Sleep in Restrictive Lung Disease

Restrictive lung disease patients exhibit a wide range of breathing and oxygenation abnormalities during sleep. The combination of degree of restriction, whether it is intrapulmonary or extrapulmonary, and confounding factors, such as obesity, age, and sex, will ultimately determine the degree of disturbed nocturnal physiology. The sleep literature is still sparse in most restrictive diseases. For patients with interstitial lung disease, the role of nocturnal oxygen in chronic established fibrosis, and also in acute alveolitis (e.g., farmer's lung, bird fancier's lung, etc.), has not been addressed. As fibrotic lung disease progresses, the degree of nocturnal desaturation and breathing dysrhythmias will progress. Changes in sleep architecture are likely related to the progression of the disease, but this is not known with certainty. Long-term evaluation of sleep and breathing in interstitial lung disease will give further insight into whether or not sleep changes are primary or secondary events. For kyphoscoliosis patients, again, we need more information on sleep as the thoracic deformity changes. In addition, the use of drugs (acetazolomide, medroxyprogesterone, and almitrine) and/or nasal CPAP to treat nocturnal desaturation needs to be assessed in a controlled fashion. In neuromuscular disease, the dynamics of gas exchange and sleep structure need to be defined in a larger group of patients. Factors such as degree of muscle weakness, degree of underlying lung diseases, and medications must be taken into consideration. Nocturnal hypoxemia may cause muscle weakness and fatigue, which in time, could cause more nocturnal hypoventilation and further hypoxemia. Supplemental nocturnal oxygen should be evaluated in this population.