What is the recommended assessment and management for a patient who has had 16 episodes of emesis over the past two days?

Management of Severe Vomiting (16 Episodes Over 2 Days)

Immediately assess hemodynamic stability and initiate aggressive IV fluid resuscitation with normal saline while administering scheduled ondansetron 8 mg IV/sublingual every 4-6 hours, as this represents a medical emergency requiring urgent evaluation for underlying causes and prevention of life-threatening complications. 1, 2, 3

Immediate Assessment and Stabilization

Hemodynamic Evaluation

• Check vital signs immediately including pulse, blood pressure, and signs of shock, as severe vomiting can lead to hypovolemic shock in approximately 15% of cases 2, 4
• Look specifically for tachycardia, hypotension, decreased urine output, and altered mental status as indicators of volume depletion 2, 3

Fluid Resuscitation

• Initiate aggressive IV fluid resuscitation with isotonic normal saline (0.9% NaCl) using 10-20 mL/kg boluses for any signs of volume depletion 2, 3, 4
• Continue fluid administration until hemodynamic stability is achieved 2, 3

Electrolyte Management

• Check and correct electrolyte abnormalities immediately, particularly potassium, sodium, magnesium, and chloride, as severe vomiting causes hypochloremic hypokalemic metabolic alkalosis 1, 3, 5, 6
• Severe hypokalemia (K+ <2.5 mmol/L) can cause life-threatening cardiac arrhythmias and neuromuscular symptoms 5, 6
• Obtain complete metabolic panel, liver function tests, and complete blood count urgently 3

Thiamine Supplementation

• Administer thiamine 100 mg PO three times daily or IV (Pabrinex) before any dextrose administration to prevent Wernicke's encephalopathy, especially with prolonged vomiting or reduced dietary intake 3

Antiemetic Management

First-Line Therapy

• Administer ondansetron (5-HT3 antagonist) as first-line antiemetic due to superior efficacy and safety profile 1, 2, 3, 4
• Dosing: 8 mg sublingual every 4-6 hours during the episode 1
• Use scheduled dosing every 4-6 hours rather than PRN administration for better symptom control 1, 3
• Baseline ECG is advised as ondansetron is associated with prolonged QTc interval 1

Alternative Routes

• The oral route is not feasible with ongoing vomiting; use IV or rectal routes as needed 1, 3
• Rectal suppositories provide an effective alternative when IV access is challenging 1

Second-Line Agents (If Ondansetron Fails)

Add agents from different drug classes with different mechanisms of action 1, 3:

• Metoclopramide (dopamine antagonist): 10 mg IV administered over 3 minutes to minimize extrapyramidal effects 3
• Prochlorperazine: 5-10 mg every 6-8 hours or 25 mg suppository every 12 hours 1
• Promethazine: 12.5-25 mg by mouth/per rectal every 4-6 hours (caution: peripheral IV administration can cause tissue injury including gangrene) 1

Adjunctive Therapy

• Lorazepam 0.5-2 mg IV every 4-6 hours for anxiety-related nausea and to reduce anticipatory symptoms 1, 3
• Dexamethasone 8-12 mg IV can be added for refractory cases 3
• Haloperidol 0.5-2 mg IV/IM may be required for breakthrough emesis 1, 3

Multiple Concurrent Agents Strategy

• Consider alternating schedules or routes of administration if single-agent therapy fails 1, 3
• Multiple concurrent agents from different drug classes may be necessary for severe refractory vomiting 1

Diagnostic Workup

Document Emesis Characteristics

• Photograph the emesis to guide management decisions and help differentiate true pathology from benign causes 2, 3
• Note color: coffee-ground appearance suggests upper GI bleeding, bile-stained (yellow) suggests duodenal reflux or intestinal obstruction, purple may indicate altered blood or food coloring 2, 3, 4

Basic Laboratory Workup

• Complete blood count, serum electrolytes, glucose, liver function tests, and lipase 1
• Urinalysis to assess hydration status and rule out metabolic causes 1
• Urine electrolytes if metabolic alkalosis is severe: characteristic pattern in surreptitious vomiting shows high sodium and potassium with chloride <5 mmol/L 6

Imaging Considerations

• One-time esophagogastroduodenoscopy (EGD) to exclude obstructive lesions if upper GI pathology is suspected 1, 3, 4
• Avoid repeated EGD or upper GI imaging studies 1
• Consider CT angiography if hemodynamically stable but upper GI bleeding remains in differential 2, 4
• Brain imaging if any localizing neurologic symptoms are present 1

Specific Diagnostic Considerations

• Rule out cyclic vomiting syndrome (CVS) if episodic pattern with symptom-free intervals 1
• Assess cannabis use patterns: prolonged (>1 year) and heavy use (>4 times weekly) preceding symptoms suggests cannabinoid hyperemesis syndrome (CHS) 1
• Consider workup for Addison's disease, hypothyroidism, and hepatic porphyria if presentation is atypical 1

Reassessment for Underlying Causes

Red Flags Requiring Urgent Investigation

• Severe abdominal pain or peritoneal signs suggesting bowel obstruction or perforation 3
• Neurologic symptoms suggesting increased intracranial pressure or brain metastases 1
• Signs of upper GI bleeding (hematemesis, melena, hemodynamic instability) 2, 4

Non-GI Causes to Consider

• Medication effects or coagulopathy 2
• Metabolic derangements (diabetic ketoacidosis, uremia, hypercalcemia) 3
• Pregnancy in women of childbearing age 3
• Tumor infiltration of bowel or other GI abnormality 1

Common Pitfalls to Avoid

• Do not delay endoscopy if upper GI bleeding is suspected, as approximately 80-85% of cases cease spontaneously but carry high risk of rebleeding, massive hemorrhage, and death without source identification 2
• Do not use PRN dosing for antiemetics in severe vomiting; scheduled around-the-clock administration is far more effective 1, 3
• Do not administer dextrose-containing fluids before thiamine in patients with prolonged vomiting or malnutrition 3
• Do not perform gastric emptying scans routinely in suspected CVS, as few patients have delayed emptying and results during an episode are uninterpretable 1
• Do not stigmatize cannabis users; cannabis use often postdates CVS onset and may be therapeutic rather than causative 1
• Do not misinterpret epiphenomena of recent vomiting on EGD (mild gastritis, Mallory-Weiss tear, esophagitis) as causal 1