How do you manage metabolic alkalosis?

Management of Metabolic Alkalosis

The management of metabolic alkalosis should focus on identifying and treating the underlying cause, correcting fluid and electrolyte abnormalities, and in severe cases, using pharmacologic interventions such as acetazolamide to enhance renal bicarbonate excretion. 1

Etiology and Assessment

• Metabolic alkalosis is commonly caused by diuretic therapy (especially loop and thiazide diuretics), hypokalemia, and hypochloremia 1
• Other causes include vomiting, mineralocorticoid excess, adrenogenital syndrome, licorice ingestion, and genetic disorders like Bartter's and Gitelman's syndromes 2, 3
• Determining the urinary chloride level can help distinguish between saline-responsive alkalosis (very low urinary chloride, often due to gastric H+ loss) and saline-resistant alkalosis 4

Initial Management Approach

• Discontinue or reduce doses of diuretics when possible, as they are common contributors to metabolic alkalosis 1
• Address volume status and electrolyte abnormalities:
  • Correct volume depletion with appropriate fluid therapy, as volume contraction is a maintaining factor for metabolic alkalosis 2
  • Replace chloride and potassium deficits, as hypochloremia and hypokalemia perpetuate metabolic alkalosis 1, 2

Pharmacologic Interventions

• Acetazolamide is particularly useful in patients with heart failure and diuretic-induced alkalosis who have adequate kidney function 1
  • As a carbonic anhydrase inhibitor, acetazolamide promotes renal loss of bicarbonate, which carries out sodium, water, and potassium, resulting in urine alkalinization and diuresis 5
• For patients with Bartter syndrome, treatment includes:
  • Potassium and chloride supplements
  • NSAIDs to reduce prostaglandin-mediated salt wasting 1

Management of Severe Metabolic Alkalosis

• In severe cases resistant to conventional therapy or requiring rapid correction:
  • Mineral acids may be administered when more rapid resolution is needed or when the patient cannot tolerate fluid and electrolyte therapy 6
  • Ammonium chloride is the primary drug of choice for severe metabolic alkalosis 6
  • Dilute hydrochloric acid (0.1-0.2 N) may be given intravenously through a central venous catheter for patients with hepatic dysfunction 6
  • In patients with concomitant kidney failure, low-bicarbonate dialysis may be considered 7, 3

Special Considerations for Heart Failure Patients

• In patients with congestive heart failure and metabolic alkalosis:
  • Address the underlying circulatory failure 7
  • Consider adding an aldosterone antagonist to the diuretic regimen 7
  • If using loop diuretics, consider switching to longer-acting formulations or adding a potassium-sparing diuretic 1
  • Acetazolamide can be particularly effective in heart failure patients with diuretic-induced alkalosis and adequate renal function 1, 7

Monitoring and Follow-up

• Regularly monitor serum electrolytes, acid-base status, and volume status 1
• Adjust therapy based on clinical response and laboratory parameters 1
• Be vigilant for side effects of treatments, particularly with acetazolamide, which can cause electrolyte disturbances 5

Common Pitfalls to Avoid

• Failing to identify and address the underlying cause of metabolic alkalosis 2
• Overlooking the contribution of diuretics to metabolic alkalosis in patients on chronic diuretic therapy 1
• Not recognizing that hypokalemia and hypochloremia perpetuate metabolic alkalosis 1, 2
• Using acetazolamide in patients with severe renal dysfunction, where its effectiveness is limited 6