1. This lecture was conducted during the Nephrology Unit Grand Ground by Nephrology Registrar under Nephrology Division, Department of Medicine in King Saud University. Nephrology Division is not responsible for the content of the presentation for it is intended for learning and /or education purpose only.

2. Acid – Base disturbance Metabolic Acidosis By: Lubna Al-Shibani

3. Objectives: Definition. Pathophysiology. Causes. Symptoms & signs. Diagnosis. Treatment.

4. Definition: Metabolic acidosis is a clinical disturbance characterized by decreased blood pH and a decreased plasma bicarbonate concentration.

5. Pathophysiology When a fixed acid (lactate) is added, the H+ from fixed acid is buffered by the bicarbonate system. CO2 is formed and removed by the lungs. HCO3 levels is decreased in ECF. Metabolic acidosis is primary reduction in HCO 3 −, typically with compensatory reduction in Pco 2 ; pH may be markedly low or slightly subnormal.

6. Metabolic acidosis is typically classified as having a normal AG (ie, non-AG) or a high AG based on the presence or absence of unmeasured anions in serum.

7. Causes

9. Diagnosis History is important. ABG and serum electrolytes Anion gap. Winter's formula for calculating compensatory changes.

10. Treatment Treat the UNDERLYING cause. Sodium bicarbonate sometimes is needed. Mechanical ventilation.

11. THANK YOU

12. References; Noritomi DT, Soriano FG, Kellum JA, Cappi SB, Biselli PJ, Libório AB, et al. Metabolic acidosis in patients with severe sepsis and septic shock: a longitudinal quantitative study. Crit Care Med. Oct 2009;37(10):2733-9. [Medline].[Medline] Reddy P, Mooradian AD. Clinical utility of anion gap in deciphering acid-base disorders. Int J Clin Pract. Oct 2009;63(10):1516-25. [Medline].[Medline] Maciel AT, Park M. Differences in acid-base behavior between intensive care unit survivors and nonsurvivors using both a physicochemical and a standard base excess approach: a prospective, observational study. J Crit Care. Dec 2009;24(4):477-83. [Medline].[Medline] Morimatsu H, Toda Y, Egi M, Shimizu K, Matsusaki T, Suzuki S, et al. Acid-base variables in patients with acute kidney injury requiring peritoneal dialysis in the pediatric cardiac care unit. J Anesth. 2009;23(3):334-40. [Medline].[Medline] Walsh SB, Shirley DG, Wrong OM, Unwin RJ. Urinary acidification assessed by simultaneous furosemide and fludrocortisone treatment: an alternative to ammonium chloride. Kidney Int. Jun 2007;71(12):1310-6. [Medline].[Medline] Pereira PC, Miranda DM, Oliveira EA, Silva AC. Molecular pathophysiology of renal tubular acidosis. Curr Genomics. Mar 2009;10(1):51-9. [Medline]. [Full Text].[Medline][Full Text]