Local Anesthetics Flashcards
what is the action of local anesthetics?
suppress pain by blocking impulse conduction (block sodium channels) along axons (in all neurons they have access to)
what neurons are affected with local anesthetic?
only those located near site of administration
what neurons are blocked more frequently - myelinated or non-myelinated?
non-myelinated
what sensation is lost first?
pain
what other sensations are lost?
warmth, touch, and deep pressure
what is the advantage of using local anesthetic instead of general anesthetic?
pain can be suppressed without causing local generalized depression of the entire nervous system
- also less risks than general
what is methemoglobinemia?
- blood disorder
- Hb modified so it cannot release oxygen to tissues
can methemoglobinemia be fatal??
yes
what is methemoglobinemia caused by?
topical benzocaine (not for kids under 2 years)
what is procaine?
an ester-type anesthetic
how is procaine given?
by injection
what is given with procaine to delay the absorption?
epinephrine
what does procaine increase the risk of?
allergy
what is lidocaine?
amide-type agents
what are the routes of lidocaine?
topical and parenteral
what can result from lidocaine?
cardiac and CNS toxicity
what does lidocaine inactivate?
hepatic metabolism
what can lidocaine treat?
dysrhythmias
what is infiltration anesthesia?
directly into immediate area of Sx or manipulation
what is nerve block anesthetic?
- small dose of anesthetic injection into or near the nerves that supply the surgical field
where is intravenous regional anesthetic get injected into?
distal vein in arm or leg
how do you prevent intravenous regional anesthetic from entering the rest of the circulation from the limb?
tie a tourniquet to the limb
what are ester type agents?
contain ester linkage in their structure
where are ester like agents metabolized?
in blood
what is an example of an ester type agent?
procain (novocain)
what are amide type agents?
aminde linkage
what are amide type agents metabolized?
enzymes in the liver
what is an example or amide type agents?
lidocaine (xyloxaine)
