What is the management approach for a patient presenting with persistent vomiting in clinical practice?

Management of Persistent Vomiting: IPD and OPD Prescription Protocol

Initial Assessment and Diagnostic Workup

For persistent vomiting, immediately obtain complete blood count, serum electrolytes, glucose, liver function tests, lipase, and urinalysis to exclude metabolic causes and assess dehydration severity. 1

Critical Laboratory Tests

• Electrolyte panel: Check for hypokalemia, hypochloremia, and metabolic alkalosis from prolonged vomiting 1
• Additional metabolic screening: Consider hypercalcemia, hypothyroidism, and Addison's disease if clinically indicated 1
• Urine drug screen: Essential to assess for cannabis use, particularly in younger patients where Cannabis Hyperemesis Syndrome is increasingly common 1

Imaging Studies

• One-time upper GI imaging or EGD: Recommended to exclude obstructive lesions 1
• Avoid repeated endoscopy unless new symptoms develop 1

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OPD (Outpatient) Prescription Protocol

First-Line Pharmacologic Management

Start with dopamine receptor antagonists as first-line therapy, titrated to maximum benefit and tolerance. 1, 2

Option 1: Metoclopramide (Preferred)

• Dosage: 10 mg PO three times daily before meals 2
• Mechanism: Promotes gastric emptying and has antiemetic properties 2
• Black box warning: Monitor for tardive dyskinesia, though risk may be lower than previously estimated 2
• Monitor for: Extrapyramidal symptoms, particularly in young males 1

Option 2: Prochlorperazine

• Dosage: 5-10 mg PO three times daily 2
• Alternative formulation: Rectal suppositories available if oral route not feasible 2

Option 3: Haloperidol

• Dosage: 0.5-2 mg PO every 4-6 hours 3
• Particularly useful: In elderly patients or palliative care settings 3

Supportive Care Measures

• Hydration: Ensure adequate fluid intake ≥1.5 L/day 4
• Dietary modifications: Small, frequent meals (4-6 meals/day), eat slowly, separate liquids from solids by 30 minutes 4
• Thiamin supplementation: Essential in cases of persistent vomiting to prevent Wernicke's encephalopathy 4

Second-Line Therapy (If Symptoms Persist After 4 Weeks)

Add 5-HT3 antagonist to the dopamine antagonist regimen rather than replacing it. 1, 2

Ondansetron

• Dosage: 8 mg PO 2-3 times daily 2
• Alternative formulation: Sublingual tablets (improves absorption in actively vomiting patients) 2
• Critical monitoring: QTc prolongation, especially when combined with other QT-prolonging agents 1
• Maximum dose: 16 mg per dose 5

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IPD (Inpatient) Prescription Protocol

Indications for Admission

• Severe dehydration with inability to tolerate oral fluids 6
• Serum bicarbonate ≤13 mEq/L: Strong predictor of need for prolonged IV therapy 6
• Bilious or bloody vomiting: Suggests mechanical obstruction requiring urgent evaluation 1, 7
• Altered mental status or severe electrolyte abnormalities 1

Intravenous Rehydration Protocol

Initiate rapid IV rehydration with 20-30 mL/kg isotonic crystalloid over 1-2 hours. 6

Fluid Management

• Initial bolus: Normal saline or Ringer's lactate 20-30 mL/kg over 1-2 hours 6
• Add dextrose early: Consider dextrose-containing fluids to help terminate vomiting and prevent hypoglycemia 8
• Electrolyte correction: Aggressively correct hypokalemia and hypomagnesemia 1

Intravenous Antiemetic Regimen

First-Line IV Therapy

Metoclopramide 10 mg IV every 6-8 hours 2

• Administer over 2-5 minutes 5
• Continue until patient tolerates oral intake 2

Add Ondansetron for Persistent Symptoms

• Dosage: 4 mg IV over 2-5 minutes every 8 hours 5
• Alternative: 0.15 mg/kg IV (maximum 16 mg per dose) 5, 7
• Pediatric dosing: 0.15 mg/kg IV for children, 0.1 mg/kg for postoperative vomiting 5

Nasogastric Decompression

Insert NG tube and maintain on continuous suction if bilious vomiting is present to prevent aspiration and decompress the stomach 7

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Treatment Algorithm for Refractory Cases

Third-Line Options (If First Two Lines Fail)

Consider adding agents from different drug classes for synergistic effect rather than replacing existing therapy. 2

Olanzapine

• Dosage: 2.5-5 mg PO daily 3
• Evidence: Superior efficacy compared to metoclopramide for breakthrough vomiting in some studies 2
• Particularly useful: In palliative care or refractory cases 3

Benzodiazepines (For Anxiety-Related Component)

• Lorazepam: 0.5-1 mg PO/IV every 4-6 hours 3
• Caution: Avoid long-term use due to dependence risk 2

Proton Pump Inhibitors (If Gastritis/GERD Suspected)

• Add PPI or H2 blocker to address underlying gastric pathology 1, 2

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Critical Pitfalls to Avoid

Absolute Contraindications

Never use antiemetics in suspected mechanical bowel obstruction as this can mask progressive ileus and gastric distension 1, 2

Monitoring Requirements

• Extrapyramidal symptoms: Monitor closely with dopamine antagonists, especially in young males 1
• QTc prolongation: Serial ECGs when using ondansetron with other QT-prolonging medications 1
• Electrolyte monitoring: Daily checks until stable, particularly potassium and magnesium 1

Cannabis Hyperemesis Syndrome Considerations

• Do not stigmatize patients with cannabis use 1
• Offer treatment even with ongoing use: Antiemetics can still be effective 1
• Definitive diagnosis requires: 6 months cannabis cessation or 3 typical cycle lengths without vomiting 1

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Transition from IPD to OPD

Discharge Criteria

• Tolerates oral fluids after trial of clear liquids 6
• Improved hydration status with normalized vital signs 6
• Electrolytes corrected or trending toward normal 1
• No bilious vomiting or red flag signs 7

Discharge Prescription

• Continue oral dopamine antagonist (metoclopramide 10 mg TID) 2
• Add ondansetron 8 mg PO as needed for breakthrough symptoms 2
• Thiamin supplementation if vomiting was prolonged 4
• Clear dietary instructions: small frequent meals, separate liquids from solids 4
• Follow-up in 24-48 hours to assess response 6