Chapter 4- Diving Physiology Diving Physiology 119 block circulation to your lungs. Chokes is characterized by difficulty breathing, pain under your breastbone (sternum), a cough, and a feeling or actuality of choking. Your lungs lose their ability to filter bubbles, and more serious symptoms may begin as bubbles start reaching your arterial circulation. First Aid: Administer 100% O2 and transport to a hyperbaric treatment facility. Prompt treatment in a recompression chamber increases chances of a favorable outcome. Delay in treatment can make problems worse, or possibly permanent. If you go to an emergency room, there may be a long delay before chamber treatment is possible. Tell the doctor it is a scuba related injury, and give the number for a nearby hyperbaric facility or call them yourself. Know the location and phone number(s) of your nearest working chamber for each of your dive sites before you dive. Prevention: Plan your dive well. Check currents and other dive conditions. Stay well within depth/time guidelines. Know how to use your decompression tables or computers. Have a backup plan. Ascend slowly. Take safety stops. Don’t smoke or drink alcohol before your dives. Stay well hydrated. Get in good physical condition. Conservatism with your dive procedures, tables, and computers decreases risk. CIRCULATORY PROBLEMS Cramps A cramp is a muscle spasm producing pain and temporary disability. The most common cause of leg cramps is kicking with stiff, rigid ankles, rather than loose floppy ankles. Foot cramps mainly occur from kicking with tight, hooked toes. Sometimes people hook their toes to try to hang onto fins that are too big or to fit into fins that are too small. Usually, kicking with stiffly hooked toes is just poor kicking technique. Cramps can also occur when you suddenly ask a muscle to contract harder than it is in shape for; for example, swimming with oversized, stiff fins. Smaller factors predisposing to cramps include circulatory FIGURE 4-8. RELIEVING LEG CRAMP BY STRETCHING THE AFFECTED MUSCLE restrictions, cold, dehydration, fatigue, poor nutrition, poor health, and electrolyte imbalances due to vomiting, diarrhea, or other abnormal fluid losses and from various diseases. The most common sites for leg cramps are the calf of your leg and the sole of your foot. Other leg muscles that cramp are your hamstrings in back of your thigh and occasionally your quadriceps in front of your thigh. Effects: Cramps cause pain. A contracted muscle will pull on the bones to which it attaches, bending the joint. A calf cramp will pull your heel until your foot points down. A cramp on the bottom of your foot will pull your toes down. A hamstring cramp will bend your knee. A quadriceps cramp will straighten your knee. First Aid: Because a cramp is a tightly contracted and shortened muscle, to reverse the cramp lengthen the muscle by stretching it. Do not pound on a cramped muscle. To stretch a calf or hamstring cramp, pull your foot back while straightening your leg. When wearing fins, grab the blade tip of your fin and pull (figure 4-8). To stretch a cramp at the bottom of your foot, pull your
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