Delivering Local Anesthetics Flashcards
- Why is it critical to aspirate prior to depositing any anesthetic solution into a patient’s tissues:
a. to determine if the operator has reached the correct depth
b. to verify that the operator isn’t in a blood vessel prior to depositing the solution
c. to verify that the operator isn’t in connective tissue prior to depositing the solution
d. it isn’t critical to aspirate prior to depositing anesthetic solution
b. to verify that the operator isn’t in a blood vessel prior to depositing the solution
It is critical to aspirate prior to depositing any anesthetic solution into a patient’s tissues to verify that the operator isn’t in a blood vessel prior to depositing the solution.
Aspiration must be performed prior to any injection.
- Which gauge needle has the smallest diameter?
a. 30 gauge needle
b. 27 gauge needle
c. 25 gauge needle
a. 30 gauge needle
The smallest diameter is the 30 gauge needle. The higher the number, the smaller is the diameter of the lumen of the needle.
Therefore, between a 25, 27 or 30 gauge needle, the 30 gauge would have the smallest diameter.
- What is an advantage of using a larger gauge needle (such as a 25 gauge) over a smaller gauge needle (such as a 30 gauge):
- there is less deflection of the needle with the larger gauge
- greater accuracy of injecting at the proper site of deposition with a larger gauge
- needle breakage is less likely to occur when a larger gauge is used
- it is easier to perform aspiration with a larger gauge needle
a. 1, 3 and 4 only
b. 1, 2 and 3 only
c. 2 and 4 only
d. all of the above
e. none of the above
d. all of the above
All of the choices were correct.
there is less deflection of the needle with the larger gauge - particularly when the depth of soft tissue being penetrated is significant as in the IAN
less deflection leads to greater accuracy at reaching your target site - once again, particularly when the depth of soft tissue being penetrated is significant as in the IAN
while needle breakage is not a problem with disposable needles, it is less likely to occur with larger gauge needles
aspiration is easier and more reliable with a larger gauge needle, particularly since it takes more pressure to aspirate when a narrower, smaller gauge needle is being used
- It is an acceptable practice when giving an injection to penetrate the tissues up to the hub of the needle:
a. True
b. False
b. False
It is NOT an acceptable practice to “hub” the needle. The hub is the weakest point of the needle - if it is inserted to the hub and then breaks, the tissues will cover the needle and it will be difficult at best to remove the needle from the patient’s tissues.
- How can the clinician easily determine the gauge of a needle?
a. 30 gauge is blue, 27 gauge is yellow and 25 gauge is red
b. 30 gauge is yellow, 27 gauge is red and 25 gauge is blue
c. 30 gauge is red, 27 gauge is blue and 25 gauge is yellow
d. 30 gauge is green, 27 gauge is yellow and 25 gauge is red
a. 30 gauge is blue, 27 gauge is yellow and 25 gauge is red
- Your patient requires anesthesia for multiple teeth in the mandibular left quadrant. Which length needle should be used:
a. a short needle
b. a long needle
c. it doesn’t matter - both will work equally well
b. a long needle
This patient will need a long needle. Injections such as an IAN that pass through substantial amounts of tissue require a long needle.
- The proper manner to dispose of a needle after it has been used is:
a. “scoop” the cap back onto the needle, snap the cap on, and then dispose in a Sharp’s container
b. place the cap on the needle, bend the needle at the hub, and then dispose in a Sharp’s container
c. autoclave the needle and then dispose in a Sharp’s container
d. autoclave the syringe with the needle still attached and then dispose in the office trash receptacle
a. “scoop” the cap back onto the needle, snap the cap on, and then dispose in a Sharp’s container
The needle should have its cap “scooped” back on, the cap should then be snapped on, and then it should then be unscrewed from the syringe and disposed of in a Sharp’s container.
- It is recommended that anesthetic cartridges be soaked in either an alcohol or a sterilizing solution to assure asepsis:
a. True
b. False
b. False
Anesthetic cartridges should NOT be allowed to soak in any type of solution, whether it is alcohol or a sterilizing solution. The diaphragm on the cartridge is semi-permeable and will allow the diffusion of the solution into the cartridge, thus contaminating the solution.
If one has been soaked in a solution, it may appear to have an extruded stopper with no bubble present in the cartridge. If it is used on a patient, it may cause a burning sensation, or if it is in sufficient quantity, it may cause parasthesia.
- Bubbles of approximately 1 - 2 mm found in anesthetic cartridges are:
a. an indication that the cartridge has been contaminated
b. an indication that the cartridge has been dropped
c. unsafe to use as it indicates that oxygen has seeped into the cartridge
d. not a concern
d. not a concern
Bubbles approximately 1 - 2 mm in diameter found in the cartridge are not of concern. The bubbles are composed of nitrogen gas which has been added to the cartridge during its manufacturing process to prevent oxygen from being trapped inside the cartridge. The oxygen could potentially destroy the vasoconstrictor which may be in the solution.
However, if bubbles larger than 1 - 2 mm in diameter are found in the cartridge and it appears the stopper is extruded, this may indicate that the solution in the cartridge has been frozen. Since asepsis cannot be guaranteed, their use is not advised.
- The contents of an anesthetic cartridge may include which of the following:
- local anesthetic drug
- vasoconstrictor
- preservative for the vasoconstrictor
- distilled water
- sodium chloride
- methylparaben
a. all of the above
b. 1, 2, 4, 5, and 6
c. 1, 2, 3, 4 and 5
d. 1, 2 and 5
e. 1, 2, 3 and 4
c. 1, 2, 3, 4 and 5
An anesthetic cartridge can contain the following:
local anesthetic drug: for example, lidocaine
vasoconstrictor: Also called a vasopressor, these will lower the pH of the solution and are only found in cartridges that indicate that a vasoconstrictor is present
preservative for the vasoconstrictor: This serves as an antioxidant for the vasoconstrictor to prevent it from being biodegraded by oxygen. Sodium bisulfite is used for this purpose.
distilled water: This provides volume to the solution.
sodium chloride: Sodium chloride helps to make the solution isotonic (similar) with the body’s tissues
Methylparaben has NOT been added to dental cartridges since 1984
- The concentration of the local anesthetic drug (for example, lidocaine) found in topical anesthetics is usually greater than if that same agent were administered by injection.
a. True
b. False
a. True
The concentrations found in topical anesthetics are usually greater than if that same agent were administered by injection. That is because a higher concentration is needed for the active ingredients to diffuse through the mucous membranes.
This quick diffusion to the nerve endings helps with a faster onset of the topical anesthetic. This, however, can lead to a greater potential for toxicity not only topically, but also systemically.
A comparative example is Lidocaine which is used at 2% concentrations for injection, but at 5% for topical application.
- Which of the following vasoconstrictors is found in topical anesthetic agents:
a. Epinephrine
b. Neo-Cobefrin
c. Levophed
d. none of the above
d. none of the above
None of the options provided were correct, as vasoconstrictors are not found in topical anesthetic agents.
Additionally, since anesthetics by themselves are vasodilators, this can speed the absorption of the anesthetic by the cardiovascular system. Combined with the fact that there is no vasoconstrictor present to slow absorption, this can increase possible overdose reactions and decrease the duration of action of the topical anesthetic.
- The most common topical anesthetic, benzocaine, falls under which drug classification:
a. amide
b. ester
b. ester
Benzocaine is an ester. While it is poorly soluble in water, it also has a poor absorption into the cardiovascular system. The benefits of this are that it will be absorbed slowly which provides a long duration of effects with an absence of toxic effects.
The onset of action for benzocaine is under one minute. Contraindications for its use would be patients with a known allergy to the ester-type of local anesthetic agents. Some common brand names include: Cetacaine, Gingicaine, Hurricaine and Topicale.
- Your patient is a 56-year old woman who informs you that she is allergic to PABA (para-aminobenzoic acid). Which of the following topical anesthetics could you use when treating her:
- benzocaine
- tetracaine
- lidocaine
- lidocaine/prilocaine mixture
a. 1 and 4 only
b. 2 and 3 only
c. 3 and 4 only
d. 1, 2 and 3 only
e. all the above are acceptable
PABA is found in esters. Lidocaine is an amide, therefore it could be used for a patient with an allergy to esters. The lidocaine/prilocaine mixture is also an amide, and can be used for patients with known sensitivities to esters.
The lidocaine/prilocaine mixture is commercially available as Oraqix, but is contraindicated for people with congenital or idiopathic methemoglobinemia due to the prilocaine content.
- For the same patient as in the preceding question (a 56-year old woman who is allergic to PABA), you notice that she is experiencing pain as you are administering her last injection. She has received a PSA, MSA, ASA, GP and you are about to administer the NP. What are some things you should confirm prior to the next injection:
- is the needle dull?
- is there a barb on the end of the needle?
- is she allergic to the local anesthetic you are using?
- is she allergic to the topical anesthetic you are using?
a. 1 and 2 only
b. 3 and 4 only
c. 1, 3 and 4 only
d. all of the above should be checked
a. 1 and 2 only
Since it appears the same needle was used for the PSA, MSA, ASA and GP on this patient, the needle is most likely dull. Three penetrations are usually the limit before a needle loses its sharpness. The needle should be changed prior to any other injections.
Also, there could be a fishhook-type barb on the end of the needle. The clinician can place the needle on a sterile 2 x 2 gauze and draw it backward to see if it catches or snags. If it does, the needle should be discarded as it will cause pain upon insertion. This can usually be found out prior to any injection being given with the needle.
You should know whether the patient is allergic to the local anesthetic or topical anesthetic PRIOR to administering the injection, and an allergy would not cause this type of pain reaction.
