Chapter 29 - Local Anaesthetics Flashcards
Lidocaine is an _______
amide
Procaine is an _______
ester
How do local anaesthetics act?
suppress pain by blocking sodium channels and impulse conduction along axons
Where do local anaesthetics act?
-near administration site
-suppress pain without depression of nervous system
What is the onset of local anaesthesia?
2-15 mins
What determines the ability of an anaesthetic to penetrate the axon membrane?
-size of molecule
-lipid solubility
-degree of ionization at tissue pH
How does epinephrine act as a vasoconstrictor?
-decreases local blood flow
-delay systemic anaesthetic absorption (prolong anaesthesia)
-reduces toxicity risk
What can absorption of epi cause?
-palpitations
-tachycardia
-nervousness
-hypertension
What is the role of epi in local anaesthesia?
used along side a local anaesthetic
What are the adverse effects of local anaesthetics?
-CNS excitation followed by depression
-bradycardia
-heart block
-reduced contractile force
-cardia arrest
-hypotension
-allergic reaction (ester type anaesthetic)
-prolong labour
Do not use topical benzocaine in children younger than ____
2
Is procaine ester or not?
ester
What is the most widely used local anaesthetic?
lidocaine
How is lidocaine administered?
-ointment
-jelly
-solution
-patch
-spray
-injection
How do epinephrine and lidocaine interact?
epi extends lidocaine effects
What is another use of lidocaine?
cardiac dysrhytmias
What are the topical local anaesthetics?
lidocaine, tetracaine, and cocaine
Topical local anaesthetics can cause ___________ _________
systemic toxicity
What are rules for topical local anaesthetics?
-apply smallest amount
-don’t apply to large areas
-don’t apply to broken or irritated skin
-avoid strenuous exercise, wrapping site, heating site
How is tetracaine administered?
opthalmic drops
What are topical local anaesthetics used for?
-pain relief
-itching
-soreness from burns and bites
-mucous membrane issues
-hemorrhoids
-anal fissures
Injectable local anaesthetics are administered by…
anesthesiologist
safety for injectable local anaesthetics:
-resuscitation equipment available
-IV for rapid toxicity tx
-ASPIRIATE before injection
What needs to be monitored for injected local anaesthetic?
-CV status
-resp. function
-consciousness
Infiltation
injecting a local anaesthetic directly into the immediate area of surgery or manipulation
Nerve Block
injecting a local anaesthetic into or near nerves that supply surgical area but at a distant site
IV regional
employed to anesthetize the extremities but not entire limb
Epidural
local anaesthetic injection into epidural space
Spinal (subarachnoid)
injecting local anaesthetic into the subarachnoid space
What drugs are used for eipdural?
lidocaine and bupivacaine
What drugs are used for spinal anaesthetic?
-bupivacaine
-lidocaine
-tetracaine
What are the adverse effects of injected anaesthetics?
-hypotension
-fecal and urinary incontinence
-urinary retention
-spinal headaches
-bradycardia
-heart block
-cardiac arrest
