Development of a device for pulmonary mechanics testing in children

为评估肺力学，开发了儿童压力型体体积描记仪和信号处理计算机程序。在实际应用中，肺内气体和肺外气体之间的频率特性可以看作是相同的，并且可以将肺力学分析为从胸部容积V_1(t)到呼吸气量V_2(t)的体积透射率。通过测量一个呼吸周期内体积信号的傅里叶分量的幅值和相位角来测量肺系统的透射率。正常人的振幅和相位角在0- 5hz左右的频率范围内是恒定的。振幅随频率的增加而减小，在5hz后相位旋转达90。透光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。这种变化对检测气道阻力比特异气道电导更敏感。可以说，该方法对气道疾病的诊断和治疗等临床应用是有益的。

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.