Influence of sleep position on respiratory function of patients with sleep apnea/hypopnea syndrome / 中国组织工程研究

ABSTRACT

BACKGROUND: In patients with obstructive sleep apnea(OSA),the degree of severity of OSA is mostly related to the sleep time spent in the supine position. According to the apnea-hypopnea index(AHI), positional and n onpositional OSA has been distinguished.OBJECTIVE: To compare the clinical characteristics of positional and nonpositional OSA and investigatethe relationship between sleep position and respiratory function of patients with OSA.DESIGN: A comparative clinica] observation based on the OSA patients.SETTING: Center of Sleep Disorders,Nanjing General Hospital of Nanjing Military Area Command of Chinese PLA.PARTICIPANTS: From October 1998 to May 2002,225 patients were examined with overnight polysomnography in the Center of Sleep Disorders,Department of Respiratory Disease, Nanjing General Hospital of Nanjing Command. According to the inclusion criteria of ① AHI≥10 times/hour;② Sleep time in supine and lateral positions≥30 minutes; ③ Over 20years of age; 225 patients were selected from the total of 415 consecutive patients,including 63 with positional and 162 with nonpositional OSA.METHODS: All patients received overnight monitoring with HMS-5500polysomnography system(Respironics Inc USA) in the sleep laboratory. Queries for a detailed case history and physical examination were performed with the pulmonary functions evaluated with body p lethysmography. The clinical data and results of polysomnographic and pulmonary function tests were compared between the two groups of patients and a multiple stepwise regression analysis was employed to evaluate the determinant factors for sleep position dependence of the patients' condition.MAIN OUTCOME MEASURES: Main outcome: Comparisons of the clinical data,polysomnographic result and pulmonary function between the two groups. Secondary outcome: Correlation between classification of OSA and the clinical data.RESULTS: Totally 63 (28%) of the 225 OSA patients were identified as the positional type,who had significantly greater body mass index (BMI)then the nonpositional type patients [(43.46 ± 16.43) kg/m2 vs (23.90 ± 12.36) kg/m2,t =3. 977,P<0.01]. Except for sleeping time in lateral and supine positions, minimal SatO2 and basic SatO2 before the matching for BMI,all the other factors in polysomnograms of the two groups were significant different(P<0.05 or P<0.01). After BMI matching,all the measurements were identical to those recorded for the primary grouping with the exception of nocturnal limb movement frequency,which differed but insignificant between the two groups. The pulmonary function in the two groups was no significant difference(P>0.05) . Multiple stepwise regression analysis indicated that AHI and BMI were the two determinant factors for positional dependence of OSA with a predictive power of 26. 2%. Linear correlation analysis showed correlation of AHI and SatO2 with BMI in the whole group and nonpositional group(P<0.05 or P<0.01),but not in the positional group (P>0.05).CONCLUSION: About one-third of the OSA patients shows sleep position dependence,who may respond favorably to sleep position training. Sufficient patency can be retained in the upper airway of these patients to relieve respiratory obstruction during sleep and improve the respiratory function.