Mishima M, Higashiya K, Kawakami K, Sugiura N, Sakai N, Hirai T, Oku Y, Chin K, Ohi M, Kuno K
Department of Clinical Physiology, Kyoto University, Japan.
Front Med Biol Eng. 1997;8(1):1-18.
The influence of the resistive load on the phase difference (PD) between chest wall and mouth flow in patients with chronic obstructive pulmonary disease (COPD) was investigated, and the factors that induce an enlargement of the PD were assessed. After a resistance tube (R = 2.8 hPa/l/s) was applied to the mouth of the subjects, the PDs increased significantly both in normal (pre: 2.20 +/- 0.89, post: 5.60 +/- 2.04, P < 0.01) and in COPD (pre: 10.86 +/- 3.81; post: 13.12 +/- 3.64, P < 0.01). A significant correlation between the airway resistance and PD was noted (r = 0.730, P < 0.001). These results suggest that airway resistance is an important determinant for the PD. The predicted phase difference (PD') was then calculated by the Runge-Kutta method, using the measured chest flow, the time domain functions of airway resistance and the thoracic gas volume during a respiratory cycle, assuming that the respiratory system was a single compartment. The PD/PD' at pre-resistive load was significantly larger in COPD than in normal subjects (normal: 1.03 +/- 0.11; COPD, 1.45 +/- 0.19, P < 0.01), whereas the PD/PD' at a post-resistive load was significantly smaller than at the pre-resistive load in COPD patients. These results agree well with the two parallel or serial compartment model with inhomogeneous airway resistance, where the mechanical property of the partitioning tissue between the two compartments was taken into account. The pattern of the increase in the work energy consumed within the airway lumen calculated from this model was almost the same as for PD. Thus, we conclude that the PD may be a good index of the overload of the respiratory movement and available to predict muscle fatigue in COPD patients.
研究了慢性阻塞性肺疾病（COPD）患者中电阻性负荷对胸壁与口腔气流之间相位差（PD）的影响，并评估了导致PD增大的因素。在受试者口腔施加阻力管（R = 2.8 hPa/l/s）后，正常受试者（术前：2.20±0.89，术后：5.60±2.04，P < 0.01）和COPD患者（术前：10.86±3.81；术后：13.12±3.64，P < 0.01）的PD均显著增加。观察到气道阻力与PD之间存在显著相关性（r = 0.730，P < 0.001）。这些结果表明气道阻力是PD的重要决定因素。然后，假设呼吸系统为单室，使用测量的胸段气流、气道阻力的时域函数和呼吸周期中的胸腔气体容积，通过龙格 - 库塔方法计算预测相位差（PD'）。在施加阻力负荷前，COPD患者的PD/PD'显著高于正常受试者（正常：1.03±0.11；COPD：1.45±0.19，P < 0.01），而在施加阻力负荷后，COPD患者的PD/PD'显著低于施加阻力负荷前。这些结果与具有不均匀气道阻力的双平行或串联室模型非常吻合，该模型考虑了两个室之间分隔组织的力学特性。从该模型计算出的气道腔内消耗的功能量增加模式与PD几乎相同。因此，我们得出结论，PD可能是呼吸运动超负荷的良好指标，可用于预测COPD患者的肌肉疲劳。
