Decompression Sickness



Multisystemic disease process resulting from escape of inert gas bubbles (nitrogen) out of solution into body fluids and tissues


  • Pathophysiology:
    • Increases in ambient pressure cause increase in partial pressure of nitrogen inspired (as per Henry law, below)
    • Nitrogen accumulates in tissues in increasing concentrations the longer ambient pressures remain elevated
    • Decompression sickness (DCS) results when ambient pressure keeping nitrogen in solution decreases too rapidly (on ascent), preventing gradual removal of excess body burden of nitrogen
    • As the nitrogen removal gradient is overwhelmed, tissues become supersaturated and bubble formation occurs
  • Henry law:
    • Amount of gas that will dissolve in a solution at a given temperature is directly proportional to partial pressure of that gas
    • Increases in partial pressure result in larger amount of gas dissolved in tissue
    • Decreases in partial pressure result in gas coming out of solution
  • Bubbles are viewed as foreign material by body inciting inflammatory and coagulation responses
    • Leads to increased vascular permeability and decreased intravascular volume and hemoconcentration
  • Bubble location determines clinical effects:
    • Blood flow and lymphatic obstruction leading to ischemia, infarction, or lymphedema
    • Mechanical distention of tissues leading to pain
  • Risk factors for DCS:
    • Dive factors:
      • Greater depth
      • Longer bottom time
      • Multiple dives in a day
      • Rapid ascent
      • Cold water
    • Human factors:
      • Obesity
      • Intercurrent illness
      • Pulmonary disease
      • Dehydration
    • Proper use of dive tables and computers does not eliminate risk for DCS
    • Predive vigorous exercise may reduce risk
  • 50% of patients develop symptoms in 1 hr, 90% develop symptoms within 6 hr
  • Airplane flight following diving can precipitate DCS owing to lower cabin pressure

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