Nausea Flashcards
Causes of nausea at EOL
GI Factors:
- Pharyngeal Irritation (Oral/esophageal candidiasis, tenacious sputum/persistent cough)
- Gastric irritation (PUD, gastritis)
- Gastric stasis (Opioids or anticholinergics, hepatomegaly or GOO)
- Stretching or distortion of the GI tract (Constipation, intestinal obstruction, mesenteric mets)
- Infections of the GI tract (fungal, bacterial, parasitic infections - particularly in HIV/AIDS)
Meds:
- Opioids, particularly intro or increase
- Cytotoxic drugs
- SSRIs
- Antivirals or Antibiotics
Metabolic
- Hypercalcemia
- Renal failure
- Liver failure
- DM
- Cytokine or other tumour factors
Cranial
- Raised ICP secondary to brain mets or leptomeningeal involvement, post-rads
- CNS infections (AIDS)
Psychosomatic
- Anxiety, pain, anticipator nausea
Pathophysiology of emesis - Chemoreceptor Trigger Zone
Chemoreceptor Trigger Zone (area postrema in fourth ventricle)
- No blood brain barrier - Bathed in CSF with chemoreceptors (D2, serotonin, and cannabinoid) responsive to drugs and electrolytes - Relays neurotransmitters to Vomiting Centre and vomiting reflex
Pathophysiology of Emesis - Vomiting Centre
Vomiting Centre is a diffuse network in the medulla oblongata of the mid brainstem
- Nausea without vomiting may be due to stimulation of the VC without enough amplification to trigger the vomiting cascade - H1, acetylcholine, serotonin receptors - Input from the CTZ, vestibular apparatus and cerebellum, higher cortex, gut chemoreceptors and mechanoreceptors, mechanoreceptors in viscera/serosa (head and neck, thorax, abdomen, pelvis) - Stimulation causes parasympathetic and sympathetic output as well as neurotransmitter cascade to induce vomiting
Inputs to Vomiting Centre
CTZ (area postrema in fourth ventricle)
- D2, serotonin 5-HT3, opioid receptors, acetylcholine receptors, substance P reeptors
Vestibular system (via CN 8 - vestibulocochlear), motion sickness - muscarinic and H1 receptors
CN X (vagal nerve) - pharyngeal irritation (gag reflex)
Vagal and enteric nervous system (chemoreceptors, mechanoreceptors in gut, mechanoreceptors from viscera/serosa), D2 and Serotonin
CNS (psychiatric disorders, stress), H1 receptor
Approach to Nausea/Vomiting
- Identify likely cause(s) and evaluate for dehydration, potential for opioid neurotoxicity
- Identify pathway by which each case triggers vomiting reflex
- Identify neurotransmitter pathway
- Choose most potent antagonist to the receptor identified (dictated by binding affinity)
- Choose route (often not oral as patients may not be able to tolerate)
- Titrate carefully
- Give regularly
- If symptoms persist - review likely cause and consider overlooked causes or other contributing causes
- Consider combining antiemetics, but be mindful of interactions (antihistamines and anticholinergics may counteract prokinetics!)
Rx for Opioid nausea, neurotransmitter and site
- CTZ
- D2 receptor
- Haldol 1.5 - 5mg q8-12h, PO or SC (first line)
- Levomepromazine 5 - 12.5mg q daily, PO or SC
- Prochlorperazine 5-10mg (PO, SC, IV) BID-QID
Rx for Gastric stasis, Ileus, neurotransmitter and site
- Gastroinstestinal site
- Serotonin (to a lesser extent, dopamine, histamine, Ach)
- Prokinetics preferred
- Domperidone 10-20mg PO q4-8H AC meals
- Metaclopramide - 10-20 mg PO/SC/IV TID AC meals
Rx for Gastric Obstruction, neurotransmitter and site
- Gastroinstestinal site
- Serotonin (to a lesser extent, dopamine, histamine, Ach)
- Phenothiazines, antihistamines, anticholinergics
- Levomepromazine 5-12.5mg/24hr PO/SC
- Cyclizine 25-50mg PO/SC/PR q8h
- Scopolamine 20mg PO/SC q6h (especially if colicky)
- Dex 8mg qAM to try to relieve obstruction (trial for 4-5 days)
Rx for Chemotherapy nausea, neurotransmitter and site
**Check guidelines from ASCO for this
- CTZ (area postrema in fourth ventricle) and gastrointestinal site
- CTZ = dopamine, GI site = serotonin (to a lesser extent for both, Ach and histamine)
- 5-HT3 antagonists, NK1 antagonist, prokinetics
- Ondansetron 8mg PO/SC (consider addition of Dex to enhance efficacy)
- Aprepitant 125mg PO 1hr prior to chemo, then 80mg OD for the next two days
- Metoclopramide 10-20mg PO/SC q4h
Also consider haldol, and olanzapine 5-10mg q daily on days before and during chemo has been found to be effective, though evidence may be poor.
Rx for raised ICP nausea, neurotransmitter and site
- Cerebral Cortex
- GABA, Histamine
-Use Phenothiazines (prochlorperazine 5-10mg/12.5-25m IM q8H) along with Dex for decreasing ICP
Maxeran for Nausea (indications, dose, side effects, notes)
Metoclopramide 10-20mg PO/SC/IV q4H
CTZ and GI tract, D2. Note that metoclopramide potentiates 5-HT3 receptors (may be used with ondansetron, but watch QT) and can act on 5-HT3 at higher doses. Central antiemetic effect plus prokinetic effect and decreased pylorus activity - food passes through more quickly.
Indications: Gastric stasis, ileus (avoid in complete obstruction), may use for Chemotherapy
Do not combine with anticholinergics (scopolamine, hyoscine, diphenhydramine) due to counteracting effects. Note that olanzapine, levomepromazine also have anticholingeric effects and increase risk of EPS.
Side effects: EPS, restlessness, drowsiness, colic in GI obstruction. Risk of tardive dyskinesia, especially if used longer than 12 weeks, at higher doses, or in patients under 20 years old. Risk increased with combination with antipsychotics!
Prolonged half life in renal failure, long QTc. Caution in Parkison’s (may worsen symptoms as a dopamine antagonist)
EPS with anti-nauseants - symptoms, pathophys, agents
Symptoms: Parkinsonism, dystonia, tardive dyskinesia, akathisia
Seen with Maxeran and prochlorperazine overdose (usually but not always reversible)
Levomepromazine for nausea (indications, dose, side effects, notes)
5-12mg PO/SC over 24 hrs (BID or continuous SC infusion)
Receptors: D2, 5HT2, H1, acting on VC
Indications: Intestinal obstruction, peritoneal irritation, vestibular, raised ICP, unknown causes
Side effects: Long QTc, sedating, orthostasis, anticholinergic effects (esp in elderly) - confusion, hallucinations, EPS
Non-pharm measures for nausea
Citrus Ginger Peppermint Cold, lightly carbonated beverages Hydration Decrease odours
Glucocorticoids for nausea (indications, dose, side effects, notes)
Exact mechanism unknown, likely glucocorticoid receptors in central nucleus.
Dexamethasone 4-8 mg PO qAm (higher doses if related to increased ICP)
Side effects: Hyperglycemia, Cushing syndrome, weight gain, PUD, infection, aseptic necrosis (femoral/humerol heads), impaired wound healing, steroid psychosis, adrenal suppression,