Pain and Anxiety Week 3 Flashcards
What is the mechanism of action for topical anesthetics?
- Blocks nerve conduction at mucous membrane surfaces
- Decreases Na+ permeability = decreases depolarization = blocks nerve impulse
(MOA is similar to injectable LAs)
What are the different forms of topical anesthetics?
Gel
Ointment
Metered and unmetered sprays
Cream
Liquid
Lozenges
What is the range of effective concentrations for topical anesthetics? What does this depend on?
0.2% - 20%, depends on form
What is the choice of method of delivery for topical anesthetic based on?
Each individual patient
Which topical anesthetic is associated with methemoglobinemia?
Benzocaine sprays
(recall that injectable procaine has the same issue)
Why do we need the site to be dried with gauze or sponge before we apply the topical anesthetic?
dryer site = will absorb the anesthetic better
(won’t get washed away by saliva)
How long should topical anesthetic be placed at site?
1-2 mins
What is the tissue depth of topical anesthetic?
2-3 mm
What are 3 common topical anesthetics used in dentistry?
Benzocaine
Lidocaine
Combination of Benzocaine + Butamben + Tetracaine = Cetacaine
Is Benzocaine (topical) an ester or amide?
Ester
Which topical has a very low toxicity due to the fact that it has SLOW absorption?
Benzocaine
What is the onset of Benzocaine (topical)?
30 seconds - 2 mins
What is the duration of Benzocaine (topical)?
5-15 mins
Which topical has a 20% concentration?
Benzocaine
Where is Benzocaine (topical) metabolized?
Plasma + some liver
What is the MRD of Benzocaine (topical)?
None
What is the pregnancy category for Benzocaine (topical)?
pregnancy = category C; lactation unknown safety
What is Benzocaine (topical) spray associated with?
Methemoglobinemia
Which topical has a very low toxicity due to the fact that it has POOR absorption?
Lidocaine
Which topical is good for those with an ester allergy?
Lidocaine
Is Lidocaine (topical) an ester or amide?
Amide
What is the onset of Lidocaine (topical)
2-10 mins
What is the duration of Lidocaine (topical)
15-45 mins
Which topical has a concentration of 2%-5%?
Lidocaine
Where is Lidocaine (topical) metabolized?
Liver
What is the MRD for Lidocaine (topical)?
MRD = 300 mg, but we use 200 mg safely
What is the pregnancy category for Lidocaine (topical)?
pregnancy = category B; small amount enters breast milk
What is Cetacaine (topical) a combination of?
Benzocaine + Butamben + Tetracaine
Is Cetacaine (topical) an ester or amide?
Ester
T/F: Benzocaine, Lidocaine, and Cetacaine are all topicals that have a very LOW toxicity
True
What is the onset of Cetacaine (topical)?
30 seconds
What is the duration of Cetacaine (topical)?
30-60 mins
What is the concentration of Cetacaine (topical)?
14% benzocaine + 2% butamben + 2% tetracaine
Where is Cetacaine (topical) metabolized?
Plasma + some liver
What is the MRD for Cetacaine (topical)?
MRD = 200 mg
What is the pregnancy category for Cetacaine (topical)?
pregnancy = category C; lactation - use caution
Topical anesthetics increase ________ __________, which increases ___________
blood levels; toxicity
T/F: The concentration of topicals are lower than injectable LA’s.
False!! They’re higher
Why do we need a higher concentration in topical anesthetics?
Must diffuse thru mucous membranes
T/F: There are NO vasoconstrictors in topicals
True
Because there are NO vasoconstrictors in topicals, there is an increased __________ __________ and therefore an increased _____________
absorption rate; toxicity
Which groups of people have an increased risk of toxicity and adverse reactions to topical?
Elderly
Children
Medically compromised
What are the toxicity and adverse reactions of topical anesthetic?
Irritation @ site
Sloughing
Taste alteration
CNS effects (excitation -> depression)
CV effects (decreased HR/BP; cardiac arrest)
T/F: The CNS and CV effects of toxicity/adverse reactions in topical anesthetic have the same signs and symptoms as in injectable LAs
True!
What are the 7 ways to avoid toxic rxns from topicals?
- Know relative toxicity of drug
- Know concentration of drug
- Use smallest volume
- Use lowest concentration
- Use least toxic drug
- Limit area of application
- Avoid sprays
What does a (+) and (-) result for the aspiration test mean?
(+) aspiration = blood entered carpule
(-) aspiration = no blood; small bubble may have entered carpule
What is aspiration test and what does it determine?
Negative pressure within a cartridge prior to injecting to determine if needle is within a blood vessel
Angled surface of the needle tip
Bevel
Diameter of a needle
Gauge
The larger the gauge, the __________ the diameter
smaller
What is the weakest part of the needle?
Hub
What does the hub + needle adaptor attach?
Attaches needle to syringe adaptor
What materials can the hub + needle adaptor be?
Plastic or aluminum
What does a plastic hub + needle adaptor allow for?
Movement to align bevel
Why is the hub + needle adaptor usually marked with ink?
For bevel location
What is the end of the needle shaft that penetrates the diaphragm of the carpule?
Carpule-penetrating end
When should the carpule-penetrating end be placed?
After carpule is loaded and the harpoon is engaged
What must remain covered until ready for use?
Needle shaft
What are the 2 needle lengths commonly used in dentistry?
Long = 32 mm
Short = 20 mm
What is needle length selection based on?
Amount of tissue that must be penetrated to reach target location
Where should the needle NEVER be inserted to?
The hub
What needle length is ALWAYS required for a mandibular block?
Long
Each needle is used on _____ pt
one
________ _______ remains over needle until ready to inject
Plastic shield
When should the needle be replaced?
After 3-4 penetrations (dulls the tip)
What should you do immediately after done injecting?
Cover needle with plastic shield, using the 1-handed scoop technique
You should know where an _________ _________ is at all times
uncovered needle
What should you do if a needle becomes contaminated?
Recap and dispose; replace needle
Where should you put all contaminated needles?
Approved sharps container
How many mL of LA are in each carp? How many mL does the stopper remove?
1.8 mL
Stopper removes 0.2 mL
What are 5 systemic complications of LA?
- Syncope
- LA overdose
- Epi overdose
- Allergic rxn
- Any potential medical emergency
Causes of syncope
Drastic drop in BP
Emotional response to injection
Prevention of syncope
Identify fearful pt in pre-anesthetic assessment
Hide needle
Supine position
Symptoms of syncope
Sweating, nausea, pallor
Increased HR and RR
Treatment for syncope
Supine position w/ legs higher than head
Ammonia capsule or O2
Cool damp cloth on forehead/neck
Monitor vitals
Reassure pt (don’t let them sit up or stand)
Causes of LA overdose
Injecting into vessel (MOST COMMON)
Administering too large of dose
Metabolism/excretion of LA is slow
Prevention of LA overdose
Aspirate in 2 planes
Calculate MRD
Pre-anesthetic assessment for LA selection
Symptoms of LA overdose
CNS excitation (low overdose)
CNS/CV depression (higher overdose)
What is treatment of LA overdose determined by?
Onset and severity
How do you treat mild LA overdoses?
No treatment
How do you treat moderate/severe LA overdoses?
Stabilize pt
Activate EMS
Rapid onset = ?
More severe reaction
Causes of epinephrine overdose
1:50,000 conc
Intravascular injection
CV pts
Prevention of epinephrine overdose
Aspirate in 2 planes
Use lowest effective conc.
Pre-anesthetic assessment to identify CV pts
Symptoms of epinephrine overdose
Fight or flight response
(lasts 5-10 mins)
Treatment of epinephrine overdose
Healthy pts -> reassure
CV pts -> prepare for medical emergency
Allergic reactions to LA can be __________ or ___________
delayed; immediate
Causes of allergic reactions
Methyparaben (preservative used until 80s)
Sodium bisulfite (in vasoconstrictors)
Ester topicals
How to prevent allergic reactions
Pre-anesthetic assessment
Symptoms of allergic reactions
Delayed: rash, itching
Immediate: anaphylaxis
Treatment of allergic reactions
Delayed: antihistamine, document
Immediate: stabilize pt, activate EMS, document
Examples of local complications of LA
Needle breakage
Pain/burning during injection
Hematoma
Facial paralysis
Paresthesia
Trismus
Infection
Edema
Soft tissue injury
Sloughing
Causes of needle breakage
Sudden unexpected movement
Poor technique
Prevention of needle breakage
Use 25g or 27g needles
Use long needle for IA block
Do not bend needle, insert needle to hub, or force needle
Treatment of needle breakage
Keep hands in pts mouth
Remove needle if visible
Refer to OS
Document
Causes of pain during injection
Dull/barbed needle
Prevention of pain during injection
Inject slowly
Use topical
Use sharp needle
Use anesthetic at room temp
Treatment of pain or burning during injection
Reassure pt
Slow down delivery of anesthetic
Causes of burning during injection
Contaminated/expired anesthetic
Heated anesthetic
Prevention of burning during injection
Inject slowly
Check carp before use
Store anesthetic at room temp
Causes of hematoma
Puncturing blood vessel
Multiple needle penetrations
Prevention of hematoma
Use 27 short for PSA
Know anatomy
Treatment of hematoma
Apply ice and pressure ASAP
Inform pt of swelling/discoloration (7-14 days)
Document
Causes of facial paralysis
LA deposited in parotid gland
Bone not contacted during mandibular block
Prevention of facial paralysis
Contact bone before depositing LA
Treatment of facial paralysis
Reassure pt
Document
Causes of parasthesia
Trauma to nerve sheath (pt feels a shock)
Edema/hemorrhage near nerve
Contaminated anesthetic (soaked in disinfectant)
Possible association w/ Articaine
Prevention of parasthesia
Minimize needle within tissue
Do NOT soak carps in disinfectant
Treatment of parasthesia
Reassure pt (3 weeks - 3 months; possibly 1 year)
Document
Causes of trismus
Muscle trauma from multiple needle insertions
Contaminated anesthetic
Prevention of trismus
Use sharp needle
Inject slowly
Store anesthetic properly
Treatment of trismus
Reassure pt (2-3 days)
Moist heat (20 mins on/20 mins off)
Document
Causes of infection
Contaminated needle/cartridge
Administer anesthetic thru infected area
Prevention of infection
Sterile needle -> replace if contaminated
Store anesthetic properly
Do not inject infected area
Treatment of infection
Antibiotics after 3 days
Causes of edema
Trauma
Contaminated needle
Allergic rxn
Prevention of edema
Good technique
Pre-anesthetic assessment to identify allergies
Store anesthetic properly
Treatment of edema
NONE (goes away 3-4 days)
Causes of soft tissue injury
Self-inflicted (usually kids)
Prevention of soft tissue injury
Select LA w/ appropriate duration
Warn pts/parents
Treatment of soft tissue injury
OTC analgesics
Antibiotics if severe
Warm salt water rinse
Vaseline for lips
Which branches of CN V have sensory only?
CN V1 + CN V2
Which branch of CN V has sensory + motor?
CN V3
CN V1 opening
Superior orbital fissure (sphenoid bone)
3 major branches of CN V1
Nasociliary
Frontal
Lacrimal
(NFL)
CN V2 opening
Formen rotundum (sphenoid bone)
CN V2 enters the…
Pterygopalatine fossa
5 major branches of CN V2
Nasopalatine
Greater palatine
PSA
Infraorbital -> ASA + MSA
Zygomatic
CN V3 opening
Foramen ovale (sphenoid bone)
3 trunks of CN V3 and their contents
Undivided: muscular branches
Anterior: long buccal nerve + muscular branches
Posterior: IA, lingual, auriculotemporal nerves
5 branches of CN V3
Long buccal
Muscular branches (to mm of mastication)
Auriculotemporal
Lingual
IA -> mylohyoid, mental, incisive
What does CN VII do?
Motor to mm of facial expression
Sensory to ant 2/3 tongue (taste)
Path of CN VII
- Internal acoustic meatus
- Stylomastoid foramen
- Parotid gland (no innervation)
What branches of CN VII are in the internal acoustic meatus?
Chorda tympani (submandibular/sublingual glands)
Greater petrosal (lacrimal gland)
What branches of CN VII are in the parotid gland?
Temporal
Zygomatic
Buccal
Mandibular
Cervical
What cranial nerve wraps around the parotid gland?
CN VII
(be careful when doing mandibular block!)
What does the external carotid artery terminate as?
Maxillary artery
Superficial temporal artery
Where does the maxillary artery begin within?
Parotid gland (at neck of mandibular condyle)
The maxillary artery runs between ___________ and ___________ ____________ (lingula)
mandible; sphenomandibular ligament
The maxillary artery enters the __________ fossa and then the ___________ fossa, giving off 4 branches at each
infratemporal; pterygopalatine
4 branches of maxillary artery within infratemporal fossa
- Middle meningeal
- Inferior alveolar -> mental + incisive + mylohyoid
- Branches to mm of mastication
- Buccal
4 branches of maxillary artery within pterygopalatine fossa
- PSA
- Infraorbital -> ASA
- Greater palatine
- Sphenopalatine -> nasopalatine
What protects the maxillary A from being compressed during mandibular movement?
Pterygoid plexus
What is associated with hematoma and spread of infection during incorrectly administered PSA injections?
Pterygoid plexus
What is a venous plexus of small anastomosing vessels?
Pterygoid plexus
Where is the pterygoid plexus located?
Around pterygoid muscles; surrounds maxillary artery in infratemporal fossa
