The Haldane effect under different acid-base conditions in premature and adult humans

Abstract

The Haldane effect (HE) was investigated in human adults and prematures under normal metabolic acid-base conditions but at different levels of PCO2. Venous blood samples were equilibrated with low and high PCO2 in either O2 or N2. The change in plasma pH of oxygenated blood by deoxygenation did not differ between both groups. Thus, ontogenetic differences of human hemoglobin structure do not influence the net proton Haldane effect measured in terms of whole blood pH-changes. Since the present data quantitatively agree with those we reported earlier for rabbits, cats and dogs (Kiwull-Schone et al., 1992), phylogenetic differences in hemoglobin structure of these mammalian species do not either seem to play a role in this respect. The influence of the Haldane effect on plasma pH has to be considered in blood-gas and acid- base analysis of samples with incomplete oxygenation. This is important for the indirect determination of PCO2 through pH by the equilibration method (Astrup and Schroder, 1956), serving as reference method for determination of metabolic acid-base status and CO2 buffering capacity. Likewise, HE- correction is important for indirect estimation of metabolic acid-base status (BE and HCO3/-st) from clinical routine PCO2- and pH-measurement. In spite of the vaste amount of literature on the Haldane effect in human blood, quantitative data for practical purpose are less available and still equivocal. By the present study, a strong inverse linear correlation between the HE-induced ΔpH and lg[HCO3/-] could be shown over a wide range of acid-base changes. The determined parameters A and B were checked for accuracy to approach the true value when estimating either PCO2 or standard [HCO3/-] indirectly. Thus, a highly valuable empirical [HCO3/-]-related pH-correction of the Haldane effect is established to improve blood-gas and acid-base analysis in hypoxic blood.