Anaesthesia
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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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A previously fit patient underwent laparoscopic cholecystectomy. During the procedure arterial oxygen saturation fell and clinical examination revealed signs of a right pneumothorax confirmed by chest X ray. Aspiration of the pleural cavity and analysis of the gas removed showed it to be composed entirely of carbon dioxide. Possible mechanisms of entry of carbon dioxide into the pleural space are discussed.
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The relationships between patients' height, weight, age, body mass index, gender and presence of maxillary incisors and a series of laryngoscopic factors have been studied. These included the duration of laryngoscopy, maximally applied force, mean applied force and the integral of force over time. ⋯ This latter factor was the dominant patient characteristic influencing the measured laryngoscopic factors. Use of these laryngoscopic factors as a measure of difficulty of laryngoscopy is discussed.
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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.