Rasmussen J P, Sorensen B, Kann T
Acta Anaesthesiol Scand. 1975;19(3):210-8. doi: 10.1111/j.1399-6576.1975.tb05243.x.
Impedance cardiography was used for non-invasive determinations of systolic time intervals (STI) and cardiac output. The results were compared with simultaneously obtained invasive measurements of STI from central aortic pressure curves and of cardiac output using the dye-dilution technique. The study was performed on eight dogs during increasing halothane concentration. A close correlation was found between non-invasively and invasively measured left ventricular ejection time = LVET (r = 0.986) and pre-ejection period - PEP (r - 0.948). Measurements of cardiac output derived from changes in thoracic impedance were determined 1) using a fixed value of p (p - the resistivity of blood) and 2) using an individual value of p based on the actual hematocrits. When compared to cardiac outputs obtained by dye-dilution the correlation coefficients were r = 0.806 and r = 0.816, respectively. Impedance cardiography is a useful method of evaluating changes in cardiac output. The method permits simultaneous observations of changes in STI and cardiac output as an index of cardiac function.
阻抗心动图用于无创测定收缩期时间间期（STI）和心输出量。将结果与同时通过中心主动脉压力曲线进行的STI侵入性测量以及使用染料稀释技术进行的心输出量测量结果进行比较。该研究在八只犬身上进行，期间氟烷浓度逐渐增加。发现无创和有创测量的左心室射血时间（LVET，r = 0.986）和射血前期（PEP，r = 0.948）之间存在密切相关性。基于胸阻抗变化测定心输出量时，1）使用固定的血液电阻率（ρ）值，2）根据实际血细胞比容使用个体的ρ值。与通过染料稀释法获得的心输出量相比，相关系数分别为r = 0.806和r = 0.816。阻抗心动图是评估心输出量变化的一种有用方法。该方法允许同时观察STI变化和作为心功能指标的心输出量变化。
