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Plasma acid-base changes in chronic renal failure: a Stewart analysis
D A Story1, A Tosolini, R Bellomo
1Department of Surgery, University of Melbourne, Austin Health, Melbourne--Australia.
The International Journal of Artificial Organs
|November 17, 2005
Summary
The Stewart approach reveals chronic renal failure causes metabolic acidosis due to altered sodium and chloride levels. Unmeasured ions play a minor role in this acid-base imbalance.
Area of Science:
- Nephrology
- Physiology
- Biochemistry
Background:
- Traditional bicarbonate-centered models complicate acid-base explanations in chronic renal failure (CRF).
- The Stewart approach offers a more quantitative method for analyzing acid-base chemistry.
Purpose of the Study:
- To apply the alternate Stewart approach to quantify acid-base chemistry in predialysis CRF patients.
- To compare the strong ion difference and weak acid effects between CRF patients and healthy volunteers.
Main Methods:
- Examined plasma and urine chemistry in 19 predialysis CRF patients and 20 healthy volunteers.
- Utilized a simplified Fencl-Stewart method to assess the impact of sodium, chloride, albumin, and unmeasured ions on base excess.
- Compared plasma strong-ion-difference and weak acid contributions.
Main Results:
- CRF patients exhibited greater metabolic acidosis (mean base excess difference of -2.7 mmol/L, p=0.04).
- This acidosis was linked to increased chloride and decreased sodium concentrations.
- Anion gap, strong-ion-gap, and base-excess effects of unmeasured ions were similar between groups.
Conclusions:
- The Stewart approach effectively quantifies acid-base disturbances in CRF.
- Metabolic acidosis in CRF is primarily driven by alterations in measured ions (chloride and sodium), not unmeasured ions.