29. Local anesthetics Flashcards
Hydrophobicity in LA
More hydrophobic more potent longer lasting blocks decrease onset (moderate)
Inflamed tissues and L.A.
Acid, increase protonation, decrease penetration
LA main barrier to diffusion
Perineurium
A delta funtion
Muscle tone
Pain, cold thermo, touch
Peripheral vascular effects of LA
Low concentrations vasoconstriction
High concentrations vasodilation
Most effective additive for prolonging block duration
Dexamethasone
Bier’s block charac
Lido + prilocaine
Side effects of LA
Amides (lido) Seizures
Esters (chlorp) Thrombophlebitis
Absorption of LA
Higher:
Intercostal > caudal epi > lumbar epi > Brachial plx > SC tissue
Degradation of LA
Esters. By plasma
Aminoamides By liver.
Speed lido > Mepiv > Bupi
PharmacoK alterations of LA by patient status
Last longer with age
Less dose for kids (not yet developed liver)
Increase 1/2l in liver disease
LAST
First excitatory CNS symptoms
After CNS depression
Direct effect on cardio (LA)
Decrease inotropic
Decrease contractility
Size and myelination of nerve fibers
Small. C, A delta A gamma
Myelin A
Fastest conduction. Big and myelin (A alpha and beta)
Most susceptible to block A delta
Maximum dosage of lido
5 mg/kg
