When I was a houseman, a young man with shoulder pain came to me, saying he had gone diving in Sai Kung the night before.
Given the aggressive depth and time of his dive, I assumed his was a case of decompression sickness, also known as divers’ disease, and reported it to my superiors who thought likewise.
Fortunately, the patient was not in any severe danger, and senior doctors on the duty arranged a hyperbaric oxygen therapy for him. Since then, I have not encountered another case of decompression sickness.
Diving tanks contain mainly nitrogen and oxygen. The deeper and longer the dive is, the more the nitrogen goes into the blood.
Before getting out of the water, divers must allow time for excessive nitrogen in the bloodstream to be exhaled through respiration. Otherwise, excessive nitrogen will form small bubbles in the body, blocking blood vessels or causing inflammation. The amount of nitrogen in the blood is directly related to the number of bubbles in the body and the seriousness of the disease.
Decompression sickness is one of the many conditions related to diving. Some beginner divers who get nosebleeds think their nasal mucous membrane has been compressed by the face mask. The truth is, their paranasal sinuses have been damaged by the change in air pressure, causing blood to run from their nostrils.
Divers who have a toothache underwater are advised to see the dentist as they are likely to have tooth cavities. If left untreated, the pressure difference can break a decaying tooth.
Diving can be a dangerous sport but by receiving proper training and not exceeding one’s limits, everyone can enjoy the fun of diving without risking life and limb.
One of the most important precautionary measures is to have diving buddies. Do not dive alone. Form a team of two or three and stay close in the water so that when an accident happens, someone can offer immediate help.
Some of the most tragic diving accidents in Hong Kong were not due to the lack of preparation but involved divers who came up to the surface without being noticed by a passing boat or ship.
Water sports offer lots of fun, but always be alert and don’t get carried away.
This article appeared in the Hong Kong Economic Journal on July 3
Translation by John Chui
[Chinese version 中文版]
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