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Health Matters
• gastroenteritis: the widespread tourist if a diver is dehydrated the heart and respiration
disease’ normally leads to diarrhoea and/or rates increase and the nitrogen uptake of the
vomiting. if water is being lost through those body tissues increases accordingly. on the
abnormal mechanisms, an imbalance of other hand, the tissues will receive a reduced
electrolytes can develop very quickly into a blood flow due to the increased viscosity. this
medical emergency. negatively affects the ability of the tissues to
release nitrogen during the decompression
• Certain medical conditions such as diabetes time. scientific studies in rats have revealed that
can cause severe loss of fluids leading to pre-dive oral hydration decreases circulatory
dehydration or even hypovolemia (osmolaric bubbles, offering a relatively easy means
diuresis due to glucosuria). other: diuretic of reducing decompression sickness risk.
medication taken for high blood pressure. additionally, if dehydrated, the diver will fatigue
more rapidly and is more likely to suffer muscle
• insufficient or inadequate fluid uptake cramps.
is a common cause. Drinking does not
automatically mean you are providing Half of the cases managed by Divers alert
enough fluids for the body. Diuretic drinks, network (Dan) during the past years have
such as alcohol, coffee and black tea can not been related to an obvious violation
cause a negative fluid balance through of decompression procedures – they have
enhanced kidney function. We also have been ‘unpredictable’ or ‘undeserved.; But
to put into consideration that ramadan – have they been really undeserved? in cases
2009 starts in august - the hottest month
We recommend the ‘double-tank
of “unpredicted” decompression sickness
of the year. it means that the local muslim
principle’– if you carry one tank of
dehydration is usually the most frequent cause.
dive-guides, who might fast from sunrise compressed air on your back, carry
to sunset, are deficient in fluids of any kind. one tank of water in your hand.
the average adult needs to consume at least
it is not difficult to achieve the proper level
2.5litres of water over 24 hours – without
of hydration before and while scuba diving. Before setting off, drink
consideration of physical exercise. Hot weather, diving and the
lots water or a sports drink which does not contain too much sugar.
accompanying activities raise the daily needs for liquids considerably
in warmer weather and for longer dives, you will need to drink more
– even up to 6 litres per day.
fluids. Drink BeFore you get thirsty. if you are thirsty, your body
already has a lack of fluids. remember to avoid caffeinated drinks such
Symptoms of dehydration as coffee and colas or any alcoholic beverages for many hours before
Dehydration is classified as mild, moderate, or severe based on how the dive.
much of the body’s fluid is lost or not replenished and also how much
the electrolyte balance is affected. When severe, dehydration is a life- excess alcohol the night before will lead to dehydration. a decent
threatening emergency. it is a known hazard to divers by increasing pre-hydration condition before the dive might increase the urgency to
the risk of decompression illness. urinate underwater, however it decreases diving induced dehydration
and hypovolaemia. urinating in a wet or even drysuit is more
• mild dehydration: thirst, dry mouth, headache, decreased urine favourable than the best case of DCs.
volume, abnormally dark urine, unexplained tiredness, irritability,
dizziness when standing due to orthostatic hypotension. We recommend the ‘double-tank principle’– if you carry one tank of
compressed air on your back, carry one tank of water in your hand.
• moderate to severe dehydration: possibly no urination, lethargy or avoid the bright sun, especially when already dressed in a wetsuit and
extreme sleepiness, seizures, fainting, increased heart and respiration put on a hat or wear a cap to cover your head.
rate, drop of blood pressure and a lack of tears when crying
if you feel dehydrated underwater, ascend at a slower rate than
• severe dehydration: rise of body temperature, cardiac arrhythmia, normal (less than 0 feet per minute) and also make longer stops on
unconsciousness, delirium and even death if there is kidney failure. the way up. if you regularly feel thirsty underwater, you may use a
at around five to six percent water loss, one may become groggy sCuDa (underwater drinking bag) to substitute fluids during the dive
or sleepy, experience headaches or nausea, and may feel tingling in (highly recommended for diabetic divers!).
the limbs (paresthesia). With ten per cent to 15 per cent fluid loss,
muscles may become spastic, skin may shrivel and wrinkle, vision may once you have surfaced, re-hydrate slowly, best with plain water
dim, urination will be greatly reduced and may become painful, and or sugar reduced – or sugar free sport-drinks. latest research has
delirium may begin. losses greater than 15 per cent are usually fatal. proven that the intake of an oral rehydration solution (ors, such as
rehydran, elotrans or paedoral) with reduced osmolarity (sodium
Dehydration and decompression sickness
40-50mmol/l) has more positive effects on the body than plain water.
the increased risk of decompression sickness (DCs) caused by
the fluids will remain longer in the body and are not ‘washed out’
dehydration has been extensively studied and explored by scientists.
through the kidneys as fast as plain water. they also reduce the stool
in swine and rat models it was documented that dehydration
frequency and vomiting in case of gastroenteritis. if ors are on hand,
significantly increases the overall risk of severe DCs and death.
it is advisable to have them once a day during the time of strenuous
specifically, it increased the risk of cardiopulmonary DCs (arterial
physical exercise in hot weather and every couple of days in calmer
gas embolism), and showed a trend toward increased Cns (central
times in between to restore the fluid balance.
nervous system) symptoms in DCs ii with neurological symptoms).
in addition, dehydrated subjects manifested cardiopulmonary DCs
strict fasting without any intake of fluids whatsoever during the day
sooner and showed a trend of more rapid death.
excludes diving and ultimately working as a dive guide or instructor
during ramadan.
issue 2 august / september 2009 1
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