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Abstract：
BACKGROUND: Overlap syndrome (OS), the coexistence of chronic obstructive pulmonary disease and obstructive sleep apnea, is frequently characterized by the presence of daytime hypercapnia (pCO2 ≥ 45 mmHg). The aim of this study was to investigate potential differences in anthropometric, sleep and respiratory characteristics between hypercapnic and normocapnic patients with OS.
METHODS: Consecutive patients who underwent polysomnography, pulmonary function testing and arterial blood gases and had been diagnosed with OS were enrolled in the study.
RESULTS: According to pCO2 levels in wakefulness, the patients were divided into group A, consisting of OS patients without hypercapnia (n = 108) or group B, consisting of OS patients with hypercapnia (n = 55). The majority of included patients in both groups were males (n = 92 in group A vs. n = 50 in group B). Group B had increased BMI (p = 0.001), neck (p = 0.017) and waist circumference (p = 0.013), higher scores in Epworth sleepiness scale (ESS) (p = 0.008), increased sleep efficiency (p = 0.033), oxygen desaturation index (p = 0.004) and time with oxyhemoglobin saturation <90% (p = 0.006) than group A. Also, Group B had decreased average and minimum oxyhemoglobin saturation during sleep (p < 0.001). Hypercapnic patients had lower FEV1% (p = 0.003), FVC% (p = 0.004), pO2 and pCO2 (p < 0.001 for both) values compared with normocapnic patients. In binary regression analysis, which assessed various predictors on the likelihood of having hypercapnia, it was found that BMI (OR: 1.313, 95% CI: 1.048-1.646, p = 0.018) and FVC (OR: 0.913, 95% CI: 0.845-0.986, p = 0.020) were the major determinants of hypercapnia in OS patients.
CONCLUSIONS: Hypercapnic OS patients were more obese and sleepy and presented worse respiratory function in wakefulness and sleep hypoxia characteristics compared with normocapnic OS patients.
METHODS: Consecutive patients who underwent polysomnography, pulmonary function testing and arterial blood gases and had been diagnosed with OS were enrolled in the study.
RESULTS: According to pCO2 levels in wakefulness, the patients were divided into group A, consisting of OS patients without hypercapnia (n = 108) or group B, consisting of OS patients with hypercapnia (n = 55). The majority of included patients in both groups were males (n = 92 in group A vs. n = 50 in group B). Group B had increased BMI (p = 0.001), neck (p = 0.017) and waist circumference (p = 0.013), higher scores in Epworth sleepiness scale (ESS) (p = 0.008), increased sleep efficiency (p = 0.033), oxygen desaturation index (p = 0.004) and time with oxyhemoglobin saturation <90% (p = 0.006) than group A. Also, Group B had decreased average and minimum oxyhemoglobin saturation during sleep (p < 0.001). Hypercapnic patients had lower FEV1% (p = 0.003), FVC% (p = 0.004), pO2 and pCO2 (p < 0.001 for both) values compared with normocapnic patients. In binary regression analysis, which assessed various predictors on the likelihood of having hypercapnia, it was found that BMI (OR: 1.313, 95% CI: 1.048-1.646, p = 0.018) and FVC (OR: 0.913, 95% CI: 0.845-0.986, p = 0.020) were the major determinants of hypercapnia in OS patients.
CONCLUSIONS: Hypercapnic OS patients were more obese and sleepy and presented worse respiratory function in wakefulness and sleep hypoxia characteristics compared with normocapnic OS patients.
摘要：
背景：重叠综合征（OS），慢性阻塞性肺疾病与阻塞性睡眠呼吸暂停并存,通常以存在白天高碳酸血症（pCO2≥45mmHg）为特征。这项研究的目的是调查人体测量学的潜在差异，OS高碳酸血症和正常碳酸血症患者的睡眠和呼吸特征。
方法：连续接受多导睡眠监测的患者，本研究纳入了肺功能检测和动脉血气检测,并已诊断为OS.
结果：根据清醒时的pCO2水平，将患者分为A组,由无高碳酸血症的OS患者（n=108）或B组组成，包括高碳酸血症OS患者（n=55）。两组中的大多数纳入患者均为男性（A组中n=92，与B组n=50)。B组BMI增加（p=0.001），颈部（p=0.017）和腰围（p=0.013），Epworth嗜睡量表(ESS)得分较高(p=0.008)，睡眠效率提高（p=0.033），氧饱和度指数(p=0.004)和氧合血红蛋白饱和度<90%(p=0.006)的时间比A组好。B组睡眠期间平均和最低氧合血红蛋白饱和度降低(p<0.001)。高碳酸血症患者的FEV1%较低（p=0.003），FVC%(p=0.004)，pO2和pCO2(两者p<0.001)值与正常二氧化碳患者相比。在二元回归分析中，它评估了高碳酸血症可能性的各种预测因素，结果发现，BMI（OR：1.313，95％CI：1.048-1.646，p=0.018）和FVC（OR：0.913，95％CI：0.845-0.986，p=0.020）是OS患者高碳酸血症的主要决定因素。
结论：高碳酸血症OS患者与正常碳酸血症患者相比，在清醒和睡眠缺氧方面表现出更差的呼吸功能。
方法：连续接受多导睡眠监测的患者，本研究纳入了肺功能检测和动脉血气检测,并已诊断为OS.
结果：根据清醒时的pCO2水平，将患者分为A组,由无高碳酸血症的OS患者（n=108）或B组组成，包括高碳酸血症OS患者（n=55）。两组中的大多数纳入患者均为男性（A组中n=92，与B组n=50)。B组BMI增加（p=0.001），颈部（p=0.017）和腰围（p=0.013），Epworth嗜睡量表(ESS)得分较高(p=0.008)，睡眠效率提高（p=0.033），氧饱和度指数(p=0.004)和氧合血红蛋白饱和度<90%(p=0.006)的时间比A组好。B组睡眠期间平均和最低氧合血红蛋白饱和度降低(p<0.001)。高碳酸血症患者的FEV1%较低（p=0.003），FVC%(p=0.004)，pO2和pCO2(两者p<0.001)值与正常二氧化碳患者相比。在二元回归分析中，它评估了高碳酸血症可能性的各种预测因素，结果发现，BMI（OR：1.313，95％CI：1.048-1.646，p=0.018）和FVC（OR：0.913，95％CI：0.845-0.986，p=0.020）是OS患者高碳酸血症的主要决定因素。
结论：高碳酸血症OS患者与正常碳酸血症患者相比，在清醒和睡眠缺氧方面表现出更差的呼吸功能。
