Complications

What are types of LOCAL complications associated with local anesthesia?

Hematoma

Trismus

Broken needles

Self-injury

Paresthesia

Facial nerve paralysis

Post-anesthetic mucosal lesions

Infections

Ocular complications

When and how do hematomas occur?

-occur when blood leaks from a vessel into the surrounding tissues.

-usually due to inadvertent nicking of the blood vessel walls by the injection needle

The extent of the hematoma depends on the vessel that is pierced. What is the difference between nicking an artery VS a minor vessel?

An artery will result in a more rapid and extensive hematoma, while a minor vessel may not even produce any observable hematomas

Some injections are more prone to producing hematomas. Which type of injection/block do you think is most likely to result in a hematoma?

The PSA and division 2 (maxillary tuberosity approach) nerve blocks have a higher risk of hematoma due to the proximity of the pterygoid plexus of veins and maxillary arteries

T or F? The IA and mental incisive nerve blocks are also associated with high risks of hematomas, but less so than that associated with PSA nerve blocks.

TRUE - IA is going to be more common for paresthesia

How can hematomas hinder the depth and duration of anesthesia?

by transporting the drug away from its target area and initiating an inflammatory response that lowers the pH

What steps would you take after successive IA nerve blocks have failed to establish anesthesia?

Use alternative techniques such as the Gow-Gates nerve block or PDL injections

What are some guidelines the help PREVENT the occurrence of hematomas?

-Minimize the number of needle penetrations

-Avoid trauma in general by maintaining good access, observing appropriate angulations and penetrations depths, and avoiding rapid penetrations and bowing of needles

-Avoiding PSA nerve blocks in patients on anticoagulant therapy.

How can we manage hematomas?

-Limit the extent by immediately applying pressure and ice to the area, limiting the spread of blood

-Instruct the patient to apply ice for the next 6 hours (then maybe switch to heat?)

-Avoid taking anticoagulant pain medications

What is trismus?

Limited opening of the mouth due to motor disturbance of the trigeminal nerve

While trismus may be induced by many factors (tumors, tetanus, infection, etc...), how is trismus triggered by local anesthesia?

associated with local anesthetic toxicity to the skeletal muscles as well as hemorrhage and muscle trauma from needle penetration.

The most common muscle affected by trismus is the ____________, usually through the IA, Gow-Gates, and Vazirani-Akinosi nerve blocks.

medial pterygoid

How can we prevent the occurence of trismus from local anesthesia?

-Minimizing the number of needle penetrations

-Discarding barbed needles

-Preventing needle contamination prior to injection

How can we manage trismus?

-Apply a moist towel to the affected site for 20 minutes every hour

-Use ibuprofen or another analgesic as needed.

-Perform jaw exercises

-Monitor for signs of infection

-Refer to an OS if symptoms persist.

What are some reasons pain on injection may occur when administering local anesthesia?

- Lack of topical anesthesia

- Rapid deposition resulting in tissue distension

- The acidic nature of the local anesthetic solutions

- LA solutions that are too cold or too hot.

How can we prevent or minimize pain on injection?

-Adequate topical anesthesia (using topical or pressure)

-Slow rate of deposition

-Administering plain solutions prior to using one with a vasoconstrictor

-Substituting LA drugs

Where is the weakest point of the needle?

THE HUB

What are factors that may increase the risk of needle breakage?

- Using needles of higher gauges in deeper penetrations

- Bending needles at the hub

- Needle penetration to the hub

How can we prevent needle breakage?

-Inspect the needles before use

-Avoid hubbing by choosing a needle gauge and length appropriate for the depth of penetration

-Use long needles for deeper penetrations

-Use lower gauge needles

-Avoid excessive forces on the needle (bowing or repositioning)

-Avoid excessive penetrations with the same needle.

-Avoid bending at the hub

What should we do if a needle breakage occurs?

-Have a hemostat on hand for retrieval

-Instruct the patient not to close their mouth

-If the needle is not visible, you should inform the patient, take a radiograph, refer them to an OS, and document the event.

T or F? Surgical removal of an embedded needle is not always indicated to prevent extensive tissue damage.

TRUE, we need to decide whether to retain or remove the needle

The main risk of self injury after local anesthesia is associated with ...?

biting of oral soft tissues following treatment and from drinking and eating hot liquids and foods

How can we help prevent self-injury?

informing the patient of the associated risk or by using a reversal agent. (vasodilation will occur)

How do we manage a patient that returns to us with signs of self-injury after local anesthesia?

Instruct them to apply a cold pack to prevent swelling if the injury occurred shortly after the appointment, or a warm pack to stimulate circulation and promote healing if the injury took place after a certain amount of time. 0.12% chlorhexidine (CHX) has shown to be effective

Are antibiotics indicated for patients with signs of self-injury?

Antibiotics are not indicated and prescribed only if infection is present.

What is paresthesia?

refers to altered sensation and/or persistent partial or complete numbness

What nerve is most commonly associated with paresthesia after administering local anesthesia?

the lingual nerve is most frequently involved usually as a result of the IA block.

T or F? Most paresthesias are temporary (resolving within 2 weeks).

TRUE

What are common etiologies for paresthesia?

routine procedures, surgical trauma, sulfite preservatives, detergent action of LA drugs, increased apoptotic activity, and vasoconstrictor toxicity.

Paresthesias are more commonly associated with ____% solutions.

4% (articaine, prilocaine)

HOWEVER - Evidence suggests that there is no reliable strategy for preventing paresthesia

What are some ways to lower the risk of paresthesia when using 4% LA drugs?

-Using the Gow-Gates or Akinosi techniques instead of the IA block

-Reducing volumes by 50%

-Providing slow rate of deposition

How do we manage paresthesias?

-Reassure the patient

-Schedule a re-evaluation appointment

-Document the conversations

-Examine the patient

-Diagram and document the paresthesia

-Explain that most paresthesia are temporary but can last a while

-Refer if necessary

-Use alternate injection techniques for future appointments.

The blocks most commonly associated with CN VII (facial nerve) paralysis are the ________ and __________blocks, both due to over-insertion.

IA ; Vazirani-Akinosi

How does facial nerve paralysis occur?

Over-insertion of the needle can result in penetration of the capsule surrounding the deep lobe of the parotid gland. If anesthetic is deposited at this site, the facial nerve will be anesthetized and unilateral paralysis of the face will occur!!!!!!

How long does facial nerve paralysis last?

This should only last as long as the anesthetic is in effect.

How can we prevent facial nerve paralysis?

-Observe proper injection technique

-Confirm bony resistance prior to depositing

-Use smaller gauge needles to avoid deflections from the bone

-Avoid overinsertion

How can we manage facial nerve paralysis?

-Discontinue treatment

-Reassure the patient

-Remove contact lens if present and place a patch over the affected eye due to blinking impairment

-Document the incident

-Follow up

What are Post-anesthetic Mucosal Lesions?

May result from an infectious or immune process, direct injury to the mucosa, overly vigorous hemostasis from high concentrations of vasoconstrictor, or necrosis from topical anesthetic left in contact with mucosa too long

T or F? Herpetic lesions can develop after anesthetic injection in patients with a history of recurrent herpes.

TRUE!!! can be a trigger - use the past history to discriminate between herpetic ulcers and recurrent aphtous ulcerations

Are there any prevention strategies for the development of herpetic or aphtous lesions?

NO - but necrosis can be prevented

How can we prevent tissue necrosis from local anesthesia?

-Avoiding 1:50,000 epinephrine concentrations in attached gingiva.

-Avoiding excessive durations of topical anesthetic

-Avoiding excessive blanching and tissue distension by allow the anesthetic to diffuse

How can we manage Post-anesthetic Mucosal Lesions?

-Determine the cause through evaluation of past history

-Recommend OTC anesthetics and analgesics for pain control

-Avoid spicy and acidic foods

Manifestations of post-anesthetic infections include _______ and ________.

pain ; trismus

While post-operative infections are rare today, _______________ present the greatest threat of infection.

contaminated needles (especially for our immunocompromised patinets)

How can we prevent post-operative infections?

-Use sterile needles

-Use a new needle for every new penetration if infection is present

-Discard the needle if extra-oral or intra-oral contamination occurs

-Use prophylactic antibiotics or apply antiseptics to penetration sites in immunocompromised patients

What do we do if post-op infection occurs?

-Schedule an evaluation ASAP

-Prescribe antibiotics as needed

-Document

-Follow up until resolved

What are some ocular complications of local anesthesia?

blurring of vision, temporary blindness, pupil dilation, drooping of the eyelid, and double vision

How do ocular complications from local anesthesia occur?

It is the result of unintentionally anesthetizing the nerves of the eye through anesthetic diffusion to the orbit or cavernous sinus. (diffusion of LA drug)

How do we prevent ocular complications from local anesthesia?

You should aspirate frequently before depositing solution and anesthetic should be administered slowly.

How do we manage ocular complications from local anesthesia?

-Reassure the patient that these effects are transient only

-Cover the eye to restore monocular vision

-Have the patient escorted home.

-Refer to an ophthalmologist if symptoms persist

What are some systemic complications of local anesthesia?

Syncope

Overdose

Allergic responses

Idiosyncratic reactions

Atypical plasma cholinesterase

Methemoglobinemia.

What is syncope and what is it associated with?

-another term for loss of consciousness

-associated with anxiety, but also related to hyperventilation, postural hypotension, severe cardiac disorders, and drug interactions.

How do we manage a patient with syncope?

It is vital that we restore adequate oxygenated blood within the brain!!!! Put pt in supine position, provide supplemental O2, elevate the legs, and loosen any tight fitting clothing that may restrict breathing

Activate BLS response protocols if pt does not respond

How do we manage a PREGNANT patient with syncope?

Exception to the supine position and should instead be placed on their right side to allow for continuous venous return to the heart!!!!!!!!!!!!! alleviates compression of the left side of the body (heart)

Overdose potential varies from drug to drug. Which drug is known for its equal toxicities to the CNS and CVS?

bupivacaine (it has been reported that CVS collapse often precedes any evidence of CNS toxicity.)

Overdose is usually the result of either 1 of 2 things ...?

Intravascular deposition, OR

Non-intravascular administration of excessive doses

What does it mean when we say the effects of overdose are biphasic?

First, depression of the CNS inhibitory pathways will result in CNS excitation. Continued overdosing then results in depression of both inhibitory and excitatory pathways, resulting in CNS depression

What does CNS excitation look like? What can it be confused with?

-CNS excitation: ringing of ears, metallic taste, increased anxiety, circumoral tingling and numbness

-Can mimic anxiety BUT anxiety can be controlled with relaxation techniques, it does not result in circumoral numbness, and it does not lead to CNS depression

What does CNS depression look like?

includes twitching, tremors, slurred speech, fatigue, and unconsciousness. Seizures, CVS depression, and coma may occur if overdosing continues beyond that point.

What are some CVS effects from LA drug overdose?

decrease of contractility and conduction volumes leading to bradycardia, arrhythmias, and asystole (absence of a heart beat).

T or F? All effects and symptoms of the CNS/CVS are only reversed once the circulating drugs have been eliminated.

TRUE

How can we prevent LA drug overdoses?

-Calculating the MRD for the patient based on weight

-Aspirating and re-aspirating

-Slow rate of deposition (most important!)

Overdose reactions occur within _______ up to ______ post-injection. Generally, the more DELAYED the onset, the more MILD the overdose reaction!!!!!!!!

minutes ; an hour

How do we manage LA drug overdose?

While management of mild overdose on requires supportive techniques, moderate overdoses require aggressive management and activation of the emergency system.

Localized allergic reactions to LA drugs are most common to ____________ and _____________.

topical anesthetics (PABA metabolite) ; ester drugs (sulfite)

How do localized allergic reactions to LA drugs present?

Type IV reactions that occur within 30-60 minutes of contact, presenting as well-demarcated swellings on the skin, accompanied with hives/itching, OR may result in angioedema.

How do we manage localized allergic reactions to LA drugs?

They are generally respond well to antihistamine therapy. Must document and refer for allergy testing

How do we prevent localized allergic reactions to LA drugs?

-Avoid medications that have induced reactions in the past

-Avoid same-class topical preparations that have induced reactions in the past

-Consult with provider if the patient had a past reaction

-Obtain allergy testing

_________ allergic reactions are far more serious and result from allergy to either sulfites, LA drug itself, or PABA.

SYSTEMIC

If medical response to the systemic reaction is delayed, it may manifest in localized or systemic _____________ and result in respiratory and cardiovascular arrest.

anaphylaxis (Type I reaction)

T or F? Localized anaphylaxis may develop into systemic anaphylaxis.

TRUE

How do we manage systemic allergic reactions to local anesthesia?

-Terminate treatment

-Activate emergency protocols and call 911

-Administer epinephrine 0.3mg intramuscularly or subcutaneously

-Administer diphenhydramine (benadryl) 50mg

-Obtain allergy testing once symptoms have subsided.

What genetic condition impairs the metabolism of esters?

Atypical plasma cholinesterase

**avoid using any ester drug, including topical anesthetics.

What is Methemoglobinemia? Who is at risk?

A condition characterized by diminished O2-carrying capacity of the blood. At risk patients include those who have genetic pre-dispositions, patients with breathing conditions (asthma, etc...), and smokers.

How do we manage methemoglobinemia?

In the event of methemoglobinemia, you should call 911 for treatment in an emergency room.

which 2 drugs are most likely to induce methemoglobinemia?

prilocaine and benzocaine (also articaine in large doses)