[Analysis of nocturnal disturbed breathing in the elderly using desaturation index]

This study was conducted to examine the nocturnal ventilatory parameters and gas exchange in the elderly with nocturnal disturbed breathing. In order to facilitate analysis of ventilatory parameters with minimum manpower, we developed an unattended continuous nocturnal monitoring system for ventilation and arterial oxygen saturation. Using this system, nocturnal ventilatory parameters and gas exchange were investigated in our geriatric ward. We investigated 30 elderly subjects aged between 65 and 94 (mean age 77.8 +/- 6.5 years, male; female = 15:15). The subjects were free of severe cardiovascular and cerebrovascular disorders, and underwent 10 hours of continuous monitoring of ventilation and arterial oxygen saturation (SaO2). Number of significant desaturation (SDS; desaturation greater than 4% in SaO2 from the baseline value) and desaturation index (DI; sigma SDS(%) x duration (hour)) were calculated using the same system. The number of apnea episodes significantly correlated with DI and the number of SDS. DI also significantly correlated with lowest SaO2, while the number of SDS and the number of apneas were not found to be correlated with lowest SaO2. The number of SDS and the number of apnea episodes did not correlated with lowest SaO2. From the view point of gas exchange during the night, newly introduced DI is more comprehensive parameter when compared with the number of apneas or SDS. Subjects with a DI of over 0.5 were assigned to the group A (n = 8, mean age = 77.8) and the remaining subjects were assigned to group B (n = 22, mean age = 77.8). We compared the group A with the group B regarding nocturnal ventilatory parameters and SaO2.(ABSTRACT TRUNCATED AT 250 WORDS)