British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Dose requirements, efficacy and side effects of morphine and pethidine delivered by patient-controlled analgesia after gynaecological surgery.
We have compared the dose requirements and side effects of morphine with those of pethidine when administered by patient-controlled analgesia in 40 patients (ASA I-II, 20-65 yr) after elective total abdominal hysterectomy. Patients were allocated randomly, in a double-blind manner, to receive either morphine (bolus dose 2 mg, lockout time 10 min) or pethidine (bolus dose 20 mg, lockout time 10 min) for postoperative pain relief. ⋯ Four patients receiving pethidine were withdrawn because of postoperative confusion and one receiving morphine because of intractable nausea and vomiting. The 95% confidence interval for this difference between the groups for VAS scores of sedation, nausea and pain were approximately 30 mm.
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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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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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We have examined the effects of sedation with midazolam 0.1 mg kg-1 and reversal with flumazenil 0.5 mg on beat-to-beat heart rate (HR) variability (HRV), systolic arterial pressure (SAP), finger photoplethysmograph amplitude (PLA) and impedence pneumography in eight volunteers. With the onset of sedation there was a small decrease in SAP and increase in HR (ns). ⋯ These were thought to be secondary to activity of coupled cardiorespiratory neurones within the brain stem and the ventilatory periodicity appeared similar to that observed during the early stages of sleep. The diminished high frequency and increased low frequency oscillations induced by midazolam sedation were reversed by administration of flumazenil.