[Development of nocturnal desaturation in 35 patients with chronic obstructive bronchopneumopathy (COBP). Relation to...

35 patients with chronic airflow obstruction in a stable state were studied using nocturnal oximetry on two occasions with an interval of 25 +/- 10 months between them. First we studied the predicted value for the pulmonary function factors during the day to compare with nocturnal desaturation. On the second occasion we compared the progress of the desaturation indices and the outcome of the functional and hemodynamic data. The PaO2, the PaCO2 and the VEMS/CV ratio (FEV1/VC) were the only elements during waking which correlated with the degree of nocturnal desaturation. In spite of this correlation and the fact that the confidence intervals were large, the predictable element of these daytime measurements remained weak in daily practice. The progress between the two oximetric measurements of the PaO2 and the PaCO2 as well as the fall in the FEV1 (VEMS) was strongly linked to the evolution of desaturation during sleep. This progressive aspect shows the value of nocturnal oximetry in patients who are evolving towards alveolar hypoventilation. Finally, the outcome of pulmonary arterial pressure appears predictable as a result of the progress of nocturnal desaturation.