IV Anesthetics Flashcards
Compare the contributions of distribution and metabolism to the duration of IV anesthetic effects. Describe organ system effects of IV anesthetics and use this information to make decisions on clinical use of these drugs. Compare IV anesthetics based on general pharmacokinetic properties.
Main contributor to termination of effects of most anethstics
distribution
Distribution definition
initial dispersion of drug into body compartments
affects drug distribution
hemodynamics, disease states
terminates the effect of thiopental
redistribution
formerly most common used barbituate (no longer available)
thiopental
time course of thiopental
ultra-short acting, but long elimination
name the drug: rapid unconciousness, good amnesia but poor analgesia, poor muscle relaxation, pleasant induction
Thiopental
MOA of thiopental
binds to GABAA receptor and stimulates inhibitory neuronal systems
drug that best protects against hypoxic/ischemic injury
thiopental
drug that reduces cerebral blood flow, but not perfusion pressure
thiopental
CV effects of thiopental
hypotension in shock pts, lowers contractility. (HR increases via reflex),
IV drug that can cause massive BP drops in pts with high sympathetic tone
Thiopental
IV drug that causes hiccups
thiopental
drug that depresses mucocillary reflexes
thiopental
drug needed to be added to thiopental to overcome tracheal/laryngeal reflexes
muscle relaxants
clinical uses of thiopental
general anesthetic induction, brain protection
Best amnestic agents
Benzodiazapines
benzodiazepines class examples
midazolam and lorazepam
drug to give synergestic sedative effects with opiods
benzos
MOA of Benzos
bind to GABAA receptor, fires inhibitory neurons
receptor occupancy of benzo giving anxiolysis
20%
receptor occupancy of benzo giving sedation
30-50%
receptor occupancy of benzo giving hypnosis or unconciousness
60%
drug that is pH 3.5 in vial and pH 6.2 in plasma
midazolam
CNS effect of midazolam
reduction in cerebral metabolism and blood flow.
benzo used for anticonvulsant
midazolam
drug causing antegrade, but not retrograde amnesia
midazolam
CV effects of midazolam
hypotension in hypovolemia
Resp effects of midazolam
hypnotic dose - apnea.
Amnestic dose gives minimal depression
clinical uses of benzos
premedication before anesthesia
Conscious or heavy sedation
induction of anesthesia
drugs that are not reliable for amnesia
opiods
clinical use of opiods
premedication, maintenance of anesthesia, postop pain control
MOA of opiods
acts on G-protein linked mu receptors
SE of opiods
itching, chest wall regidity, “forgetting to breathe”
opioid only used for shivering
meperidine
fentanyl class
opoid
sufentanil class
opioid
alfenranil class
opioid
used as adjunct with inhaled agants for intraoperative analgesia
hydromorphone
opioid that’s termination of action is due to elimination - not redistribution
remifentanil
shortest acting opioid
remifentanil
drug that may result in acute tolerance to other opioids
remifentanil
MOA of Ketamine
NMDA antagonist, inhibits stimulatory systems
“dissociatibe anesthetic”
ketamine
CNS effects of ketamine
bad dreams, halluciations, delirium
raises ICP
antidepressent effects
treats ketamine “bad trip”
benzo, barbiutates, N2O
CV effects of ketamine
central sympathetic stimulation (higher HR/BP, catchecolamine levels)
direct myocardial depressent drug
ketamine
respiratory effects of ketamine
small doses = minimal ventilory depression
bronchodilation from sympathetic effects
causes nystagmus
ketamine
increases salivary and tracheobroncial secretions
ketamine
Etomidate MOA
activates GABAA receptors
etomindate CNS effects
lowers ICP and cerebral O2 metabolic rate
etomindate respiration effects
minimal vent depressant
good choice for short procedures, due to lower risk of apnea
etomidate
DOC for pts with CV factors
etomidate
propofol MOA
some action at GABAA complex, may enhance Cl-conduction at glycine receptors
CNS effects of propofol
reduces cerbral blood flow and metabolism
CV effects of propofol
decreasd BP, HR, CO, vascular resistance. no change to central venous pressure
good drug for CABG pts
propofol
fast acting drug that burns on injection
propofol
drug that causes euphoria
propofol
MOA of dexmedetomidine
central a-2 agonist, results in sedation and analgesia
excellent sedative for admin by infusion
dexmedetomidine
hemodynamic effects of dexmedetomidine
bradycardia with hypotension to hypertension (dose dependant)
very long t 1/2 IV drug (non opioid)
thiopental
very short t 1/2 IV drug (non opiod)
propofol
shortest opioid t 1/2 life
remifentinil
longest opioid t 1/2
fentanyl/meperidine