Note sull'episodio
In 1670 Robert Boyle put a viper in his new vacuum chamber and watched a bubble form in its eye, the first recorded case of what became decompression sickness. Henry's law explains it: gas dissolved in blood and tissue under high pressure comes out as bubbles when pressure drops too fast, and helium in heliox or trimix avoids narcosis but bubbles just as readily. Tribonucleation may seed tiny bubbles in joints as cartilage surfaces pull apart. The disease first struck on land as caisson disease, when sandhogs worked in compressed air beneath rivers: 15 workers died building the Eads Bridge in St. Louis, and Washington Roebling suffered lasting neurological damage from the Brooklyn Bridge caissons in the 1870s. Astronauts face the same risk stepping from a one atmosphere cabin into a suit at about a third of an atmosphere.
Susceptibility varies with ascent rate, time at depth, cold, dehydration, and body fat, since nitrogen is about five times more soluble in fat than in water. A patent foramen ovale, open in 20 to 25 percent of adults, can shunt bubbles past the lung filter into the brain and spinal cord, one explanation for so-called undeserved hits on divers who followed their computers. The name came from sandhogs hobbling in a stoop that onlookers mocked as the Grecian Bend, a fashionable posture of the 1870s. In 1890 Ernest William Moore, facing a death rate above 25 percent on the Hudson River tunnel, built the first medical airlock, the ancestor of hyperbaric oxygen therapy.
- Airliner cabins are pressurized to about 7,900 feet, which is why divers wait up to 48 hours before flying.
- Symptoms can take up to 48 hours to appear as bubbles grow and trigger inflammation.
- Cutis marmorata marbles the skin, the chokes hit the lungs, and the staggers wreck balance.
- Patients are laid flat so buoyant bubbles do not rise toward the brain.
- Skeletons of sperm whales and extinct marine reptiles show bone damage matching chronic decompression sickness.