Chapman F W, Newell J C
IEEE Trans Biomed Eng. 1989 Apr;36(4):405-13. doi: 10.1109/10.18746.
Extended least-squares algorithms using transpulmonary pressure and airway flow data from ventilatory waveforms were studied for their ability to track parameters of one- and two-compartment models of lung mechanics. A recursive extended least-squares algorithm with discounted measures estimated parameters of discrete-time models during synchronized intermittent mandatory ventilation. In tests on seven dogs developing oleic acid-induced unilateral hemorrhagic pulmonary edema, the one-compartment estimator responded rapidly and appropriately to changes in mechanics: compliance fell to 0.55 +/- 0.15 of its initial value and resistance rose by a factor of 1.8 +/- 0.5 in 3 h following injection of oleic acid. One-compartment parameter estimates revealed a difference between the airway resistance of inspiration and expiration. Two-compartment estimates were seldom physiologically plausible. The difference between inspiratory and expiratory resistance may have caused the two-compartment estimator to fail when applied to data from the entire respiratory cycle; when only expiratory data were used for estimation, the two-compartment estimates were meaningful. These estimates demonstrated increasing lung inhomogeneity after oleic acid was injected; at the end of 3 h, the ratio of the time constants of the two compartments ranged from 5 to 20 in six of the seven dogs. We conclude that the one- and two-compartment estimates may be combined to provide a meaningful assessment of lung mechanics.
研究了利用通气波形中的跨肺压和气道流量数据的扩展最小二乘算法跟踪肺力学单室和双室模型参数的能力。一种带折扣测量的递归扩展最小二乘算法在同步间歇指令通气期间估计离散时间模型的参数。在对7只因油酸诱导单侧出血性肺水肿的犬进行的测试中，单室估计器对力学变化迅速且适当地做出反应：注射油酸后3小时内，顺应性降至初始值的0.55±0.15，阻力增加了1.8±0.5倍。单室参数估计显示吸气和呼气气道阻力之间存在差异。双室估计在生理上很少合理。吸气和呼气阻力之间的差异可能导致双室估计器在应用于整个呼吸周期的数据时失败；当仅使用呼气数据进行估计时，双室估计是有意义的。这些估计表明注射油酸后肺不均匀性增加；3小时末，7只犬中有6只双室时间常数之比在5至20之间。我们得出结论，单室和双室估计可以结合起来，以提供对肺力学的有意义评估。
