Decompression Sickness

Epidemiology

  • Pulmonary decompression sickness is more common in military aviators than divers
  • Pulmonary decompression sickness is rare and occurs in <1% of decompression sickness cases

Risk Factors

(these factors enhance the accumulation of inert gases in tissues)

  • Older age:
  • Obesity:
  • Poor physical fitness:
  • Female sex:
  • Repetitive dives: nitrogen in tissues is removed slowly over hours (may accumulate with multiple dives)

Physiology

  • Prolonged exposure at depth causes supersturation of N2 and O2 in tissues -> during ascent, O2 is readily released but N2 release is delayed (forming the nidus for bubbles to develop and circulate)
  • Pulmonary decompression sickness: due to air bubbles lodging within pulmonary vasculature, causing partail obstruction (causes mediator release and oxygen radical release): increased PA pressures and PVR/ decreased CO (without significant change in ventilation or perfusion)
  • Silent (asymptomatic bubbles) may occur during ascents in normal range of safety: these cause subtle cortical MRI changes

Diagnosis

  • CXR/ Chest CT patterns:
    • Pulmonary Edema: in cases of pulmonary decompression sickness

Clinical

  • Symptoms/ signs:
  • Arthralgias (75%):
  • Parasthesia (4%):
  • Rash (4%):
  • Vertigo (2.5%):
  • Visual changes (1%):
  • Paralysis (<1%):
  • Other: fatigue/ agitation/ headache/ seizures/ cranial nerve deficits

Pulmonary Decompression Sickness

  • Substernal discomfort and cough (“the Chokes”):
  • Other signs of pulmonary edema: dyspnea, hemoptysis, etc.:

Treatment

  • Avoidance of rapid ascent: use decompression tables for guidance
  • Hyperbaric oxygen: decompression sickness is the only indication for hyperbaric oxygen that has been proven efficacious in randomized trials

References

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