What is the management for a patient who develops ileus after starting intravenous (IV) iron infusions?

Management of Ileus After Starting Iron Infusions

For patients who develop ileus after starting intravenous iron infusions, the recommended management is to discontinue the iron infusion immediately, provide supportive care, and consider early enteral nutrition to expedite resolution of the ileus.

Pathophysiology and Recognition

Ileus following IV iron administration is a rare but significant adverse event that can occur through several mechanisms:

1. Direct effect: IV iron formulations, particularly those with higher labile iron content, can cause gastrointestinal side effects
2. Complement activation-related pseudo-allergy (CARPA): This reaction to IV iron can manifest with various symptoms including gastrointestinal disturbances 1
3. Hypophosphatemia: Certain IV iron formulations (especially ferric carboxymaltose) can cause hypophosphatemia, which may contribute to ileus symptoms 1

Initial Management

When ileus develops after IV iron infusion:

1. Stop the iron infusion immediately

   • Switch IV line to normal saline at keep-vein-open rate 1
   • Monitor vital signs closely (BP, pulse, respiratory rate, O2 saturation)

2. Assess for infusion reaction severity

   • Mild reactions: Self-limiting, monitor for 15 minutes
   • Moderate reactions: Consider IV corticosteroids (hydrocortisone 200 mg)
   • Severe reactions: Treat as anaphylaxis with epinephrine and emergency protocols 1

3. Supportive care

   • Bowel rest
   • IV hydration
   • Nasogastric decompression if significant distention or vomiting

Specific Interventions

1. Early Enteral Nutrition (EEN)

   • Strong evidence supports EEN to expedite resolution of ileus 2
   • Begin as soon as clinically feasible
   • Start with clear liquids and advance as tolerated

2. Avoid promotility agents

   • Neither metoclopramide nor erythromycin have shown effectiveness in resolving ileus 2

3. Monitor for complications

   • Electrolyte abnormalities, particularly hypophosphatemia
   • Ongoing gastrointestinal bleeding (rare but reported with IV iron) 3

Follow-up Management

1. Consider alternative iron formulations

   • If IV iron is still needed, consider switching to a different formulation with lower risk of reactions 1
   • Formulations differ in their physiochemical properties, labile iron content, and risk of adverse effects 1

2. Rechallenge considerations

   • Only after complete resolution of symptoms
   • Use slower infusion rate (50% of initial rate)
   • Monitor closely for recurrence of symptoms 1

Prevention for Future Iron Administration

1. Risk assessment before future infusions

   • Identify high-risk patients (history of reactions, multiple drug allergies)
   • Consider oral iron if feasible 1

2. Administration techniques

   • Use slower infusion rates
   • Observe closely during first 10 minutes when immediate reactions are most likely 1
   • Consider premedication in high-risk patients

3. Alternative iron replacement strategies

   • Consider oral iron formulations if tolerated 1
   • If IV iron is necessary, choose formulations requiring fewer infusions 1

Pitfalls and Caveats

• Do not administer diphenhydramine for infusion reactions as it can worsen symptoms and be mistaken for worsening of the reaction 1
• Do not restart iron infusion until complete resolution of ileus symptoms
• Monitor phosphate levels, especially with ferric carboxymaltose, as hypophosphatemia can contribute to gastrointestinal symptoms 1
• True anaphylaxis to IV iron is very rare; most reactions are CARPA and should be treated accordingly 1