Quiz 9 Flashcards
General population N/V risks? High risk Pts? How long can increase discharge time?
Nausuea 50%
Vomiting 30%
High risk: 70-80% N or V
25%
Places where sensory of n/v can originate?
Medulla Chemoreceptor Trigger Zone Neural pathway in vestibular system Reflex afferent pathways Midbrain afferents
all vomiting signals sent to?
medulla
What sensory areas are effected by Chemotherapy? by Radiotherapy?
Chemo: CTZ, stomache/small intestines
Radio: Stomach/small intestines
neural pathways of stomach/small intestine?
what drugs effect which paths?
to CTZ and Medulla (everything else just goes to medulla)
- sphincter modulators and 5HT3 antagonists effect to CTZ
- 5HT3 antagonists effect to Medulla
sensory imput such as pain, smell, site, memory, fear, anticipation, all effect what?
What drugs effect its path?
Higher cortical centers
-Benzos
What drugs effect the CTZ pathways?
- Histamine antagonists
- Muscarinic antagonists
- Dopamine antagonists
- Cannabanoids
times of early, late, delayed, and post-discharge post-op n/v?
early: 2-6 hours
late: 6-24 hours
delayed: > 24 hours
post-discharge: 24 hours post-discharge
PONV risk factors (18yo or older):
which actually proven?
- Female
- History of PONV - or motion sickness
- Non-smoker
- Age <50
- General vs regional
- Volatile anesthetics and Nitrous oxide
- Post-op opioids – best data to optimize NSAIDS use
- Duration of procedure
- Type of procedure (cholecystectomy, gynecologic, laparoscopic) – high incidence
risk factors and compounding percentages?
beyond one risk factor do what?
Ppl with no risk factors still 10%
One risk factor = 20%, two = 40%. Three = 60%, 4 = 80%
Beyond 1 risk factor should give at least 2 meds, beyond 3 risks give 3 meds
Post Discharge NV risk factors
Female < 50yo Hx of PONV Opiates in PACU Nausea in PACU
Risk factors for Children (which is highest):
Procedure >30 minutes
Age >3 years
Strabismus surgery (highest risk factor)
Hx of PONV or PONV in relatives
who pre-treat n/v meds?
moderate to high risk pts
Anesthesia considerations:
Propofol reduces by 20%
Regional vs General Anesthesia (If use TIVA can reduce by 20%)
NSAIDs over Opiates
No longer recommended to reduce Neostigmine dose just use normal dose
Pretreatment options:
Dexamethasone Droperidol 5HT3 antagonists Scopolamine Patch H1 blockers NK1 antagonists
Rescue meds:
Reglan
D2 blockers
H1 blocker
5HT3 antagonists
(as long as different MOA than pretreatment med)
When to give zofran? dexamethasone? scop patch? aprepitant?
end of procedure
pre-induction
at least 4h before
1-3 hours before
which 3 drugs were equally effective and what percentage improvement?
- zofran
- droperidol
- dexamethasone
25%
5HT3 antagonists?
(serotonin antagonists) (in gut and CNS)
the “-setrons”
5HT3 antagonists info: metab, prodrug, half-lives
Metabolism: CYP450 3A4 substrate
Prodrug: Dolasetron
Half life O: 4 hours so given Q8 (2 half lives) G: 9-11 hours D: 7-9 hours P: 40 hours
Dexamethasone: side effects?
Impaired wound healing/infection
Increased glucose (bacteria loves glucose)
Hypertension, edema
Altered mental status (agitation)
(Rare with 1x dose)
Dexamethasone is what with other antiemetics?
synergistic
Most potent D2-blockers? (2) (dopamine antagonists)
concerns?
Droperidol
Haloperidol
qTc prolongation and torsades
D2 blocker side effects:
Dysphoria
Hypotension
EPS (tardive dyskinesia: Parkinson like symptoms. If used for too long, these can become permenant)
Phenothiazines?
what class?
what metabolism?
the “-zines”
D2-receptor antagonist
hepatic
what drugs are highly sedating compared to Haldol/droperidol?
side effects?
Phenothiazines
EPS
H1 antagonists:
Dimenhydrinate (Dramamine)
Vistaril
benadryl
What can compound opiate constipation?
H1 antagonists
anticholinergic med?
Scopolamine
Neurokinin 1 Receptor Antagonist
used for?
effects?
Aprepitant
Chemo induced n/v
substance P
metoclopramide actions:
- Increase L.E.S. tone. (Lower esophageal sphincter)
- Enhance peristalsis
- Accelerates gastric emptying.
Dopamine antagonist
metoclopramide metabolism
- hepatic with extensive first-pass effect
- renal - impairment prolongs so need dose adjustment
- crosses BBB and placenta
- excreted in breast milk
metoclopromide side effects
Abdominal cramping with rapid I.V. administration (< 3 minutes). **
Akathesia can occur with preoperative I.V. administration.
- Feeling of unease. But don’t show movement
- Restlessness in the lower extremities. Very extreme, need to move so bad or something bad will happen
Dystonic extrapyramidal reactions (oculogyric crisis, opisthotonus, trismus, torticollis) <1% of patients.
- Chronic oral treatment.
- Oral doses 40 to 80 mg/day.
Metoclopramide: Interactions and Cautions
May prolong the activity of succinylcholine and mivacurium.*
May slow metabolism of ester anesthetics.
May increase the sedative actions of CNS depressants.
May increase the extrapyramidal reactions caused by certain drugs.
- Avoid administering in combination with:
- Phenothiazines or butyrophenones.
Avoid administration to:
- Patients with a history of seizures or preexisting extrapyramidal symptoms.
- Patients with mechanical gastric outlet obstruction
how does reglan help with aspiration risks
Preoperative decrease of gastric fluid volume.
-10 to 20 mg I.V. over 3 to 5 minutes administered 15 to 30 minutes before the induction of anesthesia.
h2 Receptor antagonists
The “-tidines”
H-2 Receptor Antagonists: Inhibition of ________ binding to the receptors on gastric ________ cells
histamine
parietal (ATP driven so lets less H+ ions in when blocked)
Look at slide 45
.
What to do with patients undergoing procedures associated with an increased likelihood of allergic reactions?
Administer orally an H1 antagonist (diphenhydramine 0.5-1 mg/kg) and H2 antagonist (cimetidine 4mg/kg) q. 6 hrs. 12-24 hours prior.
a specific side effect for h2 antagonists?
thrombocytopenia (decreased platelets)
only drug that effects lower esophageal sphincter tone?
metoclopramide
look at slide 48
.
drug interactions of other drugs with h2 blockers?
cimetidine and rinitidine - INHIBITS P-450 slowing metabolism of drug causing toxicity
h2 blockers alter absorption of some drugs by _______ the gastric fluid pH. decreases absorption of what? give what with it to increase absorption?
increasing
magnesium, b12, ketoconazole, iron products, calcium carbonate
vitamin C
When to administer PPI?
3 hours pre-surgery
pantoprazole and rinitidine combo can be given 1 hour prior
adverse effects of PPI
C.difficile diarrhea (secondary to acid depressant)
Kidney injury
Dementia
Reduced absorption
Acts as surfactant, changes water gradient to pull more water into stool – doesn’t help with motility
stool softeners, aka - colace, docusate
change water flow gradient far greater than stool softeners and some contraction increase
Osmotic Laxatives: Miralax (polyethylene glycol 3350), Magnesium (hydroxide, citrate), Glycerin, Fleets enema (sodium phosphate), Lactulose
look at slide 56-57
.
constipation regiment
Senna S first, then add miralax, then add 5HT4 agonist
