Local anesthetics 3 Flashcards
______________ removes local anesthetics from its site of action.
Vascular uptake
The rate of vascular uptake has a profound effect on
the plasma level of local anesthetic (risk of toxicity)
The more ________________ the site, the higher the plasma concentration of local anesthetic.
vascular
Order the sites from most to least vascular:
IV> tracheal>interpleural>intercostal>caudal >epidural> brachial plexus > femoral >sciatic > subcutaneous
What factors reduce the rate of vascular uptake?
plasma protein binding (they behave like a reservoir)
rapid metabolism in the plasma (ester-type local anesthetics)
addition of a vasoconstrictor
Factors that influence vascular uptake and Cp include
site of injection
tissue blood flow
physiochemical properties of local anesthetic
metabolism
addition of vasoconstrictor
The same amount of local anesthetic injected at two different sites will
produce different plasma concentrations as a direct result of the blood flow each location receives
What is the Mnemonic for remembering tissue blood flow?
I Think Illogical Imposters Can’t Educate But Fabulous Schools Should
IV–> tracheal–> interpleural–> intercostal–> caudal–> epidural –> brachial plexus–> femoral–> sciatic –> subcutaneous
Local anesthetics preferentially bind to
alpha 1 acid glycoprotein but they also bind to albumin
The _______ also act as a reservoir that removes local anesthetic from the circulation and limits plasma concentration
lungs
In the circulation, ____________ helps limit the peak plasma concentration
plasma protein binding
Amides are metabolized by
P450 enzymes in the liver
Esters are metabolized by
pseudocholinesterase in the plasma
The addition of a vasoconstrictor such as epinephrine or phenylephrine will
decrease systemic absorption by up to one-third and prolong the duration
The addition of _________________ extends the duration of a brachial plexus block
dexamethasone
What is exparel?
a newer formulation of bupivacaine indicated for single-use infiltration into the surgical site to provide post-surgical analgesia
Benefits of exparel include
duration of action lasting up to several days + reduction in opioid consumption
What is the maximum dose of exparel?
266 mg
How does exparel work?
aqueous droplets of bupivacaine are housed inside a liposomal suspension
as the lipid membranes in the suspension erode and reorganize over time, bupivacaine is released in a predictable way
Exparel is contraindicated for
paracervical block in the obstetric population
Exparel is not recommended for
epidural anesthesia
intrathecal anesthesia
intraarticular administration
during pregnancy
Exparel should be used in caution for patients with
hepatic and/or renal dysfunction
Co-administration of other local anesthetics with Exparel can
disrupt the liposomal suspension causing immediate release of bupivacaine
What are the rules for administering lidocaine and Exparel to a patient:
after infiltrating lidocaine–> no liposomal bupivacaine for at least 20 minutes
after infiltrating liposomal bupivacaine–> no lidocaine (in any form) for at least 96 hours
What is the maximum dose for levobupivacaine
2 mg/kg
What is the maximum dose for bupivacaine?
2.5 mg/kg
What is the maximum dose for bupivacaine + epinephrine?
3 mg/kg
What is the maximum dose for ropivacaine?
3 mg/kg
What is the maximum dose for lidocaine?
4.5 mg/kg
What is the maximum dose for lidocaine + epineprine?
7 mg/kg
What is the maximum dose for mepivacaine?
7 mg/kg
What is the maximum dose for prilocaine?
8 mg/kg
What is the maximum dose for procaine?
7-10 mg/kg
What is the maximum dose for chloroprocaine?
11 mg/kg
What is the maximum dose for chloroprocaine + epinephrine?
14 mg/kg
What is the max total dose for levobupivacaine?
150 mg
What is the max total dose for bupivacaine?
175 mg
What is the max total dose for bupivacaine + epinephrine?
200 mg
What is the max total dose for ropivacaine?
200 mg
What is the max total dose for lidocaine?
300 mg
What is the max total dose for mepivacaine?
400 mg
What is the max total dose for lidocaine + epi?
500 mg
What is the max total dose for prilocaine?
if <70 kg–> 500 mg
if >70 kg–> 600 mg
What is the max total dose for procaine?
350-600
What is the max total dose for chloroprocaine?
800 mg
What is the max total dose for chloroprocaine + epi?
1000 mg
At what plasma concentration would you expect lidocaine to produce seizures?
10-15 mcg/mL
Local anesthetic toxicity syndrome affects the
central nervous system and cardiovascular system
The most common cause of LAST is
inadvertent intravascular injection during regional anesthesia
