M5 L4: Anesthetics Flashcards
components of general anesthesia
- hypnosis (loss of consciousness)
- amnesia (loss of memory)
- analgesia (loss of response to pain)
- areflexia (loss of autonomic response)
- relaxation (skeletal muscle relaxation)
general anesthesia mech of action
- facilitation of GABA-mediated inhibition at GABAa receptor: strengthens the inhibitory function of GABA, increasing CNS depression
- antagonism of glutamic acid excitation of NMDA receptor: decreases excitation in CNS, enhancing CNS depression
2 ways general anesthesia is administered
- inhaled
- IV
commonly used inhaled anesthesias
- nitrous oxide
- volatile anesthetics:HALOTHANE
what is nitrous oxide (N2O)
laughing gas!
- low-potency, incomplete anesthesia
- rapid onset and offset
- prominent analgesic effect
nitrous oxide (N2O) adverse effects
hypotension, respiratory depression (usually minimal)
what are volatile general anesthetics
- liquid @ room temp so you have to aerosolize them for inhalation
- potent drugs produce: unconsciousness, analgesia, muscle relaxation, bronchodilation
what are volatile anesthetics adverse effects
- hypotension, respiratory depression
minimum alveolar concentration (MAC)
- concentration of inhaled anesthetic required to prevent 50% of ppl from responding to painful surgical stim w “gross purposeful movements”
- if u need higher amount, the weaker the anesthetic
- determines anesthetic potency, inverse relationship (increased MAC = decreased potency)
what are commonly used IV general anesthetics
- propofol
- ketamine
- etomidate
what is propofol
- very rapid offset despite prolonged infusions
- ideal ambulatory anesthetic
- prevents nausea and vomiting
- dose not change HR
adverse effects: hypotension, apnea
what is ketamine
- often in pediatric anesthesia
- used as rec street drug
- anesthetic of choice for compromised blood flow
- provides analgesia
- does not usually cause apnea
adverse effects of ketamine
- hypertension
- tachycardia
- elevated intracranial pressure
- dysphoria
what is local anesthetics
- loss of sensation confined to a discrete area of the body
how do local anesthetics work?
- block voltage-gated sodium channels
- decreased action potential
- blocks sensory nerve conduction
what is the effect of local anesthetics
block pain sensation
- autonomic function
- temp sensation
- light touch
- proprioception
- motor function
how do local anesthetics terminate the effect
- systemic absorption -> distribution -> elimination
uses and administration of local anesthetics
nerve block, spinal or epidural
topical, local infiltration (like if a tooth is being pulled)
local anesthetic adverse effects and toxicity
allergy:
- mostly due to additives effects, rare
systemic toxicity:
- due to overdose or accidental IV injection
- sedation, light-headedness, visual and auditory disturbances, restlessness, convulsions, and CVS depression
ex of local anesthetic
lidocaine
