British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Is there implicit memory after propofol sedation?
Recent evidence indicates that implicit memory may be preserved during general anaesthesia. We tested for the presence of explicit and implicit memory in patients undergoing surgical procedures with local or regional anaesthesia and sedation with propofol. Initial i.v. boluses of propofol 0.5 mg kg-1 and fentanyl 1 microgram kg-1 were administered, followed by an infusion of propofol 50 micrograms kg-1 min-1. ⋯ However, the free association tests demonstrated significant priming. The mean number of critical free associations was 6.6 (SEM 0.4) compared with 5.5 (0.4) neutral free association (P < 0.05). In the absence of explicit memory, implicit memory persists after intraoperative sedation with propofol.
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We have studied rats with chronically implanted subarachnoid catheters. Xylazine, an alpha 2 adrenoceptor agonist, was injected intrathecally and nociceptive thresholds measured at two skin sites: the tail and the neck. Intrathecal xylazine (dose range 24.3-389 nmol) produced increases in electrical thresholds for nociception in the tail without any change in the neck; this observation suggested that the antinociceptive action of this drug was confined to the caudal part of the spinal cord responsible for tail innervation. ⋯ In contrast, the antinociceptive effects of intrathecal xylazine were not affected by concurrent administration of opioid or GABAA antagonists. We conclude that intrathecal xylazine produced spinally mediated antinociceptive effects by combination with spinal cord alpha 2 adrenoceptors and that neither opioid nor GABA-containing propriospinal neurones were involved in the mediation of this effect. However, alpha 2 adrenoceptors in the spinal cord appear to be involved with antinociception produced by intrathecal fentanyl.
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In pneumoperitoneum, carbon dioxide eliminated in expired gas (carbon dioxide output) contains both metabolic and absorbed carbon dioxide from the peritoneal cavity. When elimination of carbon dioxide is much higher than carbon dioxide output, storage of tissue carbon dioxide and arterial carbon dioxide concentrations change. Finally, the rate of carbon dioxide eliminated in expired gas is not a match for the real rate of metabolic production and absorbed carbon dioxide from the peritoneal cavity. ⋯ After removal of carbon dioxide from the abdominal cavity, the regression equation of excess carbon dioxide output/BSA best fitted a two-compartment model. The time constants of the rapid and slow compartments were 8.2 and 990 min, respectively. Excess carbon dioxide output/BSA was still 5.5 ml min-1 m-2, 30 min after pneumoperitoneum.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Single-dose i.v. granisetron in the prevention of postoperative nausea and vomiting.
In this randomized, double-blind, parallel group, placebo-controlled, dose-ranging study, we have compared three doses (0.1 mg, 1.0 mg and 3.0 mg) of the 5-HT3 receptor antagonist, granisetron (Kytril), as prophylactic therapy for the prevention of postoperative nausea and vomiting. The aims were to determine the optimal dose of granisetron and to evaluate its safety profile. We studied 527 adult patients, undergoing elective open abdominal surgery or vaginal hysterectomy during general anaesthesia. ⋯ The two higher doses of granisetron (1.0 mg and 3.0 mg) provided effective prophylaxis against vomiting, with 78% and 77% of patients, respectively, being free from vomiting in the first 6 h after surgery, and 63% and 62% in the first 24 h. This compares with 50% and 34% at 0-6 h and 0-24 h, respectively, in the placebo group. Granisetron was well tolerated and the optimum dose was 1.0 mg.
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Randomized Controlled Trial Clinical Trial
Magnesium sulphate enhances residual neuromuscular block induced by vecuronium.
Magnesium sulphate (MgSO4) is currently used for haemodynamic control during anaesthesia and the early postoperative period. We have investigated the effect of this treatment on residual neuromuscular block after administration of vecuronium. ⋯ MgSO4 caused rapid and profound recurarization in all 20 patients. MgSO4 decreased the amount of acetylcholine released at the motor nerve terminal and thus may lead to recurarization in patients previously exposed to neuromuscular blocking agents.