British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
High-dose ondansetron regimen vs droperidol for morphine patient-controlled analgesia.
We have performed a randomized, double-blind study comparing droperidol and high-dose ondansetron mixed with morphine for patient-controlled analgesia (PCA). To detect a reduction in the incidence of postoperative nausea and vomiting from 55% to 20% with a power of 80% at the P < 0.05 level, 29 patients per group were required. We studied 60 healthy women undergoing abdominal hysterectomy, anaesthetized using a standard technique. ⋯ In group D, 24 patients did not vomit compared with 23 in group O. The only significant difference between the groups was increased morphine consumption in the ondansetron group up until 12 h after operation (P < 0.05), but by 24 h this difference was not significant. The ondansetron regimen was more expensive (at local prices) by a factor of 27, and our results suggested no clinical advantage over droperidol.
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Randomized Controlled Trial Comparative Study Clinical Trial
Haemodynamic and electroencephalographic response to insertion of a cuffed oropharyngeal airway: comparison with the laryngeal mask airway.
We have compared the cuffed oropharyngeal airway (COPA), a modified Guedel airway device with a specially designed cuff at its distal end, with the laryngeal mask airway (LMA), on haemodynamic and electroencephalographic (EEG) responses to insertion. In addition, we examined the haemodynamic and EEG changes during initiation of the effect-compartment controlled infusion. We studied 35 female patients undergoing ambulatory gynaecological surgery allocated randomly to received an LMA or COPA to manage the airway. ⋯ The effect-compartment controlled infusion of propofol caused only mild haemodynamic changes during induction. Changes in arterial pressure and heart rate after insertion were similar in both groups and not significantly different from baseline values before insertion. Changes in BIS after insertion were minor and similar between groups.
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Randomized Controlled Trial Clinical Trial
Factors affecting assessment of cerebral autoregulation using the transient hyperaemic response test.
The transient hyperaemic response in the middle cerebral artery blood flow velocity on the release of brief compression of the ipsilateral common carotid artery has been validated as an indicator of cerebral autoregulation. We evaluated, in three stages, the effect of experimental factors such as duration of compression of the common carotid artery and magnitude of the decrease in blood flow velocity during common carotid artery compression on the transient hyperaemic response. In stage 1, 13 healthy volunteers underwent six transient hyperaemic response tests each; two tests each for either 3, 6 or 10 s duration of compression of the common carotid artery. ⋯ We conclude that experimental factors such as duration of common carotid artery compression and magnitude of the decrease in blood flow velocity during common carotid artery compression can significantly influence the transient hyperaemic response. These factors should be controlled if the transient hyperaemic response test is used for a comparison between repeated measurements. A compression time of 10 s and a compression ratio of 40% or more, allow maximum expression of the hyperaemic response in healthy volunteers.
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The pharmacokinetic models proposed for atracurium or cisatracurium are based on the assumption that spontaneous degradation via Hofmann elimination proceeds in vivo at the same rate as measured in vitro at pH 7.4 and 37 degrees C. As different degradation rates have been reported for all 10 stereoisomers of atracurium measured together, for each of its three isomeric groups, and for the single isomer cisatracurium, we studied if the rate is dependent on factors other than pH and temperature. In vitro degradation of atracurium and cisatracurium was studied at 37 degrees C and pH 7.4 in nine incubating solutions containing one of three buffer systems (phosphate, HEPES or Tris) and additives (sodium chloride, potassium sulphate or glucose). ⋯ At the same total buffer concentration (50 mmol litre-1), degradation was fastest in the phosphate, intermediate in the HEPES and slowest in the Tris buffer. Degradation rates of cisatracurium in sodium phosphate 50 mmol litre-1 and Sörensen (Na-K phosphate) buffer 66.7 mmol litre-1 were similar to those of atracurium. We conclude that, at constant pH and temperature, the degradation rate of atracurium was dependent on the total concentration of the base in the incubating solution.
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Clinical Trial
Patient-maintained remifentanil target-controlled infusion for the transition to early postoperative analgesia.
We studied 30 male patients in the early postoperative period to assess the efficacy, safety and feasibility of a patient-demand, target-controlled infusion (TCI) of remifentanil. All patients received the same TCI-based propofol-remifentanil anaesthetic for elective orthopaedic surgery. At the end of surgery, infusion of remifentanil was reduced progressively until patients were breathing spontaneously. ⋯ Nausea occurred in 26.6% of patients and 10% vomited. The majority of patients were only slightly sedated. These results imply an effective tool without respiratory side effects in the early postoperative period after anaesthesia using remifentanil as the analgesic component.