Hypoventilation in Obstructive Lung Disease — The Role of Familial Factors

Abstract

To determine the role of familial factors in the hypoventilation of chronic obstructive lung disease we measured chemical drives to breathe in normal offspring of two groups of patients with an equal degree of obstruction. One group of five patients had repeatedly normal arterial carbon dioxide tension (PaCO₂), whereas PaCO₂'s were elevated in the other group of six. Two adult offspring of each patient were studied. Drives were measured as the ventilatory response to isocapnic hypoxia, and the slopes of the ventilation/PCO₂ relation (the hypercapnic ventilatory response).

The mean response to isocapnic hypoxia was lower (P<0.01) in offspring of patients with high PaCO₂'s than in the offspring of patients with normal levels (71±7.8 [S.E.M.] vs. 113±10.3); one offspring of each patient with high PaCO₂ had a response below the range found in offspring of all patients with normal PaCO₂. Lower hypercapnic ventilatory responses (P<0.05) were also found in the offspring of patients with high PaCO₂. Familial factors in the control of breathing may be an important determinant of ventilation in chronic obstructive lung disease. (N Engl J Med 298:521–525, 1978)