Development of a device for pulmonary mechanics testing in children

本文介绍了小儿压力型肺容积描记法及其信号处理程序。肺内外气体之间的频率特性在实际应用中可以看作是相同的，从而可以将肺力学分析为从胸腔容积V_1（t）到呼吸气体容积V_2（t）的容积透过率，肺系统的透过率可以用一个呼吸周期内容积信号的各个傅立叶分量的大小和相位角来度量。正常人在0-5 Hz的频率范围内，振幅和相位角的值是恒定的。振幅随频率的增加而减小，相位在5 Hz后旋转90 °。透射率的频率特性随空气阻力的存在而变化，与呼吸模式的形式无关。这一变化比气道比导更能敏感地反映气道阻力。可以说，这种方法对临床应用，如气道疾病的诊断和治疗是有用的。

The pressure-type bodyplethysmography for children and the computer programs for signal processing are developed for the evaluation of pulmonary mechanics. The frequency characteristics betwwen the inside gas and the outside gas of the lung can be regarded as same to practical application and makes it possible to analyze pulmonary mechanics as a volume transmittance from the chest volume V_1(t) to the respiratory gas volume V_2(t).The transmittance of the pulmonary system is measured as magnitude and phase angle of each Fourier's component of the volume signals in one respiratory cycle. The values of amplitude and phase angle are constant within the frequency range of about 0-5 Hz in normal subjects. The magnitude decreases with an increase of the frequency and phase rotates upto 90 after 5 Hz. The frequency characteristics of transmittance changes with an presence of penumatic resistance and is independent from the form of breathing pattern. This change is more sensitive to detect the airway resistance than specific airway conductance. It can be said that this method is useful to clinical application such as the diagnosis and the treatment of the airway diseases.