DECOMPRESSION SICKNESSThe Bends

Overview• Can affect people under

high pressures (divers) or low pressures (pilots, astronauts, etc.)

• Caused by formation of gas bubbles in the body

• Can occur anywhere in the body

• Typically the joints, more rare in the spine or skin

Henry’s Law• The solubility of a gas in a liquid is directionally

proportional to the gas pressure• As the pressure increases, the solubility increases and

vice versa• Think of a Coke can: when under high pressure of CO2,

more CO2 dissolves in the liquid

• Open the can, reduce the pressure, the gas comes out of solution

SCUBA• Self Contained Underwater

Breathing Apparatus• Invented by Jacques Cousteau• Use pressurized gas to reach

greater depths• To get deeper, use helium

instead of nitrogen• Helium has lower solubility in

water than nitrogen

Prevention and Treatment• Divers ascend using

decompression schedules• Allow the body to adjust to

pressure changes and the dissolved gases to be exhaled

• Schedule varies with gases used (He escapes faster than N2)

• Use tables or computer programs to determine schedule

Treament• Immediate treatment is pure

oxygen followed by pure oxygen in a hyperbaric chamber• Pressure reduces the size of the

bubbles• Pure O2 keeps blood

oxygenated and displaces nitrogen from bubbles

• O2 bubbles easily absorbed by blood