The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

THE STUDY OF THE INFLUENCE OF SLEEP POSITION ON SLEEP APNEA

GUO Xiheng, Wang Chen, Zhang Hongyu, Kong Weimin, An Li, Liu Li, Weng Xinzhi
Beijing Chaoyang Hospital-Beijing Institute of Respiratory Medicine

Objectives: In order to study the influence of sleep position on the frequency of sleep apnea and its severity, and the association and clinical characters of positional apnea and non-positional apnea.

Methods:
382 patients with OSA underwent nocturnal PSG including sleep position. All patients were divided into positional apnea(P-OSA) group and non-positional apnea(NP-OSA) group according to RDI changes during sleep stage II.

RESULTS:
347 patients met the selected criteria and were including in the study. Of all 347 patients, 199(57.3%) were found to be P-OSA group, 148(42.7%) to be NP-OSA group. There were no statistical difference in sex and mean age(p>0.05, respectively).Mean BMI of P-OSA was lower than NP-OSA(p<0.05)。There were statistical differences between P-OSA and NP-OSA in sleep efficiency(p<0.05), REM latency(p<0.05), percentage of II、III+IV and REM(p<0.01, respectively). Sleep times in supine position were significantly higher than those of lateral position in both groups (p=0.001, respectively). The total RDI(p<0.01), supine RDI(p<0.01), oxygen desaturation index(p<0.01) and min-SaO2(p<0.01) were statistical differences between two groups. In P-OSA group, supine RDI(p<0.001), SaO2-des index(p<0.001) and min-SaO2(p<0.01) were significantly differences than those of lateral. Also, in NP-OSA group RDI(p<0.005),SaO2-des index(p<0.05), min-SaO2(p<0.02)。The prevalence remained high and fairly steady in the mild-moderate categories, but showed a marked and significant reduction in the prevalence of P-OSA in the most severe RDI category(p=0.001). There were 71.9% P-OSA among patients with RDIĀ£30, while 49.6% among those with RDI>30. A severe, obese and older OSA patients is significantly less likely to be positional than a mild-moderate, thin and young OSA patients. A steady, marked and significantly reduction was observed in the prevalence of P-OSA with the increase in BMI in the stuffy categories.(p=0.002). Age was a contributing factor of only borderline significance for positional apnea(p=0.045)。In seven obese OSA patients who lost weight, a much more pronounced reduction was seen in the lateral RDI(from46.9 to 11.0, p<0.001) than in the supine RDI, and six of seven who were previously NP-OSA became P-OSA. Weight loss cause a much more striking improvement in the lateral RDI than in the supine RDI.

Conclusions:
Sleep position ia one of major important factors correlating with the frequency and severity abnormalities in OSA patients. Sleep position is one of most important factors affecting OSA. There are 57.3% patients with OSA were found to have at least twice as many apnea/hypopnea in the supine than in the lateral position. These so-called positional apnea are mainly among on average thinner, mild-moderate and younger than non-positional apnea. Consequently their nocturnal sleep quality was less destruction than NP-OSA. Sleep in lateral position may be one of simple and effective therapy for this kind of patients. It is necessary to monitoring sleep position during PSG. Further research on sleep position conduce to the researches of pathogenesis and treatment of OSA.

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