慢阻肺患者体质指数对肺功能的影响

Effects of body mass index on lung function in patients with chronic obstructive pulmonary disease

目的探讨慢性阻塞性肺疾病(简称慢阻肺)患者体质指数(BMI)对肺功能的影响。方法选取2016年8月至2020年8月于兰州大学第一医院老年呼吸科门诊及住院慢阻肺患者3312例,其中稳定期1103例,急性加重期2209例。根据BMI分为低体重组(稳定期56例和急性加重期131例)、正常体重组(稳定期448例和急性加重期945例)、超重组(稳定期424例和急性加重期773例)及肥胖组(稳定期175和急性加重期360例)。采用MasterScreen PFT肺功能仪测定肺功能:深吸气量(IC)、肺活量(VC)、残气量(RV)/肺总量(TLC)、第一秒用力呼气容积(FEV_(1))、用力肺活量(FVC)、FEV_(1)/FVC、最大呼气中段流量(MMEF)、肺一氧化碳弥散量(DLCO)、单位肺泡容积一氧化碳弥散量(DLCO/VA)、呼吸总阻抗(Zrs)、总呼吸阻力的振荡频率在5 Hz时的气道阻力(R5)、中心气道阻力的振荡频率在20 Hz时的气道阻力(R20)、周围气道弹性阻力的振荡频率在5 Hz时的电抗(X5),分析BMI对肺功能的影响;并以肺功能等级为因变量,年龄、性别、吸烟史、吸烟指数和BMI为自变量,采用有序logistic回归分析影响慢阻肺患者肺功能的危险因素(以"%预计值"表示有关指标占预计值的百分比)。结果各组急性加重期慢阻肺患者肺功能Ⅲ/Ⅳ级患者占比(64.9%、37%、27.4%、24.4%)均高于稳定期(42.9%、25.9%、13.7%、9.1%),而稳定期慢阻肺患者肺功能Ⅰ级(21.4%、34.2%、38.2%、40.0%)占比高于急性加重期(7.6%、20.0%、25.4%、22.8%)(均P<0.05)。在稳定期和急性加重期,低体重组IC%预计值、VC%预计值、FEV_(1)%预计值、FVC%预计值、FEV_(1)/FVC、MMEF%预计值、DLCO%预计值、DLCO/VA%预计值、R20均显著低于其他各组(均P<0.05),低体重组RV/TLC明显高于正常体重组和超重组(P<0.05);超重组及肥胖组IC%预计值、FEV_(1)%预计值、FEV_(1)/FVC、DLCO%预计值、DLCO/VA%预计值、R5、R20高于正常体重组(均P<0.05);肥胖组RV/TLC、FEV_(1)/FVC、DLCO%预计值、DLCO/VA%预计值、Zrs、R5、R20高于超重组(均P<0.05)。有序logistic回归模型分析结果显示:低体重是稳定期[OR(95%CI):2.316(1.206~3.554)]和急性加重期[OR(95%CI):2.457(1.647~3.669)]慢阻肺患者肺功能减损的危险因素(均P<0.05)。结论低BMI对慢阻肺患者的肺功能产生不良影响,是慢阻肺患者肺功能减损的独立危险因素。

Objective To investigate the effects of body mass index(BMI)on lung function in patients with chronic obstructive pulmonary disease(COPD).Methods A total of 3312 patients with COPD were selected from outpatients and inpatients in Department of Gerontal Respiratory Medicine of the First Hospital of Lanzhou University from August 2016 to August 2020,including 1103 patients in stable period and 2209 patients in acute exacerbation period.According to body mass index(BMI),these COPD patients were divided into four groups:low weight(56 cases,131 cases),normal weight(448 cases,945 cases),overweight(424 cases,773 cases)and obesity groups(175 cases,360 cases)respectively in stable stage and in acute exacerbation stage.The lung function of inspiratory capacity(IC),vital capacity(VC),residual volume(RV)/total lung capacity(TLC),forced expiratory volume in 1 second(FEV_(1)),forced vital capacity(FVC),FEV_(1)/FVC,maximal mid-expiratory flow(MMEF),diffusing capacity of the lung for carbon monoxide(DLCO),DLCO normalized per liter alveolar volume(DLCO/VA),respiratory impedance(Zrs),respiratory resistance at 5 Hz(R5),respiratory resistance at 20 Hz(R20)and respiratory reactance at 5 Hz(X5)were measured using MasterScreen PFT in all patients,and the influence of BMI on lung function was analyzed respectively.The risk factors of impaired lung function were analyzed by ordered logistic regression with lung function grade as dependent variable and age,gender,smoking history,smoking index and BMI as independent variables(“%pred”represents the percentage of predicted value).Results The proportion of patients with lung function gradeⅢ/Ⅳin acute exacerbation period(64.9%,37%,27.4%,24.4%)was higher than that in stable stage(42.9%,25.9%,13.7%,9.1%),while the proportion of patients with lung function gradeⅠin stable stage(21.4%,34.2%,38.2%,40.0%)was higher than that in acute exacerbation period(7.6%,20.0%,25.4%,22.8%)(all P<0.05).The IC%pred,VC%pred,FEV_(1)%pred,FVC%pred,FEV_(1)/FVC,MMEF%pred,DLCO%pred,DLCO/VA%pred and R20 in low weight group were significantly lower than other groups both in stable period and acute exacerbation period(all P<0.05).The RV/TLC was higher in low weight group than that of normal weight and overweight groups in both periods(all P<0.05).The IC%pred,FEV_(1)%pred,FEV_(1)/FVC,DLCO%pred,DLCO/VA%pred,R5 and R20 in overweight and obesity groups were higher than those of normal weight group(all P<0.05).The RV/TLC,FEV_(1)/FVC,DLCO%pred,DLCO/VA%pred,Zrs,R5 and R20 in obesity group were higher than those of overweight group(all P<0.05).The ordered logistic regression analysis showed that low weight was independent risk factor for impaired lung function of COPD both in stable period[OR(95%CI)2.316(1.206-3.554)]and acute exacerbation period[OR(95%CI):2.457(1.647-3.669)].Conclusion Lower BMI has an adverse effect on lung function,and it is an independent risk factor for impaired lung function in COPD patients.