GI System Flashcards
For surgical patients, is there ever a chance for zero PONV
No
Define retching
rhythmic action of respiratory muscles preceding vomiting
Define Nausea
SUBJECTIVE personal patient experience with or without associated vomiting
The Vomiting Center is located where
Lateral reticular formation within the medulla oblongata
What two regions located near the vomiting center, once stimulated will initiate vomiting
Nucleus solitarius
Chemoreceptor Trigger Zone (located in the areas postrema near the bottom of the 4th ventricle)
What factors stimulate the vomitng center
Peripheral stimulation (sensory afferents of vagal nerve to VC)
CNS (directly relay to CTZ, AP, and NTS)
Chemicals in the CNS/Blood (directly stimulate VC)
What are the five CNS areas that are located near the VC and what are the physiological reactions associated with N/V
Balance center (motion sickness) Vasomotor center (diaphoresis, pallor, tachycardia, cardiac dysrhythmias) Salivation center Respiratory center (tachypnea) Bulbar controls (cerebellum, medulla, and pons)
True/False
Although the CTZ, AP, and NTS contain receptors for vomiting, the vomiting reflex is INITIATED from within the vomiting center
True
What receptor population live withing the CTZ
Dopamine (D2)
Opioid
Enkephalin
What receptor population live within the AP
Dopamine
Opioid
Serotonin (5-HT)
What receptro population live within the NTS
Histamine
Enkephalin
Muscarinic
What physiologic state is a potent emetic stimulus
Blood in the stomach
Between 2-14, incidence of PONV increases or decreases
increases
After 14 yoa, incidence of PONV increases or decreases
decreases
What anesthetic agents increase PONV
Neostigmine Etomidate Methohexital Opioids Ketamine NITROUS OXIDE All HALOGENATD AGENTS
What scoring system is used when a patient is at increased risk for PONV
Apfel scoring system
What four risk factors does the apfel scoring system assess
PONV
Use of Postop opioids
Female gender
Nonsmoker
If a patient has zero factors on apfel, what is the incidence of PONV
10%
If a patient has all four factors on apfel, what is the incidence of PONV
79%
If a paitent has 2 factors on apfel, what is the incidence of PONV
39%
*up/down by 20% from here
- What receptors can I stimulate to decrease PONV
Muscarinic (M3, M5)
Dopaminergic (D2)
Histamine (H1)
Serotonin (5-HT)
What antimuscarinic drug does not cross the bbb and therefore, cannot be used to treat vomiting
Glycopyrollate
Sucralfate is classified as an
anti-ulcer agent
“prazoles” are
proton pump inhibitors
Inhibition of acid production continues how long after administration of prazoles
up to 72 hours
*may not need to give to patient if taken within this time period prior to surgery
Misoprostol is used in OB to
induce labor
Misoprostal is contraindicated
during pregnancy
What is the MOA of metaclopramide
increases LES spincter tone
increases gastric emptying
decreases gastric volume
*centrally acts as a dopaminergic antagonist resulting in antiemetic properties
What are the precautions associated with metaclopramide
Contraindicated in intestinal obstruction or pheochromocytoma
Avoid in patient’s with parkinson’s
May cause tardive dyskinesia
Cisapride is a
prokinetic
What are the two anti-emetics discussed in lecture
Metoclopramide Droperidol (potent)
True/false
Droperidol is a neuroleptic tranquilizer
true
Peripherally, droperidol acts as a
alpha-adrenergic blocker
*decreases ABP
Droperidol has what effect on patient’s with pheochromocytoma
stimulate the release of catecholamines from the adrenal medulla precipitating a HTN crisis
What effect does Droperidol have on cerebral blood flow/ICP
decreases
*Does not decrease CMRO2, problem for pts with CVS disease
Droperidol has antidopaminergic activity and therefore can precipitate
extrapyramidal reactions
*dont use in patient’s with parkinsons
What drugs is countered by droperidol
dopamine
central a-adrenergic agonists
What is the “Black Box” warning on droperidol
may cause QT prolongation/torsades de points leading to potentially fatal rhthyms
- use only patients refractory to other anti-emetics. Must monitor EKG
Ondansetron works on what receptor type
selective 5-HT3
*does not effect alpha, dopamine, or histamine receptors
The phenothiazine hydroxyzine should ONLY be given
IM
*never IV
Phenothizaines examples include promethazine, prochlorperazine, and hydroxyzine and involve many reactions including:
sedative-tranquilizer antiemetic antihistamine/antipuritic adrenolytic anticholinergic extrapyramidal activity Potentiator of anesthetics
Phenothiazines may cause what syndrome
Neuroleptic Malignant Syndrome
*Fever, muscle ridgidity, AMS, autonomic dysfunction, leukocytosis, elevated CPK
Excess Fe is stored as
Ferritin
What is the ONLY clinical indication for the use of iron
Treating iron deficiency anemia
Iron sodium gluconate complex is given
ONLY IV
What is the Gold standard treatment for acute iron toxicity
Deferoxamine
*activated charcoal DOES NOT work
What is the central atom in vitamin b12
COBALT
Without vitamin b12, what two ESSENTIAL enzymatic rxn couldn’t occur
methyltetrahydrofolate to tetrahydrofolate (folate)
methylmalonyl-CoA to succinyl-CoA
