The effects of weight and chemosensitivity on respiratory sleep abnormalities: a family study.

The relationship between low-awake chemosensitivity, exogenous respiratory load (obesity) and respiratory/oxygenation patterns during sleep was evaluated in a family with overall low ventilatory responses to hypoxia and hypercapnia. Six family members were of normal weight, in good health and had normal pulmonary function tests. Only one of these subjects had totally normal responses to the chemical control of breathing. A seventh family member had loaded breathing because of severe obesity. His ventilatory and mouth occlusion pressure responses to hypoxia or hypercapnia were severely blunted. After weight loss (200 percent of ideal body weight to 133 percent) the ventilatory responses were improved but still abnormally low. Significant nocturnal respiratory abnormalities and oxygen desaturation were only seen in the overweight member and improved following weight loss (load reduction).