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.