[Respiratory function in massive obesity]

Massive obesity may be accompanied by severe and sometimes lethal respiratory complications. The restrictive ventilatory deficit which results from a decrease in thoracic wall compliance and perhaps also from diaphragmatic dysfunction is more severe in males and in subjects with abdominal obesity. Diurnal hypoxaemia results from 2 mechanisms: diminution of the ventilation/perfusion ratio at the base of the lung, and alveolar hypoventilation. Hypercapnia is a fairly frequent complication of massive obesity. Although usually moderate, hypercapnia is a major indicator as it is very often associated with sleep apnoea syndrome. The most severe respiratory complication of massive obesity is this syndrome which must be looked for systematically by questioning the patient and her husband or his wife before serious cardiopulmonary and neuropsychic disorders appear. The effects of weight loss of nocturnal apnoea are inconsistent and variable. Continuous positive pressure ventilation by means of a nasal mask is the choice treatment of sleep apnoea syndrome, especially since the results of rhino-laryngeal surgery are often disappointing.