Arterial Gas EmbolismMANAGEMENT

ENVIRONMENTAL AND EXPOSURE PRESENTATIONS · 12 SECTIONS

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622 items

☷ Legend

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Acute Mountain Sickness Arterial Gas Embolism Bee-Wasp Sting (Anaphylaxis)Chilblains Ciguatera Fish Poisoning Coral Cut Decompression Sickness Electrical Burn Injury Envenomation (snake, spider, insect)High Altitude Cerebral Edema (HACE)High Altitude Pulmonary Edema (HAPE)High-altitude illness Hypothermia Hypothermia (Mild)Hypothermia (Severe)Immersion Foot Lightning Strike Injury Scombroid Fish Poisoning Scorpion Envenomation Sea Urchin Injury Shark Bite Snake Envenomation Spider Bite (Black Widow)Spider Bite (Brown Recluse)Stingray Spine Injury Tick paralysis White Phosphorus Burn

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Endocrine and Metabolic Presentations45▾

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

01Approach to the Critical Patient/attcp56

Immediate stabilization

›Airway and oxygenation priorities

›100% oxygen via non-rebreather mask or demand valve immediately

›Promotes nitrogen washout from gas bubbles

›Reduces bubble size by increasing nitrogen gradient

›If apneic or unable to protect airway, proceed to definitive airway

›Rapid sequence intubation preparation

›Minimize FiO2 interruption during intubation

›SpO2 target 94% to 100%

›Continuous pulse oximetry

›Waveform capnography if intubated

›Circulatory stabilization

›IV access with isotonic crystalloid (non-glucose-containing preferred)

›Bolus 500 to 1000 mL for hypotension or hemoconcentration

›Target urine output >0.5 to 1 mL/kg/hr

›Identify and eliminate source of air entry

›Clamp IV lines

›Seal open wounds

›Stop insufflation if procedural cause

›If cardiac arrest, standard CPR in supine position

›HBOT not feasible during active cardiac arrest in most settings

›Consider aspiration of RV air via catheter if available

›Positioning

›Supine position for neurologically intact patients

›Trendelenburg no longer routinely recommended

›Left lateral decubitus may be used to prevent bubble passage to coronary or cerebral circulation

›Recovery position for altered mental status

›Protects airway from aspiration

02History/hx70

Presentation context

›Diving-related AGE

›Depth and duration of dive

›Ascent rate and breath-holding during ascent

›Panic events or equipment malfunction

›Timing: 92% of cases present within 5 minutes of surfacing

›Latency >10 minutes is rare

›Multiple dives in preceding days

›Predive risk exposures

›Asthma, COPD, pulmonary blebs or bullae

›Recent upper respiratory infection with air trapping

›Iatrogenic AGE context

›Recent procedures

›Central venous catheter insertion or removal

›Cardiac surgery with cardiopulmonary bypass

›Sitting-position craniotomy

›Other procedural sources

›Endoscopy or laparoscopy

›Hemodialysis circuit

›Mechanical ventilation with barotrauma

›Thoracentesis or tissue biopsy

›Failure to wake from anesthesia or new neurologic deficits post-procedure

Symptom characterization

›Neurologic symptoms

›Sudden loss of consciousness

›Most common initial manifestation in 39% of cases

›Onset immediately upon surfacing or during procedure

›Focal deficits

03Physical Exam/exam58

Vitals and general

›Hemodynamic snapshot

›Blood pressure

›Hypotension as marker of cardiovascular compromise

›SBP <90 mmHg triggers resuscitation priority

›Heart rate

›Tachycardia common in systemic AGE

›Bradycardia or dysrhythmia if coronary involvement

›Oxygen saturation

›SpO2 on room air vs 100% oxygen

›Waveform quality assessment

›Respiratory rate

›Tachypnea from hypoxemia or pulmonary barotrauma

›General appearance

›Level of consciousness

›GCS score

›Rapid deterioration trajectory

›Distress level and skin colour

›Pallor, cyanosis, or mottling

Neurological exam

›Full neurologic assessment

›GCS and mental status

›Confusion, agitation, or obtundation

›Baseline comparison when available

›Cranial nerves

›Pupillary size and reactivity (asymmetry suggests focal injury)

›Extraocular movements and visual fields

›Motor and sensory

04Differential Diagnosis/ddx51

Immediate life threats

›Tension pneumothorax

›ICD-10 J93.0

›May coexist with pulmonary barotrauma

›Must rule out before recompression

›Tracheal deviation, absent breath sounds, hemodynamic collapse

›Acute myocardial infarction

›ICD-10 I21.9

›Coronary AGE mimics acute coronary syndrome

›ST elevation or depression on ECG

›Troponin elevation with ischemic ECG changes

›Thromboembolic ischemic stroke

›ICD-10 I63.9

›Critical to differentiate — thrombolytics contraindicated in AGE

›Single vascular territory involvement favors thromboembolism

›No causative diving or procedural event

›Cardiac arrest from ventricular fibrillation

›ICD-10 I49.01

›Massive coronary gas embolism can trigger VF

›Treated with standard ACLS

Decompression illness spectrum

›Decompression sickness (DCS)

›ICD-10 T70.3

›Often clinically indistinguishable from AGE in divers

›Treatment is the same (HBOT)

›More gradual onset than AGE

›Joint pain and skin mottling (Type I DCS)

›Neurologic or cardiopulmonary (Type II DCS)

05Laboratory Tests/lt37

Core laboratories

›Haematology

›Complete blood count

›Hemoconcentration (elevated haematocrit) from extravascular fluid shift

›Nonspecific but described finding in AGE

›Coagulation studies

›PT/INR and PTT baseline

›If thromboembolic stroke in differential before anticoagulation decision

›Metabolic panel

›Electrolytes and renal function

›Sodium, potassium, creatinine

›Medication dosing adjustment inputs

›Glucose

›Rule out hypoglycemia as cause of altered consciousness

›Hyperglycemia as stress response marker

Cardiac and perfusion markers

›Troponin

›Indicated if coronary AGE suspected

›ST changes or hemodynamic instability

›Serial troponin at 0 and 3 to 6 hours

›Elevation confirms myocardial ischemia from coronary gas embolism

›Lactate

›Tissue hypoperfusion marker

›≥2 mmol/l indicates organ hypoperfusion

›Repeat at 2 to 4 hours if elevated

›Arterial blood gas

›Oxygenation status

›PaO2 in mmHg

06Diagnostic Tests/dt65

Scoring Systems

›SANDHOG criteria for diving-related AGE

›Screening tool; score ≥2 has 94.7% sensitivity and 85.7% specificity

›Score <2 has 100% negative predictive value

›Validated in emergency department setting

›Components include sudden onset, diving exposure, neurologic deficits

›Reduces misdiagnosis in ED triage

›Reference: Hayden SR et al., J Emerg Med 2015

›ECG findings as adjunct scoring

›ST-segment changes

›Elevation or depression indicating coronary AGE

›T-wave inversions

›Dysrhythmia spectrum

›Bradycardia, tachycardia, VF, PEA, asystole

›Right heart strain: right axis deviation, S1Q3T3, RBBB

MRI

›MRI brain indications

›More sensitive than CT for ischemic changes

›Multifocal areas of restricted diffusion on DWI

›Multiple vascular territory involvement distinguishes AGE from thromboembolic stroke

›Timing consideration

›Do not delay HBOT for MRI

›Reserve for stable patients after initial HBOT

›MRI findings in AGE

›Diffusion-weighted imaging (DWI)

›Multifocal hyperintense lesions across vascular territories

›Distinguishes from single-territory thromboembolic stroke

›Susceptibility-weighted imaging (SWI)

07Disposition/dispo28

Admission indications

›All patients with suspected AGE require admission

›No safe outpatient disposition exists

›Spontaneous improvement occurs in ~50% but relapse is common

›Do not be falsely reassured by transient improvement

›ICU indications

›Hemodynamic instability or vasopressor requirement

›Cardiac arrest or post-resuscitation care

›Severe neurologic deficits or active seizures

›Respiratory failure requiring ventilatory support

›Transfer to hyperbaric facility

›As soon as cardiopulmonary stabilization achieved

›Contact DAN +1-919-684-9111 for nearest chamber

›Local diving medicine advisory service as alternative

›Air transport considerations

›Maintain cabin pressure at 1 ATA (sea level) where possible

›Fly as low as safely possible to avoid further bubble expansion

›Pressurized aircraft at altitude ≤600 m preferred if available

Post-HBOT disposition

›Ongoing HBOT planning

›Daily recompression sessions (2.0 to 2.8 ATA) continued until symptoms resolve or plateau

›Functional improvement over time common even after severe presentations

›Early prognostication should be approached with caution

›26% of patients achieved modified Rankin Scale 0 at one year in published series

›Return to diving assessment

›Specialist diving medicine evaluation required

›AGE from pulmonary barotrauma is generally a contraindication to further diving

›Reversible cause must be identified before return

08Treatment/t62

Oxygen therapy

›100% oxygen first-line treatment

›Delivery method

›Non-rebreather mask at 15 L/min

›Demand valve (oxygen-only) as alternative

›Mechanism of action

›Nitrogen washout from gas bubbles

›Reduction in bubble size and volume

›Improvement in tissue oxygen delivery

›Maintain until HBOT or symptom resolution

›Do not reduce FiO2 prematurely

›Class I recommendation equivalent by expert consensus

Hyperbaric oxygen therapy

›HBOT is the definitive treatment

›US Navy Treatment Table 6 (standard protocol)

›Recompression to 2.8 ATA with 100% oxygen

›Duration 4 to 5 hours typical

›Can be prolonged or repeated for poor initial response

›Alternative protocol

›2.5 to 3.0 ATA for 2 to 4 hours

›Adjusted based on clinical response and chamber capability

›Time-sensitivity evidence

›HBOT ≤6 hours: 9-fold increased odds of favorable outcome (Fakkert et al., Critical Care 2023)

›Delayed HBOT (even 30 to 60 hours) may still provide benefit

›Do not withhold HBOT due to delay alone

Fluid resuscitation

›Isotonic crystalloid

›Indication: hemoconcentration, hypotension, or dehydration

09Special Populations/sp69

Pregnancy

›Physiological considerations

›Increased cardiac output and blood volume

›May alter gas embolism haemodynamics

›Venous air embolism risk higher during caesarean section and hysteroscopy

›Aortocaval compression

›Left lateral tilt for positioning where feasible

›Avoid supine hypotension during resuscitation

›HBOT in pregnancy

›Relative contraindication but NOT absolute in life-threatening AGE

›Risk to mother from untreated AGE outweighs HBOT risk to fetus

›Fetal bradycardia and transient hypoxia reported during HBOT

›Monitoring during HBOT

›Continuous fetal heart rate monitoring where feasible

›Neonatology or obstetrics on standby

›Imaging considerations

›CXR with abdominal shielding when indicated

›Radiation risk minimal compared to benefit

›CT only when benefit outweighs fetal radiation exposure

›MRI preferred over CT for neurologic assessment in stable patients

›No ionizing radiation

›Gadolinium generally avoided in first trimester

Geriatric

›Iatrogenic AGE risk

›Higher frequency of invasive procedures

›Central venous catheter placement and removal

›Cardiac catheterisation and angiography

›Increased risk of venous air embolism from dehydration and low central venous pressure

10Background/b70

Epidemiology

›Diving-related AGE

›Incidence approximately 1 per 5000 to 1 per 10000 recreational dives

›Most common cause of diving-related death after drowning

›Primarily affects recreational and military divers

›Mortality without treatment: estimated 20 to 30% in historical series

›With prompt HBOT: significantly reduced

›26% modified Rankin Scale 0 at 1 year in cerebral AGE series

›Iatrogenic AGE

›Incidence varies by procedure

›Central venous catheter: 0.13 to 0.5% per procedure

›Sitting-position craniotomy: up to 25 to 45% subclinical venous air embolism detected by Doppler

›Often missed or misdiagnosed

›Clinical context must be actively considered

›Procedural staff awareness is critical

›Reference population

›Divers Alert Network (DAN) annual injury report tracks dive-related AGE

›Male predominance in recreational diving injuries

›Mean age in recreational divers: 30 to 40 years

Pathophysiology

›Bubble formation and entry

›Pulmonary barotrauma mechanism

›Lung overexpansion on ascent with breath-holding

›Rupture of alveoli allows gas to enter pulmonary veins

›Gas passes to left heart and enters arterial circulation

›Iatrogenic mechanism

›Air entrainment through open vascular access above the heart

›Venous pressure less than atmospheric when central venous pressure is low

›Gas travels via right heart; PFO permits arterial crossing

›End-organ injury

›Cerebral AGE

›Gas lodges in cerebral arterioles causing mechanical obstruction

›Ischemia with secondary inflammatory cascade

›Endotheliopathy: complement activation, neutrophil adhesion, thrombosis

›Coronary AGE

›Gas enters coronary ostia preferentially in upright or head-up position

›Right coronary artery preferentially affected

›ST elevation, arrhythmia, cardiogenic shock

›Bubble physiology

›Nitrogen-oxygen bubble expands with altitude and contracts with pressure

›Boyle's law governs size changes with ambient pressure

›100% oxygen breathing displaces nitrogen, shrinks bubble

›Inflammatory cascade

›Complement activation at bubble-blood interface

›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

11Patient Discharge Instructions/pdi30

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

12References/r26

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

›Vann RD, Butler FK, Mitchell SJ, Moon RE. Decompression Illness. Lancet. 2011

›Tibbles PM, Edelsberg JS. Hyperbaric-Oxygen Therapy. New England Journal of Medicine. 1996

›Cao D et al. Part 10: Adult and Pediatric Special Circumstances of Resuscitation. AHA Guidelines for CPR and ECC. Circulation. 2025

›Guo JL et al. TEE Detection of Air Embolism During Endoscopic Surgery and Validity of HBOT. Medicine. 2021

›ICD-10 T79.0 Air embolism (traumatic)

›ICD-10 T70.3 Caisson disease (decompression sickness)

›ICD-10 T78.9 Adverse effect, unspecified (iatrogenic cause)

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