Definition: metabolic acidosis is a clinical disturbance characterized by a low pH (increased H+ concentration) and a low plasma bicarbonate concentration
- It can be produced by a gain of hydrogen ion or a loss of bicarbonate (Swenson, 2001)
- It can be divided clinically into two forms according to values of serum anion gap
- High anion gap acidosis
- Normal anion gap acidosis
- Anion gap = Na+ + K+ – (Cl– + HCO3)
- Anion gap = Na+ – (Cl– + HCO3)
- Potassium is often omitted from the equation because of its low level in the plasma
- The normal value for an anion gap is 8 to 12mEq/L (8 – 12 mmol/L) without K+ in the equation
- Normal anion gap acidosis results from the direct loss of bicarbonate as in diarrhea, lower intestinal fistulas, use of divertics
- High anion gap acidosis results from excessive accumulation of fixed acid
- If it increased to 30mEq/L (30mmol/L) or more than a high anion gap metabolic acidosis is present regardless of what the pH and the HCO3 are
- High ion gap occurs in ketoacidosis, lactic acidosis
Clinical Manifestation
- Signs and symptoms of metabolic acidosis vary with the severity of the acidosis may include Headache
- Confusion Drowsiness
- Increased respiratory rate and depth Nausea and vomiting
- Peripheral vasodilatation
- And decreased cardiac output occurs when the pH falls below 7 On Examination physical findings
- Low BP
- Cold and Clammy skin Shock (Swenson 2001)
Diagnosis
- ABG’s – expected blood gas changes, low bicarbonate level less than 22mEq/L and low pH less than 7.35
- Serum electrolytes Hyperkalemia ECG
Management
- Treatment is directed at correcting the metabolic defects (Swenson 2001) Decrease source of chloride
- Administer bi carbonate if pH level is less 7.1 Serum K+ level monitored closely Hypokalemia is corrected
- In chronic metabolic acidosis low serum Ca+ are treated Hemodialysis or peritoneal dialysis