ABSTRACT
The functions of the lungs include the mechanics of moving gas to and from the gasexchanging regions through the non-exchanging dead space of the tracheobronchial tree and the exchange of gases between the alveoli and pulmonary capillary blood. The main functional disturbance in infants and young children who wheeze, as in older children and adults, is obstruction principally of the smaller airways. In most disorders associated with wheezing, disturbance to the mechanical function of the lungs results in varying degrees of mismatching of alveolar ventilation and perfusion. This in turn disturbs gas exchange, chiefly of oxygen, and causes some degree of hypoxemia.
