Wreb study for local anesthesia questions – Flashcards
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Local anesthesia depresses excitation in nerve endings or inhibiting the conduction of what nerves?
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periphreal
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LA differe from other drugs in that most other drugs are absorbed in the blood stream but LA stop their action once absorbed where?
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systemic circulation
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Why are vasoconstrictors added to LA?
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decrease blood flow at injection site, constrict blood vessels and allows for a longer working time more profound anesthesia and less bleeding
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Why are additives and preservatives added to LA?
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prolong the shelf life by using antioxidant properties
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What are two examples of additives and preservatives?
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sodium bisulfite and sodium metasulfite
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Asthma patients are sensitive to what additive?
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sulfites
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If a person is allergic to sodium bisulfite do you use vasoconstrictor?
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No
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What does a yellow brown tint indicate?
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oxidation
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What should you do if there is oxidation in the carpule?
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dispose of it.
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Are LA's vasodilators or vasoconstrictors?
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vasodilators except cocaine its a vasoconstrictor
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What phase of nerve conduction has positive ca+ on the outside and negative on the inside with no movement of ions?
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resting state
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What phase of nerve conduction has increase permeability to NA+ ions becomes less negative within the nerve?
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deolarization slow phase
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What phase of nerve conduction has enough stimulous to make nerve fire with influx of sodium?
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rapid depolarization
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What phase of nerve conduction returns to resting state which Na goes out of the nerve and k returns in the nerve. influx of K+
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Repolarization
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What is the site of action for a LA?
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nerve membrane
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LA are alkaloid bases meaning they are?
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wea combine with acids to form water soluble salts.
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Base form is lipophilic and non ionized or hydrohillic and ionized?
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lipophilic and non ionized.
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ph of normal tissue is
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7.3 to 7.4
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ph of local anesthesia is
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5.5
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ph of local anesthesia with epinephrine is
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3.3
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ph of inflamed tissue is
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5.5 to 5.6
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when there is an inflamed area it means less or more anesthesia is absorbed causing a slower or faster onset of action...meaning it reduces the potency of the drug and poor anesthesia.
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slower onset, less anesthesia
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Esters hydrolyzed to ______________in the blood by pseudocholinesterase.
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PABA
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Amides metabolized by the ___________ except prilocaine which is metabolized in the ___________
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liver, lungs
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What should you avoid in patients who have liver failure?
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amides
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Where do amides and esters excrete?
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kidneys
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People who have kidney trouble renal disease have a hard time excreting which LA?
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mepivicaine.
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Which LA do we want to avoid if a patient is allergic to a sulfa?
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articaine
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What happens if a patient is allergic what happens to them?
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rash or anaphylaxis
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Do amides cause allergic reactions?
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No
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Vasoconstrictors have an alpha or beta effect on vasoconstrictor causing constriction of blood vessels?
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alpha
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Vasoconstrictors exert their action directly on the what receptors?
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adrenergic
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An overdose amount of vasoconstrictor would produce what effect alpha or beta?
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Beta affect heart and smooth muscle reactions, vasodilation and bronchodilation
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Persistent anesthesia or altered sensation well beyond the expected duration is called
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paresthesia
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how do you give a patient facial paralysis
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deposit anesthesia near the facial (cranial 7) nerve in capsule of paratid gland
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prolonged spasm of the muscles of mastication is called
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trismus
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Trismus happens most offten with what injections?
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psa and ianb
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What is the treatment for trismus
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heat therapy for twenty min every hour or anti inflammatory analgesic diazepam 10mg
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how can you give a patient a hematoma
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nicking an artery
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when is a hematoma most likely to occur what injection?
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psa, ia, mental, io outside of face is psa
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can you get a hematoma on the palate?
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no
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how do you treat hematoma?
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ice for 2 min with reasure
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burning on injection what is the cause
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ph of la solution more acidic, rapid injection, contamination of LA, la too hot
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if you are allergic to one ester are you allergic to all?
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yes
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What is common preservative in fruit and vegies?
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sodium bisulfite
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If a person has a allergic reaction to a sodium bisulfate is it the LA or the Vaso?
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Vaso
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Can you have an allergy to epinephrine?
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no
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What is the most dramatic and acutely life threatening allergic reaction?
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Anaphylaxis
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If a patient has a non lifethreatning reaction what do you do
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benedryl/diphenydramine 50mg for 4 days
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if the patient has a life threatning anaphylaxis immediate reaction what do you do
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activate ems, administer oxygen, epi 0.3 mg every 15 min, 50 mg diphenhydramine
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what is an increased tolerance to a drug that is administered repeadatly
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trachyphlaxis
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What initiates nerve conduction
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dendric zone
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what is not involved in impulse transmission?
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cell body
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What are terminal branches that distribute incoming signals to various CNS nuclei responsible for processing
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axon
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what is term for the ability of the impulse to jump quickly from one node to the next?
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salutatory conduction
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What are the smallest nerve fibers
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cfibers
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what are the largest fibers the most rapid conducting axons and transmite sharp dental pain
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a fibers
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what fibers are not involved in transmitting dental pain
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b fibers
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what fibers cause dull or burning pain
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c fibers
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Afferent or sensory nerves conduct impulses to the
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CNS
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Efferent or motor neurons conduct messages from
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the CNS to the periphery of the body
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What starts the afferent nerve conduction?
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dendric zone
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What is a long nerve fiber that runs the whole length of the nerve?
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axon
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What is the axon incased nerve membrane called
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axolemmas and are surrounded by myelin sheath
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What is the gelatinous substance inside the axon membrane called
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axoplasm
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What is the theory that postulates that the local anesthetic interferes with the sodium channel and blocks the sodium transfer necessary for nerve conduction?
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specific receptor theory
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The anesthetic must permeate how many mm of the nerves length to profoundly block the generation of nerve impulse.
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8-10mm
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If an injection is done two times and still does not produce pain control why is that?
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because of a lower ph of the tissues, edema, hemmorrhage or transudation of surrounding areas.
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Why is anesthesia not as effective when there is an infection?
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ph of the tissue is too low to allow anesthetic to penetrate the nerve
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What is the largest fiber
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A fiber
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The smallest fiber
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C fiber
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Which fiber does not have a myeline sheath
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c fibers.
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What fibers are most easily blocked by local anesthesia
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c fibers. because no myelin sheath makes it easier to access the nerve.
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What can happpen with toxic blood levels?
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anesthesia depress the CNS and cause patient to have convulsions.
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Ester anesthetics are metabolized in the blood stream by
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pseudocholinesterase
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Esters are contraindicated in patients who report they have
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atypical pseudocholinesterase production
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Where are amides metabolized
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liver
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Why are vasoconstrictors added to local anesthetics?
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decrease the absorption of the drug, prolong the anesthetic effect reduce risk of toxisity
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What are the most commonly used vasoconstrictors used in dentistry?
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epinephrine and levonordefrin
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Epinephrine is good for
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hemostatis
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What is the recommended topical form of lidocaine?
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200mg
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What is the most commonly chosen anesthetic today
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lidocaine with 1:100,000 ei.
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Why is 3% mepivicaine without vasoconstrictor used
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patients who cannot take a vasoconstrictor or for short procedures.
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What do you use if you want pulpal anesthesia for longer apointments or when post operative pain is anticipated?
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Bupivicaine
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Why is Bupivicaine not recommended to children or handicapped patients?
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increased risk of postoperative injury (chewing on a numb lip)
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Why would there be mild burning sensation during administration of anesthesia?
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ph of solution, too warm, contamination.
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Does an artery or vein cause hematoma?
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artery
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What is treatment for trismus?
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Heat therapy 20 minutes every hour. and analgesic and muscle relaxants if necessary.
