General Anesthetics Flashcards
What is anesthesia?
- no movement in response to painful stimuli
- loss of consciousness
Components of anesthetic state
- amnesia
- unconsciousness
- analgesia
- immobility to painful stimuli
- attenuation of autonomic responses to noxious stimuli
How is anesthetic potency usually measured
- Concentration of anesthetic that prevents movement in response to pain
How are inhaled anesthetic’s potency measured
- Minimal alveolar concentration (MAC) that prevents movement in response to pain in 50% of subjects
Advantage to MAC as measure
- can be continually monitored
- provides direct correlate to anesthetic concentration @ site of action in CNS
- Simple to measure end-point (lack of movement)
How are IV anesthetic’s potency measured
- Usually free plasma concentration that produces loss of response to surgical incision in 50% of subjects
What are the common effects shared by all anesthetics
- membrane hyper polarization and effects on synaptic function, such that inhibitory neurotransmission is increased and excitatory neurotransmission is reduced
What are the parenterally administered anesthetics
Sodium thiopental, Propofol, Ethomidate, Ketamine, Midazolam*
Generalities of parenterally administered anesthetics
- All hydrophobic
- Single iv bolus –> high conc. in brain and spinal cord w/in single circulation time; results in rapid induction of anesthesia
- Subsequently, blood levels drop and anesthetic redistributes back into blood from brain and winds up in other tissues where it is slowly released and metabolized
- Thus, half-life of anesthetic in body and duration of action are not same
A barbiturate
Sodium thiopental*
Sodium thiopental* half-life, unconsciousness time, duration of action (1 dose)
long (12hrs), 10 - 30s, 10min
When should Sodium thiopental* dose be reduced?
patient has been premeditated w/ other CNS depressants
How is Sodium thiopental* given to pediatric patients if needed
rectally
