Clinical and polysomnographic differences in obstructive sleep apnea patients with different arousal threshold: a clinical study of 894 patients

Aim: We aimed to explore the clinical and polysomnographic differences in obstructive sleep apnea patients with different arousal threshold (AT) which plays a key role in the model of PALM (Pcrit, AT, loop gain, genioglossus muscle responsiveness) of OSA. Method: We divided 894 OSA patients into two groups: low AT and non-low AT according to three independent predictors including AHI 82.5% and the fraction of events that are hypopneas >58.3%. A score of 2 or above points can predict low AT. Differences in clinical and polysomnography characteristics between 387 OSA patients with low AT and 507 with non-low AT. Results: In OSA patients with low AT, body mass index, neck circumference, waist circumference were decreased. And patients with non-low AT was more sleepy assessed by Epworth Sleepiness Scale. Apnea-hypopnea index, both REM AHI and NREM AHI were higher in non-low AT patients. The result of oxygen desaturation index and the indicators of degree of hypoxia, such as minimum arterial oxygen saturation, mean arterial oxygen saturation, percentage of time of oxygen saturation lower than 90% was more serious which was consistent with the above. Compared with low AT patients, apnea events may be more likely occur in non-low AT ones. Conclusions: these data suggested that the severity of patients with low AT maybe lower than non-low AT both in AHI and the degree of hypoxia. Therefore, we may take AT into account when evaluate the severity of OSA and adjust the AT by changing individual differences to improve therapeutic effect.