Platelet aggregation and thromboin formation on bubble surface
Endothelial injury from leukocyte adhesion
Therapeutic Considerations
HBOT mechanism and evidence
Primary mechanism: mechanical bubble compression
2.8 ATA compresses bubble volume by approximately 64% (Boyle's law)
Tissue oxygen delivery markedly enhanced
Secondary mechanism: nitrogen supersaturation
Breathing oxygen at high pressure creates large nitrogen gradient
Nitrogen diffuses out of bubble into tissues and blood
Evidence quality
No randomized controlled trials (RCT) exist for HBOT in AGE
Case series and observational data support benefit
Expert consensus strongly recommends HBOT (Class I equivalent)
Oxygen toxicity considerations
Central nervous system oxygen toxicity
Risk increases above 2.8 ATA or with prolonged exposure
Air breaks given during treatment tables to reduce risk
Seizure is the primary concern
Pulmonary oxygen toxicity
Relevant for multiple sessions or extended protocols
Standard treatment tables within safe exposure limits
Adjunct therapy evidence
NSAIDs (tenoxicam) as adjunct to recompression in decompression sickness
Limited evidence; some benefit reported
Not standard of care for AGE specifically
Lidocaine neuroprotection: experimental, not guideline-endorsed
Theoretical reduction in CNS ischemia-reperfusion injury
Aspirin: not routinely recommended; thrombotic contribution unclear
Patient Discharge Instructions
copy discharge instructions
Arterial gas embolism home care after HBOT
Complete all prescribed hyperbaric oxygen sessions
Do not miss follow-up recompression appointments
Inform staff immediately of any new or worsening symptoms
Rest and light activity as tolerated
Avoid strenuous exertion until cleared by diving medicine specialist
Hydrate well with non-alcoholic, non-carbonated fluids
Avoid flying until cleared by diving medicine specialist
Cabin pressure changes can worsen residual gas emboli
Minimum 72 hours after last recompression; longer if symptoms persist
Warning signs to return to emergency immediately
Recurrence of neurologic symptoms
New or returning weakness, numbness, or paralysis
Confusion or altered consciousness
Vision changes or speech difficulty
Seizures
Chest pain or difficulty breathing
Worsening headache
Any new or concerning symptoms
Return to diving
Do NOT return to diving without specialist diving medicine clearance
AGE from pulmonary barotrauma is generally a permanent contraindication
Specialist evaluation required to assess underlying lung pathology
Inform any treating physician about the AGE episode
Important for anaesthesia and procedural planning
Follow-up plan
Diving medicine or hyperbaric medicine clinic follow-up within 1 to 2 weeks
Neurology follow-up if neurologic deficits persist
Cardiology follow-up if coronary AGE occurred
Echocardiogram with bubble study to assess for PFO if not yet done
References
Guidelines and key sources
Primary evidence sources
Mitchell SJ, Bennett MH, Moon RE. Decompression Sickness and Arterial Gas Embolism. New England Journal of Medicine. 2022
Comprehensive review of diving-related decompression illness and AGE
Timing data: 92% present within 5 minutes of surfacing
Muth CM, Shank ES. Gas Embolism. New England Journal of Medicine. 2000
Pathophysiology of venous and arterial gas embolism
Iatrogenic and diving etiologies
Systematic reviews and meta-analyses
Fakkert RA et al. Early Hyperbaric Oxygen Therapy Is Associated With Favorable Outcome in Patients With Iatrogenic Cerebral Arterial Gas Embolism. Critical Care. 2023
HBOT ≤6 hours: 9-fold increased odds of favorable outcome
Systematic review and individual patient data meta-analysis
Tekle WG et al. Factors Associated With Favorable Response to HBOT in Iatrogenic Cerebral AGE. Neurocritical Care. 2013
Diagnostic tools
Hayden SR, Buford KC, Castillo EM. Accuracy of SANDHOG Criteria for Diagnosis of AGE. Journal of Emergency Medicine. 2015
Score ≥2: sensitivity 94.7%, specificity 85.7%
Score <2: NPV 100%
Brown AE, Rabinstein AA, Braksick SA. Clinical Characteristics, Imaging Findings, and Outcomes of Cerebral Air Embolism. Neurocritical Care. 2023
Additional references
Marsh PL, Moore EE et al. Iatrogenic Air Embolism: Pathoanatomy, Thromboinflammation, Endotheliopathy, and Therapies. Frontiers in Immunology. 2023
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