PONV Flashcards
When does PONV peak PONV and persist
Peaks 6 hours postop
Persists 24-48 hours
Risk Factors for Adults PONV: Patient Specific (6)
*Female
*Non-smokers
*History of PONV
*History of motion sickness
Delayed gastric emptying
Preoperative anxiety
Risk factors for Adults PONV: Anesthesia/PACU (8)
Volatiles
Nitrous oxide >50%
*Intra/Postop opioids
Neostigmine
Preanesthetic medication
Gastric distention
Duration of anesthesia
Mandatory po fluids before discharge
Risk Factors for Adults PONV: Surgical Factors
Longer duration of surgery
High-risk surgery;
Laparoscopy
Ear, nose, throat surgery
Neurosurgery
Laparotomy
Breast, strabismus, or plastic surgery
Risk factors for peds PONV
Increases with age until puberty
Male = female
Vomiting 2x adults
Specific pediatric procedures;
-Adenotonsillectomy
-Strabismus repair
-Hernia repair
-Orchiopexy
-Penile surgery
Strategies to reduce risk of PONV
Regional anesthesia
Propofol for induction and maintenance
Intraoperative supplemental O2
Adequate hydration
Avoid nitrous
Avoid volatiles
Minimize opioids
Minimize neostigmine
Minimize mandatory motion and early ambulation
Emetic Center location
Located in lateral reticular formation of brainstem
No substances act directly on the emetic center
Incoming stimuli to the emetic center come from where? (4)
(afferent input)
Pharynx
GI tract
Mediastinum
Afferent nerves from higher brain centers
Afferent nerves from higher brain centers that cause PONV (2)
CTZ (chemotrigger tactic zone) from area postrema
Vestibular portion of 8th CN (auditory nerve-> inbalance)
Chemoreceptor Trigger Zone features and receptors
Has no BBB
Chemicals, drugs in blood or CSF can trigger
Receptors;
Dopamine
Serotonin (5-HT3)
Opioid
Histamine
Muscarinic
Neurokinin-1?
Cannabinoid?
Data on management of PONV
No single drug is gold standard
Patients should not receive the same drug for prophylaxis and treatment
Work on identifying and preventing as treating is +/- effective
Preoperative Prevention of PONV
Opioid premedication ↑ risk
BZD may ↓
Induction prevention of PONV
Volatiles, ketamine, etomidate ↑ risk
Propofol ↓…short duration; better if used induction and maintainence
nitrous and PONV
Associated with PONV
50% and greater
Opioid avoidance and PONV
Single dose of morphine associated with…
Regional nerve blocks, high dose acetaminophen, wound infiltration
Nursing protocols for PONV
Forcing position changes
Forcing ambulation/early po fluids
Reversal of NMBD and PONV
Anticholinesterases: muscarinic actions on GI
Dose related (> 2.5mg of neostigmine-> PONV)
Atropine reduces PONV (give instead of robinol w/ neostigmine)
Give NMBD that aren’t reversed
Apfel score
Predictors: female, hx, postop opioids, nonsmoker
Identified high risk procedures: breast, dental, ENT, lap BTL
0 risk factors: 10%
1 risk factor: 20%
2 risk factors: 39% *** prophylaxis indicated
3 risk factors: 60 %
4 risk factors: 79%
Low risk surgery with Low risk of medical sequela treatment for PONV
5Ht3 antagonsit
Low risk of PONV with High risk of medical sequela PONV prevention and treatment
Prophylaxis; 5HT3
treatment; phenothiazine
antihistamine
metroclopramide
Moderate risk for PONV and any risk of medical sequela Prevention and treatment of PONV
Prophylaxis; 5HT3 & Steroid
Treatment; Phenothiazine, antihistamine, metroclopramide
History of PONV with any risk of medical sequela PONV prevention and treatment
Prophylaxis; 5HT3, steroid, Propofol TIVA, Scop
Treatment; Phenothiazine, antihistamine, metroclopramide
Acupuncture and Acupressure MOA
P 6 stimulation
Results in hypophyseal secretion of beta-endorphins -> And subsequent inhibition of CTZ
Decreases acid secretion
Better at inhibiting nausea than vomiting
Anti-dopaminergics Subtypes
Butyrophenones
Phenothiazines
Anti-dopaminergics MOA
Receptor antagonists are anti-emetic
Also antipsychotic and neuroleptic
Anti-dopaminergics Side effects
Can cause drowsiness, sedation, EPS effects
Butyrophenones drugs
Haloperidol
Droperidol
Haloperidol PONV characteristics
Not really approved for PONV
Not approved for IV use
Droperidol (inapsine) PONV characteristics/ dose/ side effects and adjuncts
never > 0.625 mg
As effective as Ondansetron 4mg
With metoclopramide 10mg more effective
Weak alpha blocker…hypotension
Black box: torsades de pointes and sudden death
Phenothiazines Drugs
Prochlorperazine (Compazine)
Chlorpromazine (thorazine)
Promethazine (Phenergan)
Torsades characteristics
type of polymorphic v tach (coming from different places) -> qrs is different (up and down)
Qt is long and being twisted around the horizontal axis
Polymorphic v tach from MI treatment
Lidocaine
procaindamide
Torsades treatment
Isoproterenol (speed up atrial rate and over drive the qrs)
Magnesium
Promethazine PONV characteristics/ dose/ side effects
Also antagonizes alpha adrenergic, histamine, muscarinic cholinergic receptors
Sedation, hypotension, EPS
12.5-25 mg
Black box: tissue damage; respiratory arrest < 2 y/0
5HT3 antagonists MOA
Antagonize serotonin
On vagal nerve and CTZ
Side effects of 5HT3 antagonists
Side effects HA, constipation, mild elevation in liver enzymes
Examples of 5HT3
Dolasetron (Anzemet)
Granisetron (Kytril)
Ondansetron (Zofran)
Palonosetron
Ondansetron (zofran) dose
4mg within 15-20 of surgery end; data unclear on 4mg vs. 8mg
Scopalamine dose and placement
1.5 mg transdermal patch; leave in place 48-72 hours
placement; upper chest, upper outer arm, lower abdomen, hip
Scopolamine MOA
blocks ach
Scopolamine SE
Causes drowsiness, dry mouth, dizziness
Care with handling
Dexamethasone on PONV and dose
Decrease postop pain and edema
Anti-inflammatory reaction
No adverse side effects
Not useful for rescue
Glycemic effect?
Dose: 4mg as effective as 8mg
Given during/just after induction
Gastrokinetics drugs
Metoclopromide (Reglan)
Metoclopromide (Reglan) effect
Increases LES tone and GI motility
Less efficacious than droperidol
Metoclopromide (Reglan) dose and SE
½ of studies indistinguishable from saline
Restlessness, EPS
Dose: 10-20mg IV
Short ½ life…dosing closer to the end of surgery
NK-1 antagonists drugs for PONV
Aprepitant
NK-1 antagonists MOA
Antagonize Substance P in the emetic center;
Depress neural activity of the nucleus tractus solitarius
May also interfere with afferent messages from enterochromaffin cells
Dose, effects and when to give for Aprepitant
Dose 40mg or 125 mg
Greater anti-vomiting than anti-nausea
Given 2-3 hours prior to induction
Propofol MOA on PONV
Blocks serotonin release at 5HT3 receptors
In subhypnotic doses
May also inhibit CTz
Propofol for PONV dose
Dose 16.7 mcg/kg/min (subhypnotic) or TIVA dose
What to give with prop for PONV for associated bradycardia
Glycopyrrolate
Prehydration to prevent PONV
Adequate pre-hydration
10-30 ml/kg
Isopropyl Alcohol on PONV
Isopropyl alcohol: 50% reduction in nausea
Chewing gum on PONV
Potential improvement in nausea; stimulates motility
What else could cause PONV (5)
Hypotension
Hypoxemia
Elevated ICP
Gastric bleeding
Hypoglycemia
