Wet-to-dry ratio of lung tissue and surfactant outwash after one-lung flooding.

Unilateral flooding of the lung after intubation with a double-lumen tube enables intraoperative sonography of the lung tissue. The flooding restricts the pulmonary blood stream of the flooded lung in a relevant degree and thus reduces the right-to-left shunt volume. The deficient perfusion of the lung tissue during the flooded phase might cause capillary permeability disorders and secondary oedema development. This can be determined by examination of extravascular lung water (EVLW) after draining and reventilation of the flooded lung. Although one-time unilateral lung flooding must be distinguished from bronchopulmonary lavage, it is interesting to study the effects of flooding on the surfactant system. The wet-to-dry ratio of the lung tissues of 13 female pigs was ascertained at different times following one-lung flooding (1 to 11 weeks). A trend towards an increased wet-to-dry ratio in the previously flooded lung was found only in the tissue samples taken 1 h after reventilation. After only 24 h, the two lungs no longer differed in their wet-to-dry ratio. In six pigs, the phospholipid content of the drained flooding liquid was determined. It was shown that the surfactant loss caused by flooding was maximally 47% of the calculated surfactant pool of the respective lung.