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Arterial Gas Embolism

Hyperbaric Oxygen Therapy for Decompression Illness in Divers

DIVERS ALERT NETWORKDECOMPRESSION ILLNESS IN DIVERS: A REVIEW OF THE LITERATURE

Diana Marie Barratt, MD, MPH, Paul C. Harch MD, and Keith Van Meter, MD

(THE NEUROLOGIST 8:186-202, 2002)

BACKGROUND- Neurologists may be consulted to diagnose and treat the severe neurologic injuries that can occur in divers with decompression illness (DCI).

REVIEW SUMMARY- Subclinical bubbles form during normal diving activity. DCI, a diffuse and multifocal process, results when bubbles cause symptoms by exerting mass effect in tissues, or obstructing venous or arterial flow. The lower thoracic spinal cord is a commonly affected area of the central nervous system. The most commonly described form of brain DCI is cerebral arterial gas embolism with middle cerebral artery or vertebrobasilar distribution involvement. Bubbles exert secondary damage to the vascular endothelium, causing activation of numerous biochemical cascades.

CONCLUSIONS- Divers can develop DCI on very short dives or in shallow water, even when adhering to protocols. DCI should be strongly considered when divers experience pain after diving. Any neurologic symptoms after a dive are abnormal and should be attributed to DCI. Even doubtful cases should be treated immediately with hyperbaric oxygen (HBOT), after a chest x-ray to rule out pneumothorax. The Divers Alert Network should be contacted for emergency consultation. Delay to treatment can worsen outcome; however, the overwhelming majority of divers respond to HBOT even days to weeks after injury. Although DCI is a clinical diagnosis, magnetic resonance imaging, somatosensory evoked potentials, single-photon emission tomography, and neuropsychologic testing help to document disease and monitor response to therapy. Divers should be treated with HBOT until they reach a clinical plateau. Complete relief of symptoms occurs in 50% to 70% of divers; 30% have partial relief.

Decompression illness (DCI) is a systemic disease that can result in severe neurologic consequences. Neurologists may be consulted to assist in the diagnosis and management of injured divers. This article reviews the English literature on the diagnosis and treatment of DCI, with an emphasis on United States practice patterns.

From the Department of Neurology, Louisiana State University in New Orleans, New Orleans, Louisiana and the Department of Medicine, Section of Emergency Medicine and Hyperbaric Medicine, Louisiana State University in New Orleans, New Orleans, Louisiana.