新型阻抗式呼吸信号分析仪的实验和临床评价

Experimental and clinical evaluation of a prototype impedance respiratory signal analyzer

目的 对前期研发的阻抗式呼吸信号分析仪进行改良,提高振荡发生器的稳定性和线性.方法 重点改进振荡发生器,包括采用直线音圈电机作为振荡动力源、磁栅尺伺服控制电机运行以及优化振荡泵的结构等.模拟机械通气的工作环境,向振荡发生器施加不同的压力负荷,测量音圈电机线圈的位移并与预设值比较,评价振荡发生器工作的稳定性.采用5 Hz不同振幅的振荡信号测量呼吸力学模型的吸气阻抗,同时采用吸气末闭合法测量模型的吸气阻力,比较两者的差异,评价振荡发生器的线性.选择机械通气的慢性阻塞性肺疾病（COPD）及肺部影像正常的重型颅脑损伤患者各1例,采用5 Hz振荡信号分别测定患者的呼吸阻抗（Rrs）和电抗（Xrs）.结果 新设计的振荡发生器在压力负荷为15 ～ 40 cmH2O（1cmH2O=0.098 kPa）范围内,持续输出稳定的正弦振荡气流,振荡频率为0.01～ 16Hz、振幅为0.5～2 cmH2O范围内可调.振荡频率为5 Hz,振幅分别为0.5、1、1.5和2 cmH2O的信号分别测定的模型吸气阻抗均值为（16.56±1.17） cmH2O·s-1 ·L-1,吸气末闭合法测定的模型吸气阻力均值为（19.33±0.67） cmH2O·s-1 ·L-1,两者存在线性相关（r=0.51,P＜0.05）.临床试验测试显示,COPD患者Rrs和Xrs均高于肺部影像正常者,均差ΔRrs和ΔXrs分别为（8.9± 6.96） cmH2O· s-1·L-1和（12.31±8.46）cmH2O· s-1· L-1,以ΔXrs增加为显著.结论 新型阻抗式呼吸信号分析仪受机械通气的干扰小、振荡发生器振动具有线性、工作状态稳定,其测量结果能够反映COPD患者的肺部力学特征,区分不同部位的气道阻塞.

Objective To optimize the prior designed impedance respiratory signal analyzer,focusing on the improvement of the stability and linearity of the oscillator.Methods Focusing on the improvement of oscillator,a voice coil linear actuator was used as the power source,a magnet-grid position feedback transducer was used for the servo-control of the actuator,and a oscillatory pump was reconfigured,etc.Through simulating the operative condition of mechanical ventilation,the displacement of the actuator coil under different pressure load was measured and compared to the preset values for evaluation of the stability of the oscillator.Then,the inspiratory impedance of a ventilated resistance-inertance-elastance model was measured by using 5 Hz oscillatory signal with various amplitudes and compared to the resistance of the model measured by end-inspiratory airway occlusion for the assessment of the linearity of the oscillator.One patient with chronic obstructive pulmonary disease （COPD） and 1 patient with normal lung image and severe craniocerebral injury were selected,and the respiratory resistance （Rrs） and reactance （Xrs） of the patients were measured respectively by using 5 Hz oscillatory signal.Results The oscillatory flow output from the new designed oscillator was stable and almost sinusoidal under pressure load ranged from 15 to 40 cmH2O （1 cmH2O =0.098 kPa）,and the oscillatory frequency and the amplitude were adjustable from 0.01 to 16 Hz and from 0.5 to 2 cmH2O,respectively.The mean inspiratory impedance of the model measured by 5 Hz oscillatory signal with amplitudes of 0.5,1,1.5 and 2 cmH2O,respectively,was （16.56± 1.17） cmH2O · s-1 · L-1,and the mean inspiratory impedance of the model measured by end-inspiratory airway occlusion was （19.33±0.67） cmH2O·s-1· L-1,with a linear correlation between these parameters （r=0.51,P＜ 0.05）.The clinical test showed that the Rrs and Xrs in the COPD patient were higher than those in the patient with normal lung image.The mean differences of /Δ Rrs and /Δ Xrs were （8.9±6.96） cmH2O· s-1· L-1 and （12.31 ±8.46） cmH2O· s-1· L-1,respectively,and the increase in Δ Xrs was higher.Conclusions The prototype impedance respiratory signal analyzer is not interfered by the ventilator.The operative condition of the oscillator is of stability and linearity.The measuring result can reveal the pulmonary mechanics characteristics in COPD patient,and differentiate airway obstructions in different site of the body.