British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Spinal anaesthesia with hyperbaric bupivacaine: effects of concentration and volume administered.
A double-blind study was carried out using hyperbaric solutions of bupivacaine to compare the effects of varying the concentration of bupivacaine and the volume of solution administered intrathecally. Fifty-seven patients were studied. Ten patients received each volume of each concentration: 0.5% bupivacaine in 8% dextrose, 2 ml, 3 ml or 4 ml and 0.75% bupivacaine in 8% dextrose, 1.3 ml or 2 ml. ⋯ The use of 3 ml of this solution was abandoned after seven patients had received it because of the excessive spread. With both solutions, increasing the volume produced a longer duration of action. The use of a 0.75% solution of hyperbaric bupivacaine for spinal anaesthesia did not appear to confer any advantage over the 0.5% solution.
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Comparative Study
Alfentanil: a study of its analgesic activity and interactions with morphine in the mouse.
Alfentanil has a short duration action which did not markedly increase with increasing dose in mice. It is approximately one-fourth as potent as fentanyl. ⋯ This has been demonstrated with injection of alfentanil 15 min before, simultaneously with and 30 min after morphine injection. There were not significant effects on depression of respiratory rate produce by morphine.
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Neuromuscular transmission was measured using train-of-four stimulation, during and after anaesthesia, in 20 patients with end-stage renal failure. Neuromuscular blockade was provided with pancuronium in single doses of either 3 or 6 mg per 70 kg, and antagonized at 10% recovery with atropine and neostigmine 2.5 mg per 70 kg. ⋯ It is concluded that, when pancuronium is antagonized with neostigmine in patients with renal failure, neuromuscular transmission recovers without evidence of recurarization. However, when large doses of pancuronium are antagonized with neostigmine 2.5 mg, recovery may be insufficient to ensure normal ventilatory function.
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Clinical Trial Controlled Clinical Trial
Effect of hypocarbia and hypercarbia on the antagonism of pancuronium-induced neuromuscular blockade with neostigmine in man.
The effects of variations in carbon dioxide concentration on the antagonism of pancuronium-induced neuromuscular block by neostigmine were studied in 21 patients: normocarbia (PE'CO2 5.4%, PaCO2 4.93 kPa, n = 7), hypocarbia (PE'CO2 3.6%, PaCO2 3.30 kPa, n = 7) and hypercarbia (PE'CO2 7.5%, PaCO2 7.13 kPa, n = 7). Mechanical and electromyographic responses to ulnar nerve stimulation (0.1 Hz and 2 Hz) were recorded. A 90% block during nitrous oxide in oxygen anaesthesia was maintained by incremental single injections of pancuronium and reversed with neostigmine 0.35 mg kg-1 with atropine 0.0175 mg kg-1. ⋯ A residual block of about 10% was seen in hypercarbic patients. However, the recovery of e.m.g. amplitude and train-of-four ratios was similar in all groups. Thus, the impaired recovery of twitch tension seems to be the result of depressed contractility rather than failure of neuromuscular transmission.