To find out the predictors of nocturnal arterial oxygen desaturation in patients with respiratory diseases, transcutaneous oxygen saturation(StcO2) monitoring studies using a pulse oximeter were performed during sleep in 20 patients. StcO2 was decreased more than 4% from the baseline value in 18 patients(90%) and more than 10%('Desaturator') in 8(40%). Five of the seven patients(71.4%) with awake PaO2<60mmHg and three of the thirteen patients(23.1%) with awake PaO2≥60mmHg were 'desaturators'. The awake PaO2/FIO2 and PaO2/PAO2 could distinguish 'desaturator' from 'nondesaturator, and PaO2, SaO2 or StcO2 could not. These results suggest that the nocturnal oxygen desaturation depends on the severity of the underlying disease rather than the baseline PaO2. Anthropomorphic and lung function factors could not separate between 'desaturator' and 'non-desaturator', and about a quarter of patients with a wake PaO2≥60mmHg developed significant desaturation. Therefore, it is necessary to monitor the nocturnal arterial oxygen saturation in patients with respiratory diseases regardless of their severity of airflow obstruction or awake PaO2.
Humans ; Lung ; Oxygen*