Chapter 17 - LA Complications and Management

Question 1

Q17-1: Provide examples of possible local complications related to the administration of local anesthesia.

Answer 1

A17-1: Local complications may include anything from postoperative soreness to prolonged anesthesia. The majority of adverse events related to local anesthesia in dentistry involve mild reactions such as postoperative discomfort in the area of injection, syncope, pain from patient self-injury, and mild inflammation following muscle penetrations. These usually present as no more than limited inconveniences or short-term management situations.

Question 2

Q17-2: Provide examples of possible systemic complications related to the administration of local anesthesia.

Answer 2

A17-2: Systemic reactions such as overdose, allergy, and idiosyncratic response occur far less frequently but are generally more serious. While fewer more serious adverse events may be expected, clinicians nonetheless must be prepared to respond appropriately if and when they occur.

Question 3

Q17-3: Explain why the most likely occurrence of hematoma follows PSA and Maxillary (tuberosity approach) nerve blocks.

Answer 3

A17-3: The most likely occurrence of hematoma follows PSA and maxillary nerve blocks (tuberosity approach) due to the proximity of the pterygoid plexus of veins and maxillary arteries to the target sites in the infratemporal and pterygopalatine fossae.

Question 4

Q17-4: Discuss recommendations for minimizing the occurrence of hematoma.

Answer 4

A17-4: Minimizing the number of needle penetrations is recommended, considering that one penetration involves a certain degree of risk, two penetrations double the risk, three triple the risk, and so on. Avoiding trauma in general is also important, as any aspect of an injection that traumatizes tissues increases the risk of hematoma. This can be accomplished by maintaining good access, observing appropriate angulations and penetration depths, and avoiding rapid penetrations and bowing of needles.

Question 5

Q17-5: What injection technique can be substituted for PSA nerve blocks to decrease the risk of hematoma in patients requiring anticoagulant medications?

Answer 5

A17-5: Infiltrations are excellent substitutes for PSA nerve blocks in patients with increased risk of hematoma because of the relatively minimal risk of hematoma formation.

Question 6

Q17-6: What anatomical factor limits the extent of a hematoma formation?

Answer 6

A17-6: Extent of hematoma formation is limited by the degree of flexibility of the tissues into which the blood is emptying. For example, where the tissues are less flexible, such as in the palate, hematoma sizes tend to be more limited.

Question 7

Q17-7: What are the first two protocols to the recognition and management of hematoma?

Answer 7

A17-7: Early recognition and response to developing hematoma can alter its clinical course. Clinicians can create an opposing force by applying pressure and keeping the pressure in place long enough for clotting to begin.

Question 8

Q17-8: What are the primary causes of trismus related to local anesthesia injections?

Answer 8

A17-8: The primary causes of trismus are hemorrhage and muscle trauma following needle penetrations.

Question 9

Q17-9: What is the most frequent muscle to experience trismus?

Answer 9

A17-9: The medial pterygoid is the most frequent muscle to experience trismus.

Question 10

Q17-10: How is the occurrence of trismus minimized?

Answer 10

A17-10: The occurrence of trismus can be minimized by decreasing the number of penetrations, changing needles frequently (especially whenever tips may be barbed), and assuring that needle contamination does not occur before penetration.

Question 11

Q17-11: List the five steps in response to and management of trismus.

Answer 11

A17-11: In the management of trismus, instruct patients to:
1. Apply hot, moist towels approximately 20 minutes every hour (5 minutes on, 10 minutes off).
2. Use analgesics for discomfort, particularly ibuprofen, if appropriate.
3. Open and close the mouth gradually and repeatedly to maintain mobility of the temporomandibular joint.
4. Monitor for signs of infection that may require antibiotics, such as increasing heat, redness, elevated temperatures, and pain.
5. Refer to an oral surgeon or physician if signs and symptoms fail to improve, or worsen

Question 12

Q17-12: What are the possible causes of pain on injection?

Answer 12

A17-12: There are many possible causes of pain on injection. Needle penetrations of well-innervated anatomic structures can cause pain. Rapid deposition of solution can distend tissues, causing pain. Pain can occur due to the irritating and acidic nature of local anesthetic solutions, and can also occur if solutions are too cold or too hot compared to oral temperature.

Question 13

Q17-13: Discuss causes of needle breakage.

Answer 13

A17-13: Although rare, needle breakage has occurred after unexpected patient movements. Factors that increase risks for needle breakage include using needles of higher gauges in deeper penetrations, bending needles at hubs, and needle penetrations to hubs. While needle breakage is not common today, litigation is possible should it occur.

Question 14

Q17-14: Provide prevention strategies to avoid needle breakage.

Answer 14

A17-14: Prevention strategies to avoid undue stresses on needles include:
1. Inspect needles before use.
2. Avoid inserting needles to the hub.
3. Use long needles for deeper penetrations.
4. Use lower gauge needles.
5. Avoid excessive forces on needles (such as when repositioning, or when needles are bowed).
6. Avoid excessive numbers of penetrations with the same needle.
7. If bending is desired, avoid bending at the hub.

Question 15

Q17-15: Discuss situations when removal of broken needles is not indicated.

Answer 15

A17-15: Surgical removal of a broken needle may not be indicated due to the potential for extensive tissue damage which can result during removal. Retaining needle fragments might ultimately cause less tissue damage than removal.

Question 16

Q17-16: What are two strategies to prevent self-injury following local anesthesia?

Answer 16

A17-16: Two strategies to prevent self-injury following local anesthesia include communicating the risks to patients and caregivers, and the use of an anesthesia reversal agent.

Question 17

Q17-17: What drug has the potential to reduce the incidence of self-injury?

Answer 17

A17-17: Recent studies have suggested that the use of an anesthetic reversal agent, phentolamine mesylate (a vasodilator, brand name OraVerse), by reducing the residual soft-tissue duration of anesthesia, may result in fewer self-inflicted injuries. While this suggestion has not been confirmed, a recent study revealed an improvement in safety outcomes when phentolamine mesylate was administered to pediatric dental patients.

Question 18

Q17-18: Define paresthesia.

Answer 18

A17-18: Paresthesia is a broad term for a number of related but clinically diverse neurological effects that all result from nerve injury. It has been defined as an altered sensation and/or as a persistent partial or complete numbness.

Question 19

Q17-19: Which nerve is most frequently involved in paresthesias following dental injections?

Answer 19

A17-19: The lingual nerve is most frequently involved in paresthesias following dental injections.

Question 20

Q17-20: What is the overall risk of paresthesia following local anesthetic injections?

Answer 20

A17-20: Based on data from the ADA and other sources, the apparent risk of local anesthesia-related paresthesia ranges from approximately 1.0 to 2.3 cases in one million.

Question 21

Q17-21: What injection technique error can cause temporary paralysis of the facial nerve?

Answer 21

A17-21: During IA nerve blocks, overinsertion of the needle can penetrate the capsule surrounding the deep lobe of the parotid gland. If anesthetic drugs are deposited into the gland, the facial nerve can be anesthetized.

Question 22

Q17-22: List the steps to manage facial nerve paralysis.

Answer 22

A17-22: Steps in the management of facial nerve paralysis include:
1. Discontinue treatment.
2. Reassure patient.
3. Remove contact lens, if present.
4. Place an eye patch over the affected eye.
5. Document the incident.
6. Follow up as indicated.

Question 23

Q17-23: What strategies are effective for reducing risk of tissue necrosis following injections?

Answer 23

A17-23: The following strategies are effective for reducing risks of necrosis:
1. Avoid epinephrine concentrations of 1:50,000, especially in attached gingiva.
2. Avoid excessive durations of topical anesthetic contact as recommended in the product instructions.
3. Avoid excessive blanching by allowing sufficient time for solution to diffuse into tissue during deposition; tissues should not turn “stark white” in appearance.

Question 24

Q17-24: What is the greatest threat of iatrogenic infection following injections?

Answer 24

A-17-24: The greatest threat of iatrogenic infections following injections is contaminated needles, along with other devices if handled inappropriately.

Question 25

Q17-25: What are three primary non-syncopal causes of systemic complications to local anesthesia?

Answer 25

A17-25: When they occur, non-syncopal systemic complications manifest primarily as overdoses, allergic responses, and idiosyncratic reactions.

Question 26

Q17-26: Which non-syncopal systemic complication of local anesthesia occurs most frequently?

Answer 26

A17-26 Overdoses of local anesthesia occur most frequently.

Question 27

Q17-27: Discuss result and causes of syncope.

Answer 27

A17-27: Syncope usually is the result of insufficient perfusion of oxygenated blood within the brain (cerebral ischemia secondary to inadequate cerebral perfusion). Anxiety is frequently cited as the main cause of syncope but other factors should be considered, including hyperventilation, postural hypotension, severe cardiac disorders, and drug interactions.

Question 28

Q17-28: List the guidelines for the management of syncope.

Answer 28

A17-28: The following steps serve as a guideline for the management of syncope:
1. Activate emergency protocols.
2. Place the patient in a supine position, with legs slightly elevated and brain and heart at the same level.
3. Administer supplemental oxygen.
4. Monitor vital signs until baseline is achieved.
5. Provide patient safety from injury if convulsive activity occurs.
6. Observe for pallor, clamminess, and weakness.
7. Dismiss with escort or emergency transport as indicated.
8. Document the incident.

Question 29

Q17-29: Describe initial signs and symptoms of local anesthesia overdose.

Answer 29

A17-29: Initial signs and symptoms of overdose have been described as a manifestation of central nervous system excitation. These may include ringing in the ears (tinnitus), a metallic taste in the mouth, increased anxiety, and circumoral tingling or numbness.

Question 30

Q17-30: Describe later signs and symptoms of local anesthetic overdose.

Answer 30

A 17-30: As overdose continues and progresses, previously unopposed excitatory pathways are depressed, and signs and symptoms of CNS depression prevail. These may include twitching and tremors, slurred speech, fatigue, unconsciousness, and seizures. If drug levels continue to rise, coma, respiratory arrest, and cardiac arrest are possible.

Question 31

Q17-31: What guidelines are recommended to prevent local anesthetic overdose?

Answer 31

A17-31: The following guidelines are recommended to prevent local anesthetic overdose:
1. Establish maximum doses based on weight and physical status, before injection.
2. Aspirate whenever there is the possibility of intravascular deposition.
3. Administer all doses slowly.
4. Re-aspirate throughout injections.

Question 32

Q17-32: What are the guidelines for management of a patient exhibiting signs of a mild local anesthesia overdose?

Answer 32

A17-32: In response to mild overdose the following guidelines are recommended:
1. Activate emergency protocols as necessary
2. Reassure
3. Observe
4. Monitor
Dental procedures may continue (if tolerable), or the patient may be dismissed. The patient may not need an escort if full recovery has occurred; however, an escort or emergency transport may be indicated.

Question 33

Q17-33: What is the major difference between an overdose and an allergy to local anesthetic drugs?

Answer 33

A17-33: The major difference between overdose and allergy is that allergies are not dose-dependent.

Question 34

Q17-34: List potential causes of allergic reactions related to local anesthesia.

Answer 34

A17-34: Potential allergens related to local anesthesia include:
1. Para-aminobenzoic acid (PABA) (metabolite of ester topical anesthetics)
2. Sulfite (a preservative contained in local anesthetics with vasoconstrictors)
3. Bitartrate (the typical salt form of epinephrine)
4. Latex (a component of cartridges; cartridges in North America have been replaced with latex-free components)
5. Lidocaine (topical and injectable; in recent reports several patients experienced positive reactions suggesting a true allergic reaction versus an irritant effect)

Question 35

Q17-35: What are signs and symptoms of localized allergic reactions?

Answer 35

A17-35: Hives (urticaria) present as well-demarcated swellings on the skin usually accompanied by itching and can occur after local anesthetic administration. A similar, but less frequent manifestation to anesthetics is known as angioedema. Angioedema is not usually accompanied by itching due to involvement of less superficial vessels.

Question 36

Q17-36: What are the guidelines for management of a patient exhibiting localized symptoms of allergy to a topical local anesthetic drug?

Answer 36

A17-36: In response to local allergic events, the following guidelines are recommended:
1. Schedule patient immediately to evaluate possible postoperative allergic lesions/reactions.
2. Recommend OTC Benadryl or prescribe diphenhydramine as appropriate.
3. Refer for allergy testing, depending on signs and symptoms.
4. Send samples of anesthetic and of non-anesthetic substances that also contacted the site.
5. Document in the patient record.

Question 37

Q17-37: What are the effects of epinephrine when used in response to allergic reactions?

Answer 37

A17-37: Epinephrine reverses bronchial constriction and peripheral vasodilation and is not, itself, an antigen. It is important to note that epinephrine’s effectiveness is limited to relatively short intervals due to its rapid biotransformation. Clinicians must be prepared to deliver repeated doses until emergency medical personnel arrive.

Question 38

Q17-38: What are progressive signs and symptoms of generalized anaphylaxis?

Answer 38

A17-38: In the event of generalized anaphylaxis, signs and symptoms will progress through phases that include:
1. Skin reactions - itching, flushing, hives
2. GI/GU reactions - cramps, vomiting, diarrhea, nausea, incontinence
3. Respiratory - chest tightness, cough, wheezing, dyspnea, laryngeal edema
4. CVS - palpitations, lightheadedness, tachycardia, hypotension, unconsciousness, cardiac arrest

Question 39

Q17-39: Define idiosyncratic events.

Answer 39

A17-39: Idiosyncratic events are adverse events that have no known etiology and are likely of genetic origin.

Question 40

Q17-40: What local anesthetic topical drugs are used to avoid complications in patients reporting atypical plasma cholinesterase?

Answer 40

A17-40: Topical anesthetics containing esters such as benzocaine and tetracaine must be avoided. Preparations containing lidocaine, prilocaine, or dyclonine hydrochloride can be used.

Question 41

Q17-41: What local anesthetics must be avoided in individuals who have a genetic predisposition to methemoglobinemia?

Answer 41

A17-41: Primarily prilocaine and benzocaine.

Question 42

Q17-42: What percentage of the world’s population is affected by needle phobia?

Answer 42

A17-42: Needle phobia is considered a formal medical condition affecting approximately 10% of the world’s population.

Question 43

1. A clinician is administering an IA nerve block when the patient suddenly jerks and the needle breaks. The embedded portion is not visible. What should the clinician do?
   a. Attempt removal
   b. Refer for removal
   c. Reappoint to remove once the needle has developed a fibrous cocoon around it
   d. Refer for evaluation

Answer 43

d. Refer for evaluation

Question 44

2. A second cartridge of 2% lidocaine has been administered for an IANB when the 160-lb patient becomes anxious and states that she doesn’t feel well, even a little nauseous. She becomes less anxious as she becomes increasingly fatigued, her speech becomes slurred, and she reports a numb feeling all around her mouth. The pt is likely suffering from:
   a. sever anxiety & fatigue
   b. drug overdose due to excessive administered doses
   c. overdose due to intravascular administration
   d. allergy to lidocaine

Answer 44

c. overdose due to intravascular administration

Question 45

3. Allergies to topical anesthetic drugs that cause mucosal signs & symptoms hours to days after exposure are best explained by:
   a. delayed hypersensitivity
   b. anaphylaxis
   c. angioedema
   d. immunopathology

Answer 45

a. delayed hypersensitivity

Question 46

4. Pt calls several days after an IANB and reports that numbness is still present along with some annoying, occasional sharp pains. Best description of what’s happening:
   a. Paresthesia, anesthesia
   b. Paresthesia, hypoesthesia
   c. Paresthesia, dysesthesia
   d. Anesthesia, hyperesthesia

Answer 46

c. Paresthesia (prolonged pain), dysesthesia (sharp pain)

Question 47

5. Most appropriate response after rapid tissue swelling is noticed after PSA block?
   a. get ice pack, then place pressure on the area with the ice pack
   b. apply pressure x10 minutes, then resume tx
   c. place pressure on area while someone else looks for ice, terminate procedure
   d. reassure pt and continue once numb

Answer 47

c. place pressure on area while someone else looks for ice, terminate procedure

• advise pt of development of discoloration
• instr. pt to apply ice intermittently for 6 hours & to avoid aspirin for pain
• advise pt to notify office immediately of any change, especially S/S of infection or limited jaw opening

Question 48

6. Which of these [systemic] adverse reactions occurs most frequently?
   a. allergy
   b. idiosyncratic response
   c. overdose

Answer 48

c. overdose

Question 49

7. Which of these measures is MOST IMPORTANT for preventing overdose?
   a. Calculating doses
   b. Slow administration
   c. Aspiration
   d. Reassuring patients

Answer 49

b. Slow administration

= most important
–> increases the safety of ALL THE OTHER preventive strategies mentioned
- aspiration critical, but not 100% reliable
- calculating appropriate doses critical, but hyper-responders may react to doses considered appropriate
- reassurance does not address this issue