Anaesthesia
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Randomized Controlled Trial Clinical Trial
Enhancement of pressor response to ephedrine following clonidine medication.
We studied pressor responses and changes in plasma catecholamine concentrations following two consecutive doses of ephedrine 0.1 mg.kg-1 with (n = 20) and without (n = 20) clonidine 5 micrograms.kg-1 premedication in patients presenting for a variety of major surgical procedures under general anaesthesia. Arterial blood pressure and heart rate were measured at 1 min intervals for 10 min, and plasma catecholamines were measured before and 3 min after each dose of ephedrine. ⋯ Plasma catecholamine concentrations tended to be lower in the clonidine group throughout the study. The augmented pressor response to ephedrine in clonidine-treated patients can be attributed to enhanced cardiovascular response rather than clonidine-induced accumulation and subsequent increased release of catecholamine.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect of tunnelling on epidural catheter migration.
A prospective, randomised study of 82 patients having postoperative epidural analgesia was performed to determine whether the tunnelling of an epidural catheter influences its migration. Tunnelling of the catheter subcutaneously for a distance of 5 cm reduced the incidence of inward migration of 1 cm or more (p < 0.01) compared to a standard method of fixation with a transparent adhesive dressing. ⋯ Sixty two percent (n = 26) of tunnelled catheters remained within 0.5 cm of their original position compared to 38% (n = 16) of non-tunnelled catheters, although this difference was not statistically significant. Outward catheter migration was not reduced by subcutaneous tunnelling.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of intravenous fluid preload on vasoactive peptide secretion during Caesarean section under spinal anaesthesia.
The endogenous release of the vasoactive peptides atrial natriuretic peptide and endothelin-1 may modify maternal haemodynamic responses to a rapid intravenous volume load used to prevent hypotension at elective Caesarean delivery under spinal anaesthesia. Twenty-two healthy pregnant women were examined during elective Caesarean section at term pregnancy. ⋯ A slight decrease in endothelin-1 levels was found during colloid infusion. A significant increase in the release of atrial natriuretic peptide in response to volume load may decrease vascular tone and initiate diuresis, thereby attenuating the effect of volume load on blood pressure during elective Caesarean delivery.
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Randomized Controlled Trial Clinical Trial
The effect of alkalinisation of lignocaine on axillary brachial plexus anaesthesia.
Alkalinisation of local anaesthetic drugs is a controversial technique for improving regional blockade. Forty-two patients scheduled for upper limb surgery received axillary brachial plexus anaesthesia using a cannula technique. Patients were randomly allocated to receive either lignocaine 1.5% with 1 in 200,000 adrenaline (pH = 4.2) or lignocaine 1.5% with 1 in 200,000 adrenaline (pH = 7.2). ⋯ The percentage of patients with complete anaesthesia at 10, 20 and 30 min following injection was significantly increased in the alkalinized group with regard to the ulnar and median nerves, and the median cutaneous nerve of the arm (p < 0.05). In the alkalinized group, there was a significant reduction in the time to useful anaesthesia and a reduced requirement for adjuvants (p < 0.05). There was no effect on the duration of anaesthesia.
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Randomized Controlled Trial Clinical Trial
Quantifying the effect of isoflurane on mivacurium infusion requirements.
We evaluated the effect of different concentrations of isoflurane in a nitrous oxide/oxygen mixture on the infusion requirements of mivacurium in 60 adult surgical patients. Anaesthesia was induced with thiopentone and fentanyl, and intubation was facilitated with mivacurium 0.15 mg.kg-1. The patients were randomly assigned to one of four study groups. ⋯ The mean (SD) steady-state infusion requirements of mivacurium in patients receiving nitrous oxide-fentanyl anaesthesia or isoflurane 0.25-0.5 MAC were similar, ranging from 6.1 (2.2) to 5.1 (2.1) micrograms.kg-1.min-1. Isoflurane 1.0 MAC reduced mivacurium infusion requirements by 32% (p < 0.01). Interindividual differences in mivacurium infusion requirements were large.