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Multisystemic disease process resulting from escape of inert gas bubbles (nitrogen) out of solution into body fluids and tissues
- 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:
- Intercurrent illness
- Pulmonary disease
- Proper use of dive tables and computers does not eliminate risk for DCS.
- Predive vigorous exercise may reduce risk
- Dive factors:
- 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.