Corbanese U, Possamai C
Servizio di Anestesia e Rianimazione, Ospedale Civile Santa Maria dei Battuti, Conegliano, Treviso.
Minerva Anestesiol. 1995 May;61(5):191-9.
To evaluate the effectiveness of two cardiac output measurement methods based on a modified Fick equation, that calculate the O2 consumption (VO2) dividing the CO2 production (VCO2) by a fixed respiratory quotient (RQ).
Comparative study.
One 5 beds general intensive care unit in a 500 beds general hospital.
Ten mechanically ventilated critically ill patients requiring the right heart catheterization. The mean age was 65.5 years and the mean APACHE II score at admission was 24.
The cardiac output was measured using two modified Fick methods. The VO2 was calculated dividing VCO2 by 0.9, while the arteriovenous O2 content difference was calculated using the mixed venous O2 content in the first method (COF), and the central venous O2 content in the second one (COFra). Moreover the cardiac output was measured with the thermodilution technique (COTD) as gold standard.
The mean difference between the COTD and COF determinations was 0.571 L +/- 1.81 L, with limits of agreement ranging from -3.057 to +4.200 L. The mean difference between the COTD and COFra determinations was -0.322 L +/- 2.05 L, with limits of agreement ranging from -4.430 to +3.785 L. Both differences were nonsignificant. The correlation coefficients with COTD were: COF determinations 0.72, COFra determinations 0.70. In the group of COFra determinations less than 7 L the mean difference between COTD and COFra was 0.495 L with limits of agreement ranging from +2.208 L to -1.218 L.
The correlation coefficients of the two modified Fick methods with COTD are good, and the mean differences between their results and the gold standard are small, but the low precision of both tested methods demonstrated by the very large limits of agreement, severely reduce the clinical reliability of the measurements. Only for the less than 7 L cardiac outputs the COFra limits of agreement with COTD are narrow enough, and in this range the technique can be useful e.g. revealing a low cardiac output.
评估基于修正菲克方程的两种心输出量测量方法的有效性，这两种方法通过将二氧化碳产生量（VCO2）除以固定呼吸商（RQ）来计算氧耗量（VO2）。
对比研究。
一家拥有500张床位的综合医院中的一个设有5张床位的普通重症监护病房。
10名需要进行右心导管插入术的机械通气重症患者。平均年龄为65.5岁，入院时平均急性生理学与慢性健康状况评分系统（APACHE II）评分为24分。
采用两种修正菲克方法测量心输出量。VO2通过将VCO2除以0.9来计算，而动脉血氧含量差在第一种方法（COF）中使用混合静脉血氧含量计算，在第二种方法（COFra）中使用中心静脉血氧含量计算。此外，以热稀释技术（COTD）测量的心输出量作为金标准。
COTD与COF测量结果之间的平均差值为0.571 L±1.81 L，一致性界限为-3.057至+4.200 L。COTD与COFra测量结果之间的平均差值为-0.322 L±2.05 L，一致性界限为-4.430至+3.785 L。两种差值均无统计学意义。与COTD的相关系数分别为：COF测量结果为0.72，COFra测量结果为0.70。在COFra测量结果小于7 L的组中，COTD与COFra之间的平均差值为0.495 L，一致性界限为+2.208 L至-1.218 L。
两种修正菲克方法与COTD的相关系数良好，其结果与金标准之间的平均差值较小，但两种测试方法的一致性界限非常大，表明精度较低，严重降低了测量的临床可靠性。仅对于心输出量小于7 L的情况，COFra与COTD的一致性界限足够窄，在此范围内该技术可能有用，例如用于揭示低心输出量。
