CPAN - Local Anesthesia
Identify the mechanism of action of local anesthetics.' Correct Answer -
local anesthetic agents impair conduction of nerve impulses along nerve fibers
by altering cell
membrane permeability to sodium ions
Local aesthetics diffuse into the cell and attach to specific receptor sites near
the sodium channel
Sodium channels are maintained in a closed position causing slowed
depolarization and blocked
conduction
Impaired transmission of sensory input to CNS results in loss of sensation in
affected region of the
body
What types of nerve fibers are found in nerve roots? Correct Answer -
Several types with varying sensitivity to local anesthetics
Which nerves are more difficult to block: motor or sensory? Correct Answer
- Motor nerves
Which nerves are more difficult to block: sensory or sympathetic? Correct
Answer - Sympathetic nerves
Order of loss of function is: Correct Answer - Sympathetic: vasomotor
block causing dilatation of skin vessels, increased blood flow to
cutaneous tissues
Sensory: loss of temperature discrimination (inability to differentiate hot from
cold), loss of pain
perception (nociception), loss of touch
Motor: loss of movement, awareness of body and position of extremities
(proprioception)
Order of return of function is: Correct Answer - Motor: movement,
proprioception
Sensory: temperature discrimination, pressure, pain
Sympathetic or autonomic functions
, Differentiate between the 2 classifications of local anesthetics.! Correct
Answer - Amides
Very stable in solution
Good penetration of nerve fibers
Metabolized by the liver
Rare allergic reactions
Includes bupivacaine, etidocaine, levobupivacaine, lidocaine, mepivicaine,
prilocaine, and
ropivacaine
Esters
- Less stable in solution
Poor penetration of nerve fibers
Metabolized by pseudocholinesterase; effect may be prolonged with
individuals with
pseudocholinesterase abnormalities
Allergic reactions associated with the metabolite para-amino benzoic acid
(PABA)
Includes benzocaine, chloroprocaine, cocaine, procaine, and tetracaine
What are the characteristics of amides? Correct Answer - Very stable in
solution, good penetration of nerve fibers, metabolized by the liver, rare
allergic reactions
Name some examples of amides used as local anesthetics. Correct Answer -
Bupivacaine, etidocaine, levobupivacaine, lidocaine, mepivacaine, prilocaine,
ropivacaine
What enzyme metabolizes esters? Correct Answer - Pseudocholinesterase
What is a common allergic reaction associated with esters? Correct Answer
- Para-amino benzoic acid (PABA)
Name some examples of esters used as local anesthetics. Correct Answer -
Benzocaine, chloroprocaine, cocaine, procaine, tetracaine
What is a characteristic of esters in solution? Correct Answer - Less stable
Identify the mechanism of action of local anesthetics.' Correct Answer -
local anesthetic agents impair conduction of nerve impulses along nerve fibers
by altering cell
membrane permeability to sodium ions
Local aesthetics diffuse into the cell and attach to specific receptor sites near
the sodium channel
Sodium channels are maintained in a closed position causing slowed
depolarization and blocked
conduction
Impaired transmission of sensory input to CNS results in loss of sensation in
affected region of the
body
What types of nerve fibers are found in nerve roots? Correct Answer -
Several types with varying sensitivity to local anesthetics
Which nerves are more difficult to block: motor or sensory? Correct Answer
- Motor nerves
Which nerves are more difficult to block: sensory or sympathetic? Correct
Answer - Sympathetic nerves
Order of loss of function is: Correct Answer - Sympathetic: vasomotor
block causing dilatation of skin vessels, increased blood flow to
cutaneous tissues
Sensory: loss of temperature discrimination (inability to differentiate hot from
cold), loss of pain
perception (nociception), loss of touch
Motor: loss of movement, awareness of body and position of extremities
(proprioception)
Order of return of function is: Correct Answer - Motor: movement,
proprioception
Sensory: temperature discrimination, pressure, pain
Sympathetic or autonomic functions
, Differentiate between the 2 classifications of local anesthetics.! Correct
Answer - Amides
Very stable in solution
Good penetration of nerve fibers
Metabolized by the liver
Rare allergic reactions
Includes bupivacaine, etidocaine, levobupivacaine, lidocaine, mepivicaine,
prilocaine, and
ropivacaine
Esters
- Less stable in solution
Poor penetration of nerve fibers
Metabolized by pseudocholinesterase; effect may be prolonged with
individuals with
pseudocholinesterase abnormalities
Allergic reactions associated with the metabolite para-amino benzoic acid
(PABA)
Includes benzocaine, chloroprocaine, cocaine, procaine, and tetracaine
What are the characteristics of amides? Correct Answer - Very stable in
solution, good penetration of nerve fibers, metabolized by the liver, rare
allergic reactions
Name some examples of amides used as local anesthetics. Correct Answer -
Bupivacaine, etidocaine, levobupivacaine, lidocaine, mepivacaine, prilocaine,
ropivacaine
What enzyme metabolizes esters? Correct Answer - Pseudocholinesterase
What is a common allergic reaction associated with esters? Correct Answer
- Para-amino benzoic acid (PABA)
Name some examples of esters used as local anesthetics. Correct Answer -
Benzocaine, chloroprocaine, cocaine, procaine, tetracaine
What is a characteristic of esters in solution? Correct Answer - Less stable
