British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Measurement of entrainment ratio during high frequency jet ventilation.
We have measured tidal (VT), entrained (Ve) and "blowback" (Vbb) volumes during high frequency jet ventilation (HFJV) through a Mallinckrodt Hi-Lo Jet tracheal tube in anaesthetized patients. The above volumes were calculated by digital integration of the appropriate regions of flow curves derived from a pneumotachograph placed between the bias flow tubing and the tracheal tube. ⋯ Blowback volumes were considerable, especially at ventilatory frequencies used clinically (1-2 Hz). We conclude that it is not possible to entrain predictable concentrations of volatile agents from the low pressure bias flow during HFJV.
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Randomized Controlled Trial Clinical Trial
IV lignocaine fails to attenuate the cardiovascular response to laryngoscopy and tracheal intubation.
I.v. lignocaine has been used with varying success to attenuate the cardiovascular responses to laryngoscopy and tracheal intubation. We determined the optimal time of administration in 45 ASA I and II Chinese patients premedicated with morphine and hyoscine, and anaesthetized with thiopentone and suxamethonium. Patients were allocated randomly to a control group or three treatment groups to receive lignocaine 1.5 mg kg-1 i.v. 1, 2, or 3 min before laryngoscopy. Analysis of variance for measured and derived cardiovascular variables failed to show any significant difference between any of the groups.
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Randomized Controlled Trial Clinical Trial
Effect of flumazenil on midazolam-induced amnesia.
We have studied the effect of i.v. flumazenil 0.01 mg kg-1 on the amnesia and sedation caused by midazolam 2 mg and 5 mg i.v. in volunteers in order to determine the relationship between the actions of the antagonist on these two effects. Midazolam caused dose-dependent central neural depression as assessed by critical flicker fusion frequency, and dose-dependent amnesia for word cards. In subjects given flumazenil 5 min after administration of midazolam, fusion frequency readings and memory were restored to levels comparable to those before midazolam administration. ⋯ Flumazenil given alone had no effect on memory. The study has demonstrated anterograde amnesia following benzodiazepine administration and antagonism by flumazenil. There was neither retrograde amnesia nor retrograde antagonism of amnesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Double-blind comparison of topical lignocaine-prilocaine cream (EMLA) and lignocaine infiltration for arterial cannulation in adults.
In a double-blind, double-dummy study, the efficacy of topical 5% EMLA cream was compared with that of lignocaine infiltration in alleviating the pain of arterial cannulation. Forty unpremedicated adults were allocated randomly to four groups to receive EMLA cream alone, EMLA and 0.9% saline infiltration, EMLA and 1% lignocaine infiltration or placebo cream and 1% lignocaine infiltration. ⋯ Significantly lower pain scores were observed in all patients receiving EMLA compared with those receiving placebo cream and lignocaine infiltration by both patient (P less than 0.01) and observer (P less than 0.001) assessments. There were no significant differences between the three EMLA groups.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of two ventilators used with the T-piece in paediatric anaesthesia.
The Nuffield 200 ventilator was compared with a new valveless ventilator (CW 200) in 20 children undergoing general anaesthesia for paediatric surgery. The new ventilator incorporates design features which overcome the main disadvantages of the Nuffield 200 and make it an inherently safer machine. At identical ventilator settings it produced a significantly greater tidal volume with a reduction in end-tidal carbon dioxide partial pressure. This may have advantages in avoiding pulmonary barotrauma in children.