Kim Chul-Ho, Fuglestad Matthew A, Richert Maile L Ceridon, Shen Win K, Johnson Bruce D
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States.
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States.
Respir Physiol Neurobiol. 2014 Oct 1;202:75-81. doi: 10.1016/j.resp.2014.08.001. Epub 2014 Aug 14.
It is unclear how dynamic changes in pulmonary-capillary blood volume (Vc), alveolar lung volume (derived from end-inspiratory lung volume, EILV) and interstitial fluid (ratio of alveolar capillary membrane conductance and pulmonary capillary blood volume, Dm/Vc) influence lung impedance (Z(T)). The purpose of this study was to investigate if positional change and exercise result in increased EILV, Vc and/or lung interstitial fluid, and if Z(T) tracks these variables.
12 heart failure (HF) patients underwent measurements (Z(T), EILV, Vc/Dm) at rest in the upright and supine positions, during exercise and into recovery. Inspiratory capacity was obtained to provide consistent measures of EILV while assessing Z(T).
Z(T) increased with lung volume during slow vital capacity maneuvers (p<0.05). Positional change (upright→supine) resulted in an increased Z(T) (p<0.01), while Vc increased and EILV and Dm/Vc decreased (p<0.05). Moreover, during exercise Vc and EILV increased and Dm/Vc decreased (p<0.05), whereas, Z(T) did not change significantly (p>0.05).
Impedance appears sensitive to changes in lung volume and body position which appear to generally overwhelm small acute changes in lung fluid when assed dynamically at rest or during exercise.
尚不清楚肺毛细血管血容量（Vc）、肺泡肺容量（由吸气末肺容量得出，EILV）和间质液（肺泡毛细血管膜传导率与肺毛细血管血容量之比，Dm/Vc）的动态变化如何影响肺阻抗（Z(T)）。本研究的目的是调查体位改变和运动是否会导致EILV、Vc和/或肺间质液增加，以及Z(T)是否跟踪这些变量。
12名心力衰竭（HF）患者在直立位和仰卧位休息时、运动期间及恢复过程中接受测量（Z(T)、EILV、Vc/Dm）。在评估Z(T)时获取吸气容量以提供一致的EILV测量值。
在缓慢肺活量动作期间，Z(T)随肺容量增加（p<0.05）。体位改变（直立→仰卧）导致Z(T)增加（p<0.01），而Vc增加，EILV和Dm/Vc降低（p<0.05）。此外，运动期间Vc和EILV增加，Dm/Vc降低（p<0.05），而Z(T)无显著变化（p>0.05）。
在静息或运动时动态评估时，阻抗似乎对肺容量和体位变化敏感，而这些变化似乎通常会掩盖肺液的小幅度急性变化。
