Donovan K D, Dobb G J, Woods W P, Hockings B E
Crit Care Med. 1986 Dec;14(12):1038-44. doi: 10.1097/00003246-198612000-00009.
Cardiac output was measured 120 times in 27 critically ill patients using the thermodilution and transthoracic electrical impedance methods. Both the minimum and mean values for the distance between the inner electrodes, and a variety of values for the resistivity of blood (rho) were substituted in the Kubicek's empiric formula for calculating cardiac output by transthoracic electrical impedance. Using the mean distance between the inner electrodes and a rho-value of 150 ohm X cm gave the best agreement between the methods (mean difference 0.17 +/- 2.4 L/min). Ventilation alone or with positive end-expiratory pressure did not significantly affect the bias of the estimate, but both affected its precision when compared with measurements in spontaneously breathing patients (SD of mean difference 2.4 and 3.2 L/min, respectively, vs. 1.5 L/min). The pulmonary artery wedge pressure was significantly higher in patients with an abnormal diastolic impedance waveform (zero-wave), but there was no relationship between wedge pressure and base impedance per unit length between the measuring electrodes.
采用热稀释法和经胸电阻抗法对27例危重症患者的心输出量进行了120次测量。将内电极之间距离的最小值和平均值，以及血液电阻率（ρ）的各种值代入库比克经验公式，以通过经胸电阻抗计算心输出量。使用内电极之间的平均距离和150欧姆·厘米的ρ值时，两种方法之间的一致性最佳（平均差异为0.17±2.4升/分钟）。单独通气或加用呼气末正压通气对估计偏差无显著影响，但与自主呼吸患者的测量值相比，二者均影响其精度（平均差异的标准差分别为2.4和3.2升/分钟，而自主呼吸患者为1.5升/分钟）。舒张期阻抗波形异常（零波）的患者肺动脉楔压显著更高，但楔压与测量电极之间单位长度的基础阻抗之间无相关性。
