[Meconium aspiration syndrome. 2. Pathophysiology, clinical aspects, therapy]

MAS can be divided into 2 stages, distinguishable with respect to morphology of the lungs, clinical symptoms and laboratory data. The reason for the vasoconstriction of the pulmonary vascular bed typical for stage 2 is not yet fully understood. It seems, however, plausible that meconium contains substances (enzymes?) which may trigger the release or the synthesis of vasoactive compounds during the process of an aseptic inflammation. Cleaning the upper respiratory tract of an infant with meconium in the amniotic fluid immediately after birth is the most effective step in the prevention of MAS. This measure has led to a dramatic decline in both morbitity and mortality of the disease. In rare instances rinsing of the trachea with saline can help to remove considerable amounts of meconium too thick and sticky to be removed by simple suction.