A comprehensive, computer-model-based approach for diagnosis and treatment of complex acid–base disorders in critically-ill patients

• Published in: Journal of clinical monitoring and computing Vol. 25; no. 6; pp. 353 - 364
• Main Authors: Wolf, Matthew B., DeLand, Edward C.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.12.2011; Springer; Springer Nature B.V
• Subjects: Acid-Base Equilibrium; Acid-Base Imbalance - blood; Acid-Base Imbalance - diagnosis; Acid-Base Imbalance - therapy; Algorithms; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthesiology; Biological and medical sciences; Blood Chemical Analysis - methods; Blood Gas Analysis - methods; Computational fluid dynamics; Computer Simulation; Computerized, statistical medical data processing and models in biomedicine; Critical Care Medicine; Diagnosis, Computer-Assisted - methods; Disorders; Fluid flow; Fluids; Gain; Health Sciences; Humans; Intensive; Intensive care medicine; Magnesium; Mathematical models; Medical computing and teaching; Medical sciences; Medicine; Medicine & Public Health; Models, Biological; Patients; Reproducibility of Results; Sensitivity and Specificity; Statistics for Life Sciences; fluid therapy; Siggaard-Andersen acid–base approach; acid–base model; Stewart acid–base approach; acid–base disorders; extracellular base excess; Human; Intensive care; acid-base disorders; Computer simulation; Critically ill; Base excess; Treatment; Stewart acid-base approach; Diagnosis; Siggaard-Andersen acid-base approach; Resuscitation; acid-base model
• ISSN: 1387-1307; 1573-2614
• DOI: 10.1007/s10877-011-9320-2

We have developed a computer-model-based approach to quantitatively diagnose the causes of metabolic acid–base disorders in critically-ill patients. We use an interstitial-plasma-erythrocyte (IPE) model that is sufficiently detailed to accurately calculate steady-state changes from normal in fluid volumes and electrolyte concentrations in a given patient due to a number of causes of acid–base disorders. Normal fluid volumes for each patient are determined from their sex, height and weight using regression equations derived from measured data in humans. The model inputs (electrolyte masses and volumes) are altered to simulate the laboratory chemistry of each critically-ill patient. In this process, the model calculates changes in body-fluid volumes, osmolality and yields the individual values of IPE base excess (BE IPE ) attributed to changes due to: (1) fluid dilution/contraction, (2) gain or loss of Cl − , (3) hyper- or hypoalbuminemia, (4) presence of unmeasured ions, (5) gain of lactate, (6) gain or loss of phosphate, (7) gain or loss of calcium and magnesium, (8) gain or loss of potassium and (9) gain or loss of sodium. We use critically-ill patient data to show how our new approach is more informative and much simpler to interpret as compared to the approaches of Siggaard-Andersen or Stewart. We demonstrate how the model can be used at the bedside to diagnose acid–base disorders and suggest appropriate treatment. Hence, this new approach gives clinicians a new tool for diagnosing disorders and specifying fluid-therapy options for critically-ill patients.