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NAUI Master Scuba Diver 128 Diving Physiology Dental Barotrauma (Tooth Squeeze) Tooth decay and incomplete fillings can create air spaces in your teeth. The openings to these cavities can be so small that gas takes much time to get in there. When you ascend, the pressure release is too rapid to get the collected gas back out. Changing pressure can create a squeeze or reverse block (figure 4-17). Effects: Effects start on or after ascent. You may have pain, bleeding, or may even break the tooth. Tooth pain can be mistaken for sinus barotrauma because the roots of some upper teeth extend to your sinus cavities. First Aid: Go to a dentist to repair the affected tooth. Prevention: Go for regular visits to your dentist. Gastrointestinal (GI) Barotrauma Some foods and drinks can give you gas. Some people are more sensitive to this than others. Gas can also get into your GI tract if you swallow it. Stomach and intestinal gas can be uncomfortable when it expands on ascent. Effects: Effects range from belching and discomfort to considerable abdominal pain. Severe trauma is rare. If you have a hernia, expanding gas trapped in a loop of bowel could make the hernia irreducible. Ambient pressure pushing on a stomach full of gas can cause belching with some backflow of stomach contents (heartburn). First Aid: Stop your ascent. Descend to vent the gas and relieve discomfort, then slowly re-ascend. It often helps to keep your legs moving. If you have to surface before you can relieve the pressure, you may benefit from various over-the-counter, anti-gas preparations. In extreme cases, go for medical attention. Prevention: Breathe normally. Don’t swallow air. If you are a habitual air-swallower, find out why so you can stop doing that. If you are sensitive to gas-producing food and drink, avoid them before diving. EFFECTS OF THE DIVING ENVIRONMENT You can dive in cold conditions in ice diving, winter diving in quarries, oceans, and lakes, or any time in cool latitudes. Other times, you might prepare for your dives under the hot sun, on a humid day, and in a hot exposure suit. Dive boats rock in the waves. Surge tosses you at the surface. Many dive conditions are disorienting or dehydrating, and there are the usual dings, cuts, and bumps of an active life around the water. What fun it is to dive! This section covers chilling, overheating, seasickness, disorientation, vertigo, diving infections, and some ways to avoid them all. Chilling A variety of freezing and nonfreezing injuries to your body are possible in the cold (figure 4-18). Exposure to damp cold with temperatures around freezing produces frostnip and trench foot (immersion foot). Exposure to dry cold with temperatures well below freezing causes frostbite. This section deals only with chilling from immersion. Your body is pretty good at maintaining a healthy, warm, internal temperature range despite exposure to a wide range of cold environments (figure 4-20). You produce body heat several ways as part of the processes of being alive. You have to get rid of some of that heat or you would cook. A certain amount of regular heat loss is normal and healthy. You lose heat several ways. None of them, by themselves, is a problem. Moreover, when you increase heat loss through one avenue, your body helpfully reduces heat loss another way too keep things even. Losing heat is not a problem as long as you replace what you lose. Chilling results when you lose more than you replace. Any downward variation of body temperature is frequently, but mistakenly referred to as hypothermia. Your body temperature normally falls several degrees at night when you sleep, for example, which is normal and is not hypothermia. True clinical hypothermia is the reduction of your core temperature (not your skin temperature) below 35°C/95°F. You can become incapacitated by cold, even drown, without ever being hypothermic. Whether you will get cold while in cold water depends on many things. Your rate of heat loss depends on the quality and fit of your wet or dry suit. Your ability to keep and store heat depends on many of your body


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