MWIR LASER-BASED BREATH SENSOR FOR ASTHMA GRADING

最近的研究表明，与非哮喘患者相比，哮喘患者混合呼出的空气含有更高水平的一氧化氮(NO)。这些和其他观察结果导致了一种假设，即由呼吸道酶促产生的NO可能作为呼吸道炎症微环境的指示器。为了更好地回答这个问题，需要一种新型的呼气分析仪。目前，没有可用的分析仪无法充分解析一次呼气过程中NO浓度与过期体积之间的时间分布。物理科学公司(PSI)建议开发和演示一种可调谐的MWIR激光传感器，用于快速、非侵入性地测量人体呼气中的NO和其他选定的呼气物种。激光光源将围绕一种室温、可调谐的MWIR半导体激光器建造。在第一阶段，我们将把新的污染源与现有的超灵敏检测技术相结合，以演示对人体呼气中ppb水平的高速、原位测量。我们还将展示合并呼气二氧化碳的同步动态测量的可行性。我们的目标是开发一种仪器，能够以等于或大于10赫兹的采样率以等于或小于25毫升的样本体积进行这种测量。在第二阶段，将向一个领先的哮喘研究小组交付一个原型仪器，用于临床研究。这项研究的目的将是非侵入性地确定哮喘患者混合呼出空气样本中观察到的NO水平增加在多大程度上是由于死腔分数相对于肺泡分数增加所致。如果死腔分数中的NO水平能够被证明与哮喘状态相关，那么就建立了一种明确的、非侵入性的测量呼吸道炎症的方法的基础。拟议的商业应用：一种“非侵入性”和明确的测量呼吸道炎症的方法将在全国各地的哮喘诊所具有重要价值。建议的传感器也可能被证明对评估人类受试者的氧化应激很有用。

Recent studies have shown that the mixed expired air from asthmatics contains elevated levels of nitric oxide (NO) compared to that recovered from nonasthmatic individuals. These and other observations have led to the hypothesis that NO produced enzymatically by the airway may serve as an indicator of the inflammatory microenvironment of the airway. To better answer this question, a new type of exhaled breath analyzer is needed. Currently available NO analyzers cannot adequately resolve the temporal profile of NO concentration vs expired volume over the course of a single expiration. Physical Sciences Inc. (PSI) proposes to develop and demonstrate a tunable MWIR laser sensor for the rapid, non-invasive measurement of NO and other selected breath species in human breath. The laser source will be built around a type of room-temperature, tunable MWIR semiconductor lasers. In Phase I we will combine the new source with existing ultrasensitive detection technology to demonstrate high speed, in situ measurements of ppb levels of NO in human breath. We will also show the feasibility of incorporating simultaneous dynamic measurements of breath CO2. The goal is to develop an instrument that can yield such measurements at equal to or greater than 10 Hz sampling rates in sample volumes equal to or less than 25 ml. In Phase II, a prototype instrument will be delivered to a leading asthma research group for clinical studies. The study objective will be to non- invasively determine the extent to which the increased NO levels observed in samples of mixed expired air of patients with asthma are due to increased NO in the deadspace fraction versus alveolar fraction of the lung. If the level of NO in the deadspace fraction can be shown to correlate with asthma status, then the basis for an unambiguous, "non-invasive" method of measuring airway inflammation will be established. PROPOSED COMMERCIAL APPLICATIONS: A "non-invasive" and unambiguous method for measuring airway inflammation would be of great value in asthma clinics all over the country. The proposed sensor is also likely to prove useful for assessments of oxidative stress in human subjects.