Dysbarism is a collective term for all illnesses resulting from changes in ambient pressure that occur at a rate exceeding the capacity of the person to adapt safely. Conditions such as decompression sickness (the bends), arterial gas embolism (AGE), and barotrauma may result.
Decompression illness is a term that refers to both decompression sickness and AGE.
Diagnosis of dysbarism can usually be made on history and examination alone.
Gas coming out of solution and forming bubbles is the prime cause of decompression sickness, whereas gas contraction and expansion causes barotrauma.
Any body tissue can be affected, resulting in a wide variety of clinical presentations. Any new symptom with a close temporal relation to diving should be presumed to be due to dysbarism until shown to be otherwise.
The unpredictability of ultimate outcome at the onset of any decompression illness requires each case to be managed as a medical emergency.
Recompression is the mainstay of treatment for decompression illness. Early administration improves outcome.
Oxygen administration plays a key role in all cases of decompression illness, both as emergency treatment and during recompression.
Dysbarism includes decompression sickness, arterial gas embolism (AGE), and barotraumas.
Decompression sickness is a complex of symptoms and disease caused by the formation of an excess of bubbles in body tissues. This occurs after an exposure to breathing gases at increased pressure, followed by a reduction in environmental pressure. AGE refers to the precipitation of gas bubbles in the arterial circulation. Decompression illness encompasses decompression sickness and AGE. Barotrauma is damage to tissues caused by the pressure-induced expansion and contraction of gases in enclosed spaces.
Nitrogen narcosis is a syndrome of reversible neurological and behavioural changes produced by an increased partial pressure of nitrogen in the body.
History and exam
- ear or sinus pain
- dizziness or vertigo
- shortness of breath
- difficulty in walking
- reduced hearing
- middle-ear bleeding or tympanic membrane perforation
- reduced level of consciousness
- reduced breath sounds
- subcutaneous emphysema
- diving or other activity involving increased atmospheric pressure (decompression illness)
- increasing depth and duration of dives (decompression illness)
- strenuous exercise during diving (decompression illness)
- rapid ascents (decompression illness)
- multiple ascents (decompression illness)
- missed safety stops (decompression illness)
- repetitive diving (decompression illness)
- altitude exposure (decompression illness)
- right-to-left shunt (decompression illness)
- dehydration (decompression illness)
- cold temperature (decompression illness)
- hot temperature (decompression illness)
- high body fat content (decompression illness)
- increasing age (decompression illness)
- menstruation (decompression illness)
- poor physical fitness (decompression illness)
- recent physical injury (decompression illness)
- carbon dioxide retention (decompression illness)
- failure to equilibrate pressure (barotrauma)
- breath-holding during ascent (barotrauma)
- lung disease (barotrauma)
- Eustachian tube dysfunction (barotrauma)
- sinus ostia blockage (barotrauma)
- incorrect auto-inflation (barotrauma)
- trapped gas in or near teeth (barotrauma)
- Fallopian canal dehiscence (barotrauma)
- deep diving (nitrogen narcosis)
Oliver M. Firth, MBBs, BSc, MRCGP
Diving Physician & Director
OMF declares that he has no competing interests.
Dr Oliver M. Firth would like to gratefully acknowledge Dr John D. King, the previous contributor to this topic. JDK declares that he has no competing interests.
Avi Shupak, MD
Head Otoneurology Unit
Carmel and Lin Medical Centers
AS declares that he has no competing interests.
John R. Fitz-Clarke, MD, PhD
Staff Hyperbaric Physician
Queen Elizabeth II Health Sciences Centre
JRFC declares that he has no competing interests.
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