Gavaghan D J, Hahn C E
Nuffield Department of Anaesthetics, University of Oxford, Radcliffe Infirmary, UK.
Respir Physiol. 1996 Nov;106(2):209-21. doi: 10.1016/s0034-5687(96)00066-7.
We have shown previously that it is possible to assess the cardio-respiratory function using sinusoidally oscillating inert gas forcing signals of nitrous oxide and argon (Hahn et al., 1993). This method uses an extension of a mathematical model of respiratory gas exchange introduced by Zwart et al. (1976), which assumed continuous ventilation. We investigate the effects of this assumption by developing a mathematical model using a single alveolar compartment and incorporating tidal ventilation, which must be solved using numerical methods. We compare simulated results from the tidal model with those from the continuous model, as the governing ventilatory and cardiac parameters are varied. The mathematical model is designed to be the basis of an on-line, non-invasive, cardio-respiratory measurement method, and will only be useful if the associated parameter recovery techniques are both reliable and robust. We demonstrate, in the presence of simulated measurement errors, that: (a) accurate recovery of the ventilatory parameters end-tidal volume, VA, and airways series dead-space, VD, are possible using the tidal breathing model; and (b) that a robust technique for recovery of pulmonary blood flow, QP, can be obtained using the more familiar continuous ventilation model.
我们之前已经表明，使用一氧化二氮和氩气的正弦振荡惰性气体强迫信号来评估心肺功能是可行的（哈恩等人，1993年）。该方法采用了兹瓦特等人（1976年）引入的呼吸气体交换数学模型的扩展，该模型假设通气是连续的。我们通过开发一个使用单个肺泡腔并纳入潮式通气的数学模型来研究这一假设的影响，该模型必须使用数值方法求解。随着控制通气和心脏参数的变化，我们将潮式模型的模拟结果与连续模型的模拟结果进行比较。该数学模型旨在作为一种在线、非侵入性心肺测量方法的基础，并且只有在相关参数恢复技术既可靠又稳健的情况下才有用。我们在存在模拟测量误差的情况下证明：(a) 使用潮式呼吸模型可以准确恢复通气参数潮气量、肺泡通气量和气道串联死腔；(b) 使用更常见的连续通气模型可以获得一种稳健的肺血流量恢复技术。
