British journal of anaesthesia
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We have tested a published algorithm for pharmacokinetic model controlled infusion of propofol to supplement 67% nitrous oxide for general anaesthesia in Chinese children aged 4-10 yr. Initially we studied 10 children undergoing minor procedures with spontaneous ventilation; mean duration of surgery was 38 min and mean propofol infusion rate 497 micrograms kg-1 min-1. The precision of the model was 24.8% and bias -18.5%. ⋯ The mean blood concentration required for satisfactory anaesthesia was 6.6 micrograms ml-1 (range 3-11 micrograms ml-1) and the mean blood concentration at the time of waking, which occurred 40 min after switching off the infusion, 0.86 microgram ml-1 (range 0.40-1.45 micrograms ml-1). Our patient population required different pharmacokinetic variables from those in the previous study. Recovery was slow because of the high infusion rates required to maintain satisfactory anaesthesia and large difference between the blood concentration required for anaesthesia and that at which waking occurred.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of a bupivacaine-clonidine mixture with plain bupivacaine for caudal analgesia in children.
In a randomized, double-blind study in children undergoing elective orthopaedic surgery, we have assessed the clinical value of combining clonidine with bupivacaine for caudal analgesia. Forty-six children, aged 1-10 yr, were allocated randomly to two equal groups to receive 0.25% bupivacaine 1 ml kg-1 combined with either normal saline 1 ml (group A) or clonidine 2 micrograms kg-1 in normal saline 1 ml (group B). Mean (SD) duration of caudal analgesia for groups A and B were 5.2 (1.2) h and 9.8 (2.1) h, respectively (P < 0.0001). ⋯ There was no significant difference in the incidence of side effects between the two groups. The longer duration of sedation in group B (9.1 (2.5) h) resulted partly from the sedative effect of clonidine and partly from the longer duration of analgesia provided by clonidine. We conclude that, when added to bupivacaine, clonidine improves the efficacy of caudal analgesia in children.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of anaesthesia on the cytokine responses to abdominal surgery.
Plasma concentrations of interleukins, particularly IL-6, increase after trauma and surgery. We have undertaken this study to see if the choice of anaesthetic directly or indirectly influences cytokine release. Twenty women (ASA I-II, aged 26-60 yr) undergoing elective hysterectomy for non-malignant disease were allocated randomly to receive either inhalation anaesthesia with isoflurane and nitrous oxide (group 1), or total i.v. anaesthesia with alfentanil and propofol (group 2). ⋯ Cortisol concentrations increased more rapidly and reached greater maximum concentrations in group 1. Prolactin concentrations increased immediately and to the same degree after induction in both groups, but were greater in group 2 after operation. We conclude that anaesthesia with alfentanil and propofol diminished release of IL-6 in response to abdominal surgery compared with isoflurane and that this reduction was an effect of alfentanil.
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We have examined the relationship between perioperative headache and various factors in 219 patients who fasted from midnight and underwent minor surgery under general anaesthesia. Four to six hours after operation all patients completed a questionnaire on previous frequency of headache, daily consumption of caffeine and occurrence of perioperative headache. ⋯ After multivariate logistic regression analysis a significant risk of preoperative headache was found in patients who normally experienced headache more than twice a month (odds ratio (OR): 7.7; confidence interval (CI): 2.9-20.1), had a daily caffeine consumption > 400 mg/24 h (OR: 5.0; CI: 1.6-14.8) and who were anaesthetized after 12:00 (OR: 3.7; CI: 1.4-9.8). The risk of postoperative headache was significantly greater in patients with preoperative headache (OR: 16.9; CI: 6.5-43.8), daily caffeine consumption > 400 mg/24 h (OR: 3.9; CI: 1.5-9.6) and in those patients who received atracurium, which was similar to the risk of tracheal intubation.
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Randomized Controlled Trial Comparative Study Clinical Trial
Changes in haemodynamic variables during transurethral resection of the prostate: comparison of general and spinal anaesthesia.
We have compared changes in haemodynamic variables before and during transurethral resection of the prostate in 22 patients under general or spinal anaesthesia. In the general anaesthetic group there was a significant decrease in cardiac output (mean 32% (SEM 5%)) and mean arterial pressure (14% (3%)) after induction of anaesthesia and a significant decrease (27% (3%)) in heart rate before the start of resection. ⋯ We conclude that with both these anaesthetic techniques the greatest changes in haemodynamic variables occurred shortly after induction, and that these changes were greater during general than spinal anaesthesia. The resection period was not associated with significant haemodynamic changes.