This educational session focuses on nausea and vomiting etiologies and developing rationale for management.
Key Causes of Nausea in Serious Illness
Nausea is common in patients with advanced cancer, particularly GI and gynecologic malignancies. Causes may be multifactorial, including:
- Acute: opioids (via CTZ/mu receptors), infections, immobility, antibiotics.
- Chronic: peritoneal carcinomatosis, malignant ascites, liver metastases.
- Other: constipation, bowel obstruction, CNS metastases, anxiety, existential distress.
Pathophysiology Highlights
The chemoreceptor trigger zone (CTZ) and vomiting center in the medulla coordinate nausea.
Key neurotransmitters and receptors:
- Dopamine (D2) – CTZ
- Serotonin (5-HT3) – GI tract
- Acetylcholine, Histamine, NK-1 – vestibular/CNS
- Triggers may originate from the GI tract, sensory input (smell/sight), cortex, or vestibular system.
Management Approach
Non-Pharmacologic:
- Replete electrolytes, ensure hydration.
- Evaluate need for imaging if obstruction suspected.
- Consider paracentesis for symptomatic ascites.
- Encourage mobility, bland/low-acid diet.
- Address anticipatory anxiety.
Pharmacologic:
- Dopamine antagonists: haloperidol, prochlorperazine (IV), olanzapine (multi-receptor, risk of sedation), metoclopramide.
- Serotonin antagonists: ondansetron (IV/SL/PO), granisetron, palonosetron.
- If QTc >500ms, correct electrolytes and avoid QT-prolonging agents.
- Adjuncts: dexamethasone, lorazepam, antihistamines, cannabinoids (e.g., dronabinol), NK-1 antagonists (refractory cases).
Chemotherapy-Induced Nausea and Vomiting (CINV)
Types: anticipatory, acute, delayed, breakthrough.
Example high-risk regimens (e.g., cisplatin, doxorubicin) require prophylaxis targeting multiple pathways:
- Day 1: olanzapine, 5-HT3 antagonist, NK-1 antagonist, dexamethasone
- Days 2–4: olanzapine, dexamethasone ± continued NK-1 coverage
Prophylaxis should cover both acute and delayed CINV phases.
Complementary Therapies
- Acupuncture/acupressure (evidence-supported)
- Guided imagery
- Inhaled isopropyl alcohol wipes
- Trigger avoidance (e.g., strong smells)
Bottom Line: Effective nausea management in palliative care requires assessing all potential causes, using multi-receptor pharmacologic strategies, and incorporating supportive non-drug interventions.