British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of midazolam, diazepam and placebo i.m. as premedication for regional anaesthesia. A randomized double-blind study.
In a randomized double-blind study, midazolam 0.1 mg kg-1 i.m. was compared with diazepam 0.2 mg kg-1 and placebo as premedication for patients undergoing urological interventions under spinal anaesthesia. The sedative and anxiolytic effects of midazolam were evident 5-10 min after administration, and were maximum between 30 and 90 min. ⋯ Amnesia was not seen in the patients receiving diazepam or placebo and, in contrast to midazolam, diazepam had almost no sleep-inducing effect. In a few patients, the depth of sleep achieved with midazolam 0.1 mg kg-1 was such that co-operation was impaired.
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Randomized Controlled Trial Clinical Trial
Clinical study of a lignocaine-prilocaine cream to relieve the pain of venepuncture.
The efficacy of a topical anaesthetic formulation, EMLA 5% cream (Eutectic Mixture of Local Anaesthetics) in obtunding the pain produced by venepuncture, was determined in a double-blind randomized, cross-over study in 31 adult volunteers. Pain was registered on a 10-cm visual analogue scale. ⋯ Transient skin reactions (blanching, erythema and oedema) were observed with both formulations. These reactions were not found to be aggravated by repeated applications.
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Airway patency was explored in patients breathing spontaneously under deep halothane anaesthesia. Opening and closing of the airway was observed with a flexible bronchoscope looking proximally from the nasopharynx at the epiglottis and the tongue. With the occiput elevated at various angles the smallest angle of retroflexion of the neck necessary to open the airway was measured. ⋯ Cadaveric preparations of the upper airway were studied to assess the mechanisms involved in airway patency. The results indicate that the epiglottis and not the tongue is the main cause of obstruction of the upper airway. When methods are applied to displace the hyoid anteriorly, the airway will be cleared on most occasions.
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Comparative Study
Comparative pharmacology of the ketamine isomers. Studies in volunteers.
The clinical and electroencephalographic (EEG) effects of the individual ketamine isomers were compared with the racemic mixture in five volunteers who received each drug on a separate occasion. Racemic ketamine 275 +/- 25 mg, s(+) ketamine 140 +/- 21 mg or R(-) ketamine 429 +/- 37 mg produced an anaesthetic state lasting 6 +/- 2 min (mean +/- SD). However, the EEG evaluation of the R(-) isomer revealed less overall slowing, and an absence of the large slow wave complexes produced by the S(+) isomer and the racemic mixture. ⋯ The serum ketamine concentrations associated with regaining consciousness and orientation were consistent with an S(+):R(-) isomer potency ratio of 4:1. In terms of their ability to impair psychomotor function, the S(+):R(-) potency ratio varied from 3:1 to 5:1. After comparable degrees of CNS depression, we conclude that the more potent S(+) isomer of ketamine was associated with a more rapid recovery of psychomotor skills than the currently used racemic mixture.