What are the next steps in managing nausea in an 87-year-old female patient with a history of multiple abdominal surgeries, receiving Total Parenteral Nutrition (TPN) through a G-tube (gastrostomy tube), with persistent nausea despite treatment with Zofran (ondansetron) and promethazine?

Management of Persistent Nausea in an Elderly Patient with G-tube and TPN

For this 87-year-old female with persistent nausea despite ondansetron and promethazine, the next step should be adding metoclopramide as a dopamine receptor antagonist with prokinetic properties to address potential gastric stasis contributing to her nausea.

Assessment of Current Situation

• The patient has persistent nausea despite treatment with two different antiemetics (ondansetron and promethazine) 1
• She is receiving TPN for nutrition and has a G-tube draining approximately 400 mL/24 hours 1
• Recent abdominal surgeries and G-tube drainage suggest potential gastric stasis or partial bowel obstruction as contributing factors 1

Next Steps in Management

1. Add a Dopamine Receptor Antagonist with Prokinetic Properties

• Add metoclopramide (10mg IV or PO every 6 hours) to address potential gastric stasis 1
  • Metoclopramide has the strongest evidence for managing non-chemotherapy related nausea 1
  • It has prokinetic properties that may help with gastric emptying in this post-surgical patient 1

2. Consider Corticosteroids

• If metoclopramide alone is insufficient, add dexamethasone (4-8mg IV daily) 1
  • Corticosteroids are particularly beneficial when combined with metoclopramide and ondansetron 1
  • Dexamethasone at 4-5mg has similar clinical effects to 8-10mg doses with potentially fewer side effects 1

3. Evaluate for Mechanical Causes

• Consider whether gastric outlet obstruction or partial bowel obstruction is contributing to nausea 1
• If suspected, options include:
  • Corticosteroids to reduce inflammation 1
  • Consider repositioning or adjusting the G-tube 1
  • Evaluate for potential endoscopic stenting if obstruction is confirmed 1

4. Optimize Current Antiemetic Regimen

• Change from as-needed to scheduled around-the-clock antiemetic administration for 1 week 1
• Consider using lower doses of promethazine (6.25mg IV) which can be as effective as ondansetron with potentially less sedation in an elderly patient 2

Additional Considerations

• Avoid antiemetics that may mask progressive ileus or gastric distension, as ondansetron may do 3
• Monitor for QT prolongation with ondansetron, especially in elderly patients with potential electrolyte abnormalities 3
• Consider haloperidol as an alternative dopamine antagonist if metoclopramide is contraindicated or ineffective 1
• Olanzapine (2.5-5mg daily) may be especially helpful if bowel obstruction is suspected 1

Cautions and Monitoring

• Monitor for extrapyramidal symptoms with metoclopramide, especially in elderly patients 1, 4
• Assess for potential drug interactions between antiemetics and other medications 1
• Evaluate the TPN formulation, as fat emulsion components can sometimes exacerbate nausea 5
• Consider reducing the rate of G-tube drainage if clinically appropriate 1

If the above measures fail to control nausea after 1 week, reassess the cause of nausea and consider alternative approaches including scopolamine patch or dronabinol 1.