The respiratory responses to intravenous morphine sulphate (0.12 mg/kg), morphine-6-glucuronide (M6G: 0.03 mg/kg) and placebo were assessed in 6 healthy volunteers, using a single blind randomised crossover design. Five of these subjects underwent an additional study of M6G at 0.06 mg/kg. Respiratory rate, minute volume and end-tidal CO2 were continuously measured using a low resistance non-rebreathing circuit, a mass spectrometer and a dry gas meter. The ventilatory responses to CO2 exposures (5.5% for 4 min) were assessed 40 and 20 min before, and 20, 40 and 80 min after drug administration. Following placebo and M6G (at both doses) no change in end-tidal CO2 occurred whilst the subjects were breathing air, whereas following morphine a significant rise was seen (P less than 0.05). Morphine reduced the ventilatory response to 5.5% CO2 at all times tested (P less than 0.05) and M6G (at both doses) reduced the response to CO2 at 20 and 40 min after administration, but to a lesser degree than did morphine (P less than 0.05).

The analgesic efficacy and CSF pharmacokinetics of intrathecal morphine sulphate and morphine-6-glucuronide (M6G) were compared in a single-blind crossover study. Lumbar intrathecal catheters were sited in three patients with chronic cancer pain, and morphine sulphate 500 micrograms or M6G 500 micrograms given via the catheter on separate days. CSF was sampled for 24 h following drug administration and analysed for morphine and M6G by high pressure liquid chromatography. The mean (SD) requirement for patient controlled analgesia with pethidine was 393.3 (227.4) mg/24 h during the morphine limb of the trial and 226.7 (113.6) mg/24 h during the M6G limb. M6G was not detected in CSF following administration of morphine. Fitting of CSF concentrations to triexponential curves revealed mean (SD) alpha, beta and gamma half-lives of 13.2 (7.4), 54.9 (31.5) and 222.5 (100) min for morphine and 11.2 (2.4), 67.3 (49.9) and 619.3 (629.7) min for M6G.

SummaryA case is described in which paraplegia followed a coeliac plexus block performed using 90% alcohol under X ray screening. The likely cause was an ischaemic injury to the cord secondary to damage to the artery ofrldamkiewicz. This rare complication seems difficult to avoid.

Over a four-year period from October 1984 to September 1988, a total of 101 coeliac plexus blocks were performed in this unit. Of these, 89 were in patients suffering intractable abdominal pain due to cancer, and 12 were in patients with pain secondary to benign disease processes. All were performed using X-ray screening and with intravenous sedation rather than general anaesthesia. Excellent or good pain relief was obtained in 80% of the patients with malignant disease, whilst 50% of patients with benign disease had good or complete relief of pain. The only serious complication encountered was a case of paraplegia - probably due to spinal cord ischaemia secondary to damage of the artery of Adamkiewicz.