DH Local Anesthesia Board Review
Terms in this set (74)
What LA is metabolized by pseudocholinesterase?
Where are ester LA's hydrolyzed?
In the blood plasma by th enzyme pseudocholinesterase
Which antiseptic should not be used?
Before using a cartridge you should:
1) wipe it w/ disinfectant
2) soak it in alcohol
3)autoclave it annd/or sterilize it?
None of the above
What part of the syringe indicates that it is an aspirating syringe?
What is a possible cause of pain on removal of the needle?
Needle barb from impaling bone
If there is no organic basis for pain
How does a self-aspirating syringe work?
When you let off pressure from injecting, it self-aspirates (negative pressure built into the syringe)
When do you aspirate?
Immediately before you inject local anesthetic.
What is the action of vasodepressors in local anesthetic?
Increases depth and duration of anesthetic, decreases absorption of local anesthetic and vasodepressor
Maximum doses of epinephrine
Normal pt = 0.2mg
Cardiac pt = .04mg
How much epinephrine is in a cartridge of 1:50,000 epinephrine?
How much epinephrine is in a cartridge of 1:100,000 epinephrine?
How much epinephrine is in a cartridge of 1:200,000 epinephrine?
Hematoma common in:
Most common in the pterygoid plexus of veins with a PSA injection
What causes a hematoma?
the effusion of blood into extravascular spaces and can result from nicking a blood vessel, artery or vein.
Treatment of a hematoma?
Apply pressure for at least 2 minutes
Ice the area immediately 10 min on 10 min off for 48 hrs
After 48 hrs apply warm compress if neccessary
What is the volume of local anesthetic in a cartridge?
1.8 ml (actual)
1.7 (for LA board purposes)
*For NERB: If plain LA, 1.7ml; if vasoconstrictor = 1.8ml)
How do you determine gauge and lumen size of a needle?
Smaller the number, larger the lumen
30 = small
27 = intermediate
25 = large
Which needle gauge has the smallest lumen?
What sensation is lost first?
What function does sodium chloride provide in local anesthetic solution?
Makes the solution isotonic with tissue.
What antioxidant prevents biodegradation of vasoconstrictors?
Sodium (Meta) Bisulfite
What is the role of sodium bisulfite in LA?
Antioxidant prevents oxidation of the vasopressor by oxygen which might be trapped in the cartridge by the manufacturer or diffuse through the cartridge's latex diaphragm.
When does a patient receive an electrical shock sensation during an injection?
When needle contacts the nerve sheath.
most common nerve for needle to contact the nerve sheath?
Why does infiltration work better in the maxilla?
Less bone density
(Thinner cortical plate of bone)
Which injectable LA is not an amide?
How long can you safely leave a Dentipatch (EMLA) on tissue?
Most commonly used plain local anesthetic?
3% Mepivacaine Plain
What gauge needle can be used for infiltration injections?
27 or 30 gauge
Which LA is an ester?
Why would you use caution with an amide if a patient has liver (cirrhosis) disease?
Amides are metabolized in the liver.
What is the most common thing that causes pain on injection?
Injecting too fast
Injection site for palatal infiltration of maxillary teeth?
5-10mm from the free gingival margin of the teeth (in the vicinity of the root apex)
What is the difference between a nerve block and an infiltration?
Nerve Block = LA injected in close proximity to a nerve trunk
Infiltration = flooding the area you want to anesthetize with local anesthetic (above root apex; 1-2 teeth anesthetize)
A sensation of burning on injection is caused by what?
Injecting too fast
or injecting a local anesthetic containing a vasoconstrictor (lower pH)
If you need hemostasis only, what type of injection should you administer?
What topical anesthetic is not absorbed well systemically?
What occurs during depolarization?
Sodium passes into the axoplasm and potassium is pumped out (reverse polarity)
What do myelinated nerves do?
Transmits electrical impulses faster
Why do myelinated nerves transmit electrical impulses faster?
What is the effect of epi in a LA cartridge when injected into a pt taking non-specific beta blockers (propranolol) to control hypertension?
Increases systolic blood pressure
*use 1:200,000 epi w/ 1 carpule only
= vascon. w/o beta effects
Remember: (non-specific bb's block B1 & B2)
(N-S BB propranolol = BP & migraine headaches)
Which of the following is a landmark for the IANB
Is laryngeal edema life threatening?
Remember: laryngeal edema = swelling under chin; allergic rxn
Where is the pterygomandibular raphe located?
Hamulus and pterygomandibular triangle
Which injection would numb the lower lip?
Mental Nerve Block
(lower lip & buccal gingiva)
What is the depth of needle penetration for the IANB?
20-25 mm, 2/3 of length of a long needle
(Make sure of bone contact before injecting)
How should the bevel of the needle be oriented when injecting?
Toward the bone
(For most injections)
What causes facial nerve (CN VII) paralysis?
The introduction of LA into the parotid capsule located at the posterior border of the mandibular ramus
Most common injection to cause CN VII paralysis
Pt reports pain on opening the next day after an injection. What is the pt experiencing?
= prolonged tetanic spasm of the jaw muscles by which the normal opening of the mouth is restricted (lock jaw)
What causes trismus?
1) Trismus to the blood vessels and muscles in the infratemporal fossa
2) Injection of alcohol or sterilizing solution contaminated LA causing irritation to the tissues
4) Large volumes of anesthetic solution deposited in one area
5) Infection (common w/ 3rd molar extractions)
How do you manage trismus?
warm saline rinses
analgesics & muscle relaxants to manage the initial phase of muscle spasm
Is the maxillary division of the Trigeminal nerve (V-2) sensory, motor or both?
Is the mandibular division of the trigeminal nerve
(V-3) sensory, motor or both?
Both sensory and motor
(Remember: bc of muscles of mastication)
Which of the following is not anesthetized by the PSA nerve block?
MB root of the maxillary 1st molar
(if it has innervation from MSA nerve to MB root)
Numbness in the anterior portion of the tongue indicates that which nerve has been anesthetized?
Lingual nerve (IANB)
Where is the primary site of biotransformation of amides?
What causes allergic rxns in ester local anesthetics?
A metabolite of the biotransformation process: PABA (Para Amino Benzoic Acid)
What would you use to manage a delayed allergic rxn?
100 mg= adult dose
V-2 exits the cranium through?
V-3 exits the cranium through
Allergic rxn management for a patient who immediately starts gasping for air and BP drops below 90/60mmHg
What would you use to manage an immediate severe allergic rxn?
(1;1,000) (Given subcutaneously)
The mental nerve exits the mandible through?
What is the injection site for the Anterior Superior Alveolar (ASA) injection?
Mucobuccal fold mesial to the canine eminence
What is the injection site for the Posterior Superior Alveolar (PSA) injection
Mucobuccal fold above the maxillary second molar
(avg depth of penetration on adult pt = 16mm)
The _________ nerve remains in the mandibular canal and forms a nerve plexus that innervates the pulpal tissues of the 1st premolar, canine, lateral incisor via its dental branches
What is the injection site for the Middle Superior Alveolar (MSA) injection
Mucobuccal fold above the maxillary second premolar
What is the injection site for the nasopalatine injection?
Beneath the incisive papilla