History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors for decompression sickness include a large, inert gas burden; missed, inadequate, or rapid decompression; strenuous exertion; and dehydration.
Key risk factors for barotraumas include breath-holding on ascent, gas trapping, rapid decompression, and eustachian tube dysfunction.
A key risk factor for nitrogen narcosis is increased depth of diving.
musculoskeletal pain
Classically a deep boring periarticular ache, most often affecting the shoulder, elbow, or knee. Larger joints tend to be more involved than smaller ones.
There are no accompanying signs of effusion or inflammation.
numbness
Subjective sensory changes are often diffuse and not distributed according to dermatomes. They can occur in any anatomical location.[19]
tingling
Subjective sensory changes are often diffuse and not distributed according to dermatomes. They can occur in any anatomical location.[19]
paraesthesia
Subjective sensory changes are often diffuse and not distributed according to dermatomes. They can occur in any anatomical location.[19]
non-specific constitutional symptoms
Fatigue or lethargy unrelieved by adequate rest or sleep is commonly reported. Other common symptoms include malaise, anorexia, and poorly localised myalgia.
uncommon
muscular weakness
May affect any anatomical site. Spinal cord decompression sickness may present with progressive, motor and sensory deficits, characteristically causing weakness and numbness of the legs, girdle pain, and bladder dysfunction.
paralysis
May affect any anatomical site. Spinal cord decompression sickness may present with progressive, motor and sensory deficits, characteristically causing weakness and numbness of the legs, girdle pain, and bladder dysfunction.
rash
The mottled, oedematous marbling of cutis marmorata is highly specific for decompression sickness, which can also cause maculopapular, or scarlatiniform rashes.[3] Linear, non-blanching lesions may signify cutaneous barotrauma ('suit squeeze').
Other diagnostic factors
common
headache
A common, non-specific constitutional complaint in decompression sickness, if symptoms are generalised. Can be localised or attributed to sinus barotrauma.
ear or sinus pain
Barotraumatic ear or sinus pain varies on a spectrum from mild pressure or discomfort to severe pain.
dizziness or vertigo
Can occur in decompression sickness. However, may also be due to inner ear barotrauma, caloric stimulation, alternobaric vertigo (asymmetric middle ear pressures), or sea sickness. When differentiating aetiology of vertigo in divers, careful history of the timing of symptom onset is of critical importance.
nausea
May be an audio-vestibular or gastrointestinal manifestation of decompression sickness, however causes unrelated to diving are common.
vomiting
May be an audio-vestibular or gastrointestinal manifestation of decompression sickness, but causes unrelated to diving are common.
shortness of breath
Can be seen in the setting of cardiopulmonary decompression sickness, immersion pulmonary oedema, pulmonary barotrauma, non-fatal drowning, anxiety, or panic.
tachypnoea
Can be seen in the setting of cardiopulmonary decompression sickness, immersion pulmonary oedema, pulmonary barotrauma, non-fatal drowning, anxiety, or panic.
difficulty in walking
Ataxia may be a cerebellar manifestation of decompression sickness. Assessment of heel-toe gait and the sharpened Romberg test (where the subject stands heel to toe with the arms crossed so that the flat palms lie across opposite shoulders, and maintenance of this position with the eyes closed is assessed over 60 seconds) is therefore important.
reduced hearing
Conductive and sensorineural deafness may be apparent in cases of middle- and inner-ear barotrauma, respectively.
Symptoms of inner-ear barotrauma may overlap with inner-ear decompression sickness and cause considerable diagnostic confusion. A careful history and exam is critical in differentiating the two. If there are no symptoms other than hearing loss, then the disorder is barotrauma.
middle-ear bleeding or tympanic membrane perforation
Erythema, haemorrhage, or perforation of the tympanic membrane may be seen in middle-ear barotrauma, with blood in the middle ear or external auditory canal.
uncommon
pruritus
In cutaneous decompression sickness, pruritus is often described. This can be accompanied by a reticular or marbling rash. Environmental protective gear (wet suit/dry suit), sea life, and exposure to allergens are other common causes of pruritus in divers.
reduced level of consciousness
If rapid in onset, occurring during or immediately after ascent, signifies arterial gas embolism. May also be seen in cerebral decompression sickness.
crackles
Non-differentiating sign which can be seen in cardiopulmonary decompression sickness, pulmonary oedema, pulmonary barotrauma, or non-fatal drowning.
wheezing
Non-differentiating sign which can be seen in cardiopulmonary decompression sickness, pulmonary oedema, pulmonary barotrauma, or non-fatal drowning.
reduced breath sounds
Non-differentiating sign which can be seen in cardiopulmonary decompression sickness, pulmonary oedema, pulmonary barotrauma, or non-fatal drowning.
subcutaneous emphysema
May be seen in cases of pulmonary barotrauma.
Risk factors
strong
increasing depth and duration of dives (decompression illness)
Increased exposure to inert gas under pressure via increased depth and time of dives (including multiple dives over multiple days) will increase the risk of decompression sickness.[4] It is important to note that although a diver may strictly adhere to their computer or dive tables ('no deco' diving) they can still develop decompression sickness. Missed decompression stops or omission of safety stops will increase risk.[6][7]
breathing gas mixture
Gas mixes with higher concentrations of inert gasses, particularly nitrogen, will increase risk for decompression sickness. Conversely, gas mixtures with lower concentrations of nitrogen (such as nitrox) may decrease risk, particularly when used on air tables.[7]
rapid ascents (decompression illness)
Rapid ascents increase risk of both barotrauma (due to tissue over expansion) and decompression sickness (rapid decrease in ambient pressure leading to bubbles coming out of solution).[7][13] Exceeding the recommended ascent rates may be caused by poor buoyancy control, equipment failure, or panic.
altitude exposure after diving (decompression illness)
thermal stress (decompression illness)
Thermal stress will affect the body’s uptake and elimination of inert gasses. Being warm during periods of gas uptake (descent, at depth) will increase the body’s uptake of inert gas. During times of gas elimination (ascent, decompression stops), being cold will inhibit the body’s ability to eliminate inert gas due to decreased gas solubility. However, excessive heat during this time may also cause gas to come out of solution rapidly, leading to bubble formation.[7][15]
exercise stress (decompression illness)
patent foramen ovale (PFO) (decompression illness)
A PFO is a known risk factor for decompression sickness due to the venous gas emboli passing to the arterial circulation and avoiding the pulmonary filter. The exact risk is difficult to quantitate and important variables include size and presence of right to left shunt at rest. PFO is particularly associated with types of decompression sickness, including cererbral, vestibulocochlear, spinal, and cutaneous. Routine testing for PFO in divers is NOT recommended and should only be undertaken in specific circumstances, such as unexplained cases of decompression sickness.[16]
weak
increasing age (decompression illness)
There have been weak associations that increased age may increase risk of decompression sickness, but this has never been definitively demonstrated. It is also challenging to separate age as a risk factor from other comorbidities common in an older population that may increase risk.[17]
high body fat content (decompression illness)
dehydration (decompression illness)
Dehydration is commonly named as a risk factor for decompression sickness, though human evidence is lacking. Adequate hydration and euvoluemia is generally recommended.[7]
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