NAUI Master Scuba Diver 134 Diving Physiology of the extremely distressing symptoms and lack of easy remedies aside from medications, many questionable “cures” have been popularized. It has been said that the only sure cure is to sit under the nearest tree. Prevention: Preventing motion sickness is more successful than treating it once started. Get adequate rest before your trip. Eat lightly, if at all. Avoid diesel or other exhaust fumes, greasy, salty foods, and avoid watching or smelling others who are sick. Stay in the center of the boat, where motion is least. Commercial wrist bands with bumps that press into the skin have tested to be as useful as any placebo, meaning they will work for some people. A variety of drugs combat motion sickness easily and effectively. Some are available overthe counter, others require a prescription. Some make you drowsy, so don’t drive to the dive site after taking them. Drowsiness is such an issue for some divers, that they take the medication at night before bed, then dive the next day. Ginger root is a good alternative for some divers. Consult your diving physician for the medication( s) right for you. Disorientation Disorientation is loss of your sense of direction or position. On land you know about balance and position three ways. You use your sense of vision to tell you where you are and how near and far things are. Your connective and muscle tissues have lots of little sense organs called proprioceptors that tell your brain about the position of your body parts and if you are moving them. Your vestibular system in your inner ear acts like a carpenter’s level with two functions: orientation to gravity and orientation to movement through space. For orientation to gravity, you have two little sacs called the saccule and utricle that contain little granules. Your brain figures out which way is up by the position of your granules. For movement through space, you have semicircular canals. Your canals are three bony tubes at right angles to each other, one in each plane. They are filled with fluid and little sensing hairs that tell your brain about movement in each plane. Your three orientation senses work together. For example, your eyes can keep tracking even when your head is moving - you can read this even if you rock your head from side to side. You can drive over bumpy roads, but if you saw a film of driving over bumpy roads, it is more difficult to see what is going on because you are not there and your other sense organs cannot help you out. Your systems are also redundant. If one fails, you can still orient yourself using the information from the other two. However, there are limits and mix-ups. Under water, the usual orientation signals to your brain are limited or distorted. You are neutrally buoyant and your limbs seem weightless. Your visibility may be restricted by turbidity, narrow masks, or low light levels, or the water may be so clear that you cannot tell near from far or up from down. Your vestibular system can be confused by sloshing around in surge. There may be visual contradictions about up and down from watching people and fish float around. These can all leave you disoriented. Effects: Disorientation makes it hard or impossible to tell which way is up, where you are, or where the surface is. First Aid: Stop and grasp a stationary object for reference. Watch your bubbles. Most of them will go upward, and this is one way to orient yourself if you can’t tell which way is up (figure 4-21). Prevention: Look for clues which provide spatial orientation. Descend feet first. Remember that bubbles go upward, but currents will vector their rise (make them go tilty on the way up) so don’t let them confuse you. FIGURE 4-21. IT IS EASIER TO MAINTAIN ORIENTATION BY USING A LINE.
20047TC
To see the actual publication please follow the link above