List of signs and symptoms of diving disorders

Source: Wikipedia, the free encyclopedia.
recompression chamber
is used to treat some diving disorders and for training divers to recognise the symptoms.

symptoms
of these may present during a dive, on surfacing, or up to several hours after a dive.

The principal conditions are

pulmonary barotrauma (burst lung). Although some of these may occur in other settings, they are of particular concern during diving activities.[1]

The disorders are caused by breathing gas at the high pressures encountered at depth, and divers will often breathe a gas mixture different from air to mitigate these effects. Nitrox, which contains more oxygen and less nitrogen, is commonly used as a breathing gas to reduce the risk of decompression sickness at recreational depths (up to about 40 metres (130 ft)). Helium may be added to reduce the amount of nitrogen and oxygen in the gas mixture when diving deeper, to reduce the effects of narcosis and to avoid the risk of oxygen toxicity. This is complicated at depths beyond about 150 metres (500 ft), because a helium–oxygen mixture (heliox) then causes high pressure nervous syndrome.[1] More exotic mixtures such as hydreliox, a hydrogen–helium–oxygen mixture, are used at extreme depths to counteract this.[2]

Decompression sickness

A large horizontal cylinder with a bank of instruments and monitors
The recompression chamber at the Neutral Buoyancy Laboratory used for treating DCS and training

Pulmonary DCS is very rare in divers.[3] The table below classifies the effects by affected organ and bubble location.[4]

Signs and symptoms of decompression sickness
DCS type Bubble location Clinical manifestations
Musculoskeletal Mostly large joints
  • Localised deep pain, ranging from mild to excruciating; sometimes a dull ache, but rarely a sharp pain
  • Pain aggravated by active and passive motion of the joint
  • Pain which may be reduced by bending the joint to find a more comfortable position
  • Pain occurring immediately on surfacing or up to many hours later
Cutaneous Skin
  • Itching
    , usually around the ears, face, neck, arms, and upper torso
  • Sensation of tiny insects crawling over the skin (formication)
  • Mottled or marbled skin or subcutaneous crepitation, usually around the shoulders, upper chest and abdomen, with itching
  • Swelling of the skin, accompanied by tiny scar-like skin depressions (
    pitting edema
    )
Neurologic Brain
Neurologic Spinal cord
Constitutional Whole body
Audiovestibular Inner ear
Pulmonary Lungs

Arterial gas embolism and pulmonary barotrauma

Diagram showing the four chambers of the heart and the pulmonary arteries and veins connecting it to both lungs
The pulmonary circulation

If the compressed air in a diver's

arterial gas embolism (AGE), with effects similar to severe decompression sickness.[5] Although AGE may occur as a result of other causes, it is most often secondary to PBT. AGE is the second most common cause of death while diving (drowning being the most common stated cause of death). Gas bubbles within the arterial circulation can block the supply of blood to any part of the body, including the brain, and can therefore manifest a vast variety of symptoms. The following table presents those signs and symptoms which have been observed in more than ten percent of cases diagnosed as AGE, with approximate estimates of frequency.[6]

Signs and symptoms of arterial gas embolism
Symptom Percentage
Loss of consciousness
 81
Pulmonary
rales
or wheezes 		38
Blood in the ear (Hemotympanum) 34
Decreased
reflexes
 34
Extremity weakness or paralysis 32
Chest pain 29
Irregular breathing or apnea 29
Vomiting 29
Coma without convulsions 26
Coughing blood (Hemoptysis) 23
Sensory loss 21
Stupor and confusion 18
Vision changes
 20
Cardiac arrest 16
Headache 16
Unilateral motor changes 16
Change in gait or ataxia 14
Conjunctivitis 14
Sluggishly reactive
pupils
 14
Vertigo 12
convulsions
 11

Other conditions that can be caused by pulmonary barotrauma include

mediastinal emphysema and interstitial emphysema
.

Nitrogen narcosis

The central area shows an LCD display clearly, but it becomes increasingly grayed out away from the centre
Narcosis can produce tunnel vision, making it difficult to read multiple gauges.

manual dexterity. As depth increases, so does the pressure and hence the severity of the narcosis. The effects may vary widely from individual to individual, and from day to day for the same diver. Because of the perception-altering effects of narcosis, a diver may not be aware of the symptoms, but studies have shown that impairment occurs nevertheless.[7] Since the choice of breathing gas also affects the depth at which narcosis occurs, the table below represents typical manifestations when breathing air.[8]

Signs and symptoms of narcosis
Pressure (bar) Depth (m) Depth (ft) Manifestations
1–2 0–10 0–33
  • Unnoticeable small symptoms, or no symptoms at all
2–4 10–30 33–100
  • Mild impairment of performance of unpracticed tasks
  • Mildly impaired
    reasoning
  • Mild euphoria possible
4–6 30–50 100–165
6–8 50–70 165–230
8–10 70–90 230–300
  • Poor concentration and
    mental confusion
  • dexterity
    and judgment
  • Loss of memory
    , increased excitability
10+ 90+ 300+

High pressure nervous syndrome

Photograph of a subject's head with numerous small sensors covering the forehead, neck and scalp
An EEG recording net

recompression chambers and electroencephalography (EEG) monitors.[9]

Signs and symptoms of HPNS
Symptom Notes
Impairment Both intellectual and
manual dexterity
is observed at 180 metres (600 ft), rising to 40% at depths of 240 metres (800 ft)
Dizziness
convulsions
.
Tremors Tremors of the hands, arms and torso are observed from 130 metres (400 ft) onward. The tremors occur with a frequency in the range of 5–8 hertz (Hz), and their severity is related to the speed of compression; the tremors reduce and may disappear when the pressure has stabilised.
EEG changes At depths exceeding 300 metres (1,000 ft), changes in the
alpha waves
(8–13 Hz).
Somnolence At depths beyond the onset of EEG changes, test subjects intermittently
sleep stages
1 and 2 observed in the EEG. Even when decompressed to shallower depths, the effect continues for 10–12 hours.

Oxygen toxicity

Further information: Oxygen toxicity
Three people are sitting inside a small enclosure
During World War II Professor Kenneth Donald carried out extensive testing for oxygen toxicity in divers. The chamber is pressurised with air to 3.7 bars (370 kPa; 54 psi). The subject in the centre is breathing 100% oxygen from a mask.

Although

epileptic seizure.[10] Susceptibility to oxygen toxicity varies dramatically from person to person, and to a much smaller extent from day to day for the same diver.[11] Prior to convulsion, several symptoms may be present – most distinctly that of an aura
.

During 1942 and 1943, Professor Kenneth W Donald, working at the Admiralty Experimental Diving Unit, carried out over 2,000 experiments on divers to examine the effects of oxygen toxicity. To date, no comparable series of studies has been performed. In one seminal experiment, Donald exposed 36 healthy divers to 3.7 bars (370 kPa; 54 psi) of oxygen in a chamber, equivalent to breathing pure oxygen at a depth of 27 metres (90 ft), and recorded the time of onset of various signs and symptoms. Five of the subjects convulsed, and the others recovered when returned to normal pressure following the appearance of acute symptoms. The table below summarises the results for the relative frequency of the symptoms, and the earliest and latest time of onset, as observed by Donald. The wide variety of symptoms and large variability of onset between individuals typical of oxygen toxicity are clearly illustrated.[12]

Signs and symptoms of oxygen toxicity observed in 36 subjects
Signs and symptoms Frequency Earliest onset (minutes) Latest onset (minutes)
Lip-twitching 25 6 67
Vertigo 5 9 62
Convulsion 5 20 33
Nausea 4 6 62
Spasmodic respiration 3 16 17
Dazed 2 9 51
Syncope 2 15 16
Epigastric aura
 2 18 23
Arm twitch 2 21 62
Dazzle 2 51 96
Diaphragmatic spasm 1 7 7
Tingling
 1 9 9
Confusion 1 15 15
Inspiratory predominance[note 1] 1 16 16
Amnesia 1 21 21
Drowsiness
 1 26 26
Fell asleep 1 51 51
Euphoria 1 62 62
Vomiting 1 96 96
Note
  1. ^ Normally, breathing in takes less time than breathing out; inspiratory predominance is a reversal of this.

References

  1. ^
    OCLC 51607923
    .
  2. PMID 8005852
    . Retrieved 1 March 2009.
  3. ISBN 978-1-905492-07-7
    .
  4. OCLC 51607923
    .
  5. OCLC 51607923
    .
  6. OCLC 51607923
    .
  7. OCLC 51607923
    .
  8. OCLC 66524750
    .
  9. OCLC 51607923
    .
  10. OCLC 51607923
    .
  11. OCLC 51607923
    .
  12. PMID 20248086
    .

Further reading

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