O. Siggaardandersen et al., THE TANH-EQUATION MODIFIED FOR THE HEMOGLOBIN, OXYGEN, AND CARBON-MONOXIDE EQUILIBRIUM, Scandinavian journal of clinical & laboratory investigation, 53, 1993, pp. 113-119
The model of the hemoglobin-oxygen equilibrium represented by the TANH
-equation is incorporated in the Oxygen Status Algorithm, a computer p
rogram for calculating and displaying the oxygen status and the acid-b
ase status of the blood. In the presence of carbon monoxide it is nece
ssary to take the Haldane equation into account. We here describe the
necessary equations and methods for iterative solutions. The validity
of the Haldane equation has previously been demonstrated by Zwart et a
l. (J Appl Physiol 1984; 57: 14-20). We have performed a few experimen
ts to confirm this. Like Zwart et al. we find a small deviation from t
he theory, but in the opposite direction, i.e. the measured p50 values
are slightly higher than predicted. We conclude that the Haldane equa
tion adequately accounts for the carbon monoxide effect up to 30 % car
boxy-hemoglobin, but further studies are needed to confirm or exclude
any minor deviation from the Haldane relationship which may be signifi
cant at higher carboxy-hemoglobin fractions.