Asthma Associated with Decreased Hypoxic Ventilatory Drive

Hypoxic and hypercapnic ventilatory drives were measured in a 17-year-old asthmatic because of an unusual degree of hypoxemia and hypoventilation that developed during bronchospasm. A severely depressed hypoxic ventilatory drive and a normal hypercapnic ventilatory drive were found. This decrease in responsiveness to hypoxia probably contributed to the occurrence of chronic hypoxemia, CO2 retention, cor pulmonale, and polycythemia in this asthmatic patient. Ventilatory drives of all four healthy members of his immediate family were also studied. Three had a depressed hypoxic drive, and one had a depressed hypercapnic drive. This clustering suggested that hereditary factors might have played a role in the patient's low hypoxic drive. Thus, antecedent, possibly hereditary, deficiencies in ventilatory drive may detrimentally influence the clinical course of persons who develop a mechanical impediment to breathing.