High frequency jet ventilation in experimental airway disruption
Anecdotal observations suggest that high frequency jet ventilation (HFJV) is beneficial in major airway disruption. Quantitative evaluation is, however, unavailable. In 12 healthy mongrel dogs, a tracheal window of increasing size, from 0.5 x 1 cm to 1.5 x 2 cm, was opened. Dogs were supported on volume-cycled ventilation (VCV) and on HFJV, using injector cannulas of 1.06 and 1.62 mm internal diameter. The tracheal window was then closed and an upper lobectomy performed, followed by total pneumonectomy. Arterial blood gases were obtained after 10 min in each experimental condition. VCV could maintain life-supporting blood gases only with the tracheal window of 0.5 x 1 cm. HFJV, delivered with a 1.06-mm injector cannula, was adequate with a tracheal window of 1 x 1 cm, or after a lobectomy. In all experimental conditions, HFJV delivered with a 1.62-mm injector effectively maintained alveolar ventilation and arterial oxygenation. Gas transport on HFJV is based, in part, on the principles of jet mixing and entrainment; increasingly large tidal volumes can be delivered under conditions of low and constant pressure. Air leaks through pathological openings remain constant even when tidal volume is increased, so that alveolar ventilation can be adequately maintained.