Salvo P, Ferrari C, Persia R, Ghimenti S, Lomonaco T, Bellagambi F, Di Francesco F
Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
National Research Council of Italy, C.N.R., Istituto Nazionale di Ottica, (INO) - UOS Pisa, Via G. Moruzzi 1, 56124 Pisa, Italy.
Med Eng Phys. 2015 Jun;37(6):539-44. doi: 10.1016/j.medengphy.2015.03.013. Epub 2015 Apr 25.
This work presents a breath sampler prototype automatically collecting end-tidal (single and multiple breaths) or dead space air fractions (multiple breaths). This result is achieved by real time measurements of the CO2 partial pressure and airflow during the expiratory and inspiratory phases. Suitable algorithms, used to control a solenoid valve, guarantee that a Nalophan(®) bag is filled with the selected breath fraction even if the subject under test hyperventilates. The breath sampler has low pressure drop (<0.5 kPa) and uses inert or disposable components to avoid bacteriological risk for the patients and contamination of the breath samples. A fully customisable software interface allows a real time control of the hardware and software status. The performances of the breath sampler were evaluated by comparing (a) the CO2 partial pressure calculated during the sampling with the CO2 pressure measured off-line within the Nalophan(®) bag; (b) the concentrations of four selected volatile organic compounds in dead space, end-tidal and mixed breath fractions. Results showed negligible deviations between calculated and off-line CO2 pressure values and the distributions of the selected compounds into dead space, end-tidal and mixed breath fractions were in agreement with their chemical-physical properties.
这项工作展示了一种呼吸采样器原型，它能够自动收集潮气末（单次和多次呼吸）或无效腔空气部分（多次呼吸）。这一成果是通过在呼气和吸气阶段实时测量二氧化碳分压和气流来实现的。用于控制电磁阀的合适算法可确保即使受试对象换气过度，一个耐龙（®）袋也能充满所选的呼吸部分。该呼吸采样器具有低压降（<0.5 kPa），并使用惰性或一次性部件，以避免给患者带来细菌学风险以及呼吸样本受到污染。一个完全可定制的软件界面可实现对硬件和软件状态的实时控制。通过比较（a）采样期间计算出的二氧化碳分压与耐龙（®）袋内离线测量的二氧化碳压力；（b）无效腔、潮气末和混合呼吸部分中四种选定挥发性有机化合物的浓度，对呼吸采样器的性能进行了评估。结果表明，计算出的和离线的二氧化碳压力值之间的偏差可忽略不计，所选化合物在无效腔、潮气末和混合呼吸部分中的分布与其化学物理性质相符。
