Assessment of a high frequency ventilator breathing system for use in the operating theatre. An experimental and clinical study.

A breathing system capable of delivering positive pressure ventilation to the lungs at high frequencies and using anaesthetic gases and vapours is assessed. The recommended fresh gas flow at the ventilatory rates tested in this study was 100 ml kg-1. At 80 and 100 b.p.m. the system provided adequate ventilation, good oxygenation and haemodynamic stability. When compared with conventional positive pressure ventilation (CPPV), peak airway pressure (peak Paw) was lower and mean airway pressure (Paw) was lower (80 b.p.m.) or unchanged (100 b.p.m.). There was some inherent positive end-expiratory pressure (PEEP) associated with the technique.