Hargreaves M, Jennings G
Clin Exp Pharmacol Physiol. 1983 Sep-Oct;10(5):609-14. doi: 10.1111/j.1440-1681.1983.tb00230.x.
We have compared the indirect Fick, a non-invasive CO2 rebreathing method for measuring resting cardiac output, with the thermodilution method in eleven subjects including some with cardiac and pulmonary disease. Three alternative methods for calculating veno-arterial CO2 content difference were used: (i) from end-tidal and rebreathing bag equilibrium PCO2 modified from the equations developed for use during exercise by Jones et al. (1975); (ii) by using the uncorrected difference between end-tidal and equilibrium PCO2 and the standard CO2 dissociation curve; (iii) by direct measurement of arterial PCO2. Each method was satisfactory in that reproducibility was similar to thermodilution (5-10%) and the equations relating thermodilution to indirect Fick cardiac output were linear with slope and intercept, close to 1 and 0, respectively. End-tidal PCO2 accurately predicted arterial PCO2 except in five patients with liver disease. Direct measurement of arterial PCO2 is recommended in such patients. In other subjects there was no advantage in either correcting non-invasive measurements of alveolar gas to obtain veno-arterial CO2 content difference, or in direct measurement. The indirect Fick is an accurate method for measuring cardiac output at rest in normal subjects and those with cardiovascular disease. Its use can be extended to other groups by a single arterial blood sample.
我们在包括一些患有心脏和肺部疾病的11名受试者中，将用于测量静息心输出量的非侵入性二氧化碳重呼吸法——间接菲克法，与热稀释法进行了比较。使用了三种计算静脉-动脉二氧化碳含量差的替代方法：（i）根据琼斯等人（1975年）为运动期间使用而开发的方程式修改的潮气末和重呼吸袋平衡PCO2来计算；（ii）使用潮气末和平衡PCO2之间的未校正差值以及标准二氧化碳解离曲线来计算；（iii）通过直接测量动脉PCO2来计算。每种方法都令人满意，因为其重现性与热稀释法相似（5-10%），并且将热稀释法与间接菲克心输出量相关联的方程式呈线性，斜率和截距分别接近1和0。除了五名肝病患者外，潮气末PCO2准确预测了动脉PCO2。对于此类患者，建议直接测量动脉PCO2。在其他受试者中，无论是校正肺泡气体的非侵入性测量以获得静脉-动脉二氧化碳含量差，还是直接测量，都没有优势。间接菲克法是一种准确测量正常受试者和心血管疾病患者静息心输出量的方法。通过采集一次动脉血样，其应用可扩展到其他人群。
