Wednesday, October 30, 2013

Anything for science.

One of the biggest hazards of deep sea diving is something called the ‘bends’. The air was breath is 80% nitrogen. Put the human body under pressure, and the nitrogen is transformed into tiny bubbles that migrate into the blood and tissues. If the pressure is changed too rapidly, as with a too quick ascent by a diver; the bubbles trapped within the body begin to fizz like a freshly opened soda bottle, clogging tiny blood vessels and depriving cells of oxygen and causing so excruciating pain that sufferers are prone to bend in agony. A great deal of what we know about surviving at extremes is owed to extraordinary father and son team of John Scott and J.B.S. Haldane. Haldane’s gift to diving was to work the rest intervals necessary to manage an ascent from the depths without getting the bends. With Admiralty funding, JBS acquired a decompression chamber that he called the ‘pressure pot.’ This was a metal cylinder in which three people could sit at a time and could be sealed and subjected to tests of various types. Volunteers were required to sit in ice water while breathing ‘aberrant atmosphere’ or subjected to rapid changes or pressure. In one experiment, Haldane simulated a dangerously hasty ascent and the dental fillings in his teeth exploded. It is said that every experiment ended with someone having seizures, vomiting or bleeding. The chamber was virtually soundproof, so the only way for occupants to signal distress was to tap insistently on the chamber wall or to hold up notes on the small window. Once while poisoning himself with elevated levels of oxygen, Haldane had a fit so severe that he crushed several vertebrae. Collapsed lungs were a routine hazard. Perforated eardrums were quite common. Haldane in one of his essays writes “ the drum generally heals up; and if the hole remains in it, although one is somewhat deaf, on can blow tobacco smoke out of the ear in question, which is a social accomplishment.” It was not just Haldane, but even his colleagues and family were subjects of his experiments. Sent on a simulated descent, his wife had a fit that lasted 13 minutes. When at last she stopped bouncing across the floor, she was helped on her feet and sent home to cook dinner. Haldane happily employed anyone who happened to be around and on one occasion a former prime minister of Spain, Juan Negrin. Dr Negrin complained afterward of minor tingling and ‘curious velvety sensation on the lips’ Dr Negrin was lucky, a similar experiment with oxygen deprivation left Haldane without feeling his buttocks and lower spine for six years.

Adapted from Bill Bryson’s “A short history of nearly everything”

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