The appeal of exhaled breath gas as a potential source of novel respiratory biomarkers is clear. It provides an inexhaustible source of a medium that can be sampled noninvasively, and one that has been in direct contact with the organ of interest. Targeting volatile organic compounds (VOCs) allows us to see even deeper: these small molecules diffuse across barriers and hence breath sampling also captures VOCs from the pulmonary interstitium, the circulation and beyond. Whilst analytical chemists, engineers, and a few forward-thinking clinical researchers have been exploring the breath volatilome since the early 1970s, it is only in the last decade or so that clinical interest has really grown [1–6]. There are probably two main reasons for the slow speed of uptake. First, the medium is extremely complex, and the source of VOCs difficult to define. The air we breathe out contains VOCs from three main sources: the external environment (either inhaled or absorbed through the skin or via ingestion) [7, 8], and metabolism both human [9, 10] and non-human (the microbiome) [11, 12]. To further complicate matters these volatiles may interact, and may be themselves utilised in metabolic processes. The second challenge is common to all ’omics research: the lack of external validation needed to give confidence in findings and support clinical effectiveness studies. Potential breath volatile signatures emerge for key clinical characteristics and phenotypes in airways disease http://ow.ly/7HzJ30hoCIJ

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用于气道疾病无标记表征的呼吸分析

呼出气体作为新型呼吸道生物标志物的潜在来源的吸引力是显而易见的。它提供了一种取之不尽用之不竭的介质来源，可以无创地进行采样，并且可以直接与感兴趣的器官接触。以挥发性有机化合物 (VOC) 为目标使我们能够看得更深入：这些小分子会穿过屏障扩散，因此呼吸采样还可以从肺间质、循环和其他地方捕获 VOC。虽然分析化学家、工程师和一些有远见的临床研究人员自 1970 年代初以来一直在探索呼吸挥发物，但直到最近十年左右，临床兴趣才真正增长 [1-6]。吸收速度缓慢可能有两个主要原因。一是介质极其复杂，VOCs来源难以界定。我们呼出的空气含有来自三个主要来源的 VOC：外部环境（吸入或通过皮肤吸收或通过摄入）[7, 8]，以及人类 [9, 10] 和非人类的新陈代谢（微生物组） [11, 12]。使问题进一步复杂化的是，这些挥发物可能会相互作用，并且本身可能被用于代谢过程。第二个挑战是所有“组学研究”的共同点：缺乏对研究结果充满信心和支持临床有效性研究所需的外部验证。气道疾病的关键临床特征和表型出现了潜在的呼吸波动特征 http://ow.ly/7HzJ30hoCIJ 10] 和非人类（微生物组）[11, 12]。使问题进一步复杂化的是，这些挥发物可能会相互作用，并且本身可能被用于代谢过程。第二个挑战是所有“组学研究”的共同点：缺乏对研究结果充满信心和支持临床有效性研究所需的外部验证。气道疾病的关键临床特征和表型出现了潜在的呼吸波动特征 http://ow.ly/7HzJ30hoCIJ 10] 和非人类（微生物组）[11, 12]。使问题进一步复杂化的是，这些挥发物可能会相互作用，并且本身可能被用于代谢过程。第二个挑战是所有“组学研究”的共同点：缺乏对研究结果充满信心和支持临床有效性研究所需的外部验证。气道疾病的关键临床特征和表型出现了潜在的呼吸波动特征 http://ow.ly/7HzJ30hoCIJ