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
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 assessed postoperative delirium in 24 patients undergoing thoracotomy for pulmonary malignancy throughout their stay in hospital. Arterial oxygen saturation was measured with a pulse oximeter on the night before operation and on the second night after operation. Five patients (21%) developed clinically significant postoperative delirium, and delirium occurred in all patients who had inadequate oxygenation. ⋯ When patients were delirious, the first treatment of choice was supplementary oxygen and all patients were treated successfully by this simple regimen. In two patients, supplementary treatment with zuclopenthixol 6 mg daily was necessary. We conclude that hypoxaemia may be a contributing factor in postoperative brain dysfunction, as postoperative delirium was associated with hypoxaemia and was treated successfully with supplementary oxygen.
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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
Pretreatment with alfentanil reduces pain caused by propofol.
We have compared two groups (n = 22) of unpremedicated patients to determine if the pain caused by injection of propofol could be modified by alfentanil. In group I, alfentanil 1 mg was given as a bolus i.v. injection 15 s before administration of propofol i.v., while group II received saline. ⋯ All injections were given through the same i.v. cannula on the dorsum of one hand. We found that alfentanil pretreatment reduced pain on injection of propofol (P = 0.001).