抽象
人工通气时呼吸力学通常与它需要特定的呼吸模式的方法研究。另一种方法是分析气管压力(P)之间的关系和流量(V')通过使用适当的模型多元线性回归(MLR)。这种方法的值在12周未镇静的患者进行评价,机械通气急性呼吸衰竭,和最与慢性阻塞性或限制性呼吸系统疾病的病史。After correction for the non-linear resistance of the endotracheal tube, the data were analysed with the linear first order model: P = P0 + E.V + R.V' where E and R are total respiratory elastance and resistance, and P0 is the static recoil pressure at end-expiration. After exclusion of the cycles which clearly exhibited muscular activity, a good fit was observed in 25 out of 36 records (relative root-mean-square error less than 10%); the values of E and R were reproducible within cycles, and consistent with the patient's condition and the ventilatory mode. The intrinsic positive end-expiratory pressure (PEEPi), as derived from P0 and the applied PEEP, averaged 1.1 +/- 1.0 hPa. Using more sophisticated models, allowing for mechanical non-homogeneity or non-linearity of R or E, rarely improved the fit and often provided unrealistic data. In several subjects the discrepancy between the data and the first order model was consistent with expiratory flow limitation, which may severely impair the analysis. We conclude that, except in the case of expiratory flow limitation, the method is useful for routine clinical use and better implemented with the simple linear model.