bends (Caisson disease, decompression disease)

Etiology

• expansion of a gas that occurs because of changes in barometric pressure after ascent during scuba diving or deep tunnel work (origin of caisson)
• scuba diving
• high risk patent foramen ovale increases risk of the bends

Pathology

• arterial gas embolism
  • inhaled compressed air under high pressures of scuba diving results in increased nitrogen & oxygen dissolved in blood
  • the bends occurs when dissolved nitrogen forms bubbles in a diver's vasculature due to changes in pressure during ascent
• potentially lethal disorder

Clinical manifestations

• symptoms develop within 1 hour (75%, 90% within 12 hours) of surfacing
• neurologic symptoms within minutes after surfacing
  • focal motor, sensory or visual deficits
  • unconsciousness
• fatigue, malaise, headache, joint pain, pruritus, erythema
• marbling over upper torso
• focal pallor of the tongue
• pulmonary
  • pneumothorax 10%
  • pneumomediastinum
  • hemoptysis
  • chest pain
  • interstitial emphysema (> 10%)
• palpitations, arthralgias, vomiting (case report)
• violaceous skin mottling (cutis marmorata) (image)

Laboratory

• serum ALT, serum AST, serum creatine kinase, & serum lactate elevated

Radiology

• abdominal CT not routine
  • may show air in the portal venous system

Complications

• damage to spinal cord (lumbar, thoracic) may progress to paraplegia, loss of sphincter control
• CNS manifestations - memory loss, ataxia Differetial diagnosis:
  • nitrogen narcosis
    • confusion, poor judgement & or euphoria

Management

• hydration
• oxygen 100%
• place in left lateral decubitus position with mild Trendelenbug position
• hyperbaric oxygen therapy
• Divers should wait 12-48 hours before air travel.

More general terms

• barotrauma