View source for 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)<ref>Vascular Access. In: Marino, P. The ICU Book. 4th, North American Edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2013</ref>
*Dialysis related
**Due to negative intrathoracic pressure from spontaneous breathing
*Diving related
**Results from pulmonary barotrauma (most common) and decompression sickness, most commonly in last 10m of ascent. Patients with a patent foramen ovale may shunt normally-present venous system bubbles into the arterial system with any effortful action which causes valsalva.
**Classically presents as LOC within 2 minutes of surfacing, can lead to stroke-like symptoms.
***A "lucid interval" of asymptomatic period after initial symptoms, lasting perhaps hours, until progressive decompensation is common. Any report of LOC, seizure-like activity, stroke-like symptoms, or other temporary neurologic impairment within 10 minutes of surfacing, '''even if it has since resolved''', should result in high suspicion for AGE and emergent recompression therapy (hyperbaric chamber treatment) should be pursued. Consult hyperbarics/dive medicine if available or call Divers Alert Network +1-919-684-9111.

===Prevention===
*Positive pressure mechanical ventilation reduces positive pressure gradient
*Trendelenburg for insertion/removal of IJV and subclav lines
*Reverse Trendelenburg for femoral
*Slow and controlled ascent when diving, with special precaution to exhale during ascent in the last 10m so the lungs do not over-pressurize.

==Clinical Features==
*Asymptomatic
*Mild: [[dyspnea]], [[cough]]
*[[Cardiogenic shock]]: [[hypotension]], oliguria, [[altered mental status]], [[chest pain]]
*[[dialysis complications|Dialysis]] related
**Acute [[dyspnea]], [[chest pain|chest tightness]], [[syncope|LOC]], [[cardiac arrest]], [[arrhythmia]]<ref>Diving Medicine, Karen B. Van Hoesen and Michael A. Lang, Auerbach's Wilderness Medicine, Chapter 71, 1583-1618.e6</ref>
*Scuba related
**Symptoms develop during ascent or immediately upon surfacing
**Causes variety of [[stroke syndromes]] depending on part of brain affected
***Immediate [[cardiac arrest|death]], [[syncope|loss of consciousness]], [[seizure]], [[vision loss|blindness]], [[weakness|hemiplegia]]

==Differential Diagnosis==
{{Scuba diving DDX}}

{{Dialysis complications DDX}}

==Evaluation==
[[File:PMC3829274 IJNL-12-030-g001.png|thumb|Cerebral air embolism with multiple air bubbles.]]
[[File:PMC2772239_IJCCM-13-108-g001.png|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]]
[[File:PMC3420467 CRIM.PULMONOLOGY2012-416360.002.png|thumb|Arterial air embolism (arrows)]]
*Low ETCO2 in significant venous air embolism
*[[echocardiography|TEE]]: most sensitive, invasive not available in emergencies
*Doppler US: noninvasive; air in chamber = high pitch sound
*Divers with suspected AGE should likely be screened for patent foramen ovale

==Management<ref>*Shaikh N., Ummunisa F. Acute management of vascular air embolism. J Emerg Trauma Shock. 2009 Sep-Dec; 2(3): 180–185.</ref><ref>Gordy S and Rowell S. Vascular air embolism. Int J Crit Illn Inj Sci. 2013 Jan-Mar; 3(1): 73–76.</ref>==
*Central line aspiration of air from right heart
*100% [[O2]] non-rebreather
**Regardless of SaO2 (to reduce embolism size)
*Hemodynamic support with positive [[vasopressors|inotropes]]
*[[CPR]] in large air embolus
*Positioning
**Durant's maneuver - left lateral decubitus and Trendelenburg (head down)
**Traps air in apex of RV, relieves obstruction of pulmonary outflow tract
*Hyperbaric oxygen therapy - descent to an equivalent pressure/depth of 60 feet of sea water (fsw) (US Navy Treatment Table 6) causes any gas bubble to be crushed to approximately 40% of its original size, as well as easing the entry of those gasses into solution so they can be removed with respiration
*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

===Diving Related===
*[[IVF]] (increases tissue perfusion)
*Rapid recompression, [[Hyperbaric medicine|hyperbaric oxygen therapy]]

==Disposition==
*Likely admission

==See Also==
*[[Dialysis complications]]
*[[Scuba diving emergencies]]
*[[Diving medicine]]
*[[Hyperbaric medicine]]

==External Links==
*[https://www.merckmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/arterial-gas-embolism Merck Manual - Arterial Gas Embolism]

==References==
<references/>

[[Category:Pulmonary]]
[[Category:Neurology]]
[[Category:Environmental]]