一口气法与重复呼吸法测定肺弥散功能的比较

Single-breath and rebreathing methods for measurement of pulmonary diffusing function： a comparative study

目的比较-口气法与重复呼吸法在健康人群及间质性肺疾病（ILD）和慢性阻塞性肺疾病（简称慢阻肺）患者肺弥散功能检测中的差别。方法2011年9月至2012年2月广州呼吸疾病研究所的ILI）患者32例为ILD组，其中男15例，女17例，年龄41～72岁；慢阻肺患者32例为慢阻肺组，其中男28例，女4例，年龄40—75岁；健康体检者29名为对照组，其中男9名，女20名，年龄42～74岁。随机数字表法交叉进行-口气法或重复呼吸法弥散功能测试。以对照组-口气法D。CO占预计值％为标准，分别校正3组的重复呼吸法D，CO占预计值％、D，CO／肺泡容积占预计值％。两组间比较采用配对t检验，多组问比较采用单因素方差分析，计算受试者工作特征曲线下面积（AUC）及其95％CI。结果用重复呼吸法检测，对照组中15例的D．CO占预计值％〈80％，其均值[（78．8±2．1）％]也低于80％。用-口气法检测对照组的D．CO占预计值％为标准，对重复呼吸法D．CO占预计值％进行校正，以校正值（1．097）分别校正3组的重复呼吸法D。CO／肺泡容积占预计值％。校正前-口气法和重复呼吸法测得的D。．CO占预计值％：对照组分别为（91．2±1．9）％和（78．8±2．1）％，ILD组分别为（45．8±2．6）％和（60．0±1．9）％，慢阻肺组分别为（66．3±2．9）％和（56．6±1．6）％；D．CO／肺泡容积占预计值％：对照组分别为（99．8±2．3）％和（84．6±4．5）％，ILD组分别为（75．9-t-3．0）％和（88．5±5．4）％，慢阻肺组分别为（80．2±3．7）％和（50．6±2．5）％，3组均有显著差别。校正后-口气法和重复呼吸法测得值，仅ILD组D．CO占预计值％[（45．8±2．6）％和（65．8±2．1）％]、D．CO／肺泡容积占预计值％[（75．9±3．0）％和（102．2±6．2）％]，慢阻肺组DI．CO／肺泡容积占预计值％[（80．2±3．7）％和（58．34-2．8）％]的差异有统计学意义（t值为-6．00～4．68，均P〈0．叭）。重复呼吸法测试时间：慢阻肺组[（106±5）s]显著长于ILD组[（73±4）s]和对照组[（79±5）s]，差异有统计学意义（F=11．99，P〈0．01），且重复呼吸法测定D．CO／肺泡容积占预计值％与测试时间的相关性（-0．661，P〈0．01）显著高于D。．CO占预计值％与测试时间的相关性（-0．391，P〈0．01）。重复呼吸法测定ILD组D．．CO占预计值％的AUC为0．893，95％CI为0．817～0．970，慢阻肺组D．CO／肺泡容积占预计值％的AUC为0．895，95％CI为0．811～0．979。结论-口气法与重复呼吸法测定D。CO、D。co／N泡容积存在差别，重复呼吸法更符合呼吸生理，可能更适用于疾病状态下患者肺弥散功能的检测。

Objective To compare the difference of pulmonary diffusing capacity measured by single-breath （SB） and re-breathing （RB） in normal subjects, patients with interstitial lung disease （ILD） and chronic obstructive pulmonary disease （COPD）. Methods We enrolled a cohort of subjects from theGuangzhou Institute of Respiratory Disease between September 2011 and February 2012： control group 29 （male 9, female 20, 42-74 y）, ILD group 32 （male 15, female 17, 41-72 y）, COPD group 32 （male 28, female 4, 40 -75 y）. All subjects underwent pulmonary diffusing capacity test using SB or RB method according to random figures order list. Diffusing capacity of carbon monoxide per predicted measured by SB method （SB-DLCO% pred） of the normal group was used as the standard to adjust the diffusing capacity of carbon monoxide per predicted measured by RB method （RB-DLCO% pred） and diffusing capacity of carbon monoxide per liter of VA per predicted measured by RB （RB-DLCO/VA% pred） in the 3 groups, respectively. Comparisons between 2 groups were performed by using the independent-sample t test, among more than 2 groups by using the One-Way ANOVA test, while the ROC curve was used to calculate the area under curve （AUC） and its 95% CI. Results In the control group, 15 subjects＇ RB-DLCO% pred was lower than 80% , and the mean value （78.8 ±2. 1）% was also lower than 80%. Using SB-DLCO%pred of the normal group as a standard to adjust the RB-DLCO% pred, the corrected value was 1. 097, and then this value was used to adjust RB-DLCO/VA% pred in the 3 groups, respectively. Before correction DLCO% pred [the control group： （91.2 ±1.9）% vs （78.8 ±2.1）%; the ILD group： （45.8±2.6）% vs （60.0± 1.9） % ; the COPD group ： （66. 3 ± 2.9） % vs （56. 6 ± 1.6） % ] and Dr CO/VA% pred [ the control group ： （99.8±2.3）% vs （84.6 ±4.5）%; the ILD group： （75.9 ±3.0）% vs （88.5 ±5.4）%; the COPD group ： （ 80. 2 ± 3.7 ） % vs （ 50. 6 ± 2.5 ） % ] between the SB and RB were statistically different among the 3 groups. After correction, only the DLCO% pred [ （45.8 ± 2. 6）% vs （65.8 ±2. 1 ）% ] , DLCO/VA% pred [ （75.9 ±3.0）% vs （ 102. 2 ±6. 2）% ] of the ILD group and the DLCO/VA% pred [ （80. 2 ±3.7） vs （58.3± 2. 8）% ] of the COPD group had significant difference between the 2 methods（ t = -6. 00 -4. 68, all P 〈 0. 01 ）. The test time of re-breathing in the COPD group （ 106 ± 5 ） s was significant longer than that of the ILD group （73 ±4） s and the control group （79 ±5） s （F = 11.99, P 〈0, 01 ）, and the correlation between DLCO/VA% pred and the test time （ r = - 0. 661, P 〈 0. 01 ） was higher than the relationship between DLCO%pred and the test time （r = -0. 391, P 〈0. 01 ）. Furthermore, in the ILD group, the area of RB-DLCO%pred under ROC was 0. 893, 95%C1 being 0. 817 -0. 970. In the COPD group, the area of RB-DLCO/VA% pred under ROC was 0. 895, 95% CI being 0. 811 - 0. 979. Conclusions There were differences between re-breathing and single-breath in measuring diffusing capacity. The present predicted value of the re-breathing method needed further study to confirm its applicability. Re-breathing method was more consistent with the respiratory physiology, and might be a better method to detect diseased states.