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Arterial Gas Embolism

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Other Names

  • Air embolism
  • Gas Embolism
  • Diving gas embolism

Background

  • This page refers to Arterial Gas Embolism (AGE), a potential catastrophic phenomenon in which compressed gases enters the arterial circulation during ascent causing end organ dysfunction

History

  • First reported by Pol in 1854[1]

Epidemiology

  • DCS is far more common than AGE in the available literature
    • In two case series of 3018 cases, only 6.5% were diagnosed as AGE[2][3]

Pathophysiology

  • General
    • Classically presents with loss of consciousness within minutes of surfacing, leading to stroke-like symptoms
    • Should be considered the most severe form of decompression sickness, but can be difficult to distinguish clinically
  • Terminology
    • Decompression Illness (DCI): broad term encompassing all disease processes related to decompression
    • Decompression Sickness (DCS): intra- or extravascular bubbles formed as a result of decompression
    • Arterial Gas Embolism (AGE): severe form of DCI in which gas bubbles are introduced into the arterial circulation
    • Decompression Stress: undefined term, need update

Etiology

  • General
    • Most commonly occurs from pulmonary barotrauma vis-a-vis ruptured alveoli
    • Less commonly from severe decompression sickness
    • Migration from the venous vasculature via a right-to-left shunt (i.e. patent foramen ovale, atrial septal defect)
  • Gas
    • Usually nitrogen
    • Expanding compressed gas trapped in the lungs as pressure falls during ascent
    • Leads to rupture of alveolar-capillary membranes, gas enters pulmonary vasculature
    • May follow breath holding, hyperinflation of the lung
    • May be associated with local lung disease (e.g. bronchial obstruction, bullae)
  • Depth
    • Can be seen after ascent from the surface from a depth as shallow as 1 m (pressure change, 0.1 atm)[4]
  • End organ dysfunction
    • Occurs due to large intra-artial bubbles
    • Cerebral embolism considered the most serious manifestation
    • Can cause ischemia to other organs (eg, spinal cord, heart, skin, kidneys, spleen, gastrointestinal tract).
  • Non-diving causes
    • Non-diving accidents involving compressed air
    • Examples include cardiopulmonary bypass, lung biopsy, neurosurgical procedures

Associated Conditions


Risk Factors

  • Sports
    • Diving
  • Occupational
    • Spaceflight
    • Aviation

Differential Diagnosis

Differential Diagnosis Dive Medicine


Clinical Features

  • History
    • Symptoms develop quickly and dramatically following ascent
      • One study found symptoms occurred at ascent to the surface or within 5 minutes after arrival in 92% of cases[5]
      • Latency greater than 10 minutes is rare should broaden the differential
    • Ascent is often rapid
      • For example, panic induced breath holding after an underwater mishap
      • However, AGE can occur during a normal ascent
    • Causes variety of stroke-like syndromes upon ascent[6]
      • Loss of consciousness (39%)
      • Confusion (37%)
      • Dizziness and presyncope (30%)
      • Hemiplegia (27%)
      • Visual changes (21%)
      • Headache (20%)
      • Dysphasia (11%)
      • Seizures (11%)
    • Sudden death can occur
    • Type II decompression sickness may also be present
      • About half of cases of symptoms of pulmonary barotrauma (chest pain, hemoptysis, etc)
      • Coronary: arrhythmias, myocardial infarction, cardiac arrest
      • Skin: cyanotic marbling of skin, focal pallor of tongue
      • Kidneys: hematuria, proteinuria, renal failure
  • Physical Exam
    • Thorough neurological exam
    • Thorough cardiopulmonary exam

Evaluation

  • The diagnosis is primarily clinical
    • There are no specific biomarkers or imaging signs
    • MRI and CT are not sensitive enough to exclude
    • Diagnostic testing often does not contribute and should not delay treatment
    • However in patients with a broader differential, relevant investigations may be appropriate

Imaging

  • May be helpful to confirm suspected diagnosis
    • Echocardiography (showing air in the cardiac chambers)
    • Chest CT (showing local lung injury or hemorrhage)
    • Head CT (showing intravascular gas and diffuse edema), although visible arterial gas is inconsistently present and its absence does not rule out arterial gas embolism
    • Abdominal CT (showing gas within mesenteric vessels or the portal vein)

Radiographs


Classification

  • Not applicable

Management

  • First Aid/ Prehospital
    • Standard resuscitation efforts should be performed if necessary
    • Place diver in supine position
    • Administer the highest oxygen fraction of inspired O2 possible
  • Positioning
    • Keep patient supine
    • Placement in lateral decubitus position or Trendelenburg is no longer recommended
  • Oxygen Therapy
    • Patients seen with suspected AGE should be placed on 100% oxygen as soon as possible
    • This should be continued until HBOT is initiated
    • Of 1045 divers who received Oxygen as first aid, 14% had complete relief of symptoms, 51% had reduced symptoms[7]
      • The cohort also had lower odds of requiring multiple recompression treatments compared to divers who did not get oxygen
  • IV Fluids/ hydration
    • Divers are often relatively dehydrated due to multiple factors, including immersion diuresis[8]
    • Active hydration strategy has been show to reduce post dive venous gas emboli[9]
    • If awake, divers should drink noncarbonated, noncaffeinated, nonalcoholic fluid containing sodium and glucose
  • Hyperbaric Oxygen Therapy (HBOT)[10]
    • Goals: reduce bubble volume (thus reducing symptoms caused by mechanical disruption of tissue and relieving ischemia)
    • Patient should be immediately recompressed
    • Patient should be flown in compressed airplane if necessary
    • Response to recompression deteriorates with increasing time from injury to compression[11]
  • Hemodynamic instability
    • Can make HBOT very tricky
    • Maintain in supine position
    • Endotracheal intubation often required
    • Mechanical ventilation, vasopressors
  • Medications
    • Tenoxicam (an NSAID), reduced he number of recompressions required to reach full recovery or a plateau[12]
    • Lidocaine is thought to be neuroprotective; its role in AGE is currently not known[13]

Prevention

  • See: Dive Medicine Prevention
  • Preventing AGE
    • Slow, controlled ascent
    • Careful exhalation during the last 10 m so that the lungs do not over pressurize

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Needs to be updated

Complications and Prognosis

Prognosis

  • Needs to be updated

Complications

  • Death
  • Permanent neurological injury

See Also


References

  1. Pol B, Watelle TJJ. Mémoire sur les effets de la compression de l’air appliquée au creusement des puits à houille. Ann Hyg Pub Med Leg 1854;2:241-279.
  2. Denoble PJ, ed. DAN annual diving report 2019 edition: a report on 2017 diving fatalities, injuries, and incidents. Durham, NC: Divers Alert Network, 2019:113-113.
  3. Azzopardi CP, Caruana J, Matity L, Muscat S, Meintjes WAJ. Increasing prevalence of vestibulo-cochlear decompression illness in Malta — an analysis of hyperbaric treatment data from 1987–2017. Diving Hyperb Med 2019;49:161-166.
  4. Hampson NB, Moon RE. Arterial gas embolism breathing compressed air in 1.2 metres of water. Diving Hyperb Med 2020;50:292-294.
  5. Leitch DR, Green RD. Pulmonary barotrauma in divers and the treatment of cerebral arterial gas embolism. Aviat Space Environ Med 1986;57:931-938.
  6. Leitch DR, Green RD. Pulmonary barotrauma in divers and the treatment of cerebral arterial gas embolism. Aviat Space Environ Med 1986;57:931-938.
  7. Longphre JM, Denoble PJ, Moon RE, Vann RD, Freiberger JJ. First aid normobaric oxygen for the treatment of recreational diving injuries. Undersea Hyperb Med 2007;34:43-
  8. Williams STB, Prior FGR, Bryson P. Hematocrit change in tropical scuba divers. Wilderness Environ Med 2007;18:48-53.
  9. Gempp E, Blatteau JE, Pontier J-M, Balestra C, Louge P. Preventive effect of pre-dive hydration on bubble formation in divers. Br J Sports Med 2009;43:224-228.
  10. Moon RE: Hyperbaric treatment of air or gas embolism: current recommendations. Undersea Hyperb Med, 46(5):673-683, 2019. PMID: 31683367.
  11. Andre S, Lehot H, Morin J, et al. Influence of prehospital management on the outcome of spinal cord decompression sickness in scuba divers. Emerg Med J 2022 February 07 (Epub ahead of print).
  12. Bennett M, Mitchell S, Dominguez A. Adjunctive treatment of decompression illness with a non-steroidal anti-inflammatory drug (tenoxicam) reduces compression requirement. Undersea Hyperb Med 2003;30:195-205.
  13. Moon RE, ed. Adjunctive therapy for decompression illness. Kensington, MD: Undersea and Hyperbaric Medical Society, 2003.
Created by:
John Kiel on 22 July 2022 13:10:24
Authors:
Last edited:
25 July 2022 20:52:46
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