24 general and local anesthetics Flashcards
what is MAC?
For inhaled anesthetics, defined as minimal alveolar concentration (MAC) that prevents movement in response to pain 50% of subjects
what do most anesthetics do to GABA?
what do they do to NDMA?
GABAa receptors are enhanced
they inhibit NDMA
what drug is useful for inducing a pt, but has side effects of hypotension and and hangover?
sodium thiopental
what IV is used for induction and maintenance but can cause hypotension and respiratory depression?
propofol
what IV is used for pt with hypotension? induction?
what is one bad side effect of this?
etomidate
causes adrenal supression
what IV causes a coma with the eyes open? it is for use in people with bronchospams,
what is a side effect?
ketamine
it causes a increase in intracranial pressure.
what IV causes conscious sedation?
what are soem concerns with it?
midazolam
there is slow induction and respiratory depression.
If the anesthetic has a low blood:gas partition coefficient:
induction is ?
need a lot or a little?
recovery is ?
– need high amounts in inspired air
– Induc0on is quick (because equilibrium is reached quickly)
– Recovery will be quick (drug will move out of blood into gas readily)
If the anesthetic has a high blood:gas partition coefficient:
induction is ?
need a lot or a little?
recovery is ?
– Need less in inspired air
– Induc0on and recovery are slow (equilibria are reached slowly)
if anesthetic has a high fat:blood PC?
– Half-life will be long (hang over) due to slow release into the blood; enough gets into the brain to make the pa0ent feel sleepy.
Increased blood flow ______ the rate of rise of arterial par0al pressure (shorter 0me for equilibra0on)
Increased blood flow slows the rate of rise of arterial par0al pressure (shorter 0me for equilibra0on)
• Anesthesia is achieved when the brain par0al pressure is ______ to MAC
• Anesthesia is achieved when the brain par0al pressure is equal to MAC
• Rate of elimina0on is dependent upon the blood:gas par00on coefficient
what is eleimnated the fastest?
– Lowest will be eliminated the fastest
• Agents with _____ solubility in blood and fat, have slower recovery AND the dura0on of the recovery will depend upon the length of 0me that the anesthe0c was administered
• Agents with high solubility in blood and fat, have slower recovery AND the dura0on of the recovery will depend upon the length of 0me that the anesthe0c was administered
what gas has Moderate blood:gas PC
is slow and is a slight airway irritatn?
has cardivascular side effects of increased intercranial pressure vasodialation of cerebral vessels and decrease in BP
Isoflurane
what gas has very low soluablity in blood? causing rapid induction and recovery?
– Respiratory- Worse as an irritant; can produce bronchospasm
desflurane
not used to induce because of respiratory irritation
Side effects: rela0ve to isoflurane
– Cardiovascular-similar
– Respiratory- Worse as an irritant; can produce bronchospasm
what gas causes renal toxciticy? how does this happen?
what is good about this one?
SERVOFLURANE
no respitory irritation very popular.
About 5% of the administered dose is metabolized to fluoride ion in the liver. can cause renal damage.
Is degraded to “compound A” by absorbants in the anesthesia administra0on apparatus
what gas is not a volitile liquid? and used as an adjunct to enhance induction.
cant be used as an anesthetics.
nitrous oxide
it dilutes oxygen.
– Weak anesthe0c, cannot get enough into the air to produce MAC
– Good for seda0on and analgesia at 50% concentra0on in inspired air
how do local anesthetics produce an effect?
Bind reversibly to a site within the pore of votage gated Na+ channels; blocking sodium entry when the channel is openned
what is the mechanism of action of local anesthetics?
binds on the intracellular side insde the pore as a cation.
has to cross in the unionized form.
they are all weak bases.
resting nerves are less sensative to local anesthetics.
b/c they are not openning alot for the drug to get in.
how does pH releate to the mechanism of action of the local anesthetics.
Efficacy decreased when 0ssue pH is decreased such as during infec0on or inflamma0on. Too liZle drug can get to site of ac0on.
what does coadministering local anesthetics with epinepherine do?
Decrease the rate of absorp0on into the circula0on thereby increasing depth and dura0on of anesthesia
Due to decreased rate of absorp0on, less poten0al for systemic toxicity and can increase the maximal dose that can be given
what nerve fiber is more sensative?
the smaller diameter.
so pain and cold goes first
