Decreased hypoxic ventilatory drive in the obesity-hypoventilation syndrome

Am J Med. 1975 Sep;59(3):343-8. doi: 10.1016/0002-9343(75)90392-7.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Forced Expiratory Volume
  • Hematocrit
  • Humans
  • Hypercapnia / physiopathology
  • Hypoxia / physiopathology*
  • Male
  • Middle Aged
  • Obesity Hypoventilation Syndrome / physiopathology*
  • Oxygen / analysis
  • Pulmonary Alveoli / analysis
  • Respiration*
  • Respiratory Function Tests
  • Vital Capacity


  • Oxygen