Anesthetic Complications Notes

These complications range from minor (e.g., infiltrated intravenous line) to catastrophic (hypoxic brain injury or death).

Involves damage to airway structures.
Daily insertion of endotracheal tubes, laryngeal mask airways, oral/nasal airways, gastric tubes, transesophageal echocardiogram (TEE) probes, and esophageal (boogie) dilators all carry risk.
Common, usually self-limiting injuries include sore throat and dysphagia.
Dental trauma is the most common permanent airway injury, often from laryngoscopy and endotracheal intubation, particularly to the upper incisors.
- Major risk factors:
  1. Tracheal intubation.
  2. Preexisting poor dentition.
  3. Patient characteristics associated with difficult airway management (limited neck motion, previous head and neck surgery, craniofacial abnormalities, history of difficult intubation).

A known complication of both regional and general anesthesia.
More frequent than other complications.
In most cases, injuries resolve within 6–12 weeks, but some persist for months or even years.
Peripheral neuropathies are commonly associated with patient positioning.

Peripheral nerve injuries are closely related to positioning or surgical procedure.
Nerves that may be involved: peroneal nerve, brachial plexus, femoral and sciatic nerves.
External pressure on a nerve can compromise perfusion, disrupt cellular integrity, and result in edema, ischemia, and necrosis.
Lower extremity neuropathies, particularly involving the peroneal nerve, have been associated with prolonged (greater than 2 hours) maintenance of the lithotomy position.
Patient risk factors include hypotension, thin body, old age, history of vascular disease, diabetes, or smoking.

Evidence of awareness under general anesthesia found in 0.2–0.4% of studies.
Surgical settings most frequently associated with awareness include major trauma, obstetrics, and cardiac surgery.
Awareness may be related to the depth of anesthesia that can be tolerated.
Recall rates for intra-operative events during major trauma surgery have been reported as high as 43%.
The incidence of awareness during cardiac surgery and cesarean sections is 1.5% and 0.4%, respectively.
Most awake paralysis is thought to be due to errors in drug labeling and administration.
Recall under general anesthesia was found to be more likely in women when anesthesia was performed by opioids and muscle relaxants without volatile anesthetic.
Factors that may increase anesthetic requirements for unconsciousness include poor tolerance of anesthesia, medication errors, younger age, smoking, and long-term use of certain drugs (alcohol, opiates, or amphetamines).

Corneal abrasion is the most common and transient eye injury.
Ischemic optic neuropathy (ION) is now the most common cause of postoperative loss of vision.
ION results from optic nerve infarction due to decreased oxygen delivery via one or more small arterioles supplying the nerve.
Most reported after cardiopulmonary bypass, radical neck dissection, abdominal and hip procedures, and spinal surgeries in the prone position.
Preexisting hypertension, diabetes, coronary artery disease, and smoking may play a role due to preoperative vascular abnormalities.
Intra-operative deliberate hypotension and anemia have also been implicated, perhaps because of their potential to reduce oxygen delivery.

Enhancing venous outflow by positioning the patient head up.
Monitoring blood pressure carefully with an arterial line.
Limiting the degree and duration of hypotension during controlled (deliberate) hypotension.
Administering a transfusion to anemic patients who appear at risk.
Discussing with the surgeon the possibility of staged operations in high-risk patients to limit prolonged procedures.

Sudden cardiac arrest during routine spinal anesthesia is uncommon but catastrophic.
A high level of block (T4 level) is a cause of arrest.
Treatment should include:
- Ventilatory support.
- Ephedrine, atropine.
- Cardiopulmonary resuscitation.

Perioperative hearing loss is usually transient, subclinical, and often goes unrecognized.
Hearing loss following dural puncture may be due to cerebrospinal fluid (CSF) leak; persistent loss can be relieved with an epidural blood patch.
Hearing loss following general anesthesia can be due to surgical manipulation, middle ear barotrauma, vascular injury, and ototoxicity of drugs (aminoglycosides, loop diuretics, nonsteroidal anti-inflammatory drugs, and antineoplastic agents).
Hearing loss following cardiopulmonary bypass is usually unilateral and is thought to be due to embolism and ischemic injury.

Hypersensitivity (or allergic) reactions are exaggerated immunological responses to antigenic stimulation in previously sensitized persons.
The antigen, or allergen, may be a protein, polypeptide, or smaller molecule bound to a carrier protein.
The allergen may be the substance itself, a metabolite, or a breakdown product.
Patients may be exposed to antigens through the nose, lungs, eyes, skin, gastrointestinal tract, as well as parenterally (intravenously or intramuscularly) and transperitoneally.