Arterial oxygen desaturation during sleep in interstitial pulmonary disease. Correlation with chemical control of breathing during wakefulness.

Patients with IPD often develop oxygen desaturation during sleep. We investigated whether or not the degree of falls in SaO2 during sleep were correlated with the daytime data of pulmonary function tests, arterial blood gas tensions, or ventilatory responses to chemical stimuli. Fourteen patients with IPD who had restrictive ventilatory impairment were studied to evaluate these relationships. The magnitude of SaO2 depression from awake to REM sleep was inversely correlated with the level of baseline SaO2. Hypercapnic ventilatory response was inversely related to the amount of maximal desaturation in both REM and NREM sleep. These results indicate that patients with IPD who have insufficient ventilatory response to hypercapnia reveal larger falls in SaO2 during sleep, particularly if they have lower baseline SaO2.