COR PULMONALE is a rare disease in the pediatric age group1but its recognition is very important since emergency therapy is often essential for survival, and many cases are completely reversible and curable.2Usually the pulmonary artery hypertension of cor pulmonale is secondary to destructive changes in the lungs, such as fibrosis and/or emphysema, but occasionally the lung parenchyma and lower air passages are normal, and abnormal pulmonary hemodynamics result from extrathoracic disease, such as obesity (the Pickwickian syndrome).3In these patients, vasoconstrictive pulmonary artery hypertension is caused by the abnormal gaseous exchange of alveolar hypoventilation. (Alveolar hypoventilation is the hypoxemia resulting from insufficient ventilation without restrictive or obstructive pulmonary disease or abnormal diffusion. Alveolar ventilation is the amount offreshair reaching the alveoli per minute and is measured by: tidal volume [VT]—dead space volume [VDS] × respiratory rate.) A seldom recognized