Abstract

Three children and two young adults with severe asthma who had frequent episodes of respiratory failure were studied. Isocapnic hypoxia and hyperoxic hypercapnia were produced separately using a rebreathing apparatus. Alveolar carbon dioxide tension and oxygen tension were estimated by continuously sampling expired gases. The three young children had a diminished response to hypoxia but a normal response to hypercapnia when compared to control asthmatic children (p less than 0.05) or healthy children (p less than 0.05). The two young adult patients had a normal response to hypoxia but one had a low response to hypercapnia. Studies of parents of these patients suggested that the chance combination of a possibly familial, inappropriate response to hypoxia with severe asthma would lead to a risk of respiratory failure.