Anesthetic Pharmacology 1 Flashcards
GA
RA
MAC
SAC
General blocks normal nociception distal from site of injury
Regional at or near site of injury
Monitored anesthesia care - level that requires creful monitoring
Not considered anesthesia and can be administered by non-anesthesiologists in different setting (sedation/analgiesia)
How anesthesia blocks
Motor reflexes
Pain and suffering
Autnomic reflexes
Akinesia
Analgesia and hypnosis
Autonomic stabilization
Balanced anesthesia
Several different agents used to maximize benefits of each agent
IV agents
Hypnotic/sedative
Opitates
Paralytics
IV agent features
Lipid soluble that cross BBB
Rapid onset to reduce anxieety and slow delays
Barbituates
Anhydrous sodium salts
Require reconstitution
pH>10
May precipitate qwith acidic
Accidental arterial injection results in thromboembolic complications
Mech of action of Barbituates
GABA-A channel agonists
Activates CNS Cl- channels…results in enhancment of both inhibitory NT and inhibition of excitatory transmission
Redistribtuion of barbitituates
Clinical effect terminated as moved from brain to lean tissues and fat
Hangover from slow elimination through metabolism
Metab of barbituates
Hepatic
Metabolites inactive (exceted in bile and urine)
Affect by CYP inducers
Increase production of porphyrins…contraindicated in patients with acute intermittent porphyria
Physio effects of barbituates
Rapid onset and awakening
May result in hypotension (vasodilation (Veno) and myocardial depression…blunts baroreceptor reflex but tachycardia will occur)
Significant resp depression (apnea common)
Decreased cerebral metabolic rate, CBF, and ICP
Benzodiazepines
Not normally as IV anesthesia
Most common preop anxiolysis
Potent amnestic agents (Lorazepam will produce hsort term retorgrade…rest as anterograde)
Lipid soluble and protein bound (albumin)(accounts for rapid onset)
Redistributed
Benzos used for anesthesiology and others
Midazolam
Lorazepam
Diazepam
Alprazolam
Oxazepam
Mech of action benzos
GABA receptor activation (gamma subunit)
Metab of benzos
Microsomal oxidation (midazolam and diazepam)
Glucuronide conjugation (lorazepam)
Diazepam oxidized to 2 major metabolites that may prolong effect
Midazolam into 1 inactive mtabolite
Physio effects of benzos
Vraible onset
Mild to moderate hypotension (vasodilation (Veno) but minimal myocardial depression)
ignifanct resp depression (apnea common)
Decreased in CMRO2, CBF, and ICP are agent dependent
Propofol
Agent of choice for IV anesthesia
Very rapid onset and rapid termination due to redistribtuion
May be used for general, MAC and sedation in OR, ICU or other procedral areas
Propofol solubility
Insoluble in aqueous
Formulated as emulsion with soybean oil, glycerol, egg yokl lecithin
Some promote bacterial grwot
Propofol mech
GABA activator in CNS
Terminated by redistribtuion
Very high plasma clearance explains lack of hangover compared to thiopental
Rapid hepatic metabolism to inactive metabolites that are excreted through kidney s
Propofol physiologic and other effects
Hypotension (vasodilation, myocardial depression, blunting of baroreceptor, abolished reflexive tachycardia)
Significant resp depression (apnea requiring vewntilator)
Reduces CMRo2, CBF, and ICP
Pain on injection
No analgesic or anxiolytic effect
Reduces risk of PONV and can be used to tx PONV
Etomidate
Hemodynamically stable
Rapid loss of consciousness
Little anxiolysis and no analgesia
Carboxylated imidazole that is insoluble
Supplied in propylene glycol mix
Etomidate Mech
Rapid onset
Lipid soluble
GABA a chloride channel efect
Recovery dependent on redistribtuion
Metabolized via plasam ester hydrolysis to inactive metabolites excreted in urine and bile
Physio effects of etomidate
CV stability after bolus
Moderate resp depression
CNS effects of etomidate
Reduces CBF and CMRO2
Produce excitatory spikes on EEG
May activate pre-existing seizure foci
Spontaneous myoclonic activity
Other effects of edomidate
Increase risk of PONV
Associated with pain
Associated with adrenocortical suppression (inhibtion of 11beta-hydroxylase needed to convert cholesterol to cortisol)
