Diving Related Injuries (Decompression Illness)



Decompression sickness clinical

Is caused by accumulation of nitrogen (bubbles) in tissues. Suspect decompression sickness, (the "Bends", dysbarism) in any patients with a history of a dive within last 48 hours who presents with:

  • Joint pains (dull ache, unaffected by movement, "niggles" may flit between joints)
  • Neurological symptoms (however vague). Particularly changes in mentation, sensation, coordination, audiovestibular function, cerebellar symptoms or fatigue. Neurological signs (equivocal or definite, particularly cranial nerve deficits)
  • Skin rashes (pruritis, erythema, marbling of the skin)
  • Constitutional symptoms (malaise, extreme fatigue, the shivers)
  • Lymphatic oedema (esp. face, neck or breast)
  • SOB - (the "chokes") - caused by embolisation of the pulmonary vasculature by venous bubbles

Have a low threshold for diagnosing decompression sickness, even in those with safe diving practice. Beware of those who have transient neurological symptoms ("TIAs"), as these may resolve then progress to full neurological deficit with an inflammatory response and clot formation at the site of the original transient bubble.


"Laws"

Boyle's law

The the volume of a fixed mass of gas is inversely proportional to the absolute pressure (assuming constant temperature)

Henry's law

At a constant temperature the amount of gas that will dissolve in a liquid is proportional to the partial pressure of the gas over the liquid ("Heineken law")

Dalton's law

In a mixture of gases, the partial pressure of each gas present is equal to the pressure that gas would exert if it alone occupied the original volume. P(total) = P(1) + P(2) +.....P(n)

Pulmonary barotrauma

Pulmonary Over Inflation Syndrome (POIS)

Results in:

  1. Arterial Gas Embolism
  2. Pneumothorax
  3. Mediastinal or surgical emphysema
  4. Pneumoperitoneum

History

  • Get as detailed dive history as possible - particularly gas mixtures used, depth and duration, decompression stops
  • Record if symptoms occurred on descent or ascent or how long after dive completed:
    • Inner or middle ear (tympanic membrane) trauma usually have difficulty clearing on descent
  • Note past medical history (particularly previous Decompression Illness), respiratory and ENT status

Management

Initial measures aim to increase oxygenation (hasten removal of nitrogen from tissues and treat tissue hypoxia) and hydration (dehydration and haemoconcentration occur due to insensible losses to the environment).

AVOID ENTONOX.

Airway

  • 100% oxygen by face mask, to hasten inert gas elimination
  • Rapid sequence intubation (RSI) if airway not protected
  • Left lateral position (not "head down" as may raise intracranial pressure)

Breathing

  • Consider chest drain if pneumothorax, surgical emphysema or pneumomediastinum
  • Even if only problem appears to be pulmonary barotrauma, refer to diving medicine unit anticipating 2° deterioration

Circulation

  • IV fluids (increased vascular permeability causes third space losses)
  • ± urinary catheter

Disability

  • Neurological examination (including gait assessment if possible)
  • Diazepam for seizures

Referral

More details on recompression procedure.

If using helicopter, low altitude (below 200m). Fixed wing aircraft should be pressurised to 1 bar (sea level).

When referring please use descriptive term for condition using the manifestation, time and evolution headings below.

Manifestation

  • Neurological
  • Pain
  • Constitutional
  • Pulmonary
  • Cutaneous
  • Lymphatic

Time of onset

Evolution

  • Progressive
  • Relapsing
  • Static
  • Spontaneous improving
  • Resolved

Please discuss ALL cases of possible barotrauma with the on-call EM consultant



Content by Dr √ćomhar O'Sullivan, Dr Jason van der Velde 12/06/2023. Last review Dr ÍOS, 24/03/24.