mg for morphine and 614 (SEM 49) mg for pethidine. Pain on movement, either during deep breathing or turning, was found to be less well controlled after nalbuphine (70, SEM 2), and pethidine (67 SEM 7) than after morphine (52, SEM 5; p < 0.01). The incidence of side effects was similar with each drug. Nalbuphine is a useful postoperative analgesic, as effective as pethidine. Nalbuphine 15 mg is apparently equipotent with morphine 10 mg or pethidine 120 mg by this mode of administration.

Intramuscular on demand analgesia: double blind controlled trial of pethidine, buprenorphine, morphine, and meptazinol.

An on demand intramuscular analgesic system using the Cardiff Palliator was tested. Forty consenting patients were studied after cholecystectomy in a double blind trial using increments of buprenorphine (0.15 mg), meptazinol (50 mg), morphine (5 mg), and pethidine (50 mg). Most patients attained good levels of pain relief (mean analogue pain score 36.5), comparable to intravenous on demand analgesia. There were no technical complications. Significant differences were found between drugs in dizziness (pethidine produced the worst score) but not with other side effects. Buprenorphine produced longer lasting analgesia than meptazinol or pethidine and also gave the lowest pain scores. Patterns of analgesic consumption were the same as with intravenous on demand systems, but larger amounts of drug were generally used. Relative analgesic potencies derived from drug consumption rates were also consistent with those from intravenous on demand studies. An on demand intramuscular analgesic system offers a simple but effective means of relieving severe postoperative pain.

Effect of premedication with controlled-release oral morphine on postoperative pain. A comparison with intramuscular morphine.

Thirty five patients presenting for elective total hip replacement were randomly allocated to receive a premedication of 60 or 90 mg controlled‐release oral morphine or 15 mg intramuscular morphine. Postoperative analgesia was assessed using on‐demand intravenous pethidine supplementation requirements. In 15 patients free plasma morphine concentrations were measured. Both 60 and 90 mg controlled‐release oral morphine led to a reduced pethidine requirement compared to the intramuscular group but the reduction was not statistically different.

A new anaesthetic record

Record‐keeping is part of the proper practice of anaesthesia and a record should be able to be quickly and easily completed. Two types of information need to be recorded: clinical, for use both immediately or subsequently and epidemiological, for detailed study of a large number of anaesthetics. A design which answers both these aims is described.

Explosion hazards in anaesthesia

During the 8 years 1947 to 1954 there were 36 explosions in the UK, of which 3 were fatal. Twenty-seven of these occurred in the last 4 years of that period and no less than 5 had occurred in the first 6 months of 1954. It was in this climate that the Ministry of Health set up a Working Party to enquire into explosions in operating theatres, which reported in 19561. The recommendations of this Working Party have formed the basis for current practice in operating theatres. There can be little doubt that the Working Party’s recommendations have been effective. Since 1956 there have not been any explosions associated with a fatality in circumstances where all the recommendations of the Working Party have been implemented. This has not been achieved without cost, however. For example, the excess cost involved in fitting sparkless switches in theatres is estimated to have been a quarter of a million pounds since 1956, although there was no evidence that any explosion had ever been caused by a fixed switch (Dobbie, A. K. -personal communication, 1969). In 1968, the then Ministry of Health approached the Association of Anaesthetists of Great Britain and Ireland and suggested that, in certain respects, the recommendations had erred on the side of excessive caution and that unnecessary expense was being incurred in protecting against hazards which, in the light of a further 20 years’ experience, were negligible. The Council of the Association considered that some additional experimental work would be helpful, and this has been undertaken with the co-operation of the Electrical Safety Engineer of the Department of Health.

Naloxone reversal of meptazinol‐induced respiratory depression

The effects of intravenous meptazinol on respiratory rate and end‐tidal CO2 concentrations were investigated in a group of 20 anaesthetised subjects. In clinically effective doses, meptazinol produced a dose‐related fall in respiratory rate and elevation in end‐tidal CO2 concentration. Naloxone reversed these effects.

The Cardiff Aldavac anaesthetic‐scavenging system

The Cardiff Aldavac system consists of a reservoir, adsorption canister, flow restrictor and the necessary pipe connections. It enables theatre pollution control without structural alteration or special installation. It utilizes the hospital piped medical vacuum system but protects the system from excessive flows or contamination by volatile anaesthetics and still allows the vacuum to be used for other purposes.

Wind of change. III. The Royal Colleges

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Antibiotics and fatigue

EDITOR, - It is bad enough when an unjustified conclusion slips past the gatekeepers, but when it is perpetrated by the editor himself1 one …