general anesthetics Flashcards
anesthetic state
analgesia amnesia hypnosis immobility reduction of autonomic reflexes
clinical phases
induction
maintenance
recovery
depth of anesthesia
partial pressure
minimal alveolar concentration
blood/gas partition coefficient
oil/gas partition coefficient
meyerton-Overton correlation
potency = lipid solubility
higher oil:gas = more potent
minimal alveolar concentration (MAC)
prevents movement in 50% pts in response to noxious stimulus
inversely related to lipid solubility
age dependent
blood/gas partition coefficient
rate of induction/recovery
solubility
lower = faster
arteriovenous concentration gradients
highly perfused tissue (vessel rich group) limits GA capacity
inspired anesthetic concentration
increase = faster induction
pulmonary ventilation
increase = faster induction
pulmonary/cerebral bloodflow
low CO = faster induction
General anesthetic MOA
enhance inhibitory post-synaptic channel activity (GABA-A, glycine)
inhibit excitatory synaptic channel activity (ACh, glutamate)
nitrous oxide
non-halogenated
balanced anesthesia
weak anesthetic
good analgesic
nitrous oxide MOA
non-competitive NMDA antagonist
nitrous oxide SE
diffusional hypoxia
neuropathies
megaloblastic anemia (oxidize cobalt in VitB12)
halogenated “flurane”
reduce BP
depress ventilation
SE: pungent odor increase cerebral bloodflow malignant hyperthermia (tx: dantrolene IV)
isoFLURANE
blood:gas 1.4
moderate onset/recovery
give w/O2 and N2O
use: neurosurgery
maintain CO
doesn’t sensitize heart to catecholamines
SE: bronchodilator
desFLURANE
blood:gas .42
rapid induction/recovery
relax smooth muscle
use: outpatient surgery
SE: pungent odor, perioperative hyperkalemia, postoperative arrhythmias
sevoFLURANE
blood:gas .69
rapid induction/recovery
relax smooth muscle
use: in/outpatient surgery
pleasant odor
SE: reacts with soda lime, nephrotoxic (compound A), epileptogenic
IV
balanced anesthesia rapid onset short halflife recovery due to redistribution less CV depression
methohexital
short-acting barbiturate
MOA: binds GABA-A receptor
use: outpatient surgery
SE: hyperalgesia, tachycardia, sweating
ketamine
dissociative anesthetic
MOA: block glutamate receptors
use: diagnostic, minor surgery
SE: increase ICP, increase catecholamine release
contraindication: CV disorders
etomidate
rapid onset
short duration
MOA: bind GABA-A
use: surgery if CV disease
SE: post-op nausea/vomiting, suppression of adrenal steroid synthesis
propofol
rapid recovery
MOA: bind GABA-A
use: induction/maintenance
anti-emetic
SE: supports bacterial growth
fospropofol
prodrug
benzodiazepines
relieve anxiety, facilitate sedation
MOA: bind GABA-A
opioids
analgesia, decrease MAC
MOA: bind opiate receptors
SE: respiratory depression
antihistamines
prevent allergies
MOA: block H1 and H2 receptors
anti-emetics
prevent nausea/vomiting
MOA: block D2, 5HT3 receptors
skeletal muscle relaxants
facilitate intubation
prevent muscle contractions
MOA: bind nicotinic receptors at NMJ, competitive antagonist of nicotinic receptors
SE: malignant hyperthermia, hyperkalemia, bradycardia, histamine relase, tachycardia
