British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
IV lignocaine fails to attenuate the cardiovascular response to laryngoscopy and tracheal intubation.
I.v. lignocaine has been used with varying success to attenuate the cardiovascular responses to laryngoscopy and tracheal intubation. We determined the optimal time of administration in 45 ASA I and II Chinese patients premedicated with morphine and hyoscine, and anaesthetized with thiopentone and suxamethonium. Patients were allocated randomly to a control group or three treatment groups to receive lignocaine 1.5 mg kg-1 i.v. 1, 2, or 3 min before laryngoscopy. Analysis of variance for measured and derived cardiovascular variables failed to show any significant difference between any of the groups.
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Randomized Controlled Trial Clinical Trial
Spinal anaesthesia with hypobaric 0.19% or plain 0.5% bupivacaine.
Hypobaric 0.19% bupivacaine (plain 0.5% bupivacaine 3 ml + distilled water 5 ml) was compared with 0.5% plain bupivacaine 3 ml for spinal anaesthesia in 29 healthy patients undergoing orthopaedic surgery of the lower extremities. The solutions were injected at the L3-4 interspace in 40 s, and patients were kept sitting for 2 min after injection. The mean maximal cephalad spread of sensory block was to the T1 segment (SD 3.6) and to T8 (4.1) in the hypobaric and plain bupivacaine groups, respectively (P less than 0.0001). ⋯ In most patients, the hypobaric bupivacaine block affected the upper thoracic nerves, and in three patients the cervical nerves also. The high levels of block were accompanied by marked hypotension. The extensive spread of the blocks makes this hypobaric spinal anaesthesia technique unsuitable for routine use.
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Randomized Controlled Trial Clinical Trial
Effect of flumazenil on midazolam-induced amnesia.
We have studied the effect of i.v. flumazenil 0.01 mg kg-1 on the amnesia and sedation caused by midazolam 2 mg and 5 mg i.v. in volunteers in order to determine the relationship between the actions of the antagonist on these two effects. Midazolam caused dose-dependent central neural depression as assessed by critical flicker fusion frequency, and dose-dependent amnesia for word cards. In subjects given flumazenil 5 min after administration of midazolam, fusion frequency readings and memory were restored to levels comparable to those before midazolam administration. ⋯ Flumazenil given alone had no effect on memory. The study has demonstrated anterograde amnesia following benzodiazepine administration and antagonism by flumazenil. There was neither retrograde amnesia nor retrograde antagonism of amnesia.
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Plasma concentrations of methadone were measured by gas chromatography in 16 patients receiving extradural methadone by continuous infusion for relief of postoperative pain. Venous blood samples were taken after a loading dose of extradural methadone 2 mg and during infusion of 0.46 mg h-1 plus patient-controlled increments of 0.2-1 mg. Mean (SD) plasma concentration of methadone was 9.8 (2.1) ng ml-1 at 15 min; this did not change significantly during the first 2 h, after which it increased gradually to 32.2 (4.6) ng ml-1 (P less than 0.001) at the end of 24 h. ⋯ No adverse effects were detected during the 2-3 days of methadone therapy. Plasma concentration of methadone increased significantly during patient-controlled infusion of extradural methadone in the first 24 h after operation, suggesting rapid vascular uptake. Systemic activity of the drug contributes to the analgesic effect of extradural methadone.