Figge-Fencl Quantitative Physicochemical Model
of Human Acid-Base Physiology
by James J. Figge, MD, MBA, FACP

Copyright 2003 - 2009 James J. Figge.
Updated 22 December, 2007; 28 December, 2008.
Updated version published 15 January, 2009 on
www.Acid-Base.org and www.Figge-Fencl.org.


Statistical Validation of the Figge-Fencl Quantitative Physicochemical Model

albumin solutions

Figure 1. pH of albumin-containing solutions as calculated by the Figge-Fencl quantitative physicochemical model (y-axis), versus measured pH (x-axis). Experimental data cover the pH range of 6.85 to 7.94. Experimental data (n = 65) are from Figge, Rossing and Fencl, J Lab Clin Med. 1991; 117: 453-467. The slope of the regression line is 0.9987 (98% confidence limits: 0.9592 to 1.0381). Thus, the slope is not significantly different than 1.0. The intercept is 0.0211. R = 0.99146, and R2 = 0.9830.


human sera

Figure 2. pH of filtrands of human sera as calculated by the Figge-Fencl quantitative physicochemical model (y-axis), versus measured pH (x-axis). Experimental data cover the pH range of 7.02 to 7.79. Experimental data (n = 72) are from Figge, Rossing and Fencl, J Lab Clin Med. 1991; 117: 453-467. The slope of the regression line is 1.0714 (98% confidence limits: 1.0226 to 1.1201). Thus, the slope is significantly different than 1.0. The intercept is -0.5217. R = 0.98746, and R2 = 0.9751. This analysis indicates that, although the predictive power of the Figge-Fencl model is very good, there is a small contribution attributed to plasma globulins that is not explained by the model. Due to the marked heterogeneity of globulins, a detailed analysis of the quantitative contribution of globulins to acid-base balance is still under investigation.


Link to Figge-Fencl Model

Link to Validation against Independent Data

Link to Albumin Titration Curve

Link to Online Model Application

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