PONV Flashcards
(80 cards)
1
Q
Define nausea.
A
Subjectively unpleasant sensation in the epigastrium and throat associated with the urge to vomit
2
Q
Define vomiting.
A
Forceful expulsion of upper GI contents through the mouth caused by powerful sustained contraction of the abdominal muscles
3
Q
Define retching.
A
Labored rhythmic activity of the respiratory muscles, including the abdominal muscles and diaphragm, without expulsion of gastric contents
4
Q
What is the role of the chemoreceptor trigger zone?
A
Involved in the pathophysiology of emesis
5
Q
What is the emetic center?
A
Area in the brain that coordinates the vomiting reflex
6
Q
What factors contribute to PONV?
A
Patient-specific, surgery-related, anesthetic-related, postoperative factors
7
Q
What is the incidence of PONV in gynecologic surgery?
A
65%
8
Q
What is the incidence of PONV for laparoscopic cholecystectomy?
A
40% to 77%
9
Q
Name a surgery-related factor that increases PONV.
A
Type of surgery
10
Q
What are the effects of benzodiazepines on PONV?
A
Decrease PONV
11
Q
Fill in the blank: The incidence of PONV is _______ with general anesthesia.
A
25% to 30%
12
Q
What are some consequences of PONV?
A
- Patient discomfort
- Decreased ability to care for oneself
- Increased cost
- Unplanned admissions
- Wound dehiscence/bleeding
- Aspiration pneumonitis
- Dehydration and electrolyte imbalance
13
Q
How does uncontrolled pain affect PONV?
A
Increases PONV after conventional surgery
14
Q
What is the effect of early ambulation on PONV?
A
Decreases PONV after laparoscopic surgery
15
Q
What is the recommended prophylactic antiemetic for patients with a history of PONV?
A
Anticholinergic Scopolamine
16
Q
What are 5-HT3 receptor antagonists used for?
A
Treatment of PONV
17
Q
What are common side effects of 5-HT3 receptor antagonists?
A
- Headache
- Dizziness
- Constipation
18
Q
True or False: Droperidol has a Black Box Warning.
A
True
19
Q
What is the elimination half-life of droperidol?
A
About 100 minutes
20
Q
What is the function of NK-1 antagonists?
A
Block Substance P in the CNS
21
Q
What is Scuderi’s Multimodal Therapy?
A
Combination of anxiolysis, three prophylactic anti-emetics, TIVA, and vigorous hydration
22
Q
Fill in the blank: The common metabolic pathway for 5-HT3 receptor antagonists is through _______.
A
Cytochrome P450 system
23
Q
What patient populations are more likely to be ultrarapid metabolizers of CYP2D6?
A
- Northern European countries: 2%-4%
- Mediterranean area: 7%-12%
- Ethiopia: 29%
- Saudi Arabia: 21%
24
Q
What is a common issue with PONV prophylaxis?
A
Some patients fail prophylaxis with 5-HT3 drugs due to human variability
25
What is the primary concern with using droperidol?
Serious proarrhythmic effects and death
26
What is the role of the vagus nerve in emesis?
Transmits signals related to nausea and vomiting
27
Patient-Related Factors
Age, sex, hx of PONV/motion sickness, obesity, nonsmoking status, anxiety, decreased gastric motility/emptying
28
Patient Factors: Age
within pediatric population increase in incidence through pre-adolescence
29
Patient Factors: Sex
women 2-3 times more likely to have PONV (4x increase during menses)
30
Patient Factors: Obesity
BMI > 30 kg/m2 (fat is a reservoir for anesthetic agents)
31
Surgeries that promote PONV
Gonadal/Reproductive
Abdominal
Oculo-gyric
Pharyngeal
32
Premedication
-Benzodiazepines decrease PONV
-Opioid analgesics stimulate the CTZ
-NSAIDs help decrease opioid use
33
PONV & Anesthesia Type
-General > major regional > peripheral regional
-Inhalational agents > propofol-based
34
PONV & Duration of anesthetic exposure
60%/30 minutes
35
PONV & Postop Factors
-Uncontrolled pain, esp visceral/pelvic pain
-Opioid administration
-Dehydration (adequate IV fluid hydration can decrease PONV)
-Early ambulation/patient handling
-Early oral intake
36
PONV & Early Oral Intake
-Increases PONV after conventional surgery
-Decreases PONV after laparoscopic surgery
37
Incidence of PONV with general anesthesia
25% to 30%
38
Incidence of PONV with high risk procedures using emetogenic anesthetics (narcotics, desflurane)
Up to 80%
39
Prophylactic Antiemetic:
Categories that get 3 Points
* History of PONV
* History of motion sickness
* Gynecologic laparoscopy
* Breast reconstruction
40
Prophylactic Antiemetic:
Categories that get 2 Points
* Facelift surgery
* Strabismus or middle ear surgery
* Neurosurgery
* Obesity
41
Prophylactic Antiemetic:
Categories that get 1 Points
* Preadolescent
* Laparoscopic cholecystectomy
* Female
*Intra/postop opioid
* Anxiety
* Duration of anesthesia > 60 min
42
Prophylactic Antiemetic is Indicated if you have how many points
3 or More Points
43
When patients do not respond to initial antiemetic therapy
adding an antiemetic agent from another pharmacologic class (a selective serotonin antagonist plus the dopamine receptor antagonist droperidol) is recommended.
44
Antiemetic Drug Classes: Anticholinergics
Ex: Scopolamine
Mechanism: Blocks muscarinic (M1) receptors in the vestibular system and CNS
45
Antiemetic Drug Classes: Antihistamines
Ex: Dimenhydrinate, Diphenhydramine, Hydroxyzine
Mechanism: Blocks histamine H1 receptors and has anticholinergic properties
46
Antiemetic Drug Classes: Benzamide
Ex: Metoclopramide
Mechanism: Blocks dopamine D2 receptors (& some 5-HT3 at higher doses); prokinetic
47
Antiemetic Drug Classes: Butyrophenones
Ex: Droperidol, Haloperidol
Mechanism: Potent dopamine D2 receptor antagonists in the CTZ
48
Antiemetic Drug Classes: 5-HT₃ Receptor Antagonists
Ex: Ondansetron, Granisetron, Dolasetron
Mechanism: Blocks serotonin (5-HT3) receptors in the GI tract and brain (CTZ).
49
Antiemetic Drug Classes: Phenothiazines
Ex: Promethazine, Prochlorperazine, Perphenazine
Mechanism: Blocks dopamine D2, H1, and muscarinic receptors.
50
Metoclopramide Bioavailability
Rapidly and completely absorbed after oral administration, but hepatic first pass effect reduces bioavailability to about 75%
51
Metoclopramide: Distribution
Distributed into most tissues and rapidly crosses the blood-brain-barrier and placenta
52
Metoclopramide: Half-life
Half life is 4-6 hours, up to 24 hours w impaired renal function
53
Metoclopramide: Side Effects
extrapyramidal symptoms and sedation
54
Butryophenones (droperidol): Elimination Half-life
about 100 minutes
55
Butryophenones (droperidol): Side Effects
extrapyramidal symptoms, hypotension, prolonged tiredness, dysphoria, anxiety & restlessness that develop after discharge
56
Butryophenones (droperidol): Doses as low as ____ have provided effects similar to ___of ondansetron
Doses as low as 0.625 mg have provided effects similar to 4 mg of ondansetron
57
Phenothiazines (promethazine and prochlorperazine) are most effective for tx
opioid associated PONV
58
Phenothiazines (promethazine and prochlorperazine): Side Effects
extrapyramidal symptoms and sedation
59
Droperidol Black Box Warning
Potential for serious proarrhythmic effects and death - INAPSINE reserved for use in pts who fail to show acceptable response to other txs, either because of insufficient effectiveness or the inability to achieve an effective dose due to intolerable adverse effects
60
Droperidol can cause _____, so all pts should undergo a _____
-QT prolongation and arrhythmias (torsades de pointes) have been reported
-all should undergo a 12-lead ECG prior to admin of INAPSINE to determine if a prolonged QT present ( QTc greater than 440 msec for M/450 msec for F)
-If prolonged QT, INAPSINE should NOT be administered.
61
Ondansetron, Granisetron, and dolasetron: Absorption
Readily absorbed after oral administration
62
Ondansetron, Granisetron, and dolasetron: Distribution
Rapid distribution to CNS
63
Ondansetron, Granisetron, and dolasetron: Metabolism & Elim
Metabolized via Cytochrome p450 system in the liver with elimination via the kidneys
64
Ondansetron, Granisetron, and dolasetron: Dose
Generally well tolerated & effective at low dose (ondansetron 1 mg/granisetron 100 mcg)
65
Ondansetron, Granisetron, and dolasetron: Side Effects
HA, dizziness, constipation
66
Ondansetron, Granisetron, and dolasetron: what effect similar to droperidol?
All have similar effects at high doses on cardiac conduction - only recognized in package inserts after Zofran introduction
- QT prolongation
67
______ is the only 1/14 serotonin receptors which is a ligand gated cation channel (nicotine/GABA)
5HT3 receptor
68
Why do some people fail prophylaxis with 5-HT3 drugs?
-Wrong basic mechanism attacked (serotonin from gut, not narcotics)
-Human variability
-Gene #/ type variations for primary enzyme CYP2D6 (genetic profile would correlate with PONV)
69
Metabolic Pathways: Ondansetron
-MAJOR: CYP2D6
-MINOR: CYP3A4, CYP1A2
-Metabolized primarily by CYP2D6 to inactive metabolites.
70
Metabolic Pathways: Dolasetron
-Carbonyl reductase (to active metabolite Hydrodolasetron)
-Then metabolized by CYP2D6 and CYP3A.
71
Metabolic Pathways: Granisetron
-CYP3A subfamily
72
CYP2D6 Genetic Polymorphism: Ultrarapid metabolizer phenotype
- Overactive CYP2D6 activity
- Reduced effectiveness of drug
-More N/V w standard doses of CYP2D6 metabolized 5-HT3 RAs
73
CYP2D6 Genetic Polymorphism (Ultrarapid metabolizer): Patient Populations
- Northern European = 2%–4%
- Mediterranean area = 7%–12%
- Ethiopia = 29%
- Saudi Arabia = 21%
74
Patient Populations with CYP2D6 Deficiency
- 5%–10% of whites
- Significant hepatic impairment
- Coadmin of potent inhibitors (quinidine, fluoxetine, or haloperidol)
75
CYP2D6 deficiency can result in
- Increased potential for drug interactions and SE
-May result in accum of CYP2D6 metabolized drugs and higher serum drug concentrations of CYP2D6 5-HT3
76
NK-1 Antagonists (Aprepitant) Uses
-Approved for CINV (chemo-induced N/V)
- Not FDA-approved for PONV
77
NK-1 Antagonists (Aprepitant) MOA
- Blocks action of substance P by preventing its binding to NK-1 receptors in the CNS
- Best in combo therapy (vs. as single agent) with 5HT-3 and steroids
78
Preoperative Anxiolysis Prevents
air swallowing ("air gulping"), which can contribute to nausea.
79
Triple Antiemetic Prophylaxis
-10 mg dexamethasone (steroid)
- 0.625 mg droperidol (dopamine antagonist)
- Low-dose 5-HT₃ antagonist (ondansetron)
- Plus gastric emptying support if indicated
80
Scuderi’s Multimodal Therapy
- preop anxiolysis to preventing air gulping
- 3 prophylactic anti-emetics + gastric emptying
-TIVA using propofol induction/infusion
- Non-lingering narcotics (remifentanil)
- NSAIDs in place of narcotics (ketorolac)
- NO nitrous oxide or potent inhaled anesthetics
- Avoidance of muscle relaxants/necessary reversal
- Vigorous hydration
