Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany.
J Aerosol Med Pulm Drug Deliv. 2010 Dec;23(6):371-9. doi: 10.1089/jamp.2009.0809. Epub 2010 May 25.
Noninvasive monitoring of airway inflammation is important for diagnosis and treatment intervention of lung disease. Mediators of interest are often nonvolatile molecules that are exhaled as aerosols and captured by breath condensation. Because analysis of exhaled breath condensate has been troublesome in the past, partly due to poor standardization and unknown dilution, we investigated in detail the influence of respiratory variables on exhaled particle number and size distribution during tidal breathing in healthy volunteers.
Particle number was detected by a condensation nuclei counter, and size distribution was determined by a laser spectrometer online with high time resolution while subjects underwent a defined protocol of normal and deep tidal breathing. Intra- and intersubject variability of particle emission was analyzed and physical properties of exhaled aerosols were correlated to pulmonary function variables obtained by body-plethysmography.
The particle size distribution was in the submicron range and stable during tidal breathing. Increasing tidal volumes dominantly influenced particle number emission while flow rates had only little effect. Reproducibility within subjects was high, but there was a large variation of particle emission between subjects. The ratio of functional residual capacity to total lung capacity was found to correlate with exhaled particle numbers. This indicates that particle generation is caused by reopening of terminal airways and is dependent on functional residual capacity.
We conclude that online determination of exhaled aerosols from the human lungs is a prerequisite to standardize the assessment of nonvolatile mediators by normalization to the aerosol emission rate.
气道炎症的无创监测对于肺部疾病的诊断和治疗干预非常重要。感兴趣的介质通常是作为气溶胶呼出的非挥发性分子，并被呼吸冷凝物捕获。由于过去呼出冷凝物的分析比较麻烦，部分原因是标准化程度差和稀释程度未知，因此我们详细研究了在健康志愿者的潮气呼吸过程中，呼吸变量对呼出颗粒数和粒径分布的影响。
通过凝结核计数器检测颗粒数，并通过在线激光光谱仪以高时间分辨率确定粒径分布，同时让受试者按照规定的正常和深潮气呼吸方案进行。分析了颗粒发射的个体内和个体间变异性，并将呼出气溶胶的物理性质与通过体描仪获得的肺功能变量相关联。
粒径分布在亚微米范围内，在潮气呼吸过程中保持稳定。潮气量的增加主要影响颗粒数的排放，而流速的影响则较小。受试者内的重复性较高，但受试者间的颗粒排放差异很大。功能残气量与总肺容量的比值与呼出颗粒数相关。这表明颗粒的产生是由终末气道的重新开放引起的，并且依赖于功能残气量。
我们得出结论，在线确定来自人肺的呼出气溶胶是将非挥发性介质的评估标准化为气溶胶排放率的前提。
