Systemic Complications of Local Anesthesia

Systemic Complications of Local Anesthesia

• Local anesthesia complications can include syncope, toxicity (overdose), idiosyncrasy, and allergy.

Syncope

• Definition: Sudden, temporary loss of consciousness due to cerebral ischemia.
• Incidence: Most common complication in dental offices.
• Synonyms: Vasodepressor attack, vasovagal syncope, fainting.
• Predisposing Psychogenic Factors: Anxiety, severe pain, emotional stress, sight of blood/instruments.
• Predisposing Physical Factors: Prolonged standing, exhaustion/hunger/starvation, hot/crowded environments.
• Clinical Manifestations: Paleness, perspiration, visual disturbances, restlessness, coldness of extremities, nausea, tachycardia, dizziness, low blood pressure, weak pulse, irregular breathing, pupillary dilation, loss of consciousness; presyncope (precursor signs).
• Postsyncope Management: Monitor vital signs, return patient to seated position, stop treatment for the day, record incident, arrange transport home.
• Management of Syncope: Terminate procedure, call medical assistance/emergency, place patient in Trendelenburg position (head lower than legs), acquire vital signs (BP, RR, HR, Temp.).
• Management of Vasodepressor Syncope: Inhale aromatic ammonia to stimulate respiratory system & raise blood pressure. Administer 6L/min of oxygen via mask or nasal hood.

Toxicity (Overdose)

• Definition: Clinical manifestations from an overly high blood level of a drug in various target tissues/organs.
• Causes: Intravascular injection (unintentional injection into a blood vessel leading to high drug levels rapidly), rapid absorption (drug diffusing into bloodstream quickly due to vasodilation from the anesthetic), presence of vasoconstrictor (reduces drug absorption). Rate of injection matters.
• Other Causes: Large dose, slow biotransformation (liver problem), slow elimination (kidney problem).
• Manifestations: Increased excitation, headache & dizziness, twitching, blurred vision, auditory disturbance, numbness, talkativeness, increased respiratory & heart rate, increased blood pressure, gagging & vomiting, tremors, drowsiness, hallucinations, disorientation, loss of consciousness (mild-moderate), generalized tonic-clonic seizures, depression of respiratory, heart, and blood pressure.
• Management: Stop procedure, reassure patient, administer oxygen, call medical assistance, monitor vital signs, administer Intravenous anticonvulsants (diazepam, midazolam).

Idiosyncrasy

• Definition: Unexpected response to medication that isn't an overdose or allergic reaction.
• Cause: Often due to genetic mechanisms.

Allergy

• Definition: Exaggerated immune response to harmless substance.
• Allergens: Esters, sodium bisulfite/metabisulfite (antioxidants), methylparaben (preservative).
• Prevention: Adequate pre-anesthetic evaluation, avoid known allergens, refer for testing for allergy.
• Clinical Manifestations: Dermatological (urticaria, angioedema, itching), respiratory (bronchospasm, laryngeal edema), cardiovascular (tachycardia, hypotension, cardiac arrest), gastrointestinal (nausea, vomiting, abdominal cramps), genitourinary (urinary incontinence), neurologic (lightheadedness, anxiety, impending doom).
• Management: Stop procedure, administer oxygen, call medical help, administer epinephrine, antihistamines (IM or IV), corticosteroids (IM or IV), closely monitor vital signs, prepare for transport.