Antiemetic, Antihistimine, and Aspiration Prevention Flashcards
Risk factors for postoperative nausea and vomiting in adults
Patient specific:
Female gender
Nonsmoking status
History of PONV/motion sickness
Anesthetic risk factors:
Use of volatile agents
Nitrous oxide use
Use of intraoperative and postoperative opioids
Surgical risk factors:
Duration of surgery (every 30min increase in duration increases PONV 60% of baseline)
Type of surgery (laparoscopy, laparotomy, breast, stabismus, plastic surgery, maxillofacial, gynecological, abdominal, neurologic, opthalmologic, urologic)
Simplified PONV risk score for adults
Simplified POV risk score for children
What are strategies to reduce baseline risk of PONV
Antiemetic timing and dosing for prevention of PONV in adults
Algorithm for management of PONV
Stimulation of H1 receptors leads to what?
Contraction of intestinal smooth muscle
Contraction of H2 receptors leads to what?
Increases gastric acid (HCl) secretion from parietal cells
H2 blockers are used to treat what?
Duodenal and gastric ulcers
Zollinger ellison syndrome
GERD
IV - critically ill patients to prevent stress ulcer (stessulcer prophylaxis)
Reduce perioperative risk of aspiration pneumonia
Must administer day before surgery at bedtime as well as 2 hours prior to surgery (renal elimination)
H1 blockers are used to treat what?
Diphenhydramine (25 to 50 mg IV or PO, Lasts 4 to 6 hours)
Suppress allergic reactions (given with H2 blocker, blocks effects of histamine)
Suppress upper respiratory symptoms of allergic reactions
Vertigo
Motion sickness and other nausea and vomiting
Sedation
Cough suppression
Antimuscarinic effects (dystonic reactions of dopaminergic antagonists, decrease secretions)
Effects of H1 blockers in anesthesia?
Sedative effects
Antianxiety effects
Decreased GI motility
Antimuscarinic like effects
What do PPI do and what are the uses?
Pantoprazole, lansoprazole, omeprazole
- *They inhibit acid secretion** (Bind to the K+/H+ pump)
- Longer lasting effect ~ 24 hours, Slower onset
Uses: Duodenal ulcer, GERD, stress ulcer prophylaxis
Metoclopramide MOA, uses, and adverse effects?
Dopamine receptor agonist - CNS with some muscarinic effects
Increases LES tone, speeds gastric emptying time by increasing GI motility, anti nausea effect requires very HIGH doses, NO effect on acid secretion
Uses: primarily for diabetic patients with gastroparesis, some GERD, prokinetic effect in anesthesia (0.15mg/kg IV), antiemetic dose is 1-2mg/kg IV -> adverse effects:
Adverse effects: dopamine antagonism, extrapyramidal effects, acute dystonic reaction (Oculogyric crisis, Torticollis), akithisia -> Treat with an antimuscarinic (or diphenhydramine)
Rescue antiemetics
If N and V occur in PACU: administer antiemetic from different class of drug from what was used for prophylaxis (unless gave subtherapeuticdose)
What are the 5 neurotrasmitters that cause PONV, what are ways to treat it?
Location of neurological pathways involved in PONV
What are the central mechanisms behind PONV
Higher cortical signals being communicated by the central pattern generator (formerly called the vomiting center) in the medulla
Fear, pain, anxiety, conditioned nausea related to environmental cues, and stimulation of the vestibular system are central stimuli that may cause nausea and vomiting
What are the peripheral mechanisms behind PONV?
Trauma causing release of substance P and serotonin from enterochromaffin cells, thereby activating the vagal and splanchnic nerve 5-HT receptors
Vagal and splanchnic nerve afferents terminate in the nucleus tractussolitariusin the brain stem, near or within the area postrema(also called the chemoreceptor trigger zone)
-Bowel surgery and blood in the gastrointestinal tract from oral or ear, nose, and throat surgery may cause nausea and vomiting via this pathway
How do opioids/volatiles induce PONV?
Both opioids and inhalation anesthetics may cause nausea and vomiting by stimulation of the area postrema at the base of the fourth ventricle in the medulla.
The area postrema then communicates with the central pattern generator via dopamine and serotonin to trigger the vomiting reflex
5HT3 mechanism of action and uses? Adverse effects?
Selective for 5HT3 receptors located in GI tract (vagal afferents), and centrally (outside BBB)
Uses: especially useful for vagal stimulated PONV (chemo, postop), given towards end of procedure to help prevent vomiting
Adverse effects: lacks sedative effects, prolonged QT (avoid in patients at risk), may need to adjust in liver disease
Dexamethasone uses and risks?
Uncertain of the antiemetic effect, slower onset (4mg IV beginning of case)
Uses: antiemetic, decreasing ICP (4-12mg)
Adverse effects: impaired glucose tolerance (6-12 hours of rise after administration), risk for wound infection
Anticholinergic drug and adverse effects?
Scopolamine (IV or transdermal 1.5mg), apply several hours prior to surgery can be equally as effective as ondanestron
Adverse effects: dry mouth, blurry vision, older age maybe cognitive impairment
Other dopamine receptor antagonists (butryophenones)?
Droperidol (0.625 to 1.25 mg IV) and Haloperidol (1 mg IV or 1 mg PO, or 1 mg IM)
Droperidol adverse effects: QT prolongation (black box warning), not used in children, risk for arrhythmia torsades de pointe, most likely at higher dose – when used for neuroleptanesthesia
Perphenazine (5 mg IV)
Promethazine (6.25 to 12.5 mg IV)
Prochlorperazine (5 to 10 mg IV)
Neurokinin receptor antagonist MOA uses?
Substance P – neuropeptide that may mediate nausea and vomiting; central and peripheral
Antagonism of neurokinin-1 receptors - NK1 (peripherally and centrally)
Uses: reduce PONV
Aprepitant (80 mg PO)
