Acid–base chemistry of plasma: consolidation of the traditional and modern approaches from a mathematical and clinical perspective

Abstract

Although different in their concepts, the traditional and modern approaches based on mathematical models can be seen as complementary giving, in principle, the same information about the acid-base status of plasma.

A method for estimation of plasma albumin concentration from the buffering properties of whole blood

“…Common to each of these approaches is a calculation describing the excess of anions in the blood. In the approach of Siggaard-Andersen, this is known as the AG (or AG corr ), and in the strong ion theory approach, it is known as the SIG [16]. Calculation of either AG corr or SIG requires measurement of plasma albumin concentration to accurately quantify unmeasured anions.…”

The Intelligent Ventilator (INVENT) project: The role of mathematical models in translating physiological knowledge into clinical practice

“…Whilst his equations do not therefore have the coverage of Siggaard-Andersen's in describing blood, it can be argued that they are more transparent and therefore accessible to the non-mathematically inclined. This type of formulation also has the benefit that appropriate, additive, state variables can be selected, a requirement which has been important for the development of INVENT From an acid-base perspective the major contribution of this work has been to illustrate the similarity between the approaches of Siggaard-Andersen and Stewart [52] and to develop a model with the coverage of Sigaard-Andersen and the structure of Stewart [62,63]. This model has been validated against literature data illustrating that it could simulate the addition and removal of CO 2 strong acid/base, and haemoglobin; and the effects of oxygenation or deoxygenation, including reproduction of values of the Haldane and BE coefficients.…”

“…This point was in itself not new, being recognized much earlier by Singer and Hastings [50]. Indeed, the Siggaard-Andersen models 16 including anion gap in its corrected form [51], can be seen as approximately mathematically equivalent [52]. The fact that the approaches can be considered complementary has been recognized by a few authors [52,53,54], and studies have been performed comparing the clinical use of parameters calculated using either approach [55].…”

“…Indeed, the Siggaard-Andersen models 16 including anion gap in its corrected form [51], can be seen as approximately mathematically equivalent [52]. The fact that the approaches can be considered complementary has been recognized by a few authors [52,53,54], and studies have been performed comparing the clinical use of parameters calculated using either approach [55]. However, as discussed by Matousek et al [52], great care should be taken when interpreting these studies to make sure that parameters compared from each approach are indeed comparable.…”

“…The fact that the approaches can be considered complementary has been recognized by a few authors [52,53,54], and studies have been performed comparing the clinical use of parameters calculated using either approach [55]. However, as discussed by Matousek et al [52], great care should be taken when interpreting these studies to make sure that parameters compared from each approach are indeed comparable. Parameters such as BE and strong ion gap (SIG) are not, the former is a measure of buffering the latter a measure of unmeasured anions.…”