Anaesthesia
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Randomized Controlled Trial Clinical Trial
Bloodletting acupuncture for the prevention of stridor in children after tracheal extubation: a randomised, controlled study.
Bloodletting acupuncture has been used for the treatment of a variety of upper respiratory tract problems, especially those of laryngeal origin. This study assesses its efficacy in reducing the incidence of stridor after tracheal extubation in children undergoing general anaesthesia with halothane. Sixty children were randomly allocated to an acupuncture group and a control group. ⋯ The incidence of stridor in the acupuncture group was significantly higher than in the control group. In addition, the severity of stridor was significantly greater in the acupuncture group. It is concluded that in children undergoing halothane anaesthesia, the incidence of postextubation stridor cannot be reduced by bloodletting acupuncture.
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By enhancing gaseous uptake from the non-ventilated lung during procedures performed thoracoscopically, the rapid diffusion properties of nitrous oxide would be expected to speed lung collapse and so facilitate surgery. To assess the effect of nitrous oxide on the speed of absorptive lung collapse, a study was conducted using 11 anaesthetised sheep. ⋯ In all assessments, it was found that the decrease in airway pressure to - 1.0 kPa occurred in a shorter time when nitrous oxide was used. The findings lend support to the hypothesis that during thoracoscopic surgery, mechanical lung ventilation with an oxygen/nitrous oxide mixture will increase the rate of gaseous uptake from the non-ventilated lung and so hasten its absorptive collapse.
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A study of 10 anaesthetised patients placed in the lateral position for thoracoscopic surgery assessed whether transient increases in pleural pressure on the side of the non-ventilated lung might increase the speed at which gas vents from that lung. The transient increases in pleural pressure were generated by the mediastinal displacement that occurs with each inspiratory phase of positive pressure ventilation of the dependent lung. When combined with a unidirectional valve allowing gas to flow out of the non-ventilated lung, and a second valve allowing ambient airflow into, but not out of, the thoracic cavity via an initial thoracoscopy access site, this mediastinal displacement could conceivably serve to 'pump' gas out of the non-ventilated lung. ⋯ Gas venting was a mean (SD) of 85.5 (11.9)% complete in 25 s (five breaths), and 96.6 (6.1)% complete in 60 s. This prompt partial lung collapse very likely reflected the passive elastic recoil of the lung, while the failure of transient increases in pleural pressure to result in ongoing venting of gas was probably a consequence of airways closure as the lung collapsed. It is concluded that techniques that aim to speed lung collapse by increasing pleural pressure are unlikely to be effective.
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Comment Letter Clinical Trial Controlled Clinical Trial
EMLA or Ametop, and for how long?