Influence of the right- versus left-sided sleeping position on the apnea-hypopnea index in patients with sleep apnea.

PURPOSE: Sleep and sleep position have a significant impact on physical, cardiac and mental health, and have been evaluated in numerous studies particularly in terms of lateral sleeping positions and their association with diseases. We retrospectively examined the relationship between the sleeping position and position-specific apnea-hypopnea index (AHI) in obstructive sleep apnea-hypopnea (OSA) patients. METHODS: We assessed the sleeping body position and the body position-specific AHI score in patients who were referred for suspected OSA and underwent diagnostic nocturnal polysomnography. In order to eliminate inter-individual differences, only those who had a similar percentage of time spent in the LSSP and RSSP for each patient were enrolled. To provide this validity, only subjects that had a similar percentage of left and right lateral sleep time (±10%) were included in the analysis. RESULTS: A total of 864 patients had nocturnal diagnostic PSG. Of them, 131 patients met the inclusion criteria. The percent rate spent in the supine sleeping position (SSP) was 31.3 ± 18.7%, in the LSSP was 31.8 ± 10% and in the RSSP was 32.6 ± 10.8%. Whereas the SSP-specific AHI score was the highest with 60.4 ± 36.2/h among all the sleeping position-specific AHI scores (p < 0.001), the LSSP-specific AHI score was statistically higher than that for RSSP (30.2 ± 32.6/h vs. 23.6 ± 30.1/h; p < 0.001). When comparing individuals sub-grouped based on OSA severity, there was a statistically significant difference between the LSSP-specific AHI score and RSSP-specific AHI score in patients with severe (p = 0.002) and moderate (p = 0.026), but not mild (p = 0.130) OSA. CONCLUSION: We found that the sleeping position had a significant influence on apneic events and RSSP decreased the frequency of obstructive respiratory events in patients with moderate and severe disease.

Influence of the severity of obstructive sleep apnea on nocturnal heart rate indices and its association with hypertension.

OBJECTIVE: Both heart rate (HR) and blood pressure parameters provide important information on the pathophysiology of the cardiovascular regulatory mechanisms, and are mainly affected by the autonomic nervous system. We sought to clarify whether the severity of obstructive sleep apnea (OSA) affects nocturnal HRs and whether there is a relationship between nocturnal HRs and the presence of hypertension. METHODS: We retrospectively reviewed medical records of all patients who performed nocturnal polysomnography with monitoring of HRs, and examined whether there is a relationship among the nocturnal HRs, the severity of OSA and the presence of hypertension. RESULTS: A total of 540 patients were included in the study. Nocturnal mean and maximal HRs were significantly higher in severe OSA group than in moderate (p=0.002 and p>0.05 in females; p<0.049 and p=0.044, in males, respectively) and mild OSA groups (p<0.001 and p=0.003, respectively in females, p<0.001 and p=0.004, respectively in males); and there was a positive correlation between the nocturnal mean HR and apnea-hypopnea index (Pearson's p=0.504, p<0.001 in female group; Pearson's p=0.254, p<0.001 in male group) and again the nocturnal mean HR and the presence of HT (Spearman's p=0.090, p=0.394 in female group; Spearman's p=0.272, p<0.001 in male group) in both gender groups. CONCLUSION: We found that nocturnal mean and maximal HRs to be associated with severity of OSA and the presence of hypertension. We speculated that increased nocturnal mean and maximal HRs caused by sympathetic nervous system activation in OSA might be one of the mechanisms in explaining the hypertension and OSA association.