Oral Surgery: Complications of Local Anesthesia

Oral Surgery: General Complications of Local Anesthesia (L.A.)

• Fainting (Vasovagal Attack):
  • This is the most common systemic complication during local anesthesia in dental offices.
  • It involves a sudden, transient loss of consciousness, usually caused by cerebral ischemia.
  • Cerebral ischemia results from vasodilation or increased peripheral blood vessel dilation, leading to a drop in blood pressure.
  • Collapse during treatment may occur without loss of consciousness, and spontaneous recovery is typical.
  • Symptoms include dizziness, weakness, nausea, pale and cool skin, and a slow pulse.

Predisposing Factors for Fainting

• Psychogenic Factors:

  • Fright, anxiety
  • Emotional stress
  • Pain, especially sudden and unexpected
  • Sight of blood, surgical instruments, or injection tools

• Non-Psychogenic Factors:

  • Prolonged sitting or standing, leading to pooling of blood in the periphery and decreased cerebral blood flow.
  • Hunger or starvation, resulting in decreased cerebral blood glucose levels
  • Poor physical condition
  • Hot, humid, or crowded environments

Mechanism of Vasovagal Syncope

• Regardless of the trigger, the brainstem activates simultaneously and enhances parasympathetic tone (vagal) while suppressing sympathetic tone.
• This triggers the following responses:
  • Cardioinhibitory response: Decrease in heart rate, contractility, and cardiac output, potentially leading to unconsciousness.
  • Vasodepressor response: Dilation of blood vessels, allowing blood pooling in the periphery, reducing blood flow to the brain.

Management of Fainting

• Immediate Measures:
  • Quickly lower the patient's head and elevate their legs by adjusting the dental chair.
  • Loosen tight collars and belts.
  • Stimulate breathing.
• Further Action:
  • If no signs of recovery within 30-60 seconds, initiate immediate help from a qualified medical emergency team. If the syncope is not a vasovagal attack, immediate medical help is critical.

Hypersensitivity Reaction

• An exaggerated immune and inflammatory response to an antigen (allergen).

• Often related to a local anesthetic agent (especially ester type agents like procaine, less common with amide type agents like lidocaine).

• True allergy to amide type anesthetics is rare.

• Causes may include the anesthetic agent itself, vasoconstrictors, or preservatives (e.g., bisulfate).

• Local Reactions:

  • More common than systemic reactions.
  • Usually resolve without treatment.

• Systemic Reactions (Allergic Response to L.A.):

  • May be localized or generalized.
  • May be immediate or delayed in onset.
  • Range from mild skin irritation to anaphylaxis.

Anaphylactic Shock

• A severe, life-threatening allergic reaction.
• Can occur within seconds or minutes of exposure to an allergen.
• Characterized by hypotension (low blood pressure), airway obstruction, and laryngeal edema.
• Immediate treatment is crucial to prevent potential fatal outcomes.

Clinical Presentation of Anaphylaxis

• General:
  • Profound fall in blood pressure
  • Dyspnea (difficulty breathing) and respiratory distress
  • Facial and laryngeal edema
  • Loss of consciousness
  • Urticaria (hives)
  • Nausea, vomiting, and diarrhea

Management of Anaphylactic Shock

• Immediate action: Seek immediate medical assistance.
• Vital Treatment: Administer epinephrine (adrenaline) into a muscle immediately.
• Supportive Measures: Oxygen, antihistamines (to combat histamine effects), and corticosteroids (e.g., hydrocortisone), IV fluids may be necessary.

Over dosage and Toxicity

• Relatively rare, potentially occurring when the concentration of local anesthetic solution enters the bloodstream too quickly, especially if injected into a highly vascular area or intravenously.

• Toxicity varies amongst patients, influenced by factors including the amount and type of anesthetic administered, patient's general health, age, weight, route of administration, and injection speed.

• Mild Overdosage Symptoms:

  • Restlessness
  • Consciousness retention
  • Talkativeness
  • Agitation
  • Potential escalation to convulsions
  • Increased blood pressure (BP), heart rate, and respiratory rate

• Treatment of over dosage:

  • Stop the dental procedure immediately.
  • Position the patient supine with legs elevated.
  • Reassure the patient
  • Administer oxygen and an intravenous (IV) anticonvulsant such as diazepam.
  • Discharge the patient if they recover and transfer to a general hospital if recovery is unsuccessful

Drug Interactions

• Local anesthetics (especially in combination with vasoconstrictors) may interact negatively with tricyclic antidepressants.

  • These interactions can increase the risk of hypertension (high blood pressure).

• Aspiration techniques can be used to avoid injection into blood vessels, reducing the risk of adverse interactions.

• Interactions can potentially occur between vasoconstrictors and some types of beta-blockers. This can result in unforeseen unwanted vasoconstrictor effects.

This quiz covers various complications related to local anesthesia in dental practice, focusing primarily on fainting or vasovagal attacks. It explores both psychogenic and non-psychogenic factors that predispose patients to these complications. Understanding these issues is crucial for improving patient safety and management during procedures.