Experimental investigations in adult respiratory distress syndrome (ARDS). Repeated pulmonary lavage in LEWE-mini-pigs. I. Pulmonary mechanics, gas exchange, and pulmonary hemodynamics.

Disturbed water balance at the alveolo-capillary membrane resulting in decreased pulmonary compliance is one of the functional characteristics in the Adult Respiratory Distress Syndrome (ARDS). In artificially ventilated LEWE Mini Pigs repeated pulmonary lavage was performed. The aim was to produce a state like ARDS by affecting the lung alveolar surfactant system which is included into the sum of factors which are responsible for the normal water balance of the alveolo-capillary membrane. This condition was supposed to be maximized if the lung compliance reached its lowest value after pulmonary lavage. Regarding this the pathophysiologic changes in this ARDS model were characterized by increased airway resistance and dead space ventilation as well as decreased arterial oxygenation. Severe ventilation perfusion abnormality was represented hemodynamically by the increased pulmonary vascular resistance and the decreased pulmonary non-shunt blood flow. The morphological (macroscopic, light-and electronmicroscopic) changes indicate strongly that in this type of ARDS model all functional compartments of the alveolocapillary membrane are severely affected. Decreased colloid osmotic pressure of blood plasma samples underlines the severity of changes in the water balance at the alveolo-capillary membrane in this type of lung injury.