Test 2 Flashcards
Are local anaesthetics vasodilators or vasoconstrictors ?
Vasodilators
What does the vasodilating property of local anaesthetic cause?
- Increased rate of anaesthetic absorption into the bloodstream by enabling the anaesthetic to be carried away frm the injection site
- Decrease in the duration of the anaesthetic’s action by enabling it to diffuse quickly from the injection site
3, Higher plasma levels of local anaesthetic increasing the risk of toxicity - Increased bleeding in the area due to increase in blood flow
What are solutions added to local anaesthetic solutions to delay the absorption of local anaesthetics?
Vasoconstrictors
What are the two vasoconstrictors currently used in North America?
Epinephrine
Levonordefrin
What are the four reasons vasoconstrictors are added to anaesthetic?
- To decrease the blood flow in the area of anaesthetic administration by constricting the blood vessels.
- To provide hemostasis
- To increase the duration of the anaesthetic effects, thus improving the success rate and intensity of the nerve blood
- To reduce the risk of systemic toxicity by allowing a lower administered dose
How many mL of solution in a LA cartridge?
1.8mL
How many mL in an articaine cartridge?
1.7mL
2% lidocaine contrains what concentration of local anaesthetic agent?
2%
What is the ratio (eg. 1:100 000)?
Concentration of vasoconstrictor
What is the most widley used LA with a vasoconstrictor?
Lidocaine 2%
What LA has less vasodilation than lidocaine and is metabolized in the liver?
Mepivacaine 3% plan or 2% Levonordefrin
What LA has limited vasodilation, is metabolized primarily in the lung and then the liver, lasts for 10-60 minutes for pulpal anaestheia when plain and 60-90 minutes with 1:200 000 epi?
4% Prilocaine
What LA has a shorter half life (45 minutes), lowest toxicity, rapid biotransformation, is mostly metabolized in plasma with 10% in the lungs and lasts 120-300 minutes with 1:200 000 epi or 180=360 minutes with 1:100 000 epi?
4% Articaine
What LA has a longer onset of action but longer duration, lasts 240-540 minutes with 1:200,000 epi, is more lipid soluble so less concentraion of drug needed than other LA agents, has the longest half-life at 3.5 hours, the highest toxicity, and is metabolized in the liver?
Bupivacaine 0.5% (Marcaine)
What LAs are metabolized in the liver?
Lidocaine
Mepivacaine
Bupivacaine
What LA is primarily metabolized in the lungs and then the liver?
Prilocaine
What LA is primarily metabolized in the plasma and 10% in the lungs?
Articaine
What are the LAs in the DC clinic?
4% Septanest 1:100 000 (Articaine)
2% Xylocaine 1:100 000 (Lidocaine)
4% Citanest Plain (Prilocaine)
Where are LAs excreted?
Kidneys
Small percent unchanged in urine
What is the composition of LA solutions?
- LA agent
2.Vasoconstrictor - vasoconstrictor preservatives: sodium bisulfite, metabisulfite, acetone sodium bisulfite - Sodium hydroxide
- Sodium chloride
What is the function of vasoconstricor preservatives?
Provide a prolonged shelf life of approximately 18 months via antioxidant properties
What are the disadvantages to vasocontrictor preservatives?
Increase solution’s acidity - slower onset of action
Potential for allergic reactions
What acts as a buffer in LA solution that alkalinizes or adjusts, the pH of the solution between 6 and 7?
Sodium hydroxide
What acts as a buffer creating an injectable solution that is isotonic and compatible with tissues?
Sodium chloride
Why do we see an increase in the potential for allergic reactions with the addition of vasoconstrictor preservatives?
Sulfites are one of the top food allergens but are not considered a true allergy. Individuals who are allergic to sulfites should not be given an anaesthetic with a vasoconstrictor
Up to __% of asthmatic clients who receive LA with vasoconstrictors are allergic to bisulfites.
10%
What are the considerations for LA selection?
- Duration
- Post-Treatment Pain Control
- Sodium Bisulfate or Metabisulfite
- Allergy
- Client’s Health Assessment
- Patient-to-Patient Variations
- Adverse Reactions/Toxicity
What are short acting anaesthetics?
Approximately 30 minute durations, pulpal anaesthesia with no vasocontrictor.
What are examples of short acting anaesthetics?
Lidocaine 2% plain
Mepivacaine 3% plain
Prilocaine 4% plain
What are immediate acting anaeshetics?
Approximately 60 minute duration of pulpal anaethesia and contains a vasoconstrictor
What are examples of immediate acting anaesthetics?
Lidocaine 2% 1:100 000 and 1:50 000
Mepivacaine 2% 1:200 000
Priolcaine 4% 1:200 000
Articaine 4% 1:100 000 and 1:200 000
What are long acting anaesthetics?
Approximately 90 minute durations of pulpal aneathesia with a vasoconstrictor.
What is an example of a long acting anaesthetic?
Bupivicaine 0.5% 1:200 000
What patient-to-patient variations need to be considered with LA selection?
- Individual response to anaesthetic
- Accuracy of anaesthetic administration
- Vascularity of tissue
- Variation of anatomic structure
- Injection technique
Adverse reactions/toxicity area directly related to
- Concetration of the drug and dose administered
- Route of tranmission
- Rate of injection
- Vacularity
- Age of client
- Weight of client
- Health of client
- Route of metabolism and exretion of drugs
What kind of contraindication is it when LA or vasoconstrictor cannot be administered safely and must be avoided?
Absolute contraindication
What type of contraindication is it when LA or vasodilator can be administered but only after careful consideration of client safety and appropriate modifications?
Relative contraindication
What is a safe dose of vasoconstrictor that can be administered to a patient with ischemic health disease by limiting the amount of epi or levonordefrin?
Cardiac Dose
Can a cardiac dose also be used for the medically compromised?
Yes
What is the cardiac dose of epi?
0.04mg
What is the cardiac dose of levonordefrin?
0.2mg
What type of contraindication are tricuclic antidepressants?
Relative
Why are are tricyclic antidepressants a relative contraindication?
Medications in combination with epi can increase BP 2x while agents with levonodeferin and norepinehrine can increase BP 5x.
Clients with arrhythmias are an even greater concern
What to do if a client is on a tricyclic antidepressant?
Limit epi to the lowest effective dose - cardiac dose (0.4mg/appt)
What type of contraindication is cardiovascular disease (bypass suergry, history of cardiovascular disease, heart attack/stroke, unstable angina)?
Relative
How long after stroke or MI before dental treatment?
4-6 weeks of cardiac event
Why is phenothiazine a relative contraindication?
Antagonizes the effects of epi (can cause hypotension). Administer lowest effective dose, limit vasocontrictor to cardiac dose
What type of contraindication is cocaine use?
Absolute contraindication
Why is cocaine use an absolute contraindication for vasoconstrictor?
Cocaine stimulates the release of norepinephrine, can cause tachycardia, severe hypertension and arrhythmia
Cocaine + vasoconstrictor =
MI (heart attack)
Are beta blockers (Atenolol, Metoprolol, Timolol) a relative or absolute contraindication?
Relative
Why are beta blockers a relative contraindication?
Drug decreases hepatic flow and inhibits hepatic metabolism of amides. Increases the half-life of amide anaesthetic thereby increasing the risk of toxic overdose
What to do for clients on beta blockers?
Use LA which is not metabolized in the liver
What type of contraindication is Tagamet (cimetidine)?
Relative
Why is Tagamet a relative contraindication?
Drug decreases hepatic flow and inhibits hepatic metabolism of amides. Increases the half-life of amide anaesthetic thereby increasing the risk of toxic overdose
How to avoid toxic overdose with Tagamet?
Use LA which is not metabolized in the liver (Articaine)
What type of contraindication is uncontrolled hyperthyroidism?
Absolute
What type of contraindication is controlled hyperthyroidism?
Relative
Why is hyperthyroidism a contraindication?
Possible exaggerated response to vasoconstrictor
What to do for a controlled hyperthyroidism client?
Use cardiac dose 0.04mg/appt
What kind of contraindication is methemoglobinemia?
Absolute to priolcaine and articaine
What is methemoglobinemia?
A blood disorder where blood has the inability to bind to oxygen
What happens to clients with methemoglobinemia given priocaine and articaine?
Cyanosis of the tissues
Respiratory distress
Lethargy response
What type of contraindication is pregnancy?
Absolute for elective treatment
What is the best approach for LA and pregnancy?
Avoid LA if possible
What trimester is LA best used in?
2nd
What to do for LA and bleeding disorders?
Infiltration injections due to decreased risk of hemotoma
What type of contraindication is glaucoma?
Absolute
Why is glaucoma an absolute contraindication?
Increase the amount of ocular pressure
What type of contraindication is kidney disease?
Relative
What to do for kidney disease clients?
Limit does of LA - use minimal effective dose
What type of contraindication is liver disease?
Relative
What to do for liver disease clients?
Use minimal effective dose - 0.04mg
What are the signs and symptoms of mild LA overdose?
- Disorientation
- Nervousness
- Flushed skin colour
- Apprehension
- Twitching, tremors, shivering
- Dizziness, light-headedness
- Visual/auditory distrubances
- Heache
9.Tinnitus
How to manage a mild LA overdose?
Terminate procedure
Reassure
Place in comfortable position
Administer oxygen
Provide CPR if necessary
Monitor vitals
Summon EMS if needed
Allow client to recover and discharge
What are the signs and symptoms of severe LA overdose?
Muscle twitching
Convulsions
Seizures
CNS and CVS depression
How to manage severe LA overdose?
Terminate procedure
Supine position, legs elevated
Summon EMS
Provide CPR if necessary
Monitor vitals
Administer an anticonvulsant
Transport patient to hospital after stablized
What are the signs and symptoms of vasoconstrictor overdose?
Increasing fear/anxiety/restlessness
Tension
Throbbing headache
Tremor
Weakness
Dizziness
Pallow
Respiratory difficulty
Increased heart rate
How to manage vasoconstrictor overdose?
Terminate procedure
Upright position
Reassurance
Summon EMS if needed
Provide CPR if needed
Administer oxygen
Monitor vitals
Allow client to recover and discharge
What is the highest amount of drug that can be safely administered per appointment to a client depending on their physical health?
Maximum Recommended Dose
Maximum Recommended Dose for LA is based on
The client’s weight
What is the maximum dose that any client can recieve per appointment regardless of their weight?
Absolute Maximum Recommended Dose
Absolute Maximum Recommended Dose is calculated on the average client weighing
150 lbs
What is the drug that limits the total amount of volume delivered based on the client’s medical condition?
Limiting Drug
For healthy clients, the limiting drug is usually ___ NOT ___.
Usually anaeshetic NOT vasoconstrictor
For medically compromised clients, the limiting drug is the
Vasoconstrictor
What do we need to calculate?
Maximum dose of LA (if limiting drug)
Mg of LA given
Mg of epi given
Maximum dose of vaso constrictor (if limiting drug)
LA carpules may contain how many drugs?
1 or 2. The anaesthetic and if needed, the vasoconstrictor.
Who determines the maximum recommended dose of LA?
Drug manufacturer
What is the checklist for LA as a limiting drug?
Patient’s weight
Drug concentration
Amount of LA in cartridge
Maximum Recommended Dose
What are the (math) steps for administering LA?
- Medical History
- Calculate Maximum Recommended Dose in mg
- Calculate mg of LA solution in 1 cartridge
- Convert MRD to cartridges
- Calculate mg administered per appointment
LA drugs are listed a percentage. How to convert to mg?
Multiply by 10. Ex.
2% solution is 20mg/ml
How to calculate the mg of epi in a carpule?
Determine the mg of vasocontrictor per 1mL (1:100,000 = 0.01mg/1mL)
Multiply that by 1.8mL
Multply that by numbers of cartridges used
Which is denser, the maxilla or the mandible?
Mandible
Which has more anatomical variation, the maxilla or the mandible?
Mandible
What is the fold of mucosal tissue where the ramus ascends?
Pterygomandibular Fold
What is the syringe placement for the inferior alveolar nerve block?
Superior to opposite mandibular second premolar
At the corner of the mouth
Insert the needle until bone is felt
Bevel of the needle is towards the bone
What is the inferior alveolar nerve block injection technique?
Must be within 1mm of target
Insert needle 20-25mm ( ⅔ to ¾ length of a 25gauge needle)
Slow deposition - 60-120 seconds
Aspirate often - every ¼ of cartridge, turn slightly and aspirate
1-2 carpules of LA
What is the failure rate of the inferior alveolar nerve block?
15% - 20%
Waht is the most common cause for comlications with the inferior alveolar nerve block?
Anatomical variances in the height of the mandibular foramen
What are the causes for complications with the inferior alveolar nerve block?
Anatomical variances in height of mandibular foramen
Greath depth of soft tissue penetration required to reach bone
Asymmetrical anatomical positioning
Incorrect syringe angle (contacting the bone too soon or not at all)
What are the complications experienced with the inferior alveolar nerve block?
- Lingual shock
- Inadequate anaesthesia
- Incomplete anaesthesia
- Transient facial paralysis
- Hematoma
- Parasthesia
What is lingual shock caused by?
The needle passing by the lingual nerve, it shocks the nerve
Should you try to deposit a small amount of LA to prevent a lingual shock?
No. The lingual shock is quick and unavoidable
What causes inadequate anaesthesia with the inferior alveolar nerve block?
Needle was below the mandibular foramen
What causes incomplete anaesthesia in the inferior alveolar nerve block?
BIFID inferior alveolar nerve
What causes transient facial paralysis?
LA going into the paratoid gland
What are the signs and symptoms of transient facial paralysis?
Eyelid won’t close
Drooping of the lips
Lasts for hours - reassure the client
True or False: Inferior alveolar nerve block has the highest positive aspiration rate of 15% - 20%?
True
What causes parasethesia from the inferior alveolar nerve block?
Trauma to the lingual nerve
What are the signs and symptoms of parasthesia with the inferior alveolar nerve block?
Burning
Pins and needles
What is the syringe placement for the buccal block?
Distal and buccal to the last mandibular molar paralell to the tooth arch line (head straight in)
What is the technique for the buccal block?
Insert needle 1-4mm
Gently contact the bone
Deposit ⅛ - ¼ of a carpule over 10-20 seconds
What are the complications with a buccal block?
- Leakage of solution
- Ballooning of tissue
- Cheek biting
How to avoid leakage of solution at the injection site with the buccal block?
Insert needle deeper
What causes ballooning of tissue with the buccal block?
Too rapid deposition of LA
How to avoid cheek biting with the buccal block?
Educate client
What is the injection technique for the mental/incisive block?
Insert needle 5-6mm to ensure the bevel is covered at the depth of the muccobuccal fold anterior to the mental foramen
DO NOT CONTACT BONE
Deposit ⅓ to ½ carpule for 30-60 seconds
Massage tissues for 2 minutes if incisor aneasthesia is required with client upright
What is the complication with mental/incisive block?
Hematoma - rare, positive aspirations can occur
When is a mental block recommended?
Anaestheia of the facial gingival tissue anterior to the mental foramen
When is an incisive block recommended?
Anaesthesia of the teeth and periodontium of the facial soft tissue anterior to the mental foramen
What is the technique for posterior superior alevolar nerve block?
Insert short needle approximately ¾ of its length at the height of the mucobuccal fold at the apex of the 7
Deposit location is superior to the 7, posterior and superior to the posterior border of the maxilla at the PSA nerve foramina
Deposit ½ to full cartridge for 60-120 seconds
What is the needle angulation for the posterior superior alveolar nerve block?
45° to the maxillary occlusal plane
What are the advantages of the posterior superior alveolar nerve block?
Atraumatic - bone not contacted
High success rate (95%)
Only one injection
Minimizes the total volume of LA solution
What are the disadvantages of posterior superior alveolar nerve block?
Risk of hematoma
No bony landmarks
What is the complication with the posterior superior alveolar nerve block?
Hematoma
What causes hematoma with the posterior superior alveolar nerve block?
Overinsertion into the pterygoid plexus of veins and/or artery
How to avoid hematoma with the posterior superior alveolar nerve block?
Use more conservative method with a short needle, advance to ¾ the depth of the short needle
Aspirate on two planes (rotate barrel) prior to LA deposition, and then re-aspirate every ¼ of deposition
Use more conservative injections instead
What is a safer alternative to the posterior superior alveolar nerve block?
Supraperiosteal Injection
When is the supraperiosteal injection commonly used?
To freeze maxillary molars
What is the deposit location of the supraperiosteal injection?
Apex of the selected tooth
What is the technique for the supraperiosteal injection?
Insert 5mm or ¼ the depth of a short needle with bevel towards bone
Deposit ⅓ of cartridge for 30-60 seconds
Do not need to contact bone
What is the techniquq for the middle superior alveolar nerve block?
Insert 5mm or ¼ the depth of a short needle at the height of the mucobuccal fold at the apex of the 5
Deposit superior to the 5
Deposit ½ to ⅔ of cartridge for 60-90 seconds
Do not need to contact bone
What is the technique for the anterior superior alveolar injection?
Insert 5 mm or ¼ the depth of short needle at the height of the mucobuccal fold at the apex of the 3
Deposit ⅓ to ½ of cartridge for 30-60 seconds
Do not contact the bone
What is the technique for the infraorbital block?
Insert ¾ of short needle at the height of the mucobuccal fold, superior to the 4
Deposit ½ to ⅔ of cartridge for 60-90 seconds superior to the rim of infraorbital foramen until bone is gently contacted
Use finger pressure of the infraorbital notch
Do the greater palatine and nasopalatine injections require you to contact bone?
Yes
Why is there a higher rate of discomfort with palatal injections?
Due to bony contact
What is the technique for the greater palatine injection?
Insert short needle 3-6mm or just until bevel is covered - need to contact bone
Deposit ¼ of cartridge until blanching of tissue at the greater palatine foramen for 20 to 30 seconds
What is the technique for the nasopalatine block?
Insert short needle 3-6mm or just until the bevel is covered lateral to the incisive papilla gently contacting bone
Deposit at incisive foramen ¼ of cartridge until blanching of tissue for 20-30 seconds
