[Chronic obstructive bronchopneumopathies. Changes in carbon dioxide pressure during sleep in environmental air and...

The effects of oxygen administration were studied in 10 patients with severe obstructive lung disease. Sleep variable and gas exchanges were measured during two nights: one when they were breathing environmental air, the other when they were receiving oxygen. Carbon dioxide saturation and partial pressure measured by the transcutaneous method were continuously recorded. Sleep was perturbed in all patients, but despite wide interindividual variations its amount and quality were improved by oxygen. None of the patients had sleep apnoea syndrome. Oxygen administration was accompanied by a nocturnal increase in carbon dioxide pressure that was about twice as high as that observed under environmental air. Thus, in patients with chronic obstructive lung disease without concomitant infection suppression of the hypoxic stimulus by oxygen therapy seems to result in an increase in carbon dioxide partial pressure identical with the increase produced by sleep alone. Correlations between diurnal and nocturnal oxygen saturation and carbon dioxide partial pressure indicate that patients with the highest degree of hypoxia and hypercapnia in daytime have the most severe nocturnal blood gas disorders.