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Dehydration can cause increased blood viscosity and can probably increase the likelihood of
developing decompression sickness (DCS). Most healthy adults can generally tolerate mild
forms of dehydration, such as that experienced during a competitive softball game during a
hot summer picnic. But scuba divers can ill afford to take such risks. Normal diving activities such as carrying heavy gear to a distant dive site, suiting up in the hot afternoon sun, or vigorous finning against a strong current may well predispose a diver to DCS due to bodily fluid loss. Continued, uncontrolled fluid loss from respiration, perspiration, and elimination inevitably spells trouble. For the scuba diver, it can contribute to a variety of physiological, painful, and perhaps incapacitating symptoms. Divers planning to dive should drink fluids frequently, particularly just prior to entering the water. Fluids should also be taken in relatively large doses during surface intervals between dive. The quantity should be enough to produce a frequent output of urine. There are a number of complex variables that make it impossible to determine exactly how much water will be lost, and there are many factors that promote dehydration in a diver.
How Divers Lose WaterImmersion Reflex . Simple immersion in sea water dehydrates the body by osmosis. The osmotic effect causes the sea water to draw pure water out of the diver's body, resulting in a loss of fluid and some dehydration.Immersion Diuresis . Water immersion also causes a reaction that promotes urine production in the kidneys. This concentration of urine is drawing vital liquid from the rest of the body, adding to the process of dehydration. Evaporation . Evaporation is a process by which valuable water is lost to the air during predive activities and during surface interval between dives. Rather than baking in the sun to achieve the ultimate vacation tan, it is far safer to seek the shade, stay cool on hot days, and help preserve precious body fluid. Breathing Dry Air . Not only is scuba air filtered before it is compressed into a scuba cylinder, but it becomes dry. Breathing this dry air adds considerably to the dehydrating process because the diver humidifies that air with each breath. The diver is actually losing water vapor with each exhalation. Perspiration . Diving is work. divers often do not realize how much they are perspiring while diving because of the liquid environment surrounding them. beads of perspiration appearing before a dive are visible signs of dehydration at work. It is important for divers to refrain from hard physical work or play prior to a dive, and then to conserve as much energy during the dive. This "non-activity" will aid the diver in conserving body fluid. Cold . When a diver gets cold, the body attempts to conserve heat by shunting blood from the extremities, creating a greater than normal amount of blood in the trunk of the body. This concentration of blood in the torso creates a greater than normal amount of urine. The effects of chilling promotes dehydration, and the colder a diver gets, the faster he or she breathes which adds to the vicious cycle of dehydration through respiration. Tropical Travel . It may take several days after arrival on a beautiful diving island before a diver's body is fully adjusted to the climate. Until that time, the diver's built-in water conservation mechanisms may not be functioning properly. Even with heavy physical work and profuse perspiration, divers may not drink sufficient quantities to replace the fluids lost. Knowledgeable divers will drink more water than the desire the first few days of a diving vacation and prior to every dive. Alcohol Level . Alcohol is a diuretic that suppresses the release of a hormone that ordinarily permits the body to retain fluids. The result is additional dehydration from alcohol in the system. As Dr. Lee Somers from the University of Michigan stated in his lecture "Alcohol and Diving" at the International Conference on Underwater Education in 1986, "When you wake up in the morning the next time you are at a dive resort, remember, if you can't spit, don't dive." Caffeine . Diuresis is triggered to some extent by coffee, tea, cola, chocolate, and food products containing caffeine. A diver who imbibes the night before a dive and drinks several cups of coffee at breakfast could be asking for trouble on his or her morning dive. Drugs and Medications . Anyone taking medications, whether prescriptions or over the counter, should consult with a diving physician for possible side effects of the drug. Some medications contain diuretics, which contribute do dehydration. Seasickness . Seasickness causes divers to lose fluid quickly through vomiting, diarrhea, and perspiration. Persons experiencing seasickness need to be careful to ingest plenty of liquids to replace that which is being lost. Decompression Sickness (DCS) .In DCS, there is often a problem of fluid leaving the blood steam and moving into the body cells. This loss of fluid from the circulatory system helps make the blood thick and sludgy.
Fluid Replacement for DCS VictimsDecompression Sickness is a very complex malady that requires analysis and treatment of several abnormalities before and during the traditional recompression therapy. First aid administration should be based upon the knowledge and abilities of those present, and the first rule of first aid is DO NO FURTHER HARM. Obviously, an emergency medical technician at the dive site should be expected to perform at a higher degree of expertise than a basic first aider.A diver exhibiting symptoms of DCS should be placed flat on his or her back and given 100% oxygen to breathe. A tight fitting double seal demand valve is recommended. Blood pressure, pulse rate, and respiratory rate need to be monitored continuously, and the victim should not be left unattended. The victim should be calmed and reassured. A detailed history of the dive and vital information about the diver and his or her activities for the previous 48 hours should begin while waiting for evacuation. Since scuba diving is a dehydrating activity that tends to increase the viscosity of the blood and make one more susceptible to decompression sickness, it may be beneficial to give fluids to patients who are suspected to be suffering the effects of DCS. Fluids can e administered by mouth or intravenously if the capability and experience exist on site. Again, do no further harm. For an injured diver at the dive site who is alert and exhibiting stable vital signs, the first responder should administer oral fluids if evacuation time to the nearest hospital will be more than one hour. The fluids should be given in quantities sufficient enough to maintain frequent and regular urination. Water is usually the most readily available liquid for the patient to drink. fruit juices are better, and balanced electrolyte solutions, such as half strength Gatorade, are best. Dextrose should not be added to the water, and diuretics such as alcohol and caffeine must be avoided. The amount of fluid administered should be the same as for victims of shock. Give the patient sixteen ounces of liquid every hour if he is conscious and not vomiting or nauseated. If on site intravenous fluids can be administered, isotonic electrolyte solutions such as normal saline or lactated Ringer's solution is preferred. Administering fluids intravenously provides certainty that the fluid will reach the vascular system, and the intravenous pathway is then available if needed later. Hypotonic electrolyte solutions, such as dextrose are not recommended. In DAN's REPORT ON 1988 DIVING ACCIDENTS, only seventeen percent of all dive accident victims were given fluids as a first aid measure. This would be acceptable if the remaining 83% were within one hour of treatment. But we know this is not true because the average elapsed time from onset of the first symptom to the first call to a medical facility was 15 hours. Prudent dive planning will involve necessary steps required to conserve vital body fluids as a preventative measure to help assure that first aid and recompression therapy are not required at the conclusion of a dive.
RECOMMENDATIONS FOR PREVENTING DEHYDRATION WHEN SCUBA DIVING.
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