[Forced diffusion ventilation (FDV). Bases and clinical application (author's transl)].

A new concept for an alternative gastransport mechanism in the lungs is introduced. It is based on an enhancement of diffusive processes in the bronchial tree and allows gas exchange under quasi apnoic conditions. This enhancement is achieved by a modified high frequency jet ventilation technique utilizing frequencies up to 3000/min. The technical equipment used for this so called forced diffusion ventilation consists of a solenoid valve that interrupts the flow from a high pressure source with adjustable frequencies and impulse pause ratios. A special tracheal tube with an additional jet line implement in its wall carring a nozzle at its tip had to be developed. Animal experiments demonstrate that a sufficient gas exchange even with frequencies of 3000/min can be achieved with this FDV. Under this conditions the lung can be kept in its expiratory inflation level. This technique using frequencies of 350/min has been successfully applied to a patient suffering from multiple bronchopleural fistulas over 16 days. Also the mechanism of FDV is jet not quite clear, penetration of fresh gas into further generation of the bronchial tree, axial diffusion and convective transport due gas oscillations and the volume displacement of the beating heart seem to be responsible for the gas exchange.