IV anesthetics Flashcards
What is Dexmedetomidine’s mechanism of action?
Alpha-2 agonist causing sedation, anxiolysis, analgesia, and cardiovascular sympatholysis.
How is Dexmedetomidine metabolized?
CYP450 and glucuronidation; NO active metabolites.
What are the uses of Dexmedetomidine?
Sedation (dose-dependent, even in non-intubated patients), analgesia, anxiolysis, reduces postoperative shivering and agitation, cardiovascular sympatholytic action.
What is the loading dose for Dexmedetomidine?
1 mcg/kg over 10 min.
What is the IV infusion dosage for Dexmedetomidine?
0.2-0.7 mcg/kg/hr (up to 24 hrs).
What is the onset time for Dexmedetomidine after loading dose?
10-20 min.
What is the duration of effect for Dexmedetomidine after stopping infusion?
10-30 min.
What are the CNS effects of Dexmedetomidine?
Easily arousable, does NOT interfere with EEG.
What are the cardiovascular effects of Dexmedetomidine?
Hypotension, bradycardia; transient hypertension with rapid initial loading dose or high maintenance dose.
What are the respiratory effects of Dexmedetomidine?
Does NOT cause respiratory depression; maintains airway reflexes.
What is a clinical note regarding Dexmedetomidine?
SPICE III Trial—not associated with reduced mortality in ICU patients.
What is Etomidate’s mechanism of action?
GABA modulator.
How is Etomidate metabolized?
Rapid hepatic metabolism via ester hydrolysis to INACTIVE metabolites; 10% excreted unchanged in urine.
What are the uses of Etomidate?
Induction of anesthesia (especially in cardiovascularly unstable patients), reduces ICP and CBF.
What is the dosage for Etomidate?
0.2-0.3 mg/kg IV.
What is the onset time for Etomidate?
30-60 sec.
What is the duration of effect for Etomidate?
5-15 min (due to redistribution).
What are the CNS effects of Etomidate?
Dose-dependent CNS depression, decreases CBF, CMRO2, ICP, and IOP.
What are the cardiovascular effects of Etomidate?
Minimal cardiorespiratory depression.
What are the respiratory effects of Etomidate?
Less respiratory depression than propofol.
What are the adverse effects of Etomidate?
Myoclonia (not seizures), pain on injection, thrombophlebitis, inhibition of adrenal steroidogenesis, nausea and vomiting.
What are the contraindications for Etomidate?
Adrenal suppression, porphyria, known hypersensitivity.
What is Ketamine’s mechanism of action?
NMDA receptor antagonist; blocks afferent pain signals to the thalamus and cortex.
How is Ketamine metabolized?
Liver CYP450, converted to norketamine (active metabolite), then glucuronidated for renal excretion.
What are the uses of Ketamine?
Induction of anesthesia in high-risk patients, OB and pediatric anesthesia, analgesia (enhances opioid-induced analgesia, prevents hyperalgesia), non-OR settings (burn units, ER, ICU, radiology procedures).
What is the induction dosage for Ketamine?
IV (2-4 mg/kg), IM (4-5 mg/kg), Oral (10 mg/kg).
What is the maintenance dosage for Ketamine?
IV infusion (10-45 mcg/kg/min), bolus 0.5-1 mg/kg as needed.
What is the onset time for Ketamine?
2-5 min.
30-60 sec
What is the duration of effect for Ketamine?
10-20 min.
What are the CNS effects of Ketamine?
Dissociative anesthesia (catalepsy, open eyes, nystagmus, intact corneal reflexes); causes emergence hallucinations (common in adults, not kids; treat with benzos or propofol); increases CBF, CMRO2, ICP, and IOP.
What are the cardiovascular effects of Ketamine?
Indirect sympathomimetic; increases BP, HR, CO, CVP.
What are the respiratory effects of Ketamine?
Potent bronchodilator, preserves airway reflexes.
What are the adverse effects of Ketamine?
Salivation, transient apnea with rapid administration.
What is Propofol’s mechanism of action?
GABA agonist—enhances GABA activity, hyperpolarizing postsynaptic membranes.
How is Propofol metabolized?
Rapid hepatic metabolism, redistribution terminates action. 1% excreted unchanged via kidneys.
What are the uses of Propofol?
Induction and maintenance of anesthesia, sedation for procedures, used in ECT, cardiac anesthesia, and status epilepticus.
What is the induction dosage for Propofol?
1-2 mg/kg IV.
What is the maintenance dosage for Propofol?
100-200 mcg/kg/min IV infusion.
What is the sedation dosage for Propofol?
25-75 mcg/kg/min IV infusion.
What is the onset time for Propofol?
10-50 Seconds.
What is the duration of effect for Propofol?
Short (rapid clearance).
What are the CNS effects of Propofol?
Decreases CBF, CMRO2, ICP, and IOP; EEG shows delta waves, burst suppression at high doses; provides cerebral protection.
What are the cardiovascular effects of Propofol?
Dose-dependent hypotension, reduced CO and SVR.
What are the respiratory effects of Propofol?
Significant dose-dependent respiratory depression, apnea.
What are the adverse effects of Propofol?
Pain on injection, risk of bacterial contamination; avoid in patients with soy, egg, or fat metabolism disorders; Propofol Infusion Syndrome (PRIS): metabolic acidosis, rhabdo, cardiac/renal failure with prolonged high-dose use (>48 hrs).
What is Midazolam’s mechanism of action?
Enhances GABA activity.
How is Midazolam metabolized?
Hepatic metabolism; effects terminated by redistribution.
What are the uses of Midazolam?
Preoperative anxiolysis, sedation, amnesia, anticonvulsant.
What is the dosage for Midazolam?
0.1-0.2 mg/kg IV.
What is the onset time for Midazolam?
30-60 secs - Rapid.
What is the duration of effect for Midazolam?
Short, 15-80 min
What are the CNS effects of Midazolam?
Dose-dependent depression, anticonvulsant, amnesia, muscle relaxation.
What are the cardiovascular effects of Midazolam?
Minimal effects, but may cause hypotension in elderly or cardiac patients.
What are the respiratory effects of Midazolam?
Dose-dependent respiratory depression. Most respiratory depressing among benzos.
What are the adverse effects of Midazolam?
Postoperative cognitive dysfunction (especially in elderly), synergistic depression with opioids.
What is the reversal agent for Midazolam?
Flumazenil (competitive antagonist), onset 1-2 min, duration 45-90 min.
