Smit Henk J, Vonk Noordegraaf Anton, Marcus J Tim, Boonstra Anco, de Vries Peter M, Postmus Pieter E
Department of Pulmonary Medicine, VU Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands.
Eur J Appl Physiol. 2004 Jun;92(1-2):45-9. doi: 10.1007/s00421-004-1043-3. Epub 2004 Feb 21.
Electrical impedance tomography (EIT) is a non-invasive imaging technique for detecting blood volume changes that can visualize pulmonary perfusion. The two studies reported here tested the hypothesis that the size of the pulmonary microvascular bed, rather than stroke volume (SV), determines the EIT signal. In the first study, the impedance changes relating to the maximal pulmonary pulsatile blood volume during systole (Delta Z(sys)) were measured in ten healthy subjects, ten patients diagnosed with chronic obstructive pulmonary disease, who were considered to have a reduced pulmonary vascular bed, and ten heart failure patients with an assumed low cardiac output but with a normal lung parenchyma. Mean Delta Z(sys) (SD) in these groups was 261 (34)x10(-5), 196 (39)x10(-5) ( P<0.001) and 233 (61)x10(-5) arbitrary units (AU) (P=NS), respectively. In the second study, including seven healthy volunteers, Delta Z(sys) was measured at rest and during exercise on a recumbent bicycle while SV was measured by means of magnetic resonance imaging. The Delta Z(sys) at rest was 352 (53)x10(-5 ) and 345 (112)x10(-5 )AU during exercise (P=NS), whereas SV increased from 83 (21) to 105 (34) ml (P<0.05). The EIT signal likely reflects the size of the pulmonary microvascular bed, since neither a low cardiac output nor a change in SV of the heart appear to influence EIT.
电阻抗断层成像（EIT）是一种用于检测血容量变化的非侵入性成像技术，能够可视化肺灌注情况。本文报道的两项研究检验了这样一个假设：肺微血管床的大小而非每搏输出量（SV）决定了EIT信号。在第一项研究中，对10名健康受试者、10名被诊断为慢性阻塞性肺疾病（被认为肺血管床减少）的患者以及10名假定心输出量低但肺实质正常的心力衰竭患者，测量了与收缩期最大肺搏动血容量相关的阻抗变化（ΔZ(sys)）。这些组中的平均ΔZ(sys)（标准差）分别为261（34）×10⁻⁵、196（39）×10⁻⁵（P<0.001）和233（61）×10⁻⁵任意单位（AU）（P=无统计学意义）。在第二项研究中，纳入了7名健康志愿者，在静息状态和卧式自行车运动期间测量了ΔZ(sys)，同时通过磁共振成像测量了SV。静息时的ΔZ(sys)为352（53）×10⁻⁵，运动期间为345（112）×10⁻⁵ AU（P=无统计学意义），而SV从83（21）增加到105（34）ml（P<0.05）。EIT信号可能反映了肺微血管床的大小，因为低心输出量和心脏SV的变化似乎均不影响EIT。
