British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial Controlled Clinical Trial
Fuzzy logic control of inspired isoflurane and oxygen concentrations using minimal flow anaesthesia.
In order to evaluate the performance of feedback fuzzy logic control of inspired oxygen and isoflurane concentrations, we studied 30 patients undergoing discectomy for lumbar (n = 26) or cervical (n = 4) disc herniation. Patients were allocated random to one of two groups: a standard group (n = 15) with low flow anaesthesia (1.2-1.3 litre min-1) and manual control of gas concentrations; and a fuzzy group (n = 15) with minimal flow (0.5 litre min-1) and fuzzy logic feedback control of gas concentrations. Fuzzy logic control achieved and maintained very accurately the desired isoflurane concentration. ⋯ Delivery and costs of oxygen and nitrous oxide were significantly lower in the fuzzy group (P < 0.01). Accumulation of foreign gases was observed in one patient during low flow and in 11 patients during minimal flow anaesthesia. In conclusion, fuzzy logic control of inspired oxygen and isoflurane concentration during minimal flow anaesthesia was reliable and reduced anaesthetic gas delivery and costs.
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Clinical Trial
Prospective evaluation of pharmacokinetic model-controlled infusion of propofol in adult patients.
We have tested prospectively the algorithm of White and Kenny for pharmacokinetic model-controlled infusion of propofol in 40 healthy Oriental adults. Anaesthesia consisted of a target-controlled infusion of propofol, 70% nitrous oxide and an infusion of alfentanil. For the first 20 patients studied, median performance error was -5%, median absolute performance error 19%, divergence -9% and wobble 6%. ⋯ There was a deterioration in performance of the revised model. Performance statistics for the original model in all 40 patients were: median performance error 2% (range -34 to 69%), median absolute performance error 21% (6-69%), divergence -17% (-92 to 49%) and wobble 7% (2-34%). The algorithm was found to perform adequately in our Oriental patient population.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of nicardipine, diltiazem and verapamil for controlling the cardiovascular responses to tracheal intubation.
We have compared the efficacy of three calcium channel blockers, nicardipine, diltiazem and verapamil, in attenuating the cardiovascular responses to laryngoscopy and intubation in 60 normotensive patients (ASA I) undergoing rapid sequence induction of anaesthesia with thiopentone and fentanyl. We also examined whether or not these blockers inhibited catecholamine release induced by intubation. The patients were allocated to one of four groups (n = 15 for each): saline (control), nicardipine 30 micrograms kg-1, diltiazem 0.2 mg kg-1 or verapamil 0.1 mg kg-1. ⋯ The greatest effect was elicited by verapamil, which attenuated the increase in HR, although nicardipine seemed to enhance tachycardia. All three drugs failed to suppress the increase in plasma catecholamine concentrations in response to tracheal intubation. These findings suggest that bolus injection of verapamil 0.1 mg kg-1 was a more effective method of controlling hypertension and tachycardia associated with intubation than diltiazem 0.2 mg kg-1 or nicardipine 30 micrograms kg-1, and that these prophylactic effects were not caused by inhibition of the catecholamine response.
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Randomized Controlled Trial Clinical Trial
Use of i.v. insulin in well-controlled non-insulin-dependent diabetics undergoing major surgery.
We conducted a randomized, prospective study to assess the effect of i.v. insulin on blood glucose control, development of ketone bodies and hormonal changes in 60 well-controlled, non-insulin-dependent diabetics (NIDDM) undergoing major surgery. In group A, patients were given only 0.9% saline; in group B, patients were given insulin as a continuous i.v. infusion (1.25 u. h-1); in group C, patients were given insulin 10 u. i.v. boluses every 2 h. Patients in all three groups were given insulin 5 u. when their intraoperative blood glucose concentration increased to greater than 11.1 mmol litre-1. ⋯ Plasma C-peptide concentrations decreased significantly in groups B and C, especially in patients given bolus injections of insulin. Plasma growth hormone concentrations also increased significantly in group B and C patients. This study indicated that the "no insulin--no glucose" regimen was a simple, effective way to control blood glucose in well-controlled NIDDM patients, provided blood glucose was measured frequently and insulin used appropriately.
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Randomized Controlled Trial Clinical Trial
Effect of ondansetron on nausea and vomiting after middle ear surgery during general anaesthesia.
The efficacy of ondansetron 4 mg and 8 mg was compared with placebo in the reduction of postoperative nausea, retching and vomiting (PONV) after middle ear surgery during general anaesthesia, in 75 patients, in a double-blind and randomized study. Both doses of ondansetron were predictors for a decrease in PONV and the number of doses of rescue antiemetic needed per patient (droperidol: from 0.72 in the placebo group to 0.32 in both the 4-mg and 8-mg groups). No reduction in PONV was observed in patients with a history of motion sickness, whereas in patients without a history of motion sickness, ondansetron reduced both the proportion of patients suffering from PONV from 53% to 20% (P < 0.05) and of those needing droperidol from 53% to 17% (P < 0.05).