British journal of anaesthesia
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Pulmonary gas exchange was studied in association with high frequency ventilation and its relation to the duration of insufflation and end-expiratory pressure investigated. Alveolar deadspace, alveolar ventilation and the alveolar-arterial oxygen difference were obtained in cats receiving a constant minute ventilation. ⋯ A positive end-expiratory pressure (PEEP) decreased the alveolar deadspace in high frequency ventilation. Thus, with the low compressible volume ventilator, more efficient high frequency ventilation can be achieved with a short period of insufflation plus low PEEP.
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Twenty-six patients were anaesthetized with isoflurane (Forane) in oxygen using a completely closed-circuit breathing system to which liquid isoflurane was injected. The rate of injection was controlled to maintain the end-tidal concentration at a pre-set value (1.5% = 1.3 MAC). ⋯ It was found to average 44.5 ml of vapour at 2 min, 23.7 ml at 10 min and 19.4 ml at 30 min. Attempts were made to correlate the data with anthropometric measurements.
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Comparative Study
Manual jet ventilation v. high frequency jet ventilation during laser resection of tracheo-bronchial stenosis.
Manual jet ventilation (20 b.p.m.) and high frequency jet ventilation (300 b.p.m.) were compared during laser resection of tracheo-bronchial stenosis under general anaesthesia. Both methods provided similar blood-gas tensions at the 10th min of surgery in patients with tracheal stenosis. In patients with bronchial stenosis high frequency jet ventilation resulted in modest hypercarbia and manual jet ventilation appeared to be the preferred method in these particular patients.
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Comparative Study
High frequency jet ventilation v. manual jet ventilation during bronchoscopy in patients with tracheo-bronchial stenosis.
Six patients with airway stenosis were submitted to bronchoscopy under general anaesthesia. Each was ventilated with a gas mixture of 50% oxygen and nitrogen using successively manual jet insufflation (JV) using the Sanders technique at 20 b.p.m., and high frequency jet ventilation (HFJV) at rates of 150, 300 and 500 b.p.m. ⋯ At the faster rate some degree of hypoxaemia and hypercarbia were noted. The correlation between PaCO2 and transcutaneous carbon dioxide tension was satisfactory.