Anesthetic Complications in Medical Procedures

Anesthetic Complications

  • Complications can range from minor (e.g., infiltrated intravenous line) to catastrophic (e.g., hypoxic brain injury, death).

Airway Injury

  • Refers to injuries sustained to airway structures during procedures.
  • Common Causes: Daily insertion of:
    • Endotracheal tubes
    • Laryngeal mask airways
    • Oral/nasal airways
    • Gastric tubes
    • Transesophageal echocardiogram (TEE) probes
    • Esophageal (boogie) dilators
  • Typical effects include sore throat and dysphagia, usually self-limiting.
  • Most Common Permanent Injury: Dental trauma during laryngoscopy and endotracheal intubation; upper incisors are frequently injured.
  • Major Risk Factors for Dental Trauma:
    1. Tracheal intubation.
    2. Preexisting poor dentition.
    3. Patient characteristics that complicate airway management (limited neck motion, prior head/neck surgery, craniofacial abnormalities, history of difficult intubation).

Peripheral Nerve Injury

  • Perioperative nerve injury occurs frequently with regional and general anesthesia.
  • Most injuries resolve within 6-12 weeks; some persist for months to years.
  • Common Causes:
    • Patient positioning (e.g., pressure on specific nerves).
    • Associated Nerves:
    • Peroneal nerve
    • Brachial plexus
    • Femoral and sciatic nerves.
  • Consequences of Nerve Compression: Edema, ischemia, necrosis due to disrupted perfusion.
  • Risk factors: Hypotension, thin body, older age, history of vascular diseases, diabetes, smoking.

Awareness Under General Anesthesia

  • Incidence of awareness during general anesthesia: 0.2-0.4%.
  • Frequently associated with:
    • Major trauma surgeries
    • Obstetric procedures
    • Cardiac surgeries.
  • Recall rates in major trauma: as high as 43%.
  • Statistics:
    • Incidence in cardiac surgery: 1.5%.
    • Incidence in cesarean sections: 0.4%.
  • Common causes of awareness include:
    • Depth of anesthesia
    • Errors in drug labeling/administration.
  • Female patients on opioids and muscle relaxants without volatile anesthetics are more likely to recall intraoperative events.

Eye Injury

  • Common Eye Injuries:
    • Corneal abrasion (transient).
    • Ischemic optic neuropathy (ION) is the leading cause of postoperative vision loss.
  • Causes of ION:
    • Optic nerve infarction due to decreased oxygen delivery.
    • Common after: cardiopulmonary bypass, radical neck dissection, abdominal/hip procedures, spinal surgeries in prone position.
  • Risk factors include: Preexisting hypertension, diabetes, coronary artery disease, smoking.
  • Intraoperative factors: deliberate hypotension and anemia can reduce oxygen delivery.

Prevention of Eye Injury

  • Strategies:
    • Positioning head-up to enhance venous outflow.
    • Careful monitoring of blood pressure.
    • Limit duration/degree of controlled hypotension.
    • Transfuse anemic patients at risk.
    • Discuss with surgeon about staged operations in high-risk patients to avoid prolonged procedures.

Cardiopulmonary Arrest During Spinal Anesthesia

  • Sudden cardiac arrest during spinal anesthesia is rare but catastrophic.
  • Common Cause: High level of block, particularly at the T4 level.
  • Treatment Considerations:
    • Ventilatory support.
    • Medications: Ephedrine, atropine.
    • Cardiopulmonary resuscitation (CPR).

Hearing Loss

  • Perioperative hearing loss is often transient and goes unrecognized.
  • Incidence after dural puncture may relate to cerebrospinal fluid (CSF) leaks; persistent cases may resolve with an epidural blood patch.
  • Causes of hearing loss following general anesthesia include:
    • Surgical manipulation.
    • Middle ear barotrauma.
    • Vascular injury.
    • Ototoxicity from certain drugs (aminoglycosides, loop diuretics, NSAIDs, antineoplastic agents).
  • Hearing loss post-cardiopulmonary bypass is usually unilateral, linked to embolism and ischemic injury.

Allergic Reactions

  • Hypersensitivity (or allergic) reactions are exaggerated immunological responses to previously sensitizing antigens.
  • Allergens can be:
    • Proteins
    • Polypeptides
    • Smaller molecules bound to carrier proteins.
  • Patients may encounter antigens through:
    • Nose, lungs, eyes, skin, gastrointestinal tract, parenterally (IV or IM), or transperitoneally.