Decreased hypoxic ventilatory drive in the obesity-hypoventilation syndrome.
Most patients with extreme obesity do not exhibit alveolar hypoventilation, but an intriguing minority do. The mechanism(s) of this phenomenon remain unknown. A disorder in ventilatory control has been suggested as a major factor in the pathogenesis of the obesity-hypoventilation syndrome. Accordingly, hypoxic and hypercapnic ventilatory drives were measured in 10 patients with the typical symptoms of the syndrome: obesity, hypersomnolence, hypercapnia, hypoxemia, polycythemia and cor pulmonale. Hypoxic ventilatory drive, measured as the shape parameter A, averaged 21.9 +/- 5.35, approximately one-sixth that in normal controls, A = 126 +/- 8.6 (P less than 0.01). The ventilatory response to hypercapnia also was markedly reduced, the slope of the response averaging 0.51 +/- 0.005, or about one-third the normal value of 1.83 +/- 0.13 (P less than 0.01). This decreased responsiveness in hypoxic and hypercapnic ventilatory drive was consistent throughout the group. The depression in ventilatory drive found in the obesity-hypoventilation syndrome may be causally related to the alveolar hypoventilation manifested by these patients.
D000328:Adult; D005541:Forced Expiratory Volume; D006400:Hematocrit; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010845:Obesity Hypoventilation Syndrome / Q000503:physiopathology*; D010100:Oxygen / Q000032:analysis; D011650:Pulmonary Alveoli / Q000032:analysis; D012119:Respiration; D012129:Respiratory Function Tests; D014797:Vital Capacity
D010100:Oxygen