BACKGROUND: Although pulmonary diffusion capacity (PDC) has been substantially proved in a declining tendency in age-dependent manner, the effects of such related factors as body mass, sex and height within an age range on pulmonary membrane conductance (Dm) and capillary blood volume (CBV), as well as the correlation of Dm with CBV and PDC deserve further investigation.OBJECTIVE: To study the correlation of Dm and CBV with PDC, age,body mass, height and sex in normaladults.DESIGN: With healthy adults as subjects, multiple factor linear correlation and regression analysis was used to elicit correlation coefficient and regression equation while F-test and Q-test were used for comparing the differences between groups.PARTICIPANTS: We randomly selected 100 healthy adults, 50 males and 50 females, who came to the clinic of the General Hospital of Chinese PLA for routine physical examination between April and October 1997.The 100 volunteers were divided into five groups according to their age:20-29, 30-39, 40-49, 50-59 and 60-69 years old groups with 20 in each group, half males and half females.METHODS: PDC and Dm of the healthy adults were examined with Sensormedics 2200 pulmonary function detector. CBV was calculated with the following formula (1/PDC=I/ Dm +1/θCBV, θrefers to the combined velocity of CO with Hb, which was in inverse proportion to the inhaled partial oxygen pressure, Dm and CBV were unaffected by θ). Multiple factor linear correlation and progressive regression analysis was used to elicit correlation coefficient of PDC, Dm and CBV. Meanwhile, regression equation was used to reveal the correlation of age, body mass and height with pulmonary functions.MAIN OUTCOME MEASURES: Correlation ofDm and CBV with PDC and age, body mass, height and sex in normal adults.RESULTS: Data of the 100 healthy adults were processed according to the objective and statistically analyzed. ① PDC and Dm were proved to decline in age-dependent manner from the onset of 40 years old in the 100 healthy adults (P＜ 0.05), and CBV also declined after 50 years old (P ＜ 0.05). ②Relationship between women's age and pulmonary function: Age was proved to have significant negative correlation with PDC,Dm and CBV (r= -0.646 0 to -0.814 6, P＜ 0.01). By contrast, PDC was found to be positively correlated with Dm, CBV and alveolus ventilation volume (AVV) (r=0.949 7, 0.740 0, 0.735 6, P＜ 0.01), and AVV was found to be positively correlated with PDC, Dm and CBV (r=0.482 1-0.740 6,P＜ 0.01). ③ Relationship between men's age and pulmonary function:Age had significant negative correlation with PDC, Dm and CBV (r=-0.712 to -0.830 5, P＜ 0.01). However, PDC was found to be moderately or highly positively correlated with Dm, CBV and AVV (r=0.585 2 to 0.946 0, P＜ 0.01), and AVV had moderately positive correlation with PDC, Dm and CBV (r=0.431 3-0.585 2, P＜ 0.01). ④ Regression analysis revealed that age and height were the main variables of the predicting equation of PDC,Dm and CBV. Body mass could not enter regression equation in females,and it was only proved to be correlated with PDC and CBV in males with the regression coefficient of 0.009 4 and 0.654 3, respectively.CONCLUSION: ① PDC and Dm begin to decline from the onset of 40 years old in healthy adults (P＜ 0.05), and CBV declines after 50 years old.② PDC, Dm and CBV of healthy adults are proved to decline in age-dependent manner. ③ PDC increases with the increment of Dm and CBV. ④ Age and/or height are the main variables in the regression equation of PDC, Dm and CBV, but body mass is not the key predictor for Dm and CBV.%背景:虽然已有充分证据表明成人的肺弥散能力随年龄增加而减少,但年龄范围中体质量、性别及身高等相关因素对呼吸膜弥散能力及肺毛细血管血流量的影响,以及此项因素下呼吸膜弥散能力与肺毛细血管血流量及肺弥散能力关系尚需深入探讨.目的:探讨正常人的呼吸膜弥散能力(Dm)和肺毛细血管血流量与肺弥散能力及年龄、身高、体质量和性别的关系.设计:以健康成人为观察对象,采用多元线性相关、逐步回归方法计算相关系数及回归方程,组间差异使用F检验及Q检验.对象:选择1997-04/1997-10解放军总医院门诊查体健康受试者100人,男女各50例,分成5个年龄组,分别为20～29,30～39,40～49,50～59,60～69岁组,每组20人,男女各10人.均自愿参加.方法:健康成人肺弥散能力和呼吸膜弥散能力测定使用Sensormedics 2200肺功能仪,肺毛细血管血流量测定后采用公式法计算(1/肺弥散能力=1/呼吸膜弥散能力+1/θ肺毛细血管血流量,θ是一氧化碳与血红蛋白结合速率,与吸入气体的氧分压成反比,呼吸膜弥散能力、肺毛细血管血流量不受θ的影响).采用多元线性相关、逐步回归方法计算肺弥散能力,呼吸膜弥散能力、肺毛细血管血流量相关性,采用回归方程显示年龄、身高、体质量与肺功能的关系.主要观察指标:正常人的呼吸膜弥散能力和肺毛细血管血流量与肺弥散能力、年龄、身高和体质量的关系.结果:按意向处理分析,健康成人100人均进入结果分析.①健康成人100人肺弥散能力、呼吸膜弥散能力在40岁以后随年龄增加而呈下降趋势(P＜0.05),肺毛细血管血流量在50岁以后随年龄增加呈下降趋势(P＜0.05).②女性年龄及各项肺功能间的关系:年龄与肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量呈显著负相关(r=-0.646 0～-0.814 6,P＜0.01).肺弥散能力与呼吸膜弥散能力、肺毛细血管血流量、肺泡通气量呈显著正相关(r=0.949 7,0.740 0,0.735 6,P＜0.01).肺泡通气量与肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量呈中度或高度正相关(r=0.482 1～0.740 6,P＜0.01).③男性年龄及各项肺功能间的关系:年龄与肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量呈显著负相关(r=-0.712～-0.830 5,P＜ 0.01).肺弥散能力与呼吸膜弥散能力、肺毛细血管血流量、肺泡通气量呈中度或高度正相关(r=0.585 2～946 0,P＜0.01).肺泡通气量与肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量呈中度正相关(r=0.431 3～0.585 2,P＜0.01).④经逐步回归统计,身高与年龄为进入肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量预计公式的主要变量,在女性组,体质量未能进入回归方程,男性组仅在肺弥散能力、肺毛细血管血流量中进入,回归系数分别为0.009 4,0.654 3.结论:①健康成人呼吸膜弥散能力和呼吸膜弥散能力在40岁以后开始降低,肺毛细血管血流量的减少发生在50岁以后.②健康成人肺弥散能力、呼吸膜弥散能力、肺毛细血管血流量随年龄的增加而减弱或下降.③肺弥散能力随呼吸膜弥散能力和肺毛细胞血管血流量增强和增大而增强.④身高和/或年龄是呼吸膜弥散能力、肺毛细血管血流量回归方程的主要变量,在呼吸膜弥散能力、肺毛细血管血流量的预计公式中,体质量并非主要预计因素.
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