British journal of anaesthesia
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It has been suggested previously that tramadol increases central nervous system activity and 'lightens' anaesthesia with volatile agents. We assessed the effects of tramadol on the minimum alveolar concentration (MAC) of isoflurane in 56 Wistar rats, instrumented chronically with an arterial and central venous catheter. The MAC of isoflurane was determined using the tail clamp method under three conditions: (1) after injection of saline (control); (2) after administration of tramadol 10 mg kg-1 i.v.; and (3) after administration of morphine 1 mg kg-1 i.v. ⋯ In contrast, after pretreatment with naloxone, tramadol (1.47 (0.04)%) or morphine (1.38 (0.07)%) did not cause a reduction in the MAC of isoflurane compared with controls (1.39 (0.06)%). We conclude that tramadol and morphine reduced the MAC of isoflurane to a small but significant extent. For both drugs, this effect was related to their action at opioid receptors.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Comparison of 0.25% S(-)-bupivacaine with 0.25% RS-bupivacaine for epidural analgesia in labour.
We have compared the efficacy of 0.25% S(-)-bupivacaine with 0.25% RS-bupivacaine in providing epidural analgesia for labour in a randomized, multicentre, double-blind study. Analgesia was initiated with 10 ml of the study solution and maintained with 10-ml top-ups. We studied 137 women and treatments were found to be equivalent for onset, duration and quality of block. ⋯ However, median duration of pain relief from the first top-up was 82 (range 3-164) min for S(-)-bupivacaine and 76 (22-221) min for RS-bupivacaine. There were no significant differences in the quality of analgesia, as assessed by the investigators. There were no significant differences in the extent of sensory block, percentage of patients with motor block or incidence of adverse events.
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Randomized Controlled Trial Comparative Study Clinical Trial
Evaluation of pressure changes in a new design tracheal tube cuff, the Portex Soft Seal, during nitrous oxide anaesthesia.
We have measured pressure changes in a newly designed tracheal tube cuff, the Portex Soft Seal, during nitrous oxide anaesthesia compared with a Mallinckrodt Lo-Contour tube and a Portex Profile tube. The pressure increases in both control groups were significantly greater than those with the new design (P < 0.0001 in each case). The mean increase in pressure in the Mallinckrodt Lo-Contour tube cuff was 9.9 (SD 3.4) mm Hg compared with 10.3 (1.8) mm Hg in the Portex Profile tube cuff and 2.1 (1.5) mm Hg in the Portex Soft Seal tube cuff. We conclude that the Portex Soft Seal cuff prevented a significant increase in intracuff pressure during nitrous oxide anaesthesia.
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Randomized Controlled Trial Clinical Trial
Posterior epidural space depth: safety of the loss of resistance and hanging drop techniques.
We have compared skin to epidural space distance (SED) and tip to tip distance (TTD), a measure of posterior epidural space depth (PESD), in 40 patients with a 27-gauge Whitacre needle after identification of the epidural space using the hanging drop (HD) or loss of resistance (LOR) to air technique. After the LOR technique, TTD was found to be 2 mm greater than that after the HD technique, whereas SED was the same. We conclude that identification of the epidural space can be performed successfully with both techniques, but with a diminished risk of dural damage after LOR compared with the HD technique.
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Randomized Controlled Trial Comparative Study Clinical Trial
Antagonism of rapacuronium using edrophonium or neostigmine: pharmacodynamics and pharmacokinetics.
We have studied the pharmacodynamics and pharmacokinetics of rapacuronium (Org 9487) in 70 healthy patients. Neuromuscular transmission was monitored using TOF stimulation of the ulnar nerve and mechanomyography of the adductor pollicis muscle. Half of the patients were given a single dose of rapacuronium 1.5 mg kg-1 and the remainder rapacuronium 1.5 mg kg-1 with three incremental doses of 0.5 mg kg-1, each given when T1/T0 had recovered to 25%. ⋯ A three-compartment pharmacokinetic model was justified. Typical values for clearance and initial volume of distribution (V1) were 4.4 ml kg-1 min-1 and 94.8 ml kg-1, respectively. In females, clearance was decreased by 38.5% compared with males and V1 was decreased by 25% in patients aged more than 65 yr.