British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Cricoid pressure applied after placement of the laryngeal mask prevents gastric insufflation but inhibits ventilation.
We studied 50 patients, in a blind, crossover study, to assess if cricoid pressure applied after placement of the laryngeal mask prevented gastric insufflation without affecting ventilation. After induction of anaesthesia and neuromuscular block, a laryngeal mask was inserted and confirmed to be placed correctly. The lungs were ventilated with a maximum inflation pressure of 15 cm H2O. ⋯ In no patient was the mask dislodged after these procedures. Thus, although cricoid pressure applied after insertion of the laryngeal mask prevented gastric insufflation, it also decreased ventilation. The inhibitory effect of cricoid pressure on ventilation without support of the neck was greater than cricoid pressure with support of the neck.
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Randomized Controlled Trial Comparative Study Clinical Trial
Spinal clonidine produces less urinary retention than spinal morphine.
We have conducted a double-blind, randomized study in two groups of 20 patients each, undergoing hip surgery during spinal anaesthesia, to compare the incidence of urinary retention after spinal morphine or clonidine. Patients received 0.5% spinal bupivacaine 15 mg combined with either clonidine 75 micrograms or morphine 0.2 mg. ⋯ Naloxone was given in 16 and one, and a catheter was placed in one and six patients in the morphine and clonidine groups, respectively (P < 0.001). We conclude that spinal clonidine impaired bladder function to a lesser extent than morphine.
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Comparative Study
Differential effects of desflurane and halothane on peripheral airway smooth muscle.
Volatile anaesthetics have been shown to have direct relaxant effects on airway smooth muscle. We have examined the effects of 0.9, 1.9, and 2.8 dog MAC of desflurane and halothane on isolated proximal and distal canine airways precontracted with acetylcholine. The proximal and distal airway smooth muscle relaxed with increasing concentration of each anaesthetic in a dose-related manner. ⋯ The distal airway smooth muscle was more sensitive to volatile anaesthetics than the proximal airway smooth muscle with either halothane or desflurane at all concentrations tested. This effect may be a result of differences in cartilage content, myosin content, epithelium-dependent effects, receptor density, myofilament sensitivity to Ca2+, sarcoplasmic reticulum Ca2+ control, or ionic fluxes in the proximal airway compared with the distal airway. The increased sensitivity of airway smooth muscle to desflurane compared with halothane is not known but may be related to possible differences in the effects of Ca2+ homeostasis.