Late Electrolyte Disturbance in Gastric Outlet Obstruction
The most significant late electrolyte disturbance in Gastric Outlet Obstruction (GOO) is Metabolic Alkalosis (M Alk) 1. This condition typically presents with hypochloremia, hypokalemia, elevated serum bicarbonate, elevated blood pH, and paradoxical aciduria.
Pathophysiology of Metabolic Alkalosis in GOO
- Mechanism: Prolonged vomiting or nasogastric suction leads to loss of gastric acid (HCl)
- Electrolyte changes:
- Chloride depletion (hypochloremia)
- Potassium depletion (hypokalemia)
- Elevated bicarbonate levels
- Paradoxical aciduria despite alkalemia
Clinical Presentation
Symptoms:
- Nausea, vomiting (often non-bilious)
- Abdominal distension
- Absence of flatus and bowel movements
- Abdominal pain
- Dehydration
Laboratory findings:
- Elevated serum pH
- Elevated bicarbonate (>26 mEq/L)
- Hypochloremia (<98 mEq/L)
- Hypokalemia (<3.5 mEq/L)
- Elevated BUN (dehydration)
Management Considerations
Fluid resuscitation: Normal saline (0.9% NaCl) is preferred to correct chloride deficit 2
Electrolyte replacement:
- Potassium chloride supplementation is essential to correct both K+ and Cl- deficits 3
- Avoid rapid correction which can lead to fluid overload
Treatment of underlying cause:
Potential Complications and Pitfalls
- Respiratory compensation: Patients may develop hypoventilation to compensate for metabolic alkalosis
- Cardiac arrhythmias: Due to severe hypokalemia
- Neurological symptoms: Confusion, tetany, seizures in severe cases
- Renal impairment: Volume depletion can lead to acute kidney injury
Best Practice Recommendations
- Monitor electrolytes closely during initial rehydration
- Replace potassium as potassium chloride rather than other salt forms
- Address the underlying cause of GOO promptly
- Consider surgical intervention for patients with life expectancy >2 months who are surgically fit 4
- Consider enteral stent placement for patients who are not surgical candidates 4
The correct answer is C. Metabolic Alkalosis.