11. Nausea

(For more information, refer to Palliative Care)

Definition

Sensation of unease or discomfort, often associated with the inclination to vomit. Most causes of nausea are not serious, but some serious causes do occur.

Differential Diagnosis

  • Chemotherapy-induced
  • Opioid-induced
  • Bowel obstruction
  • GI tract dysmotility
  • Radiation associated
  • CNS process (e.g., brain tumor)
  • Motion associated
  • Constipation
  • Metabolic (e.g., adrenal insufficiency, hypercalcemia, DKA)
  • Infectious (e.g., hepatitis, meningitis)
  • Cardiac (e.g., ACS, congestive heart failure)

Management

  • In most cases of severe nausea, primary team is already aware and may have given you suggestions about which anti-emetics are particularly effective for a given patient.
  • QTc may be a consideration for your patient. If their QTc is > 500ms, use agents that are not as QTc-prolonging, such as Benadryl or Ativan.
  • If no contraindications, Compazine, Phenergan, Zofran, and Ativan are most commonly used (it is worth asking patients what they have had success with in the past).
    • Ondansetron (Zofran) is particularly effective for nausea associated with chemotherapy or anticholinergic medication overdose. Can try higher dose 8 mg IV q8 for severe nausea (otherwise 4 mg IV q6 is a good starting dose).
    • Metoclopramide (Reglan) 10 mg PO/IV q4-6h prn.
    • Prochlorperazine (Compazine) 10 mg PO/IM/IV q6h or 25 mg PR q12h PRN. Known seizure disorder is a relative contraindication. Extrapyramidal symptoms, including dystonic reactions, are a possible side effect (treat with Benadryl 50 mg IV/IM or Cogentin 10 mg IV). Beware of neuroleptic malignant syndrome with excessive use.
    • Promethazine (Phenergan) 12.5-25 mg PO/IM/PR q4-6h.
    • Lorazepam (Ativan) 0.5-2.0 mg PO/IV q4-6h prn.

Key points

  • Check the patient’s old EKGs to make sure no QTc prolongation before giving anti-emetics. If QTc is normal on recent EKG, no need to recheck for 1-2 time dose. Consider repeating in patients with continuous high-risk medication use. 
  • A common side-effect of many anti-emetics is drowsiness.
  • As with other drug therapy, combinations of anti-emetics can sometimes succeed when single agents fail.
  • Don’t forget to consider the important causes of nausea (e.g., MI, obstruction, opiate or EtOH withdrawal), particularly if nausea is new or different from previous episodes. See relevant sections (e.g., Cardiology, GI) for more information.