Arterial gas embolism

Background

• Also known as "air embolism"
• May be fatal when air entry reaches 200-300 mL (pressure gradient of 5 mmHg across 14 ga catheter entrains air at 100 mL/sec)
• Dialysis related
  • Due to negative intrathoracic pressure from spontaneous breathing
• Scuba related
  • Results from pulmonary barotrauma (most common) and decompression sickness

Prevention

• Positive pressure mechanical ventilation reduces positive pressure gradient
• Trendelenburg for insertion/removal of IJV and subclav lines
• Reverse Trendelenburg for femoral

Clinical Features

• Asymptomatic
• Mild: dyspnea, cough
• Cardiogenic shock: hypotension, oliguria, altered mental status, chest pain
• Dialysis related
  • Acute dyspnea, chest tightness, LOC, cardiac arrest, arrhythmia
• Scuba related
  • Symptoms develop during ascent or immediately upon surfacing
  • Causes variety of stroke syndromes depending on part of brain affected
    • Immediate death, loss of consciousness, seizure, blindness, hemiplegia

Differential Diagnosis

Dialysis Complications

• Dialysis-associated hypotension
• Dialysis disequilibrium syndrome
• Air embolism
• Missed dialysis (pulmonary edema)

Diving Emergencies

• Barotrauma of descent
  • Otic barotrauma
  • Pulmonary barotrauma
  • Sinus barotrauma
  • Mask squeeze
  • Barodentalgia (trapped dental air causing squeeze)
• Barotrauma of ascent
  • Pulmonary barotrauma (pulmonary overpressurization syndrome)
  • Decompression sickness (DCS)
  • Arterial gas embolism
  • Alternobaric vertigo
  • Facial baroparesis (Bells Palsy)
• At depth injuries
  • Oxygen toxicity
  • Nitrogen narcosis
  • Hypothermia
  • Contaminated gas mixture (e.g. CO toxicity)
  • Caustic cocktail from rebreathing circuit

Evaluation

Cerebral air embolism with multiple air bubbles.

thumb|Fatal cerebral arterial gas embolism. (a) CT head showing air bubbles predominantly in the right cerebral hemisphere (b) CT head showing air bubbles predominantly in the right cerebral hemisphere

• Low ETCO2 in significant venous air embolism
• TEE: most sensitive, invasive not available in emergencies
• Doppler US: noninvasive; air in chamber = high pitch sound

Management

• Central line aspiration of air from right heart
• 100% O2 non-rebreather
  • Regardless of SaO2 (to reduce embolism size)
• Hemodynamic support with positive inotropes
• CPR in large air embolus
• Positioning
  • Durant's maneuver - left lateral decubitus and Trendelenburg
  • Traps air in apex of RV, relieves obstruction of pulmonary outflow tract
• May require open surgical or angiography for recovery of residual intracardiac or intrapulmonary air

Dialysis Related

• Prevent any further air entry
  • Immediately cover puncture site with saline soaked gauze

Scuba Related

• IVF (increases tissue perfusion)
• Rapid recompression

Disposition

• Likely admission

See Also

• Dialysis complications
• Scuba diving emergencies