Sunday, 12 February 2012

Scuba Diving Decompression Sickness: The Bends & Caisson Disease: Signs and Symptoms of DCS

Diagnosis is based mainly on the patient’s history. For example, an 80 year old lady in A&E complaining of a painful shoulder, shopping bags by her trolley, is unlikely to have DCS – whereas a 20 year old with the same presenting symptoms and a SCUBA tank next to them is a likely candidate for recompression treatment.
A useful description of DCS can be achieved by noting the area(s) of the body affected.
General signs (constitutional).
·         Nausea, weakness or fatigue.
Skin (cutaneous).
·         Itching (pruritis).
·         Generalised rash.
·         Lumps.
·         Cutis marmorata marbling (serious sign).
·         Crackling feeling (subcutaneous emphysema) - not usually around collarbone.
Musculoskeletal (muscles and joints).
·         Joint or muscle discomfort and / or pain ("bends").
·         Limitation of limb movement.
·         Crunching sound in joint. 
Gastrointestinal (stomach and bowel).
·         Nausea, vomiting.
·         Abdominal cramps, diarrhoea.
Cardiorespiratory (heart and lungs).
·         Coughing.
·         Chest pain made worse on inspiration.
·         Tachypnoea (increase in breathing rate).
Neurological (cerebrum, cerebellum, spinal cord, inner ear and peripheral nerves).
·         Headache.
·         Confusion.
·         Memory loss.
·         Tremors.
·         Visual disturbance (scotoma).
·         Involuntary eye movement (nystagmus).
·         Lack of co-ordination (AtAxia).
·         Numbness or altered sensation.
·         Pins and needles (paresthesia).
·         Urinary retention / incontinence.
·         Ringing sound in ears (tinnitus).
·         Hearing loss.
·         Dizziness, loss of balance (vertigo).
·         Partial or full paralysis of lower limbs (paraparesis / paraplegia).
·         Unconsciousness.
The “Rhomberg test” is commonly used to assess a patient with suspected DCS. The patient is asked to stand heel to toe, with legs slightly bent at the knees. They then cross the arms with them lifted off the chest and close their eyes. Those with neurological DCS are unlikely to be able to maintain their balance for more than a second or two.
It must be emphasised that even in the absence of obvious symptoms, the possibility of DCS should be considered if the diver's circumstances suggest such a risk. Those with any symptoms of DCS, however mild, are at risk of further episodes.
Classification of DCS
Decompression sickness can be classified as either Type 1 or Type 2. The different classification reflects the effect, and therefore the severity, of the condition.
Type 1 DCS can occur when bubbles affect the tissues around skeletal joints. The areas most often affected are the knees, elbows and shoulders.
Decompression sickness might also present as a skin (cutaneous) disorder. Nitrogen bubbles can cause mottling, lumps or a rash. "Skin bends", as they are colloquially termed, are more common during hyperbaric chamber 'dives' and when diving using a dry suit. Although not usually in themselves serious, skin symptoms may indicate the presence of problems elsewhere. If left untreated, Type 1 DCS may progress to Type 2.
Type 2 decompression sickness reflects involvement of the Central Nervous System (CNS) and / or the cardio-respiratory system. More than half of those diagnosed with DCS will be classified as Type 2. Cerebral symptoms arise from interruption of the blood supply to the main part of the brain, and include confusion, reduced mental function and unconsciousness. Involvement of the cerebellum may lead to tremors, loss of balance ("staggers") and a lack of co-ordination (ataxia). Balance may also be affected by damage to the vestibular part of the inner ear.
Spinal DCS may present as back pain, paresthesia (pins and needles), paralysis and loss of urinary sphincter control - resulting in either incontinence or retention.
As discussed already, the formation of small inert gas bubbles does not necessarily lead to the development of DCS. Likewise, when bubbles become trapped in the tiny blood vessels around the lungs' alveoli (air sacs), problems do not always arise. In fact, it is thought that their accumulation in this area may increase the rate that the gas is excreted from the body (Edmonds et al, 1993). However, if too many bubbles collect, breathing will become adversely affected ("chokes"). Symptoms include breathlessness, tachypnoea, chest pain and coughing. Although symptoms may resolve, this should be regarded as a life-threatening condition as it may progress to fatal respiratory collapse. 

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