Antinausea

• Nausea - sensation of abdominal discomfort intermittently and the desire to vomit
• Vomiting (emesis) - forceful expulsion of gastric contents out of the mouth
• Regurgitation - rising of gastric or esophageal contents to the pharynx as a result of stomach pressure
• Vomiting center (vc) located in medulla, coordinates the vomiting reflex
  • Nerves from the pharynx, stomach, intestinesm and other tissues connect to vc via vagus and splanchnic nerves
  • Vc responds to cerebral cortex, inner ear, and blood
• Causes of Nausea and Vomiting
  • Postoperative (PONV), motion sickness, pregnancy (morning sickness & hyperemesis gravidarum)
  • Psychogenic - vomiting in response to threatening or distasteful situations
  • Chemotherapy (CINV) - anticipatory, acute CINV, delayed emesis
  • Radiation (RINV) - associated w/ high-energy radiation, external or implanted
• Drug Therapy
  • PONV - multimodal treatment, hydration, supplemental oxygen, combination of antiemetics, NG tube (to prevent abdominal distension)
  • Motion sickness - most meds chemically related to antihistamine/anticholinergic
  • Psychogenic (diagnosis made after other cause eliminated) - metoclopramide or anti anxiety med
  • Pregnancy - diet, antihistamines (diphenhydramine, meclizine, promethazine), phenothiazines, ginger
  • CINV - combination of meds b/c emesis produced by more than one mechanism
  • Ondansetron (zofran), dolasetron (anzemet), granisetron (kytril)
  • High doses of metoclopramide (reglan), dexamethasone (decadron/hexadrol), lorazepam (ativan), diphenhydramine (benadryl/diphenhist)
  • Should be treated preventally
  • Anticipatory - benzodiazepin, muscle relaxation, mind diversion, hypnosis, systematic desensitization
  • Delayed emesis - combo of prochlorperazine, lorazepam, diphenhydramine PO 1hr before meals
  • RINV - granisetron, ondansetron, serotonin antagonists
• Nursing process
  • Assessment - history , baseline vitals, hydration status, labs
  • Implementation - prescribed diet, progression of diet, stop solid foods, PO hydration solutions/clear liquids, NPO/NG tube (infants - milk and solids dq (liquids q 30-60 mins)
  • Scheduled meds
• Dopamine Antagonists
  • Drugs - phenothiazines, butyrophenones, metoclopramide (reglan)
  • Inhibits dopamine receptors that are a part of the pathway to VC
  • Treats mild-moderate nausea and vomiting associated w/ anesthesia, surgery, radiation therapy, chemo
• Serotonin Antagonists
  • Blocks the serotonin 5-HT receptors located in the chemoreceptor trigger zone of the medulla and in specialized cells of the GI tracts
  • Treats nausea and vomiting associated w/ chemo, radiation, PONV
  • ADVERSE EFFECTS - headache, diarrhea, constipation, sedation
• Anticholinergic Agents
  • Counterbalances excessive amounts of acetylcholine thought to cause motion sickness
  • Treats motion sickness, nausea and vomiting associated w/ pregnancy
  • ADVERSE EFFECTS - anticholinergic effects (rapid pulse, dry), sedative effects
• Corticosteroids - dexamethasone (decadron, hexadrol), methylprednisolone (solu/depo Medrol)
  • Mechanism of action unknown
  • In combo w/ other antiemetics to relieve nausea and vomiting (can used alone)
• Benzodiazepines - lorazepam (ativan), diazepam (valium)
  • Combination of effects - sedation, reduction in anxiety, depression of vc, amnesic effect
  • ADVERSE EFFECTS - over sedation (hypoventilation)