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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