[Alveolar hypoventilation in the obese: the obesity-hypoventilation syndrome].
The obesity-hypoventilation syndrome (or alveolar hypoventilation in the obese) is a new name for an old syndrome, Pickwickian syndrome. It is defined as chronic alveolar hypoventilation (PaO(2)<70 mmHg, PaCO(2) > 45 mmHg) in obese patient with a body mass index > 30 kg/m(2) who have no other respiratory disease explaining the gas anomalies. The large majority of obese subjects are not hypercapnic, even in case of severe obesity. There are three principal causes explaining alveolar hypoventilation in obese subjects: high cost of the work of respiration, dysfunction of the respiratory centers, repeated episodes of nocturnal obstructive apnea. The obesity-hypoventilation syndrome is generally found in males aged over 50 years. Exercise-induced breathlessness is a constant finding. Diagnosis is often made after an episode of severe respiratory failure. Associated diseases favored by obesity are frequent: diabetes, high blood pressure, heart disease. By definition, there is a hypoxemia-hypercapnia syndrome persisting after an acute episode. Spirography usually demonstrates moderate volume restriction. Pulmonary hypertension is frequent but not constant. Obesity-hypoventilation syndrome must be distinguished from obstructive sleep apnea, although the two conditions are often associated. Obstructive sleep apnea may be absent in certain patients with obesity-hypoventilation syndrome (we have had several cases) and inversely, obesity is not observed in certain patients with obstructive apnea. It should be recalled that the term Pickwickian syndrome designates obesity-hypoventilation syndrome (with or without obstructive apnea) and not obstructive sleep apnea syndrome.
Weitzenblum
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E
Service de Pneumologie, Hôpital de Hautepierre, 67098 Strasbourg Cedex, France.
Kessler
R
R
Chaouat
A
A
D006439:Hemodynamics; D006801:Humans; D007040:Hypoventilation / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D009765:Obesity / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D011650:Pulmonary Alveoli / Q000503:physiopathology; D012891:Sleep Apnea Syndromes / Q000209:etiology; D013577:Syndrome