Induction Agents Flashcards
Pretreatment with what medication can decrease etomidate-induced myoclonus?
Opioids or benzos (fast onset, not diazepam)
Prolonged infusions of what induction agent increases mortality in ICU patients?
Etomidate (likely secondary to adrenal suppression)
Effects of ketamine on the heart
Increased sympathetics (increased HR, CO, SV) which masks the direct myocardial depression associated with large doses of ketamine
Pretreatment with what medication can decreased ketamine-induced psychotomimetic effects?
Benzos
Mixing which induction agent and opioids or LR can cause precipitation?
Thiopental
Mechanism of action for thiopental?
Enhances action (increased duration) of GABA action at GABA-A receptor
Induction dose for thiopental
3-5mg/kg
What is the primary mechanism for prompt awakening after induction dose of thiopental?
Redistribution
Treatment of intra-arterial injection of thiopental
Dilution with NS + vasomotor relaxation (lidocaine, papaverine, or phenoxybenzamine) with sympathectomy (i.e. stellate ganglion block) if meds are ineffective
When do you worry about propofol infusion syndrome?
ICU patients, usually pediatric patients, when propofol used at 150-200 mcg/kg/min for hours to days
Signs and symptoms of propofol infusion syndrome?
Progressive bradyarrhythmias, metabolic acidosis, cardiac arrest
How does propofol work?
Stimulates GABA-A receptors
Does propofol injection affect NMB?
Increases depth but not duration
How is etomidate metabolized?
Ester hydrolysis (plasma and hepatic)
How is etomidate excreted?
Inactive metabolites renally
Induction dose of etomidate
0.3 mg/kg
Etomidate has what EEG changes?
Can cause epileptiform activity and thus avoided with patients with seizures
Which induction agents do not cause cardio depression?
Etomidate and Ketamine
Which induction agents decrease ICP?
Propofol, thiopental, and etomidate
Which induction agents do not cause respiratory depression?
Etomidate, Ketamine, Midazolam
Which induction agents provide analgesia?
Ketamine
Which induction agents cause porphyria?
Thiopental and etomidate
Which induction agents cause bronchorelaxation?
Ketamine
Which induction agents cause myoclonus?
Etomidate
How does etomidate cause adrenal suppression?
Inhibits 11-beta-hydroxylase which decreases aldosterone and cortisol synthesis
Which induction agents cause significant N/V?
Etomidate
Which induction agents can cause post-op hiccups and sense of restlessness?
Etomidate
Mechanism of action for ketamine
Non-competitive antagonism at NMDA receptors; also has local anesthetic properties; can bind mu-delta-kappa receptors, inhibits reuptake of epi, dopamine, serotonin, NE; blocks Ach receptors (anti-cholinergic symptoms)
What neurotransmitter pairs with NMDA receptors?
Glutamine (excitatory)
Which induction agent increases cerebral blood flow and ICP
Ketamine
What receptor does barbiturates, benzos, and propofol target?
GABA-A receptors
How do you approach patients who are allergic to egg and need propofol?
Most patients are allergic to egg albumin (egg whites) and not egg lecithin (yolk - what propofol is used in)
What does it mean to be a more potent drug? A more efficacious drug?
More potent: same effect achieved by a lower dose
More efficacious: same dose gives a lesser effect
Blood is sampled from the hepatic vein. Which would have the lowest concentration compared to central blood: propofol, fentanyl, midazolam, etomidate, esmolol
Propofol: completely metabolized by the liver on a single pass
Midazolam, fentanyl and etomidate are only partially metabolized on a single pass
Esmolol is metabolized by RBC esterases
A drug is highly protein bound but the patient has low levels of protein. Compared to normal protein levels, the drug would be: less efficacious, more potent, higher ED50, cleared slowly
More potent (more in the free/active form)
ED50: dose at which 50% of patients respond - this would decrease in this case (lower dose for the same response)
Which of the following does not work through a G-protein coupled receptor: Fentanyl, midazolam, epinephrine, serotonin, histamine
Midazolam (GABA-A which is a ligand-gated ion channel); the rest work through GPCR (through cAMP or IP3)
What is the largest extrahepatic site of metabolism for propofol?
The lungs
How is fospropofol different from propofol?
Prodrug of propofol that needs to get metabolized in the liver to become propofol and formaldehyde; thus it has a slower onset of action
Which of the following does not have an active metabolite: midazolam, propofol, meperidine, ketamine, morphine
Propofol
Midazolam -> alpha-1-hydroxymidazolam
Meperidine -> normeperidine (CNS excitation in renal failure)
Ketamine -> norketamine
Morphine -> M6G
