Quantitative Displacement of Acid-Base Equilibrium in Metabolic Acidosis

Abstract

The quantitative relationships between various components of acid-base equilibrium in blood have been studied in 60 patients with untreated metabolic acidosis. The patients were selected by independent criteria to exclude insofar as possible any patients with concomitatnt respiratory disorders which might interfere with respiratory compensation. Linear regression equations and 95% confidence limits were fitted between the metabolic component (whole blood base excess or plasma bicarbonate concentration) as the independent variable and plasma pCO2 as the dependent variable. Similar relationships were calculated for relationships between blood pH or blood [H+] and plasma pCO2. There was a highly predictable relationship between the severity of the acidosis judged either by the reduction of the metabolic component or by the deviation in blood pH or blood [H+] and the compensatory adjustment of plasma pCO2. The 95% confidence limits for the estimate of plasma pCO2 as a function of either base excess or plasma bicarbonate were sufficiently narrow to suggest that they may serve as useful standards for the assessment of the adequacy of respiratory compensation in untreated, uncomplicated metabolic acidosis.