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Decompression Sickness

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Decompression Sickness, Constitutional DCS

  • See Also
  1. Neurologic Decompression Sickness
  2. Inner Ear Decompression Sickness
  • Epidemiology
  1. Recreational Scuba Incidence: 1 per 5-10,000 dives
  2. No-Decompression dives account for 50% of DCS cases
  • Pathophysiology
  1. Atmospheric Pressure at sea level: 14.7 psi (1 ATA or atmosphere absolute)
  2. Water Pressure Increase
    1. Water adds 1 ATA of pressure for every 33 feet (10 meters) of depth
    2. Total Pressure at Depth 33 feet: 2 ATA (29.4 psi)
    3. Total Pressure at Depth 66 feet: 3 ATA (44 psi)
    4. Total Pressure at Depth 99 feet: 4 ATA (58.8 psi)
  3. Henry's Law
    1. Describes relationship of gas solubility in liquids at Ambient pressure
    2. Compressed air contains inert gas (e.g. Nitrogen)
      1. As divers descend to higher water pressures, more nitrogen gas is dissolved in the blood stream
      2. As divers ascend to lower pressures, gradual off-gassing of nitrogen is required
  4. Rapid ascent (decompression) does not allow for adequate nitrogen off-gassing
    1. Insoluble nitrogen bubbles instead precipitate, resulting in Decompression Sickness
  • Predisposing factors
  1. Dive logistics
    1. Deeper dive profile
    2. Increased rate of ascent
  2. Hypothermia
  3. Fatigue
  4. Advanced age
  5. Dehydration
  6. Alcohol intake
  7. Female gender
  8. Obesity
  9. Patent Foramen Ovale
  • Types of Decompression Sickness
  1. Type I Decompression Sickness (Constitutional DCS)
    1. Mild Fatigue or malaise
    2. Mild symptoms involving Muscles, joint and skin
  2. Type II Decompression Sickness (Severe)
    1. Inner Ear DCS
    2. Neurologic DCS
      1. Cerebral DCS (30-40%)
      2. Spinal Cord DCS (50-60%)
  • Management
  1. See Decompression Sickness Management
  • References
  1. Clenney (1996) Am Fam Physician 53(5):1761-6 [PubMed]
  2. Newton (2001) Am Fam Physician 63(11): 2211-2226 [PubMed]