Exam 2 LA and general Flashcards
amides or esters better for LA?
amides - less allergenic, better tissue penetration and longer duration of action
which local anesthetic has the longest duration of action?
bupivacaine (Marcaine)
Islidocaine or procaine an amide or ester?
lidocaine = amide procaine = ester
what part of LA is hydrophilic or hydrophobic?
hydrophillic = amino group hydrophobic = aromatic nucleus (lipophilic)
why a decreased effect of LA if injected into an inflamed tissue?
LA is weak bases and inflamed tissue is acidic. So the inflamed tissues low pH will charge the drug and therefore the drug cannot cross the membrane as easily in healthy tissue
general vs local anethetic mechanism
general
- CNS
- activate GABA A receptors (and glycine), blocks chlorine transfer
LA
- PNS
- basic and blocks Na+ channel; Na decreases and depolarization threshold increases
charged or uncharged LA penetrate membranes better?
uncharged
List esters and list amides
Esters (PABA)
- Procaine
- Tetracaine
- ethyl aminobenzoate
- benzocaine
Amides
- Lidocaine (xylocaine)
- bupivacaine
- mepivacaine
- prilocaine
- articaine (septocaine)
more lipid soluable agents are more ____ with longer but take longer to?
more POTENT with longer duration of action but take longer to achieve clinical effect (bupivacaine is more lipid soluble)
esters (such asprocaine) are metabolized into what that causes allergies?
PABA (para-aminobenzoic acid)
what is the most important reason that LA is often combined with vasoconstrictors?
to INCREASE the duration of action of anesthesia
it also decreases blood flow, rate of systemic absorption and dose needed
Why shouldn’t you warm injections?
This can deteriorate the epi and make it ineffective
what LA is safest for pregnancy?
Lidocaine
What is the only LA that causes vasoconstriction and can be used as topical?
cocaine is the only LA that cause vasoconstirction and can be used for topical for mucous membrane surgery
if you see “methemoglobinemia” think?
benzocaine
Lidocaine can be used as an?
antiarrhythmic agent
cross allergies occurs in amides or esters?
ESTERS! (if you’re allergic to one ester LA you are probably allergic to the next one)
Lidocaine should NOT be used for? why?
epidurals bc of transient neurological symptoms
preservative allergies
methylparaben and metabisulfite (used in epi LA)
If a patient has a sulfa allergy to preservatives, use?
mepivacaine 3% and prilocaine 4%
use what to treat convulsions from toxicity?
benzodiazepinesie diazepam (Valium)
what is OraVerse?
an anesthetic reversal agent that reduces time of numbness in half (1:1 ratio to epi)
Hanaoka Seishu
first surgeon to use general anesthesia using Tsusensan
Horace Wells
first dentist to use nitrous oxide for tooth extraction
Oliver Holmes
drug induced reversible state of unconscious for surgery that patient doesn’t feel
Two types od general anesthetics?
1) complete (halothane, isoflurane, edsflurane)-can reach any stage
2) incomplete (nitrous oxide)- can reach stage 1
describe stages of general?
1) induction
- end marked by loss of consciousness
- dental procedures
2) excitement
- want to be super fast
3) surgical anesthesia
- opoid used for pain control
4) asystole happens here… bad stage!
recovery
- opposite of induction
emergence - regain consciousness
5 primary effects of general?
1 unconsciousness 2 amnesia (memory loss) 3 analgesia (no pain) 4 inhibition of autonomic reflexes 5 skeletal muscle relaxation
most general are delivered via?
inhalation and IV injection
T or F… no general achieve all 5 effects?
True. Combo of drugs is used
two drugs for anterograde amnesia?
1) midaszolam- IV
2) diazepam- IV or PO
both H1 and H2 antagonist antihistamines are used to treat and prevent
allergic reactions (mainly H1)
Name volatile and gasous general anesthetics?
volatile
- halothane (Fluothane) - not used anymore, hepatitis
- isoflurane (Forane) -
- sevoflurane (Ultane) - most commonly used in hospital
gaseous is nitrous oxide
MAC (minimum alveolar concentration)
same as ED50
the LOWER the potency, the higher the #
** alveolar concentration of a gas necessary to prevent a skeletal muscle response to a standard surgical stimulus in 50% of subjects
Ostwald Coeffecient
Give example
describes the solubility of inhaled general in the blood (ratio IN blood to conc in GAS in contact with blood)
- the more soluble to blood instead of air, the more it binds to plasma and the higher the conc.
- so large # means longer induction and recovery
Ex: low solubility (nitrous oxide) = quick induction, less soluble in blood so gas gets to brain quicker
— high solubility takes awhile to get to brain bc it goes to all tissues
List 5 general gaseous analthetics and major characteristic
1) desflurane (supane)
irritates airway
2) halothane (fluothane)
most potent (smaller MAC=more potent)
3) isoflurane (forane)
irritates airway
4) sevoflurance (ultane)
widely used in adults and kids, best for lung disease
5) nitrous oxide
least potentWhat is unique about Enflurane (Ethrane) in general?
does NOT cause liver probs such as a decrease in portal vein flow
if you see malignant hyperthermia think?
dantrolene (dantrium) - heritable genetic disorder of skeletal muscle
list intravenous general anesthetics
1) ketamine (Ketalar)
- dissociative
2) Methohexital sodium (Brevital)
- barbiturates
3) naloxone (Narcane)
- drug antagonist
4) Propofol (Diprivan)
- no analgesic effect
- induction and maintenance of anesthesia
- most pronounced decrease in BP
5) Midazolam (Versed)
- used most for dental, work thru GABA
6) Flumazenil (Romazicon)
- inhibits GABA
- only benzodiazeprine reversal agent
ketamine (Ketalar)
intravenous general anesthetic
- blocks action of excitatory nuerotransmitter, produced state of dissociative anesthesia, children, no skeletal muscle relaxant required
- side effects: increases lecrimation and salivation and causes hallucinations in adults
Flumazenil (Romazicon)
- inhibits GABA
- only benzodiazeprine reversal agent
Propofol (Diprivan)
NO ANALGESIC EFFECT (IV general)
most frequently used drug for induction and maintenance of anesthesia –has replaced barbiturates
* most pronounced decrease in BP
