Davis G M, Lands L C
Division of Respiratory Medicine, McGill University-Montreal Children's Hospital Research Institute, Québec, Canada.
Pediatr Pulmonol. 1997 Feb;23(2):105-13.
In spontaneously breathing, intubated infants, lung elastance (E) and resistance (R) can be derived from the general equation of motion of the lung, Ptp = E.V + R.V + I.V + K, where P is the pressure applied to the system, E is the elastance (the reciprocal of the compliance), V is the volume, R is the resistance to airflow (V), I is the inertance, (V) is gas acceleration, and K is a constant representing alveolar pressure. However, differences in the methods of analysis may results in variations in the derived values of E and R. Eighteen non-sedated intubated infants, with a mean post-conceptual age of 32.3 weeks and mean weight of 1.51 kg, were studied to compare values in E and R derived by 7 different methods of analysis. For each infant, the same 7 consecutive breaths were analyzed by the following methods: 1) linear regression of Ptp on tidal volume (VT); 2) a Mead-Whittenberger analysis, 3) a 2-factor linear regression of Ptp with (V) and VT; 4) a 3-factor regression of Ptp with V, VT, and V; 5) a 3-factor linear regression model of Ptp with V, VT, and a (V)2 factor (to incorporate a turbulent flow factor); 6) a 4-factor regression of Ptp with V, VT, V, and (V)2; and 7) a transformation regression plot of Ptp/VT versus V/VT. In addition, the lung impedance was calculated from the values of E and R derived by each method. There was no significant difference between the measurements of E and R in methods 2-6 (by MANCOVA, with the subjects being covariates). Methods 1 and 7 had a significantly elevated E; in addition, Method 7 also had an elevated R. Furthermore, there were no differences between the impedance values derived from the different methods. We conclude that in this group of spontaneously breathing, intubated infants with a spectrum of pathology, the results of a 2-factor regression analysis are comparable to more complex models of the mechanics of the lung.
在自主呼吸的插管婴儿中，肺弹性（E）和阻力（R）可从肺运动的一般方程推导得出，即Ptp = E·V + R·V + I·V + K，其中P是施加于系统的压力，E是弹性（顺应性的倒数），V是容积，R是气流阻力（V），I是惯性，（V）是气体加速度，K是代表肺泡压力的常数。然而，分析方法的差异可能导致E和R的推导值有所不同。本研究纳入了18名未使用镇静剂的插管婴儿，其平均孕龄为32.3周，平均体重为1.51千克，旨在比较7种不同分析方法得出的E和R值。对于每名婴儿，采用以下方法分析相同的连续7次呼吸：1）Ptp对潮气量（VT）进行线性回归；2）进行米德 - 惠滕伯格分析；3）Ptp与（V）和VT进行双因素线性回归；4）Ptp与V、VT和V进行三因素回归；5）Ptp与V、VT和（V）²因子（纳入湍流因子）进行三因素线性回归模型；6）Ptp与V、VT、V和（V）²进行四因素回归；7）Ptp/VT对V/VT的转换回归图。此外，根据每种方法得出的E和R值计算肺阻抗。方法2 - 6中E和R的测量值之间无显著差异（通过多变量协方差分析，以受试者作为协变量）。方法1和7得出的E显著升高；此外，方法7得出的R也升高。此外，不同方法得出的阻抗值之间无差异。我们得出结论，在这组患有多种病理状况的自主呼吸插管婴儿中，双因素回归分析的结果与更复杂的肺力学模型相当。
