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)[1]
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[2]
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

Scuba Diving Emergencies

Barotrauma of descent
- Otic barotrauma
- Sinus barotrauma
- Face squeeze
Barotrauma of ascent
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.

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

Arterial air embolism (arrows)

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[3][4]

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

External Links

References

Vascular Access. In: Marino, P. The ICU Book. 4th, North American Edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2013
Diving Medicine, Karen B. Van Hoesen and Michael A. Lang, Auerbach's Wilderness Medicine, Chapter 71, 1583-1618.e6
- Shaikh N., Ummunisa F. Acute management of vascular air embolism. J Emerg Trauma Shock. 2009 Sep-Dec; 2(3): 180–185.
Gordy S and Rowell S. Vascular air embolism. Int J Crit Illn Inj Sci. 2013 Jan-Mar; 3(1): 73–76.

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[1] Vascular Access. In: Marino, P. The ICU Book. 4th, North American Edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2013

[2] Diving Medicine, Karen B. Van Hoesen and Michael A. Lang, Auerbach's Wilderness Medicine, Chapter 71, 1583-1618.e6

[3] Shaikh N., Ummunisa F. Acute management of vascular air embolism. J Emerg Trauma Shock. 2009 Sep-Dec; 2(3): 180–185.

[4] Shaikh N., Ummunisa F. Acute management of vascular air embolism. J Emerg Trauma Shock. 2009 Sep-Dec; 2(3): 180–185.

[4] Gordy S and Rowell S. Vascular air embolism. Int J Crit Illn Inj Sci. 2013 Jan-Mar; 3(1): 73–76.