Contemporary interpretation of blood gas analysis employing the concept of P. Astrup and O. Siggaard Andersen does not enable differentiation and quantitative evaluation of a metabolic component of the two simultaneous but antagonist conditions and their optimal therapy. These problems are successfully solved in the concept proposed by P. Stewart, which was subsequently refined by V. Fencl. A certain weakness of their theory is the fact that it does not consider the respiratory component of the acid-base disturbance, which makes it difficult to employ this concept in the clinical practice without a prior mathematical correction and subsequent processing. Here we describe a simple procedure for the evaluation of acid-base disorders interconnecting the classical concept of Astrup with the Stewart and FencI approach. Calculations may be performed either manually using pocket calculator and/or implemented in the laboratory information system.

        Key words: acid-base disorders, metabolic components, evaluating procedures, software.