[Current problems in the Diagnosis and stage classification of sleep apnea syndrome]

We examined the relationship between daytime symptoms and respiratory disturbance indices during sleep in 60 patients with sleep apnea syndrome who had an apnea index of more than 5/hr for at least one night. Daytime hypersomnolence, morning headache, and a history of traffic accidents did not correlated strongly with apnea index or with nocturnal desaturation. The same was true of daytime blood pressure and nocturnal micturition. Both hemoglobin concentration and the mean pulmonary arterial pressure in the daytime correlated significantly with indices of nocturnal desaturation and not with apnea index, but this might reflect the positive correlation between those variables and the base-line level of daytime PaO2, in which case it would not be a direct consequence of nocturnal desaturation. These data suggest that diagnostic criteria should not be based on apnea index or desaturation alone. Long-term follow-up data on Japanese patients is needed to establish more rational diagnostic criteria and stage classification for sleep apnea syndrome.