British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Effect of apparatus on functional residual capacity.
As the route of breathing and use of airway apparatus such as mask, mouthpiece and noseclip can alter breathing pattern, this study has used the helium dilution method to estimate the effects of mouthpiece and mask breathing on functional residual capacity (FRC) in the supine position, and the change in FRC that occurs between the sitting and supine positions while breathing by mouthpiece. In 13 normal subjects, breathing by mouthpiece, FRC was smaller, by a median of 1.07 litre (interquartile values 0.73-1.43 litre) in the supine compared with the sitting position (P < 0.01), but residual volume (RV) did not change significantly. FRC measured in the supine position was significantly greater when breathing by mask than by mouthpiece (0.25, 0.04-0.38 litre) and RV was greater by similar amounts (0.20, -0.02 to 0.49 litre). This difference may result from increased inspiratory activity while breathing via the mask.
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We have studied rats with chronically implanted subarachnoid catheters. Xylazine, an alpha 2 adrenoceptor agonist, was injected intrathecally and nociceptive thresholds measured at two skin sites: the tail and the neck. Intrathecal xylazine (dose range 24.3-389 nmol) produced increases in electrical thresholds for nociception in the tail without any change in the neck; this observation suggested that the antinociceptive action of this drug was confined to the caudal part of the spinal cord responsible for tail innervation. ⋯ In contrast, the antinociceptive effects of intrathecal xylazine were not affected by concurrent administration of opioid or GABAA antagonists. We conclude that intrathecal xylazine produced spinally mediated antinociceptive effects by combination with spinal cord alpha 2 adrenoceptors and that neither opioid nor GABA-containing propriospinal neurones were involved in the mediation of this effect. However, alpha 2 adrenoceptors in the spinal cord appear to be involved with antinociception produced by intrathecal fentanyl.
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Randomized Controlled Trial Comparative Study Clinical Trial
Rocuronium pretreatment reduces suxamethonium-induced myalgia: comparison with vecuronium.
We have studied, in 150 patients undergoing elective oral surgery, the effectiveness and sequelae of pretreatment with rocuronium for reducing myalgia after suxamethonium. Patients were allocated randomly to one of three groups: anaesthesia was induced with propofol and fentanyl, and group V received vecuronium 1 mg, group R rocuronium 6 mg and group P placebo pretreatment. Suxamethonium 1.5 mg kg-1 was given 60 s after the pretreatment agent. ⋯ The incidence of postoperative myalgia on day 1 after rocuronium (20%) was significantly less than after vecuronium (42%) (P < 0.05) or placebo (70%) (P < 0.01). By day 4 the incidence of myalgia was 28.6% in the rocuronium group, 46.3% in the vecuronium group and 95% in the placebo group. Intubating conditions were not affected adversely by any pretreatment regimen.