Antiemetics/Aspiration Prophylaxis Flashcards
What is PONV?
- postop nausea/vomiting
- N/V within 24 hours of surgery
What are the highest complaints and leading cause of unanticipated hospital admission after outpatient surgery?
- pain
- PONV
PONV occurs in _____% of patients without prophylaxis after general anesthesia
40%
PONV occurs in _____% of HIGH RISK patients without prophylaxis
80%
What are some patient risk factors for PONV?
- female (strongest indicator)
- nonsmoker
- hx of PONV or motion sickness
What are some surgical risk factors for PONV?
- longer procedures
- GYN procedures
- larparoscopic procedures
- ENT procedures
- breast/plastics procedures
What are anesthetic risk factors for PONV?
- inhalational agents
- nitrous (esp in women under 35yo)
- neostigmine
- opioids
What is the difference in PONV between kids and adults?
- kids: weak association with age
- adults: risk decreases with age
What is the greatest association to PONV in children?
the surgical procedure
- hernia; tonsils/adenoids; strabismus sx; male genitalia
What factors is PONV associated with?
- dehydration
- electrolyte imbalance
- wound dehiscence
- bleeding
- airway compliance
- UNPLANNED ADMISSIONS
- PATIENT DISCOMFORT
What type of approach should we consider when preventing PONV?
multimodal approach
When is scopalamine used?
- prevent motion induced nausea
- PONV
- trauma patients
- motion sickness from simulation of vestibular apparatus
What agents increase vestibular sensitivity to motion?
- opioids
- morphine
How is scopalamine administered?
transdermally
What are the effects of administering scopalamine transdermally?
- sustained plasma concentration
- less sedation
- drying of secretions
- cycloplegia (paralysis of ciliary muscle of the eye; dilation of pupil and paralysis of accommodation)
What is cycloplegia and what agent cause produce this as a side effect?
- paralysis of ciliary muscle of the eye; dilation of the pupil and paralysis of accommodation
- transdermal scopalamine can cause this
What is the mechanism of action of ondansetron?
selective 5-HT3 receptor antagonist in the GI tract and chemoreceptor trigger zone
When is ondansetron used?
- preventative and rescue treatment for N/V; used in chemo
- lots of debate on when to give it
What are some side effects of ondansetron?
- headaches
- diarrhea
Ondansetron Dosing
4 mg IV
Ondansetron duration
4-6 hours
What is a potential cardiac effect with ondansetron?
prolonged QT interval (can lead to torsades)
How is ondansetron extensively metabolized?
hepatic metabolism
T/F: ondansetron use in OB is questionable
true
What is dexamethasone used for?
- N/V prevention
- ENT
- traumatic intubations
- lower surgical inflammation
What class of drug is dexamethasone?
corticosteroid
What are the side effects of dexamethasone?
- gential itching/burning (give to patient while asleep, not awake!!)
- hyperglycemia (however new studies say no)
Careful use with dexamethasone in ________ because of hyperglycemia
diabetics
- they can potentially have wound healing issues
Dexamethesone Dosing
4 - 12 mg on induction
Dexamethasone duration
24 hours
Dexamethasone can be used in combination with ____________
antiemetics
What is the mechanism of action of dexamethasone?
- mechanism is actually unclear
- may centrally inhibit prostaglandin synthesis and control endorphin release
What is the trade name of ondansetron?
Zofran
What is the trade name of dexamethasone?
Decadron
What is the trade name of promethazine?
Phenergan
Which antiemetic is no longer on US formulary?
IV phenergan (promethazine)
What is promethazine used for?
- N/V
- anxiety
What are the side effects of promethazine?
- sedation
- potentiates sedative effects of benzos and opioids (C section)
- hypotension
- extrapyramidal symptoms (Akathisia)
Promethazine Dosing
12.5 - 25 mg IV
- DILUTED and given SLOWLY
Promethazine onset and duration
Onset: 3-5 min
Duration: 4-6 hours
Promethazine is considered a ___________________ due to sedation potential
first-generation H1 receptor antagonist
What class is promethazine under?
- phenothiazine
What are the mechanisms of action of promethazine?
- H1 receptor antagonist (antihistamine)
- anticholinergic action (motion sickness)
- D2 antagonist in chemoreceptor trigger zone
What two factors are associated with pulmonary complications of aspiration?
- volume of gastric acid contents
- acidity of aspirated gastric contents
What is the trade name of metoclopramide?
Reglan
Metoclopramide is considered a gastrointestinal ____________
gastrointestinal prokinetic
How does metoclopramide work?
- increases LES tone
- enhances repsonse to ACh in upper GI tract to enhance gastric motility and accelerate gastric emptying, thus reducing gastric volume
Where does the antiemetic action of metoclopramide come from?
antagonism dopamine-agonist effects in the chemoreceptor trigger zone
What action does metaclopramide have on the CNS?
inhibition of dopamine receptors within the CNS (crosses the BBB)
What are the side effects of metaclopramide?
- sedation
- restlessness
- extrapyramidal symptoms (tardive dyskinesia)
When is metaclopramide contraindicated?
- bowel obstruction
- Parkinson’s disease
- restless let syndrome
- movement dysorders related to dopamine inhibition or depletion
What is metaclopramide used for?
- preop for aspiration prophylaxis
- treatment of diabetic gastroparesis
- GERD
- OB
T/F: Metaclopramide alters gastric fluid pH
false
- metaclopramide does NOT alter gastric fluid pH
Metaclopramide Dosing
5-10 mg IV in preop
Metaclopramide onset and duration
Onset: 1-3 min
Duration: 1-2 hours
Metaclopramide has potential for _____________ syndrome
Neuroleptic Malignant Syndrome
What is neuroleptic malignant syndrome?
How is neuroletpic malignant syndrome treated?
What other syndrome is neuroleptic malignant syndrome similar to?
What are the five hyperthermic toxidromes that can occur in anesthesia?
- sympathomimetic
- anticholinergic
- serotonin syndrome
- neuroleptic malignant
- malignant hyperthermia
What drug class does famotidine fall under?
H2 receptor antagonist
What is the trade name of famotidine?
Pepcid
How does famotidine work?
- inhibits gastric acid secretion/fluid volume
- raises gastric pH
Why would famotidine be given in anesthesia?
given in preop to decrease risk of pulmonary aspiration in risk patients
Famotidine Dose
20 mg IV
Famotidine onset
Onset: 30 min - 1 hour
What is the trade name of hydroxyzine?
Vistaril
What is the mechanism of action of hydroxyzine?
- blocks ACh in the vestibular apparatus
- blocks H1 receptors in the solitary tract
What drug class does hydroxyzine fall under?
antihistamine
When is hydroxyzine used?
- PONV
- pruritus (pregnancy)
- antianxiety
What are the side effects of hydroxyzine?
- sedation
- pain on injection
Hydroxyzine Dosing
- 25 mg IV mixed with Ephedrine
- 25 mg IM 20 min before the end of surgery
What cases should we be careful in with hydroxyzine use?
hypertension
T/F: there is a current national shortage of hydroxyzine
true
