General Anesthetic Flashcards
What do general anesthetics do?
They depress the central nervous system to allow surgery and other procedures.
Why are general anesthetics considered dangerous?
They have a low therapeutic index, making them dangerous if not carefully administered.
What specialty has developed around the administration of general anesthetics?
The specialty of anesthesiology.
What are the stages of general anesthesia?
Unconsciousness, Amnesia, Analgesia, Inhibition of autonomic reflexes, Skeletal muscle relaxation.
What factors affect drug absorption across membranes?
High lipophilicity, Low ionization, Low protein binding.
What are the ligand-gated ion channels involved in general anesthesia?
GABA-A, Glycine, NMDA receptors.
What is the mechanism of action of barbiturates?
They enhance GABA-A, AMPA, and glutamate receptors.
What is the induction dose of Thiopental for adults?
3-5 mg/kg.
What is a significant advantage of Thiopental?
Minimal cardiovascular depression & cerebral protection.
What are the drawbacks of Methohexital?
Excitatory movements, pain on injection, predisposition to convulsions.
What are absolute contraindications for barbiturates?
Porphyria, Proven allergy to barbiturates, Airway obstruction, History of epilepsy.
What is the induction dose of Etomidate for adults?
0.3 mg/kg.
What are the advantages of Etomidate?
Cardiostability, No histamine release, Minimal cardiovascular effects.
What is the mechanism of action of Propofol?
Direct GABA-A receptor agonist.
What is a common side effect of Propofol?
Pain on injection.
What is Propofol Infusion Syndrome (PRIS)?
Associated with prolonged high-dose infusions, featuring cardiac failure, rhabdomyolysis, and severe metabolic acidosis.
What is the onset of action for Fospropofol?
2-28 minutes.
What is the mechanism of action of Ketamine?
NMDA blocker.
What is the induction dose of Ketamine for anesthesia?
2 mg/kg.
What are the advantages of Ketamine?
Great analgesic at low doses, less cardiorespiratory depression.
What are some contraindications for Ketamine?
Elevated ICP, severe cardiac disease, psychotic disorders.
What is a common allergic reaction associated with anesthetics?
More common with barbiturates and propofol.
What is essential due to the low therapeutic index of certain anesthetics?
Proper administration and monitoring are essential.
What class do thiopental and methohexital belong to?
Barbiturates.
What is the mechanism of action of barbiturates?
Potentiates GABA-A receptor → CNS depression.
What are the effects of barbiturates on the CNS?
Sedation, hypnosis, and respiratory depression.
What cardiovascular effects do barbiturates have?
Hypotension due to vasodilation and myocardial depression.
What respiratory effects do barbiturates cause?
Respiratory depression and apnea.
Do barbiturates have analgesic properties?
No.
What are common uses of barbiturates?
Induction of anesthesia, seizures (thiopental).
What are the side effects of barbiturates?
Respiratory depression, hypotension, hangover effect.
What are the contraindications for barbiturates?
Porphyria, severe cardiovascular disease.
What class does ketamine belong to?
NMDA receptor antagonist.
What is the mechanism of action of ketamine?
Blocks NMDA receptor → dissociative anesthesia.
What are the effects of ketamine on the CNS?
Dissociative anesthesia, analgesia, and minimal respiratory depression.
What cardiovascular effects does ketamine have?
Increases blood pressure and heart rate.
What respiratory effects does ketamine have?
Minimal respiratory depression, preserves airway reflexes.
What are the analgesic properties of ketamine?
Strong analgesic.
What are common uses of ketamine?
Procedural sedation, induction in trauma patients, pain management.
What are the side effects of ketamine?
Hallucinations, emergence reactions, increased secretions.
What are the contraindications for ketamine?
Hypertension, history of psychiatric disorders.
What class does propofol belong to?
GABA-A agonist.
What is the mechanism of action of propofol?
Potentiates GABA-A receptor → CNS depression.
What are the effects of propofol on the CNS?
Hypnosis, sedation, anti-emetic, and respiratory depression.
What cardiovascular effects does propofol have?
Hypotension due to vasodilation and myocardial depression.
What respiratory effects does propofol have?
Significant respiratory depression and apnea.
What are the analgesic properties of propofol?
None.
What are common uses of propofol?
Induction and maintenance of anesthesia, ICU sedation.
What are the side effects of propofol?
Hypotension, apnea, pain on injection.
What are the contraindications for propofol?
Hypotension, egg/soy allergy.
What class does etomidate belong to?
GABA-A agonist.
What is the mechanism of action of etomidate?
Potentiates GABA-A receptor → CNS depression.
What are the effects of etomidate on the CNS?
Hypnosis with minimal cardiovascular effects.
What cardiovascular effects does etomidate have?
Hemodynamically stable (minimal effects on BP and HR).
What respiratory effects does etomidate have?
Minimal respiratory depression.
What are the analgesic properties of etomidate?
None.
What are common uses of etomidate?
Induction of anesthesia, especially in hemodynamically unstable patients.
What are the side effects of etomidate?
Adrenal suppression (inhibits 11β-hydroxylase).
What are the contraindications for etomidate?
Sepsis, adrenal insufficiency.
What is unique about ketamine?
Provides dissociative anesthesia and analgesia while maintaining cardiovascular stability.
What is a key characteristic of propofol?
Widely used for induction and maintenance of anesthesia, but causes significant hypotension and respiratory depression.
Why is etomidate preferred in hemodynamically unstable patients?
Due to its minimal cardiovascular effects, but it causes adrenal suppression.
Why are barbiturates used less frequently today?
Due to their long-lasting effects and severe respiratory depression.
