Physicochemical properties of abnormal blood acid-base buffering

• Published in: Journal of applied physiology (1985) Vol. 134; no. 1; pp. 172 - 180
• Main Author: Wolf, Matthew B
• Format: Journal Article
• Language: English
• Published: United States 01.01.2023
• Subjects: Acid-Base Equilibrium; Acid-Base Imbalance - etiology; Acidosis; Carbon Dioxide; Hemoglobins; Humans; Hydrogen-Ion Concentration; Hypoproteinemia - complications; mathematical model; acid-base mechanisms; hypoproteinemia; hyperalbuminemia; blood physicochemical properties
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00309.2022

This paper describes two new features ) development of physicochemically based, two-compartment models describing acid-base-state changes in normal and abnormal blood and ) use of model results to view and describe physicochemical properties of blood, in terms of Pco as the causative independent variable and effected [H ] changes as the dependent variable. Models were derived from an in vitro experimental study, where normal blood was made both hypoproteinemic and hyperalbuminemic and then equilibrated with CO . Strong-ion gap (SIG) values were selected to match model and experimental pH. The effect of individual physicochemical factors affecting blood acid-base-state were evaluated from their induced changes on buffer curve linearized slope (β ) and [H ] curve shift at 40 mmHg ([H ] ). Model findings were: ) in severe hypoproteinemia, hemoglobin enhances buffering (decreases β ), whereas albumin compromises it, resulting in an almost unchanged β ; [H ] decreases (alkalemia) due to hypoalbuminemia. ) Severe hyperalbuminemia greatly increases both β and [H ] , hence, compromising buffering and causing a severe acidemia. ) Pco -induced changes in the electrical-charge concentration of hemoglobin are the principal factor responsible for maintaining normal buffering characteristics in hypoproteinemia and hyperalbuminemia. ) SIG values are a third Pco -independent characteristic of blood acid-base state and ) the quantities, β +, [H ] , and SIG, derived from a [H ] vs. Pco perspective, are a more informative and intuitive way to characterize blood acid-base state. This study represents the most up-to-date, physicochemical, multi-compartment computer model of the processes involved in determining the acid-base buffering state of blood. Previous models lack this capability, notably by being single compartment and/or lacking electroneutrality and osmotic constraints. Model results, analyzed from a different perspective of dependent [H ] changes resulting from independent Pco changes, provide a new set of Pco -independent parameters, characteristic of blood buffering properties.