Functional effect of longitudinal heterogeneity in constricted airways before and after lung expansion.
Functional effect of longitudinal heterogeneity in constricted airways before and after lung expansion.
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肺扩张前后收缩气道纵向异质性的功能效应。
DOI：
10.1152/japplphysiol.01400.2010
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Venegas,JG
中科院分区：
文献类型：
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作者：
Wongviriyawong,C;Harris,RS;Zheng,H;Kone,M;Winkler,T;Venegas,JG
个体气道狭窄的异质性是气道高反应性的重要因素。本文研究了纵向异质性（横截面积和形状沿气道沿着的变异性）对气道阻力（Raw）的贡献。我们分析了8名哮喘（AS）和9名非哮喘（NA）受试者在乙酰甲胆碱（MCh）激发前和激发后以及肺扩张至总肺容量后的胸部高分辨率计算机断层扫描。在每名受试者中，计算35个直径> 2 mm的限定中心气道的Raw。忽略面积变异性和非圆形形状会导致Raw（%U总）的低估，在某些气道中是相当大的（> 50%），但通常很小（中位数<6%）。由面积的纵向异质性（%U面积）引起的Raw低估对%U总的平均贡献为36%，而其余的是由于形状的非圆形（%U形状）。MCh激发后，AS和NA的% Urea增加（P <0.05）。肺容量增加至TLC时，AS和NA的%U总和%U面积均降低（P <0.0001，AS的%U总除外，P <0.01）。只有NA组在肺容积增加到TLC后% Ushape显著降低（P <0.005）。% U面积与横截面积[CV2（A）]的平均归一化纵向异质性高度相关，但不相同，%U形状与椭圆形的平均偏心率高度相关。本研究表明，假设圆柱形并从沿其长度沿着的平均面积推导出的Raw在某些气道中可能大大低估了Raw。观察到的Raw低估的变化与肺容量的增加，总肺容量可能是一致的，并有助于部分深吸气在AS和NA科目之间的气道功能的影响的差异。
Heterogeneity in narrowing among individual airways is an important contributor to airway hyperresponsiveness. This paper investigates the contribution of longitudinal heterogeneity (the variability along the airway in cross-sectional area and shape) to airway resistance (Raw). We analyzed chest high-resolution computed tomography scans of 8 asthmatic (AS) and 9 nonasthmatic (NA) subjects before and after methacholine (MCh) challenge, and after lung expansion to total lung capacity. In each subject,Rawwas calculated for 35 defined central airways with >2 mm diameter. Ignoring the area variability and noncircular shape results in an underestimation ofRaw(%Utotal) that was substantial in some airways (∼50%) but generally small (median <6%). The average contribution of the underestimation ofRawcaused by longitudinal heterogeneity in the area (%Uarea) to %Utotalwas 36%, while the rest was due to the noncircularity of the shape (%Ushape). After MCh challenge, %Uareaincreased in AS and NA (P< 0.05). A lung volume increase to TLC reduced %Utotaland %Uareain both AS and NA (P< 0.0001, except for %Utotalin AS withP< 0.01). Only in NA, %Ushapehad a significant reduction after increasing lung volume to TLC (P< 0.005). %Uareawas highly correlated, but not identical to the mean-normalized longitudinal heterogeneity in the cross-sectional area [CV2(A)] and %Ushapeto the average eccentricity of the elliptical shape. This study demonstrates thatRawcalculated assuming a cylindrical shape and derived from an average area along its length may, in some airways, substantially underestimateRaw. The observed changes in underestimations ofRawwith the increase in lung volume to total lung capacity may be consistent with, and contribute in part to, the differences in effects of deep inhalations in airway function between AS and NA subjects.