Chapter 4- Diving Physiology Diving Physiology 133 Prevention: Although you can simply stay out of the heat, it is healthier and more convenient to acclimate yourself to the heat. Repeated exposure to heat and gradually exercising more and more in the heat improves your heat tolerance. Reduce heat stress by staying well hydrated. Your body can tolerate extreme temperatures when you drink enough water. When working in the heat for many hours, drink commercial sport drinks if you can’t stop to eat a meal. You don’t need salt tablets - they are too concentrated. Don’t wear all your dive gear when walking distances in the heat to your dive site. Occasionally splash yourself while preparing to get into the water. Your susceptibility to heat illness, particularly heatstroke, increases if you are dehydrated, out of shape, overweight, of advanced age, drinking alcohol, suffer chronic alcoholism, or using drugs such as antihistamines, water pills (diuretics), major tranquilizers, or cocaine. Stay in good physical condition and normal body weight. Exercise aerobically several times per week for at least 20 minutes. If you are aerobically fit you can tolerate heat exposure far better than someone with less aerobic conditioning. Physical fitness is a major factor in heat tolerance. Sea Sickness Some people find rocking boats and tossing waves comforting. Others find them sickening. Sea sickness can ruin dive trips, vacations, and travel. It prevents some divers from even attempting travel by boat. No one is immune, although the amount of motion required varies from person to person. It is popular to state that the cause involves conflicting signals, i.e. one motion sensing system senses motion, while another does not. However, you can be quite sick when all your sensing systems agree that you are in motion. Motion itself is the primary trigger. Among your motion and orientation detecting systems are the semicircular canals in your inner ear. These canals are filled with fluid and tiny hairs. The fluid sloshes around when you move. This moves your hairs and tells your brain about how your head is moving. When you move a lot, they slosh a lot, and the hairs signal your brain a lot. Another part of your inner ear’s balance department are two little organ sacs. These sacs contain small rock-like particles called otoliths that move in response to your orientation in space. Sensitivity to high amounts of sloshing, and possibly individual variability in otolith mass, determines how much the movement will signal your brain to be bothered. More about the interesting anatomy and effects is described in the next two sections, “Disorientation” and “Vertigo.” Effects: Early warnings include feelings of unease and dismay, pallor, and sometimes headache, followed by weakness, cold sweat, and nausea, then continued salivating, and finally vomiting. Vomiting underwater can be a safety problem. If you throw up underwater, it seems best to keep your regulator in your mouth, because a gasping inhalation commonly follows vomiting, however, there are also arguments for removing the regulator. If you retain your regulator, keep the mouthpiece pulled away from one corner of your mouth to allow materials to flow into the water. Keep the purge valve pressed to prevent clogging. First Aid: There are several, effective sea sickness prevention medications. They are not as effective after symptoms have started, but can still be tried with good effect. Your physical position in the vessel can help. Some say to remain on deck in the fresh air, while others remind that the point of least motion in a boat is at the center of the boat, below deck. It often helps to lie down. Be aware of the two usual orientations of bunks: across-ships or “the long way.” Depending whether the boat is rocking side to side or bow to stern, you will be rocked side to side or head-to-toe. Head-to-toe is usually more comfortable. If you remain on deck, some say to maintain visual contact with the moving water, thereby allowing your eyes and inner ears to sense the same movement and resolve the supposed sensory conflict. For others, watching the movement is, in itself, sickening. Try closing your eyes. Avoid the stern (back) of the boat where exhaust fumes can accumulate, or the smoke stack area in larger ships like cruise ships. Don’t read. Psychological support from companions is helpful. In other words, don’t be cruel to a seasick buddy; you may be next. Other methods of first aid are the same as those for prevention, below. Because
20047TC
To see the actual publication please follow the link above