Suki B, Peták F, Adamicza A, Daróczy B, Lutchen K R, Hantos Z
Department of Biomedical Engineering, Boston University, MA 02215, USA.
Respir Physiol. 1997 May;108(2):129-41. doi: 10.1016/s0034-5687(97)00019-4.
We measured lung impedance (ZL) before and after four doses of methacholine (Mch) infusion in five intact chest (with esophageal balloon) and six open-chest dogs from 0.2 to 8 Hz with an optimal ventilator waveform. From ZL, we estimated airway resistance (R(aw)) and inertance (Iaw) and tissue viscance (GL) and elastance (HL). Two-way analysis of variance revealed that: (1) Mch had a strong influence on all parameters (p < 0.001), but small effect on hysteresivity, nL = GL/HL; (2) closed-chest GL and HL were significantly higher and Iaw lower than their open-chest values (p < 0.002, p < 0.05 and p < 0.0001); and (3) at the highest Mch dose, the relative increase in R(aw) was six times higher in the closed-chest condition. The reduced impact of Mch on open-chest mechanics may be due to constrictions superimposed on grossly different lung configurations and/or some humoral effects initiated by the thoracotomy. We conclude that Mch doses that elicit mild constriction in open-chest condition can cause a severe constriction in intact animals.
我们在五只因胸部完整（带有食管气囊）的犬和六只开胸犬中，在输注四剂乙酰甲胆碱（Mch）之前和之后，以最佳通气波形在0.2至8Hz频率下测量了肺阻抗（ZL）。根据ZL，我们估算了气道阻力（R(aw)）、惯性（Iaw）、组织粘性（GL）和弹性（HL）。双向方差分析显示：（1）Mch对所有参数有强烈影响（p < 0.001），但对滞后性（nL = GL/HL）影响较小；（2）闭胸状态下的GL和HL显著高于开胸状态，而Iaw低于开胸状态（p < 0.002、p < 0.05和p < 0.0001）；（3）在最高Mch剂量时，闭胸状态下R(aw)的相对增加是开胸状态下的六倍。Mch对开胸力学影响的减弱可能是由于叠加在截然不同的肺结构上的收缩和/或开胸手术引发的一些体液效应。我们得出结论，在开胸状态下引起轻度收缩的Mch剂量在完整动物中可导致严重收缩。
