Effros Richard M, Peterson Barry, Casaburi Richard, Su Jennifer, Dunning Marshall, Torday John, Biller Julie, Shaker Reza
Los Angeles Biomedical Research Institute at Harbor-University of California-Los Angeles Medical Center, Torrance, 90505, USA.
J Appl Physiol (1985). 2005 Oct;99(4):1286-92. doi: 10.1152/japplphysiol.00362.2005. Epub 2005 May 26.
The exhaled breath condensate (EBC) method represents a new, noninvasive way to detect inflammatory and metabolic markers in the fluid that covers the airways [epithelial lining fluid (ELF)]. However, respiratory droplets represent only a very small and variable fraction of the EBC, most (approximately 99.99%) of which is water vapor. Our objective was to show that ELF concentrations could be calculated from EBC values by using any of three dilutional indicators (urea, total cations, and conductivity) in nine normal and nine chronic obstructive lung disease (COPD) subjects. EBC concentrations of Na(+), K(+), Ca(2+), Mg(2+), total cations, urea, and conductivity varied over a 10-fold range among individuals, but concentrations of these constituents (except Ca(2+)) remained well correlated (r(2) = 0.44-0.83, P < 0.001). Dilution (D) of respiratory droplets in water vapor was calculated by dividing plasma concentrations of the dilutional indicators by EBC concentrations. Estimates of D were not significantly different among these indicators, and urea D averaged 10,800 +/- 2,100 (SE) in normal and 12,600 +/- 3,300 in COPD subjects. Although calculated Na(+) concentrations in the ELF were less than one-half those in plasma, and concentrations of K(+), Ca(2+), and Mg(2+) exceeded those in plasma, total cation concentrations in ELF were not significantly different from those in plasma, indicating that ELF is isotonic in both normal and COPD subjects. EBC amylase concentrations (measured with an ultrasensitive procedure) indicated that saliva represented <10% of the respiratory (ELF) droplets in all but three samples. Dilutional and salivary markers are essential for interpretation of EBC studies.
呼出气冷凝液（EBC）法是一种检测覆盖气道的液体[上皮衬液（ELF）]中炎症和代谢标志物的新型非侵入性方法。然而，呼吸道飞沫仅占EBC的极小部分且比例可变，其中大部分（约99.99%）是水蒸气。我们的目的是表明，在9名正常受试者和9名慢性阻塞性肺疾病（COPD）受试者中，可通过使用三种稀释指标（尿素、总阳离子和电导率）中的任何一种，从EBC值计算ELF浓度。个体之间，EBC中Na⁺、K⁺、Ca²⁺、Mg²⁺、总阳离子、尿素和电导率的浓度变化范围达10倍，但这些成分（除Ca²⁺外）的浓度仍具有良好的相关性（r² = 0.44 - 0.83，P < 0.001）。通过将稀释指标的血浆浓度除以EBC浓度来计算呼吸道飞沫在水蒸气中的稀释度（D）。这些指标之间的D估计值无显著差异，正常受试者中尿素D平均为10800±2100（SE），COPD受试者中为12600±3300。尽管计算得出的ELF中Na⁺浓度不到血浆中的一半，而K⁺、Ca²⁺和Mg²⁺的浓度超过血浆中的浓度，但ELF中的总阳离子浓度与血浆中的无显著差异，表明正常和COPD受试者的ELF均为等渗。EBC淀粉酶浓度（采用超灵敏方法测量）表明，除三个样本外，所有样本中唾液占呼吸道（ELF）飞沫的比例均小于10%。稀释和唾液标志物对于解释EBC研究至关重要。
