Arterial Gas Embolism
Description of Medical Condition
Air released from an over-pressurized alveolus enters the pulmonary capillaries then travels through the arterial circulation causing occlusion of the cerebral and/or coronary circulation.
• Arterial gas embolism is the most serious and rapidly fatal of all SCUBA diving injuries and is second only to drowning as the leading cause of death associated with sport diving.
• Arterial gas embolism occurs on ascent and the time from alveolar rupture to the manifestation of symptoms is nearly always less than ten minutes.
System(s) affected: Cardiovascular, Nervous, Musculoskeletal
Genetics: N/A
Incidence/Prevalence in USA: It is estimated (based on injury/mortality reports collected by Divers
Alert Network) to occur in approximately 4 per 100,000 sport divers per year.
Predominant age: Young adult
Predominant sex: Male > Female
Medical Symptoms and Signs of Disease
• Group 1: Neurologic symptoms only. Divers presenting with neurologic symptoms but without impairment of spontaneous respirations and cardiac function. May be impossible to clinically distinguish from severe decompression sickness.
– Asymmetrical multiplegia or paralysis
– Tingling or numbness
– Blindness or other visual disturbances
– Deafness
– Vertigo
– Dizziness
– Headache
– Confusion
– Convulsions
– Aphasia
– Personality change; from subtle changes to unconsciousness
• Group 2: Loss of consciousness, apnea, and cardiac arrest or dysrhythmia. Divers presenting with both neurologic and cardiac impairments. All of the above signs and symptoms plus those below are possible.
– Dysrhythmias
– Cardiac arrest
What Causes Disease?
• Group 1: Localized obstruction of cerebral blood flow by an embolus of air. Local capillary endothelial damage with vasogenic edema leading to a rise in intracranial pressure and ischemia.
• Group 2: This is thought to be due to localized obstruction of both cerebral and coronary blood flow by an embolus of air
Risk Factors
• History of a rapid ascent
• History of panic during dive
• History of holding breath while diving
• History of loss of consciousness (or with other noted symptoms) within seconds to minutes after or during a dive
• History of patent foramen ovale has been associated with a 4.5-fold increase in decompression illness events and 2 times more ischemic brain lesions than divers without this condition
Diagnosis of Disease
Differential Diagnosis
Decompression sickness
Laboratory
• Hematocrit — increased indicating volume depletion
• Serum creatine kinase — the correlation between serum kinase activity and outcome suggest that elevated serum level of this enzyme may be a marker for size and severity of arterial gas embolism
• Urinalysis — increased specific gravity indicating volume depletion
Drugs that may alter lab results: N/A
Disorders that may alter lab results: N/A
Pathological Findings
N/A
Special Tests
• ECG
Imaging
• Chest x-ray to rule out pneumothorax
Diagnostic Procedures
N/A
Treatment (Medical Therapy)
Appropriate Health Care
• Hospital based hyperbaric chamber capable of performing a U.S. Navy Table 6A recompression (165 feet of seawater [FSW]).
General Measures
• Immediate transport to a suitable hyperbaric chamber for recompression as soon as possible; do not delay with nonessential procedures.
• Transport by aircraft is justifiable if it will save a significant amount of time (aircraft must fly at low altitudes or be capable of maintaining cabin pressure at about one atmosphere)
• Life-saving measures (CPR) must take precedence to sustain life
• Administration of high flow maximum concentration oxygen therapy by a tight fitting mask or by intubation and mechanical ventilation during transport
• Keep patient in recumbent position while maintaining airway
• Maintain hydration with IV fluids
• For assistance and advice in locating the nearest treatment chamber in your area (world-wide) call DIVERS ALERT NETWORK (DAN) at any hour (919) 684-8111
Activity
None until after treatment
Diet
None until after treatment
Patient Education
• Divers Alert Network (DAN)
– Diving emergency hotline for medical emergencies only- 919-684-8111 or919-684-4DAN (collect); 24 hours, 365 days a year
– Medical information line for nonemergency questions
– 919-684-2948 M-F (9-5 EST)
– DAN America information line — 800-446-2671 or 919-
684-2948 M-F (9-5 EST); website www.diversalertnetwork.org OOn-Site neurological exam by Ed Thalmann, MD: websitewww.diversalertnetwork.org/medical/neuroexam.asp
Medications (Drugs, Medicines)
Drug(s) of Choice
• Oxygen
Contraindications: N/A
Precautions: N/A
Significant possible interactions: N/A
Alternative Drugs
None
Patient Monitoring
• Frequent neurological checks in the acute pre-treat-ment and treatment phase
• Complete neurological assessment at one, three, six and twelve months
Prevention / Avoidance
• Strict adherence to diver safety protocols, especially including the buddy system
• No diving after any dive injury or with any medical condition until evaluated and approved by a physician knowledgeable in diving medicine
Possible Complications
• Long term serious neurologic impairments
• Death
Expected Course / Prognosis
• Complete to partial resolution with adequate treatment
Miscellaneous
Associated Conditions
• Pulmonary barotrauma leading to arterial gas embolism, can also cause pneumomediastinum, subcutaneous emphysema, pneumopericardium, pneumothorax. and pneumoperitoneum
• Always consider the possibility of decompression sickness in addition to arterial gas embolism in any SCUBA diver who has recently completed a dive
• Patent foramen ovale and diving has been associated with ischemic brain lesions
Age-Related Factors
Pediatric: N/A
Geriatric: N/A
Pregnancy
N/A
Synonyms
• Gas embolism
• Air embolism
International Classification of Diseases
958.0 Air embolism
See Also
Other Notes
• Any diver who has an onset of new symptom(s) or sign(s) after recently completing a SCUBA dive of any type, to any depth, for any period of time — serious consideration must be given as having sustained a dive related injury
Abbreviations
DAN = Divers Alert Network AGE = arterial gas embolism FSW = feet of seawater
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