Differential ventilation in unilateral lung disease: effects on respiratory mechanics and gas exchange.

Conventional PEEP ventilation has been recently reported to be deleterious in some cases of ARF with unilateral pneumonia. In such respect, two cases of unilateral bacterial pneumonia were intubated with a Carlens tracheal tube. Measurement of tidal volume, static compliance, and functional residual capacity of each lung showed marked inequality. Subsequently, both patients were ventilated with a selective distribution circuit, allowing the introduction of a PEEP valve in the expiratory line of the diseased lung. Evident improvement in blood gases was obtained within 24 hours, as tidal volume, static compliance, and FRC of the diseased lung were markedly improved. In one case equalisation of V/Q ratio was documented using the 81m Kr method. Final recovery was obtained in one case.