PURPOSE: The objective of this study is to investigate whether repeated arousals during sleep are associated with excessive daytime sleepiness and some cardiovascular diseases.
METHODS: We reviewed medical records and polysomnographic data of 41 patients who performed polysomnography for a diagnosis of obstructive sleep apnea syndrome from June 2005 to October 2006, retrospectively. We defined total arousal index(TAI) as the number of arousals per hour and respiratory arousal index(RAI) as the number of arousals associated with apnea or hypopnea per hour. We compared total and respiratory arousal index with clinical manifestations.
RESULTS: There were significant positive correlations between arousal indexes and apnea-hypopnea index(AHI) (AHI vs. RAI, r=0.958, p<0.001; AHI vs. TAI, r=0.840, p<0.001). RAI and mean oxygen saturation showed a significant negative correlation with each other(r=-0.460, p=0.002). No significant correlation was found between arousal index and blood pressure although an increasing tendency of arousal index was noted as blood pressure increases. There was no significant correlation between arousal index and parameters of sleepiness, such as Epworth or Stanford sleepiness scales. RAI had a significant positive correlation with body mass index and neck circumference(RAI vs. body mass index, r=0.371, p=0.017; RAI vs. neck circumference, r=0.444, p=0.004).
CONCLUSION: This study showed that arousal index, especially respiratory arousal index, could be a useful predictor of severity of obstructive sleep apnea syndrome. And it is suggested that some anthropometric factors would contribute to the development of arousal during sleep. Also, We think that another factor besides arousal might participate in the development of excessive daytime sleepiness or cardiovascular complication of obstructive sleep apnea.
CLINICAL IMPLICATIONS: Onstructive sleep apnea syndrome, Arousal index.
DISCLOSURE: Sung Kyoung Kim, No Financial Disclosure Information; No Product/Research Disclosure Information