Figge-Fencl Quantitative Physicochemical Model
of Human Acid-Base Physiology
by James J. Figge, MD, MBA, FACP
Copyright 2003 - 2008 James J. Figge.
Updated 22 December, 2007.
Published 22 January, 2008 on
www.Acid-Base.org and www.Figge-Fencl.org.
Statistical Validation of the Figge-Fencl Quantitative
Physicochemical Model
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 1.0000 (98% confidence limits: 0.9605 to 1.0395). Thus,
the slope is not significantly different than 1.0. The intercept is 0.0116.
R = 0.99147, and R2 = 0.9830.
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 1.0728 (98% confidence limits: 1.0240 to 1.1216). Thus,
the slope is significantly different than 1.0. The intercept is -0.5317.
R = 0.98745, 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.