What is the initial workup and treatment for a patient with intractable nausea and vomiting?

Workup and Management of Intractable Nausea and Vomiting

Initial Diagnostic Workup

Before initiating antiemetic therapy, immediately identify and address reversible causes: severe constipation/fecal impaction, bowel obstruction, medication-induced nausea, metabolic abnormalities (hypercalcemia, uremia), gastroparesis, and CNS involvement. 1, 2

Critical Red Flags to Assess Immediately

• Bilious or bloody vomiting suggests bowel obstruction or upper GI bleeding 3
• Altered mental status indicates possible CNS pathology, metabolic derangement, or sepsis 3
• Severe dehydration requiring immediate fluid resuscitation 4, 3
• Abdominal distension or absent bowel sounds suggesting mechanical obstruction 1

Essential Laboratory Evaluation

• Serum electrolytes, renal function, and liver function tests to identify metabolic causes 4, 5
• Blood glucose to rule out diabetic ketoacidosis 3
• Calcium level if malignancy is present 4
• Consider imaging (abdominal X-ray or CT) if obstruction is suspected 5, 3

First-Line Pharmacologic Treatment

Start immediately with a dopamine receptor antagonist on a fixed schedule (not as needed), as this is the best-established first-line treatment for intractable vomiting. 1, 2

Dopamine Antagonist Options (Choose One)

• Metoclopramide 10-20 mg PO/IV every 6 hours 1, 2
• Haloperidol 0.5-2 mg PO/IV every 4-6 hours 1, 4, 2
• Prochlorperazine 5-10 mg PO/IV every 6-8 hours 1, 2

Critical: Administer on a fixed schedule rather than as needed to maintain constant therapeutic levels and prevent emetic episodes. 1

Special Population Adjustments

• In elderly patients, reduce initial doses by 25-50% (e.g., metoclopramide 5-10 mg, haloperidol 0.5 mg) 4, 2
• Monitor closely for extrapyramidal side effects, particularly in elderly and young males 4, 2
• Have diphenhydramine 50 mg available to treat dystonic reactions 1

Escalation if Symptoms Persist After 24-48 Hours

Add (do not replace) a 5-HT3 antagonist to target different receptor pathways for synergistic effect. 1, 2

Second-Line Addition

• Ondansetron 4-8 mg PO/IV every 8-12 hours 1, 4, 6
• Alternative: Granisetron 1-2 mg PO daily 1
• Monitor for QTc prolongation, especially with other QT-prolonging agents 2, 6

Third-Line Addition

• Dexamethasone 4-8 mg PO/IV daily to potentiate the antiemetic effect 1, 2

Advanced Strategies for Refractory Symptoms

If oral route is not tolerated due to active vomiting, use rectal suppositories, subcutaneous or intravenous infusions, or sublingual formulations. 1, 2, 7

Additional Agents for Persistent Vomiting

• Olanzapine 2.5-5 mg PO daily (especially effective if not used prophylactically) 8, 4
• Benzodiazepines (lorazepam 0.5-1 mg PO/IV every 4-6 hours) for anxiety-related nausea 8, 4
• Cannabinoids (dronabinol 2.5-7.5 mg every 4 hours) for refractory cases 8, 1
• Anticholinergics (scopolamine) or antihistamines (meclizine) 1

Continuous Infusion Strategy

• Consider continuous IV/subcutaneous infusion of antiemetics if symptoms persist despite around-the-clock dosing 1, 2, 7
• Use multiple agents from different classes at alternating times or via alternating routes 1

Treatment of Specific Underlying Causes

Gastroparesis

• Metoclopramide 5-10 mg PO 30 minutes before meals and at bedtime to promote gastric emptying 4, 2

Gastroesophageal Reflux/Gastritis

• Proton pump inhibitors or H2 receptor antagonists 4

Constipation/Fecal Impaction

• Aggressive bowel regimen before escalating antiemetics 1, 2

Critical Pitfalls to Avoid

Never use antiemetics in suspected mechanical bowel obstruction, as this can mask progressive ileus and gastric distension. 2

• Do not prescribe as needed for persistent symptoms—fixed scheduling is essential 1, 2
• Do not start with high doses in elderly or debilitated patients—begin with reduced doses 1, 4
• Do not use long-term benzodiazepines in elderly patients due to increased sensitivity 4
• Monitor for akathisia with metoclopramide and prochlorperazine, which can develop any time over 48 hours post-administration 2, 9

Non-Pharmacological Adjuncts

• Small, frequent meals rather than large meals 1
• Cold foods are better tolerated than hot foods (less strong aromas) 1
• Acupuncture, hypnosis, or cognitive-behavioral therapy may be beneficial 1
• Ensure adequate hydration and correct electrolyte imbalances 4, 5

Reassessment and Follow-Up

Reevaluate control of nausea and appetite within 24-48 hours after initiating treatment. 1

• Monitor for side effects, particularly extrapyramidal symptoms with dopamine antagonists 1, 4
• If symptoms persist despite all interventions, consult or refer to specialized palliative care services 2
• Palliative sedation may be considered as a last resort for intractable symptoms in end-of-life care 4, 2