[Prediction of nocturnal desaturation in elderly patients with chronic respiratory disease]

Previous reports suggest that nocturnal disorders of sleep and breathing have increased prevalence among the elderly, and episodic nocturnal oxygen desaturation (NOD) has an increased incidence in patients with chronic respiratory disease. Current Japanese criteria for home low flow oxygen therapy (LFOT), recommend LFOT for patients with daytime PaO2 < 55 torr or with daytime PaO2 < or = 60 torr who have significant NOD. Strict adherence to these LFOT criteria requries full overnight monitoring of arterial oxygen saturation (SaO2) in all patients with daytime PaO2 < or = 60 torr. Since widespread nocturnal oximetry involves significant expenditure of time and resources, it is important among patients with chronic respiratory diseases to predict those who will have significant NOD. The aim of the present study was to formulate criteria for identification of patients who are most likely to demonstrate significant NOD based upon daytime respiratory function data. Subjects included 34 elderly patients with daytime PaO2 > or = 55 torr, who had stable severe chronic respiratory disease (15 chronic emphysema, 6 chronic bronchitis, 12 post-tuberculosis, and 1 kyphoscoliosis). Study data included medical history, assessment of dyspnea by Hugh-Jones classification, and measurement of daytime, awake arterial blood gases and spirometry. Each subject underwent full overnight oximetry monitoring. The percentage of total sleep time recorded with SaO2 < or = 85% was noted (DST85), and NOD was defined as DST85 > or = 1%. Of the 34 patients, 11 were identified as NOD, and 23 as non-NOD patients. Duration and severity of dyspnea were not different between NOD and non-NOD patients.(ABSTRACT TRUNCATED AT 250 WORDS)