Local Anesthesia Board Review 2016 – Flashcards
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What anatomical feature of the maxilla allows for a high success rate of anesthesia by infiltration techniques?
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The facial bone of the maxilla is relatively thin and permeable. Local anesthetic solutions easily diffuse through maxillary bone.
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What are the two most common causes of anesthetic failure associated with maxillary infiltration injections?
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Deposition of solution too far from the apex of a tooth and inadequate volumes of solution.
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What percentage of individuals is missing the MSA nerve?
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50% to 72%
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What is the distance from the infraorbital ridge to the infraorbital foramen in a typical adult?
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8-10 mm
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What volume of anesthetic solution is deposited for an infraorbital (IO) nerve block?
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minimum of 0.9 mL
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What vascular structures are located in the infratemporal fossa?
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Maxillary artery and its branches, and the pterygoid plexus of veins.
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Name the three basic types of intraoral injections frequently used in dentistry.
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Infiltration, field block, and nerve block injections
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Define infiltration injections
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Infiltration injections involve the deposition of local anesthetic drugs directly at or near small terminal nerve endings in the immediate area of treatment.
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Define field block injections
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Fields block injections involve deposition of anesthetic drugs near larger terminal nerve branches for treatment of areas near or a small distance away from the site of injection and areas of treatment. Field blocks are commonly referred to as infiltrations and, by some, as supraperiosteal injections.
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Define nerve block injections.
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Nerve block injections are generally characterized as depositions near primary nerve trunks at greater distances from the areas of treatment, which provide wider areas of anesthesia.
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How is needle deviation prevented from the penetration site to the deposition site?
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The greater the distance from the penetration to the deposition site, the greater the potential for deviation of the needle tip away from the deposition site. Close attention to proper landmarks and maintaining appropriate syringe barrel angles during injection will reduce these deviations.
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What is the final step in armamentarium preparation?
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The final step in armamentarium preparation is to confirm that all safety controls are in place. These controls must include appropriate personal protective equipment (PPE) for clinicians and patients and must focus special attention on the safe handling of needles.
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What is the initial penetration depth into the mucosa?
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1-2 millimeters (approximately the length of the bevel)
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How can a "false negative" aspiration be prevented?
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To check for false negative responses, rotate the syringe slightly; this will reposition bevels away from vessel walls.
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What is the correct procedure to follow if a small trickle of blood enters the cartridge following an aspiration test?
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If it does not obstruct clear vision of a subsequent aspiration, the needle can be repositioned slightly and aspiration can be repeated. After a second test is negative, the clinician may continue with the injection and deposit the drug.
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What is the most important step in the administration of a safe and comfortable injection at the optimum deposition site? Why?
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The rate of delivery. Slow delivery of the drug reduces the risk of overdose and complications if the drug is inadvertently injected into the bloodstream after a false negative aspiration.
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What is considered a safe and more comfortable rate of deposition?
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1 mL of solution per minute
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What is the final safety step following an injection?
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Properly manage and recap the needle
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Describe the six classes of the ASA Physical Status Classification System.
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ASA I A normal healthy patient ASA II A patient with mild systemic disease ASA III A patient with severe systemic disease ASA IV A patient with severe systemic disease that is a constant threat to life ASA V A moribund patient who is not expected to survive without the operation ASA VI A declared brain-dead patient whose organs are being removed for donor purposes
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What is the correct ASA classification for someone with asthma?
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ASA II
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What is the correct ASA classification for someone with epilepsy?
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ASA II
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What is the correct ASA classification for someone with congestive heart failure?
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ASA III
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What is the correct ASA classification for someone with hyperthyroidism?
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ASA II
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What is the correct ASA classification for someone with COPD requiring oxygen?
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ASA IV
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Define the term concomitant.
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Drugs that are in a patient's system when local anesthetics are administered are referred to as concomitant
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Why is it important to take vital signs before local anesthetics are administered?
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Vital signs serve as baseline values and are used for comparisons should adverse events develop after local anesthetics are administered.
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Define functional capacity
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Assessment tool to identify when a medical risk is the greatest, and is expressed in metabolic equivalent of task (MET).
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Provide examples of physical activities an individual must be able to perform in a MET 4 capacity.
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Able to do light housework, move furniture, walk up a flight of stairs without chest pain, walk up a hill, walk on level ground at 4 mph, run a short distance, participate in activities such as dancing, golf, bowling, or play doubles tennis.
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TRUE or FALSE Typically, most local anesthetic injections through tissue are not considered to be invasive and do not require antibiotic premedication.
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True
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TRUE or FALSE Patients with hemophilia and clotting disorders require antibiotic premedication and modification of injection types, drug selection, and doses of local anesthetics.
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False. Patients with hemophilia and clotting disorders do not require antibiotic premedication; however, these patients may require modification of injection types, drug selection, and doses.
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TRUE or FALSE In children, anxiety related to the administration of local anesthesia may provoke syncope or hyperventilation. In adults, anxiety more commonly provokes asthmatic episodes.
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False. In children, anxiety related to the administration of local anesthesia may provoke asthmatic episodes. In adults, anxiety more commonly provokes syncope or hyperventilation.
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TRUE or FALSE The systemic effects of local anesthesia on the respiratory system are typically minimal. Epinephrine acts on β receptors of the smooth muscles of the bronchioles to dilate air passages.
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True
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TRUE or FALSE A patient has taken a large dose of narcotics prior to local anesthetic administration. Local anesthetic drugs can have a profound effect on the central nervous system (CNS) because local anesthetic drugs are CNS stimulants.
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False. Local anesthetic drugs can have a profound effect on the CNS because local anesthetic drugs are CNS depressants. This depression is additive to any existing CNS depression.
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TRUE or FALSE Patients with sickle cell anemia should not receive local anesthesia with vasoconstrictors during a crisis without antibiotic prophylaxis.
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False. Patients with sickle cell anemia should not receive local anesthesia with or without vasoconstrictors during a crisis. Patients with sickle cell anemia should not receive dental treatment during a crisis.
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TRUE or FALSE Patients with extensive liver damage may not be able to metabolize ester local anesthetic drugs efficiently.
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False. Patients with extensive liver damage may not be able to metabolize amide local anesthetic drugs efficiently. Significant liver dysfunction in category ASA III is a relative contraindication for local anesthesia. Ester and amide local anesthetics can be used for these patients with caution.
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What LA would you give patients with liver damage?
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Articaine, particularly in significant liver disease, may have an advantage over other amide drugs because it largely avoids liver metabolic pathways when used for oral injections.
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TRUE or FALSE Pregnancy poses a temporary and relative contraindication to local anesthetics, and the second trimester of pregnancy is considered the safest period for both the fetus and the mother.
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True
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TRUE or FALSE Some patients experience allergic reactions to synthetic epinephrine.
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False. Because synthetic (exogenous) epinephrine is identical to endogenous epinephrine.
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TRUE or FALSE Individuals taking nonselective beta-blocking agents for hypertension or other conditions such as migraines should never be given epinephrine.
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False. Individuals taking nonselective beta-blocking agents for hypertension or other conditions such as migraines should be given epinephrine with caution.
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Why is it important to assess kidney function prior to the administration of local anesthetic drugs?
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The kidneys are the major excretory organs for local anesthetics.
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Define relative contraindication
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A relative contraindication for local anesthesia is one in which local anesthetics may be given, but with caution and/or modifications.
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Define atypical plasma cholinesterase.
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Atypical plasma cholinesterase impairs a patient's ability to effectively metabolize ester-type local anesthetics in any form, injectable or topical.
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What type of condition is atypical plasma cholinesterase?
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It is a genetic (autosomal recessive) condition and has a frequency of approximately 1 in 3,000 patients.
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Define methemoglobinemia.
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Methemoglobinemia is a genetic or acquired condition which reduces the oxygen-carrying capacity of blood.
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What LA agents can cause aquired methemoglobinemia?
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Benzocaine topical and injectable Prilocaine
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What is the recommendation for use of vasoconstrictors with concomitant use of nonselective β-blockers?
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Unless vasoconstriction is necessary, avoid both epinephrine and levonordefrin. When vasoconstriction is necessary, limited doses may be used with caution.
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What is the most common syringe design in dentistry?
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The sterilizable, breech-loading, cartridge-type, aspirating syringe.
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Which needle has a larger diameter, a 30 gauge or a 25 gauge?
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25 gauge
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Why is a needle designed with a bevel?
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To facilitate atraumatic penetration through mucosal and cutaneous tissues.
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What needle lengths are used in dentistry?
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long ~32 mm (1½ inches) short ~25 mm (1 inch) extra-short ~12 mm (1/2 inch)
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What is the OSHA standard for the prevention of needlestick injuries?
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"Recapping or needle removal must be accomplished through the use of a mechanical device or a one-handed technique."
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What are the typical contents of anesthetic cartridges?
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-distilled water (the diluent, majority of the solution) -local anesthetic drug -vasoconstrictor drug (if present) -sulfite preservative (when vasoconstrictor present) -sodium chloride (for isotonic tissue compatibility)
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What is the volume of solution delivered when two stopper widths are expelled?
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0.4 mL
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What are the reasons cartridges may have large air bubbles?
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Large bubbles can result when solutions have been frozen or contaminated.
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What is the typical shelf-life of local anesthetic solutions with and without vasoconstrictors?
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- 18 months with vaso - 24 months without vaso
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What is the appropriate response if a needlestick or other puncture injury occurs?
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1) All anesthetic procedures and treatment should be terminated and the injured tissues immediately and thoroughly washed with soap and water. 2) The facility exposure manager should be notified while appropriate first aid is initiated. 3) According to CDC guidelines, postexposure management should include documentation in both the patient record and the exposed individual's health record.
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What are the two types of syringes for PDL injections?
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"pistol grip" and "pen type"
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Why do PDL syringes have an enclosed barrel?
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That way if a cartridge fractures there is no danger of glass falling into the mouth.
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What are computer-controlled local anesthetic delivery devices?
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Computer-controlled local anesthetic delivery devices are preprogrammed, electronic delivery systems for the administration of anesthetic injections. The devices have variable-staged, controlled rates of delivery.
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What are the types of CCLAD devices used in dentistry?
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1) Comfort Control System 2) CompuDent/Wand Instrument 3) Single Tooth Anesthesia (STA) System Instrument
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What can topical anesthetic drugs be used for?
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- Penetration site anesthesia prior to needle insertion - During radiographic film placement - Periodontal evaluation and treatment - Procedures confined to superficial mucosa - Placement of retraction cord and rubber dams - Controlling gag reflexes
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Give examples of common topical anesthetic agents.
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benzocaine, dyclonine hydrochloride, lidocaine, tetracaine hydrochloride, butamben, and prilocaine
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Why is benzocaine poorly absorbed into the systemic circulation?
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Benzocaine exists in a nearly 100% base form. It is poorly absorbed into the systemic circulation, which gives it a very low potential for systemic toxicity.
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What is the onset time, peak effect, and duration of benzocaine?
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Onset - 30 seconds Peak effect - 2 minutes Duration - 5 to 15 minutes
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How is benzocaine metabolized?
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ester hydrolysis (via cholinesterase).
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What is the onset time and duration of lidocaine topical?
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between 2 and 10 minutes with an expected duration of 15 minutes
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What is the MRD for lidocaine topical?
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200 mg
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What is the onset and average duration of anesthesia for tetracaine?
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Slow onset, with peak effects taking up to 20 minutes. The average duration of anesthesia for tetracaine is 20-60 minutes.
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Name the three topical drugs combined in Cetacaine® topical anesthetic and provide their clinical properties.
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14% benzocaine (short-acting, fast-onset) 2% tetracaine (long-acting, slow-onset) 2% butamben (intermediate-acting, intermediate-onset)
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What are two examples of eutectic mixtures of local anesthetic drugs?
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EMLA® and Oraqix®
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What drugs are contained in Oraqix®?
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2.5% Lidocaine and 2.5% Prilocaine
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What are some local adverse reactions with the use of topical local anesthetic agents?
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Tissue sloughing, delayed hypersensitivity, redness, pain, and burning at the sites of application.
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What are possible systemic reactions of topical anesthetic overdose?
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Overdoses may manifest as mild CNS depression (restlessness, agitation, and increased heart rate) or more severe CNS and CVS depression (unconsciousness, convulsions, decreased force of myocardial contraction, respiratory collapse, and cardiovascular collapse).
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What information is needed to calculate and determine the dose of local anesthetic drug to be administered?
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1. Concentration for the selected anesthetic drug 2. Dilution percentages for vasoconstrictors 3. Standard cartridge volumes 4. Defined maximum recommended dose for each drug 5. Relevant patient factors such as general health status and weight
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How many mg of a 1% local anesthetic drug are in a standard cartridge?
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18 mg/mL
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How many mg/mL are in a 2% local anesthetic solution?
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36 mg/mL
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How many mg/mL are in a 0.5% local anesthetic solution?
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9 mg/mL
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What is the maximum recommended dose (MRD) per appointment for 2% lidocaine plain?
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MRD 500mg; 3.2mg/lb
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How many mg of 2% lidocaine plain are in two cartridges?
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72 mg
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Determine the maximum dose for 2% lidocaine plain for a 100-pound patient.
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Multiply the maximum dose for 2% lidocaine plain (3.2 mg/lb) by the patient weight (100). 3.2 mg/lb x 100 lbs = 320 mg
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Determine the maximum dose for 4% prilocaine plain for a 120-pound patient.
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Multiply the maximum dose for 4% prilocaine plain (4.0 mg/lb) by the patient weight (120). 4.0 mg/lb x 120 lbs = 480 mg
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Determine the maximum dose for 3% mepivacaine for a 195-pound patient.
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Multiply the maximum dose for 3% mepivacaine (3.0 mg/lb) by the patient weight (195). 3.0 mg/lb x 195 lbs = 585 mg
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A 150-pound patient has received 128 mg of 2% lidocaine plain. How many cartridges have been delivered?
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128 mg ÷ 36 mg/cartridge = 3.5 cartridges
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3.5 cartridges of 2% lidocaine plain have been delivered to a 150-pound patient and an additional 372 mg of the same drug may be delivered. Compute the number of additional cartridges that may be administered.
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372 mg ÷ 36 mg/cartridge = 10.3 cartridges
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When two drugs are delivered with different MRDs, which MRD is applied when calculating total drug doses?
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the lowest MRD
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A 150-pound patient can receive 372 mg of 4% prilocaine in addition to the 128 mg of 2% lidocaine. How many cartridges of 4% prilocaine can be delivered?
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372 mg ÷ 72 mg/cartridge = 5.1 cartridges This patient may receive 5 cartridges.
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What is the difference in calculating doses for vasoconstrictors compared to local anesthetic drug doses?
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Vasoconstrictors are expressed as dilution ratios rather than concentration percentages and the maximum doses for vasoconstrictors are not weight dependent.
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How much epinephrine is contained in a 1:100,000 cartridge of solution?
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0.018 mg
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How much levonordefrin is contained in a 1:20,000 cartridge of solution?
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0.09 mg/cart
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What is the maximum dose for epinephrine and levonordefrin per appointment for patients with ischemic heart disease?
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0.04 mg epinephrine 0.2 mg levonordefrin
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Mnemonic for Cranial Nerves: Oh, Oh, Oh, To Touch And Feel Very Good Vegetables, Ah Heaven!
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Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal
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Mnemonic for Afferent/Eferent Action of Each Nerve: Some Say Money Matters, But My Brother Says, "Big Brains Matter More"
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S=Sensory M=Motor B=Both
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The Nasopalatine Nerve Block is also known as...
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Incisive or Sphenopalatine Nerve Block
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What nerve is the longest branch of the posterior superior nasal branch of the maxillary nerve?
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nasopalatine
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Where does the nasopalatine nerve exit?
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incisive foramen
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What are two types of pre-anesthesia?
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1. Anesthesia that is already in effect from previous injections (eg. NP3) 2. Two-step topical method (1 min topical followed by firm pressure for 1 min)
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What is the Gate Control Therory
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States there are certain locations or gates within the spinal nervous system and when flooded with impulses from less painful stimuli, impulses from more painful stimuli can be blocked.
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What is the rate of deposition for most palatal injections?
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0.5ml over 60 seconds (3mins per cartridge)
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When using 4% solutions on the palate how much should be delivered?
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Total volume should be half due to concerns of neurotoxicity.
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What are the 3 key intraoral landmarks for the IA injection?
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Pterygomandibular raphe, coronoid notch, internal oblique ridge
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What does the pterygomandibular raphe attach together?
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Attaches the buccinator muscle to the superior constrictor muscle of the pharynx.
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What is significant about the raphe when it comes to the IA injection?
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It represents the medial extent of the area into which penetration is made. Meaning, penetration must be made slightly lateral to the raphe.
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What is the significance of the coronoid notch when it comes to the IA injection?
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It defines the height of the injection. 2-3 mm superior to the greatest concavity of the coronoid notch.
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What is the significance of the internal oblique ridge when it comes to the IA injection?
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It represents the lateral extent of the area into which penetration is made.
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What injection has the highest fail rate?
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Inferior Alveolar Nerve Block (IA)
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What is the largest nerve division of the trigeminal nerve?
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Inferior Alveolar Nerve
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Which injection has the highest rate of positive aspirations?
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IA injection (10-15%)
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What nerve is the most frequent injured nerve during injections?
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Lingual nerve resulting in "electric shock" or permanent paresthesias.
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What nerves are anesthetized by the Gow Gates Nerve Block?
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Inferior alveolar, mental, incisive, lingual, mylohyoid, and auriculotemporal nerves.
