Familial factors affecting arterial blood gas values and respiratory chemosensitivity in chronic obstructive pulmonary disease.

Arterial blood gas determinations in patients with chronic obstructive pulmonary disease (COPD) and respiratory chemosensitivity, and arterial blood gas determinations in their sons were compared. Patients with silicosis (n=17) and their sons (n=22) served as control subjects. Arterial blood gases, pH, and HCO-3 concentration in 25 patients with COPD were averaged from at least 3 determinations (mean sample number, 10.1) to compare with the data on their sons (n-34; mean age, 33.9 yr). The Paco2 obtained during stable stages correlated positively between patients with COPD and their sons. The Pao2 of patients with COPD in stable stages correlated with the hypoxic ventilatory response of their sons. The Paco2 and Paco2 obtained during acute exacerbation of COPD correlated with the hypoxic ventilatory response of the sons. Deviations in FEV1 and V25 from predicted values correlated with deviations in Pao2 in the sons of the patients with COPD. In silicosis, significant relationships between patients and sons were not seen with respect to arterial blood gas determinations and ventilatory responses except for Paco2 of patients and hypercapnic ventilatory responses of sons. Smoking habits did not correlate between patients and sons both in COPD and in silicosis. However, the concordance ratio of smokers or nonsmokers between patients and sons was higher in COPD than in silicosis. These results indicate that familial factors are involved in determining the arterial blood gases and ventilatory response to hypoxia in COPD, and blunted chemosensitivity to hypoxia and incipient airway dysfunction antedate clinically manifest COPD.