British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Prevention of tourniquet pain by spinal isobaric bupivacaine with clonidine.
In order to assess the effect of spinal clonidine on tourniquet pain, 30 patients scheduled to undergo orthopaedic surgery under spinal anaesthesia were allocated randomly to two groups. Patients in group I (n = 15) received 0.5% isobaric bupivacaine 15 mg plus isotonic saline 1 ml. Patients in group II (n = 15) received 0.5% bupivacaine 15 mg plus clonidine 1 ml (150 micrograms). ⋯ Three patients in group I, but none in group II, experienced tourniquet pain. Hypotension and bradycardia were not worsened by spinal clonidine. The use of clonidine may be a useful technique to augment bupivacaine spinal block.
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Comparative Study
The auditory evoked response as an indicator of awareness.
The latency of the early cortical wave Nb of the auditory evoked response (AER) was compared with responses to Tunstall's isolated forearm test, while the concentration of nitrous oxide was progressively reduced during light anaesthesia in seven patients. A threshold Nb latency of 44.5 ms was chosen to discriminate between an early cortical AER containing three waves and that with two waves of longer latency. ⋯ The addition of a volatile anaesthetic abolished any response, and increased Nb latency to more than 44.5 ms. The three wave AER pattern, therefore, is associated with a depth of anaesthesia at which awareness occurs.
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Comparative Study
Comparison of i.v. sedation with midazolam and inhalation sedation with isoflurane in dental outpatients.
I.v. midazolam was compared with inhalation sedation using isoflurane in 80 dental outpatients. Preoperative anxiety was comparable in both groups and decreased after operation to similar values. ⋯ Midazolam produced faster induction of sedation (P less than 0.001) and more amnesia for the injection of local analgesic (P less than 0.001), whereas isoflurane produced more euphoria (P less than 0.01) and quicker recovery (P less than 0.001). The incidence of postoperative side effects was similar in the two groups.
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Randomized Controlled Trial Clinical Trial
Transdermal fentanyl for the relief of pain after upper abdominal surgery.
Transdermal fentanyl (n = 22) was compared with placebo (n = 18) in a double-blind study of pain after upper abdominal surgery. All patients also received i.v. morphine on demand for supplementary analgesia. ⋯ After operation, pain scores were significantly lower and peak expiratory flow rates significantly higher in the transdermal fentanyl group, who demanded significantly less morphine than the control group. Mean plasma fentanyl concentrations at 12 and 24 h were within the therapeutic range (1.5 and 2.0 ng ml-1, respectively).
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This study was designed to investigate if propofol produced cardiovascular effects by direct actions or by indirect actions secondary to depression of the central nervous system. Experiments were performed on chloralose anaesthetized dogs in which all neurogenic cardiovascular reflexes were abolished by bilateral vagotomy and common carotid ligatures, in combination with i.v. bretylium and propranolol. Bolus doses of propofol followed by infusions at rates up to 160 mg kg-1 h-1 produced blood concentrations of propofol from 1.99 to 112 micrograms ml-1. ⋯ Blood concentrations of propofol less than 10 micrograms ml-1 caused an increase in mean capacitance of 8.0 (SEM 1) ml kg-1 with no significant changes in systemic vascular resistance, pulmonary vascular resistance or inotropic state of the heart. We conclude that anaesthesia with propofol may be accompanied by decreased cardiac output secondary to reduction in preload by a direct venodilator effect. Our experiments indicate that cardiac output and arterial pressure are preserved well at normal anaesthetic blood concentrations of propofol if the preload is maintained.