What is the treatment for metabolic acidosis resulting from a high output ileostomy?

Treatment of Metabolic Acidosis Related to High Output Ileostomy

The most effective treatment for metabolic acidosis due to high output ileostomy is restricting oral hypotonic fluids to 500 ml/day while providing glucose-saline replacement solutions with sodium concentration of at least 90 mmol/L. 1

Initial Assessment and Management

• Exclude other causes of high output such as intra-abdominal sepsis, bowel obstruction, enteritis, recurrent disease, or medication changes 1, 2
• Initially administer intravenous normal saline (2-4 L/day) with patient kept nil by mouth to demonstrate that output is driven by oral intake 1
• Monitor fluid output and urine sodium to guide management 1
• Aim for daily urine volume of at least 800 ml with sodium concentration >20 mmol/L 1

Fluid Management

• Restrict oral hypotonic fluids (water, tea, coffee, fruit juices, alcohol) to less than 500 ml daily 1
• Avoid hypertonic fluids (fruit juices, cola, commercial sip feeds) which can worsen stomal losses 1
• Provide glucose-saline replacement solutions with sodium concentration of at least 90-100 mmol/L 1, 2
• Options for replacement solutions include:
  • Modified WHO cholera rehydration solution (60 mmol/L sodium chloride, 30 mmol/L sodium bicarbonate, 110 mmol/L glucose in 1 liter water) 1
  • Alternative rehydration solution (120 mmol/L sodium chloride, 44 mmol/L glucose in 1 liter water) 1

Medication Management

• Administer loperamide 2-8 mg before meals to reduce motility and stoma output 1, 3
• Consider adding codeine phosphate if loperamide alone is insufficient 1
• For secretory output (>3 L/24 hours), add H2 antagonists or proton pump inhibitors 1
• Consider octreotide for patients unable to absorb oral medications, which can reduce stomal output by 1-2 L/24 hours 1

Electrolyte Correction

• Address sodium depletion first, as hypokalaemia is most commonly due to sodium depletion with secondary hyperaldosteronism 1, 4
• Correct hypomagnesaemia with intravenous magnesium sulfate initially, then oral magnesium oxide 1
• Potassium supplements are rarely needed if sodium/water depletion and magnesium levels are corrected 1, 4
• Consider sodium bicarbonate supplementation to directly address metabolic acidosis 5

Additional Strategies

• Separate solids and liquids (no drinks for half an hour before or after food) 1
• Consider salt capsules as an alternative to glucose-saline solution 1
• Try fludrocortisone if the ileum remains 1
• Add sodium chloride to liquid feeds to achieve sodium concentration near 100 mmol/L 1, 2

Common Pitfalls to Avoid

• Avoid encouraging patients to drink hypotonic solutions to quench thirst, which paradoxically increases stomal sodium losses 1, 2
• Avoid administering excessive intravenous fluids, which can cause edema due to high circulating aldosterone levels 1
• Don't focus on potassium replacement before addressing sodium depletion and hypomagnesemia 4
• Be aware that patients with ileostomies are at high risk for zinc and selenium deficiency 5

Long-term Management

• For patients with marginally high stoma outputs (1-1.5 L), combine oral fluid restriction with increased dietary salt 1
• Monitor for metabolic acidosis regularly, as it is a common complication in patients with ileostomies 6, 7, 5
• Consider parenteral or subcutaneous saline in the home setting for patients with persistent high output 1, 2