How to manage acute cyclical vomiting syndrome in the Emergency Department (ED) that is unresponsive to ondansetron (generic name: ondansetron)?

Management of Acute Cyclical Vomiting Syndrome Unresponsive to Ondansetron in the ED

For patients with acute cyclical vomiting syndrome (CVS) in the ED who are unresponsive to ondansetron, haloperidol (0.5-2 mg IV every 4-6 hours) is the recommended first-line alternative treatment. 1

First-Line Alternative Treatments

When ondansetron fails to control symptoms in CVS, consider these medications:

1. Haloperidol: 0.5-2 mg IV every 4-6 hours

   • Targets dopaminergic pathways effectively for refractory vomiting 2, 1
   • Shown to reduce length of stay in similar conditions (CHS) 3

2. Benzodiazepines: Lorazepam 0.5-2 mg IV every 4-6 hours

   • Provides sedation and anxiety reduction, which can help break the cycle 1
   • Particularly useful when anxiety is a component of the episode

3. Promethazine: 12.5-25 mg IV/PO every 4-6 hours

   • Alternative phenothiazine that targets dopaminergic pathways 2

Hydration Protocol

• Aggressive IV hydration with dextrose-containing fluids
  • 10% dextrose in normal saline 1, 4
  • Initial bolus of 10-20 mL/kg followed by maintenance fluids 2
  • Electrolyte replacement as needed based on laboratory results

Second-Line Options for Refractory Cases

If first-line alternatives fail, consider:

1. Aprepitant: 125 mg day 1,80 mg days 2-3

   • NK1 receptor antagonist shown to be highly effective in severe CVS cases 1, 5
   • Consider for patients with severe, prolonged episodes

2. Olanzapine: 5-10 mg PO/IV daily

   • Effective for breakthrough nausea and vomiting 1
   • May be particularly useful when other antipsychotics have failed

3. Droperidol: 0.625-1.25 mg IV

   • Shown to reduce length of stay and need for additional antiemetics 3
   • Monitor for QT prolongation

4. Midazolam infusion: Consider in severe refractory cases

   • Low-dose continuous infusion has shown benefit in case reports 6
   • May be combined with clonidine in particularly resistant cases

Environmental Management

• Place patient in a quiet, dark room
• Allow hot water bathing/showering if requested (effective in 48% of non-cannabis using CVS patients) 1
• Minimize stimuli that may exacerbate symptoms

Special Considerations

Cannabis Use Assessment

• Evaluate for possible cannabinoid hyperemesis syndrome (CHS)
• If cannabis use is present, standard CVS treatments can still be effective 1
• Consider haloperidol as particularly effective if CHS is suspected 3

Avoid These Pitfalls

1. Opioid use: May worsen nausea and carries addiction risk 2
2. Delayed treatment: Early intervention is critical for breaking the cycle 1
3. Inadequate hydration: Dehydration can perpetuate the cycle 1
4. Ignoring comorbidities: Anxiety and migraine can exacerbate symptoms 1

Discharge Planning

• Provide prescription for abortive medications for future episodes
• Consider prophylactic medications (tricyclic antidepressants are first-line)
• Educate about trigger avoidance and early intervention
• Arrange follow-up with gastroenterology

By following this algorithmic approach to managing CVS unresponsive to ondansetron, emergency physicians can effectively break the cycle of vomiting, reduce length of stay, and improve patient outcomes.