Anaesthesia
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Randomized Controlled Trial Clinical Trial
Perineuronal morphine in intercostal block.
In a double-blind, randomised study the potential benefits of combining low-dose morphine with bupivacaine for intercostal nerve blocks for analgesia after biliary surgery were investigated. There was no significant improvement in pain scores or consumption of supplementary analgesics when morphine was added to bupivacaine. This investigation supports the findings of other workers who showed that perineural morphine was ineffective for postoperative pain relief.
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Oxygen delivery using nasal prongs was assessed using a lung model for spontaneous ventilation. The analogue lung was attached to a manikin, which provided a model of the 'face and pharynx' to which the nasal prongs were applied. ⋯ The study demonstrated enormous variability in the both the peak-inspired (26.3-90.0%) and end-expired concentrations (25.2-78.6%) of oxygen delivered to the trachea. There was a regular relationship between the ratio of peak inspiratory flows, expressed over fresh gas inflow and the end-expired oxygen concentrations which could allow estimation of inspired oxygen concentration.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intravenous regional anaesthesia with 0.5% prilocaine or 0.5% chloroprocaine. A double-blind comparison in volunteers.
Ten healthy male volunteers received intravenous regional anaesthesia of the upper limb on two separate occasions using 40 ml of 0.5% prilocaine or 40 ml plain 0.5% chloroprocaine by random allocation. Using a double-blind method, the onset and recovery of sensory block was tested (pinprick) in the four main nerve areas. The onset and recovery of motor block was measured by squeezing a rubber balloon connected to a manometer. ⋯ Six volunteers in the chloroprocaine group showed signs of venous irritation and/or antecubital urticaria in the test arm for 30-45 min after the deflation. Four volunteers in the chloroprocaine group had increased in heart rate (greater than 20%) and one of them short periods of junctional rhythm during the first 2 min after tourniquet deflation. Mild, short-lived CNS side effects occurred in both groups.
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Clinical Trial Controlled Clinical Trial
The minimum effective dose of lignocaine to prevent injection pain due to propofol in children.
In a single-blind study of 100 children aged 1 to 10 years, the minimum effective dose of lignocaine required to prevent injection pain due to propofol was 0.2 mg.kg-1 when veins on the dorsum of the hand were used. This is more than twice the adult value. We concluded that injection pain should not limit the use of propofol in children if an adequate amount of lignocaine is mixed immediately prior to injection.
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A regulator is described for the maintenance of a constant pressure difference above airway pressure during positive pressure ventilation in a cuffed tracheal tube. It comprises a tubular threshold valve which is powered by the anaesthetic gas supply source to a breathing system. The valve is interposed between the anaesthetic gas supply machine and the breathing system creating a pressure differential. ⋯ The regulator was evaluated during anaesthesia, using a modified Mallinkrodt Hi-Lo jet ventilation tube to obtain simultaneous pressure measurements within the cuff and the lumen of the tracheal tube. A greater pressure was demonstrated in the cuff than in the airway and the two traces were approximately parallel throughout the respiratory cycle. The device should prevent excessive cuff inflation pressure and solves the problem of forgetting to let the cuff down before extubation.