British journal of anaesthesia
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Ten patients with cerebral tumours were anaesthetized with thiopentone, 70% nitrous oxide in oxygen and fentanyl. Ventilation was controlled to give mean PaCO2 4.8 (range 3.6-6.7) kPa. Enflurane 2% was administered and ICP and MAP were recorded continuously for 10-15 min. ⋯ There were significant decreases in MAP (P less than 0.001) and CPP (P less than 0.001) during the administration of enflurane. In four patients the administration of enflurane had to be terminated prematurely because of a low CPP. Thus, enflurane has very little effect on ICP in patients with cerebral tumours and low concentrations of enflurane can safely be used during anaesthesia for intracranial operations, provided that the arterial pressure is monitored carefully.
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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.