GI/Postop NV Flashcards
34, 35 5 questions
What five neurotransmitters contribute to nausea and vomiting?
muscarinic M1,
dopamine D2, histamine H1, 5-hydroxytryptamine (HT)-3 serotonin, and neurokinin 1 (NK1) -substance P
What are some complications associated with postopnv?
wound dehiscence, esophageal
rupture, aspiration, dehydration, increased intracranial pressure, and pneumothorax.
How long following surgery is nausea and vomiting considered postoperative?
24 hours
T/F length of surgery affects post opnv
True
What two classes are most useful in vestibular stimulation nausea and vomiting?
Antihistamines and anticholinergics
what is the preferred reversal agent in a patient with history of postop NV?
sugammadex (high doses of neostigmine cause NV)
What type of pediatric surgery exhibits high risk of postop nausea and vomiting?
strabismus surgery
How many antiemetic agents does every patient recieve?
at least 2
PONV is easier to ______ than to _____.
prevent, treat
What are the 4 major patient risk factors for PONV?
female
nonsmoker
hx of motion sickness
previous episode
What are the two surgical risk factors for developing PONV?
length of procedure (longer, worse), certain surgeries (inner ear)
What are the anesthetic risk factors for developing PONV?
Anesthetic: inhalation anesthetics, nitrous oxide, neostigmine, & opioids
Opioids and inhaled anesthetics
increase risk: opioid-sparing, regional anesthesia, TIVA (propofol), still give an antiemetic
What are the 4 pediatric risk factors of PONV?
- > 30min surgery
- Age >3 years old
- Strabismus surgery
- Familial or personal history of PONV
What are 1st, 2nd, 3rd, and 4th line medications used for PONV?
- ondansetron 4-8mg
- dexamethasone 4-8mg
- scopolamine patch
- benadryl 12.5mg
When should a scopolamine patch be applied for PONV?
2-4hr prior to stimulus
When should ondansetron be given to prevent PONV?
prior to stimulus. immediately after giving fentanyl during induction
When should dexamethasone be given to prevent PONV?
once patient is asleep since it cause perineal dyscomfort
Why should 4mg or 8mg be the routine dexamethasone dosage intraoperatively?
4mg: due to increase in BG, in setting of uncontrolled DM or existing hyperglycemia which can lead to decreased acute wound healing and an increased risk of infection
8mg: doesn’t make a huge difference in BG. does many different things (antiemetic, analgesic, decreased immune response and anti-inflammatory)
What is the choice 5-HT3 antagonist?
ondansetron 4-8mg
What is the anticholinergic of choice in PONV management?
scopolamine patch
What is the choice antihistamine for PONV management?
Diphenhydramine 12.5mg use w caution postop due to sedative effect
What is the only benzodiazepine that can be given for PONV and a consideration?
midazolam, should not be given postoperatively due to major sedative effects
What is the cannabinoid derivative most frequently use?
Dronabinol
What corticosteroid is the best choice for PONV?
dexamethasone 4-8mg
What Dopamine (D2) antagonists is the best choice for PONV?
haloperidol 0.5-2mg IV
What are Neurokinin-1 antagonists good at treating?
chemo induced NV
What type of NV occurs in the frontal cortex of the brain and how is it best managed?
anxiety/psychogenic related, midazolam
What is hyperemesis 2/2 cannabis use managed?
must stop using cannabis substance
Why should ondansetron be given slowly?
rapid admin can cause a headache
why is iv phenergan no longer given?
there is a high risk for thrombophlebitis which can damage IV integrity
What H2 antagonist is commonly given in the setting of allergic reaction?
famotadine
What is the MOA of ondansetron?
Blocks 5-HT3 Receptors from initiating the vomiting reflex
What are the two common reactions to a bolus of fentanyl?
euphoria/relaxation OR spinning/vomiting due to vestibular dysfunction
What is a cardiac related side effect of ondansetron?
QT-prolongation: cardiac arrhythmias
What is the MOA of a scopolamine patch?
Prevents activation of muscarinic acetylcholine receptors in the vestibular system near the chemoreceptor trigger zone (CRTZ)
What is a major patient teaching point regarding the use of scopolamine?
must remove when at home, not moving a lot. wash hands after removal
What are the symptoms of anticholinergic OD?
dry mouth, difficulty talking/swallowing, blurred vision, photophobia, tachycardia, dry,flushed skin, rash on face, neck, & chest, Increased body temperature, Increased minute ventilation
What are examples of anticholinergics that do and do not cross the BBB?
do: atropine, scopolamine
don’t: glycopyrrolate
How should an anticholinergic overdose be treated?
physostigmine 15-60mcg/kg iv Q1-2H (same tx for central anticholinergic syndrome)
What is the difference between an anticholinergic OD and central anticholinergic syndrome
AC OD is cause by too much medication while CAS is due to a weird reaction/metabolism of the medication
What are the two frequently used histamine receptor antagonists and their side effects?
Dimenhydrinate (Dramamine): block oculo-emetic reflex 1mg/kg
Diphenhydramine (benadryl): 12.5mg
SE: effects vary w/ liver disease, dry mouth, somnolence
What is the MOA of corticosteroids for PONV management?
prevents release of inflammatory mediators which prevents CTZ zone activation
T/F steroid therapy should not be given to patients with diabetes for PONV management
False
What class is droperidol in, MOA, dose, and side effects
dopamine antagonist
0.625-1.25mg
SE: qt prolong
What is a requirement for droperidol use?
EKG monitoring 2-3hr post use due to potential of causing arrhythmias
what is the choice antiemetic for a patient receiving cisplatin?
droperidol
When should neurokinin-1 antagonists (aprepitant) be given to prevent PONV?
3 hours prior to induction
What is the MOA ofa prepitant? what is the major pro and con of use?
antagonist of g-protein neurokinin receptor (prevents release of substance p)
good at tx chem NV, bad bc it doesnt treat vomiting
only prophylactic
What is the MOA of metoclopramide (reglan)?
selective cholinergic stim of the gi tract, ^ lower esoph sphincter tone, increased gastric and SB motility, relaxes pylorus + duodenum
When should metoclopramide (reglan) be given?
10-20mg iv/3-5min 15-30min prior to induction
What are anesthesia concerns of metoclopramide (reglan)?
contrai: parkinsons, RLS, movement disorders, dystonic extrapyramidal reactions, neurologic dysfunction, caution w antipsychotic medications, akathisia
*Not indicated for Bowel/GI procedures
What is a major concern regarding haloperidol use for PONV?
Sudden cardiac death related to prolonged QTc interval
What is the MOA of cannabinoids such as nabilone and dronabinol?
Binds to cannabinoid receptor type 1 peripherally (suppressing intestinal motility) and centrally in the nucleus of the solitary tract.
What patient population is at high risk of aspiration and what should they be given preop?
pregnant (due to increased progesterone causing esophageal sphincter relaxation), give oral antacids
How do antacids work and what do they treat?
neutralize gastric hydrogen ions and decrease secretion
GERD, stress gastritis, ulcers
What are some anesthesia concerns related to antacid use?
Gastric alkalinization increases gastric emptying, resulting in a faster delivery of drugs into the small intestine, absorption effects, bioavailability effects
What are side effects of antacid use?
bacterial overgrowth in the duodenum and small intestine, metabolic alkalosis, UTIs, acid rebound, phosphorus depletion
What is the MOa of H2 antagonists (famotadine)?
selective and reversible inhibition of H2 receptor–mediated secretion of hydrogen ions by parietal cells in the stomach
What are indications to give famotidine and it’s side effects?
procedures with Increased risk of aspiration, duodenal disease, decreases gastric fluid pH
Diarrhea, HA, fatigue, and skeletal m pain
What is the mechanism of action for proton pump inhibitors and their anesthesia considerations?
decrease acid secretion in the stomach
omeprazole should be given >3 hours before induction for chemoprophylaxis.
When should PPIs be d/ced prior to surgery?
they shouldn’t be ;)
What are side effects of chronic H2 blocker use?
CNS effects: headache, confusion, sedation. cardiac: bradycardia, hypotension, CHB. acute pancreatitis, low plts
What are indications for metoclopramide?
decrease gastric volume, antiemetic effect, tx gastroparesis, tx GERD, intolerance to enteral feedings in patients who are critically ill.
What are side effects of metoclopramide?
abd cramping due to rapid IV administration (<3 minutes)
- hypotension
- tachycardia
- bradycardia
- cardiac arrhythmia
Why is ondansetron the drug of choice for anesthesia?
because volatile anesthetics work in CNS which means they could hit the 5-HT3 receptor
If a patient received ondansetron 6 hours ago, and has a event of N/V. what drug should be given?
an antiemetic in a different class is best, BUT if not available, can give ondansetron again
Do oral antacids undergo first pass metabolism?
no, because the stomach is the target tissue
Does the use of epidural anesthesia increase or decrease the risk of PONV?
decrease
What random drug decreases the risk of PONV?
clonidine (systemic Alpha2 agonist)
