Comparative Study between Traditional Approach and Physico-Chemical Approach in Acid Base Disorders Interpretation in Critically Ill Patients


Objective: The traditional approach for acid base interpretation is based on Handerson-Hasselbalch formula and includes Base Excess (BE), bicarbonate (HCO3), albumin corrected anion gap. The Physicochemical approach is centered on the Carbon Dioxide tension (PCO2), the strong ion difference (SID), strong ion gap (SIG) = SID apparent-SID effective and totally weak acids (Atot). The study aims to compare between the traditional approach and the physicochemical approach in acid base disorder interpretation. Design: Prospective observational study in an adult Intensive Care Unit (ICU) recruiting six hundred and sixty one patients. Methods: Arterial blood samples were analyzed to measure pH, PaCO2 sodium, potassium, chloride and lactate. Venous blood samples were analyzed to measure ionized calcium, magnesium, phosphorous and albumin. These samples were interpreted by both techniques. Results: Normal HCO3 and BE were detected by traditional approach in 49 cases of which SIG acidosis was detected in 22 cases (46%) and Hyperchloremic acidosis was detected in 29 cases (60%) by physicochemical method. SIG was elevated in 72 cases (58%) of 124 cases with high anion gap acidosis. SIDeff and BE were strongly correlated, r = 0.8, p < 0.0001, while SIG and Albumin corrected Anion Gap (ALAG) were moderately correlated r = 0.56, p < 0.0001. Conclusion: Both approaches are important for interpretation of the acid base status. Traditional approach identifies the diagnostic description without many calculations and detects body compensatory response to acid base disorders. Physicochemical approach is essential to identify the exact causation and the severity of the acid base disorders.

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A. Redwan, R. Gatz, N. Hassan, H. Matter, A. Hammodi and A. Attia, "Comparative Study between Traditional Approach and Physico-Chemical Approach in Acid Base Disorders Interpretation in Critically Ill Patients," Open Journal of Respiratory Diseases, Vol. 3 No. 4, 2013, pp. 143-149. doi: 10.4236/ojrd.2013.34022.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] “Disorders,” Clinical Journal of the American Society of Nephrology, Vol. 4, No. 7, 2009, p. 1267.
[2] K. J. Gunnerson and J. A. Kellum, “Acid-Base and Elec trolyte Analysis in Critically Ill Patients: Are We Ready for the New Millennium?” Current Opinion in Critical Care, Vol. 9, No. 6, 2003, pp. 468-473.
[3] A. A. Sirker, A. Rhodes, R. M. Grounds and E. D. Ben nett, “Acid-Base Physiology: The ‘Traditional’ and the ‘Modern’ Approaches,” Anesthesia, Vol. 57, No. 4, 2002, pp. 348-356.
[4] O. Siggard-Andersen, P. D. Wimberly, N. Fogh-Andersen and I. H. Gothgen, “Measured and Derived Quantities with Modern pH and Blood Gas Equipment: Calculation Algorithms with 54 Equations,” Scandinavian Journal of Clinical & Laboratory Investigation, Vol. 48, Suppl. 189, 1988, pp. 7-15.
[5] D. D. Van Slyke, H. Wu and F. C. McLean, “Studies of Gas and Electrolyte Equilibria in the Blood. V. Factors Controlling the Electrolyte and Water Distribution in the Blood,” Journal of Biological Chemistry, Vol. 56, 1923, pp. 765-849.
[6] P. A. Stewart, “Modern Quantitative Acid-Base Chemis try,” Canadian Journal of Physiology and Pharmacology, Vol. 61, No. 12, 1983, pp. 1441-1461.
[7] P. A. Stewart, “Independent and Dependent Variables of Acid Base Control,” Respiration Physiology, Vol. 33, No. 1, 1978, pp. 9-26.
[8] J. Figge, T. Mydosh and V. Fencl, “Serum Proteins and Acid-Base Equilibrium: A Follow-Up,” Journal of Labo ratory and Clinical Medicine, Vol. 120, No. 5, 1992, pp. 713-719.
[9] J. Figge, T. H. Rossing and V. Fencl, “The Role of Serum Proteins in Acid-Based Equilibria,” Journal of Laboratory and Clinical Medicine, Vol. 117, No. 6, 1991, pp. 453-467.
[10] P. D. Constable and H. R. Stampfli, “Experimental De termination of Net Protein Change and Atot and Ka of Nonvolatile Buffers in Human Plasma,” Journal of Applied Physiology, Vol. 95, 2003, p. 620.
[11] O. Siggaard-Andersen, “The Acid-Base Status of the Blood,” 4th Edition, Munksgaard, Copenhagen, 1976.
[12] J. W. Severinghaus, “Siggaard-Andersen and the Great Trans-Atlantic Acid-Base Debate,” Scandinavian Journal of Clinical & Laboratory Investigation, Vol. 53, Suppl. 214, 1993, pp. 99-104.
[13] M. Moviat, F. van Haren and H. van der Hoeven, “Conventional or Physicochemical Approach in Intensive Care Unit Patients with Metabolic Acidosis,” Critical Care, Vol. 7, 2003, pp. R41-R45.
[14] A. Dubin, M. M. Menises, F. D. Masevicius, M. C. Mo seinco, D. O. Kutscherauer, E. Ventrice, E. Laffaire and E. Estenssoro, “Comparison of Three Different Methods of Evaluation of Metabolic Acid-Base Disorders,” Critical Care Medicine, Vol. 35, No. 5, 2007, pp. 1264-1270.
[15] R. G. Narins, “Maxwell and Kleeman’s Clinical Disor ders of Fluid and Electrolyte Metabolism,” 5th Edition, McGraw-Hill, New York, 1994.
[16] K. Wrenn, “The Delta (Delta) Gap: An Approach to Mixed Acid-Base Disorders,” Annals of Emergency Me dicine, Vol. 19, No. 11, 1990, pp. 1310-1313.
[17] J. Figge, A. Jabor, A. Kazda, et al., “Anion Gap and Hy poproteinemia,” Critical Care Medicine, Vol. 26, No. 11, 1998, pp. 1807-1810.
[18] D. A. Story, H. Morimatsu and R. Bellomo, “Strong Ions Weak Acids and Base Excess: A Simplified Fencl-Stew- art Approach to Clinical Acid-Base Disorders,” British Journal of Anaesthesia, Vol. 92, No. 1, 2004, pp. 54-60.
[19] T. D. DuBose Jr., “Acidosis and Alkalosis,” In: D. L. Kasper, E. Braunwald, et al., Eds, Harrison’s Principles of Internal Medicine, 16th Edition, McGraw-Hill, New York, 2005, pp. 263-271.
[20] J. A. Kellum, “Determinants of Blood pH in Health and Disease,” Critical Care, Vol. 4, 2000, pp. 6-14.
[21] V. Fencl, A. Jabor, A. Kazda, et al., “Diagnosis of Meta bolic Acid-Base Disturbances in Critically Ill Patients,” American Journal of Respiratory and Critical Care Me dicine, Vol. 162, No. 6, 2000, pp. 2246-2251.
[22] J. A. Kellum, “Disorders of Acidbasebalance,” Critical Care Medicine, Vol. 35, No. 11, 2007, pp. 2630-2636.
[23] M. M. Boniatti, P. C. Cardoso, R. K. Castilho, S. R. Vieira, G. Friedman, S. P. Ribeiro and L. Fialkow, “Prog nostic Value of Unmeasured Anions in Critically Ill Patients,” Intensive Care Medicine, Suppl. 1, 2008, p. S24.
[24] J. A. Kellum, “Strong Ion Gap: A Methodology for Exploring Unexplained Anions,” Journal of Critical Care, Vol. 10, No. 2, 1995, pp. 51-55.
[25] J. A. Kellum, “Disorders of Acid-Base Balance,” Critical Care Medicine, Vol. 35, No. 11, 2007, pp. 2630-2636.

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