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Rehydration is the replenishment of
water and
electrolytes lost through
dehydration. It can be performed by mouth (oral rehydration) or by
adding fluid and electrolytes directly into the blood stream (intravenous
rehydration).
As oral rehydration is less painful, less invasive, less expensive, and
easier to provide, it is the treatment of choice for mild
dehydration from infectious
gastroenteritis. Because severe dehydration can rapidly cause permanent
injury or even death, intravenous rehydration is the initial treatment of
choice for that condition.
Symptoms of dehydration
Symptoms
of mild dehydration include
thirst,
decreased urine
volume, urine that is darker than usual, tiredness, lack of
tears when
crying,
headache,
dry mouth, and
dizziness
when standing due to
orthostatic hypotension.
In moderate to severe dehydration, there may be no urine output at all.
Other symptoms in these states include
lethargy
or extreme sleepiness,
seizures,
sunken
fontanel (soft spot) in
infants,
fainting,
and sunken eyes.
Treatment
If someone is sufficiently dehydrated that he or she exhibits the signs of
moderate to severe dehydration listed above, medical attention should be
sought.
Oral rehydration can be accomplished by drinking frequent small amounts of
an oral rehydration salt solution. One standard remedy is the WHO/UNICEF
glucose-based Oral Rehydration Salts (ORS) solution, which contains 75 mEq/l
of sodium, 75
mmol/l of
glucose, 65 mEq/l
chloride,
20 mEq/l
potassium, and 10 mEq/l
citrate,
with a total
osmolarity of 245 mOsm/l.
It is important to rehydrate with solutions that contain electrolytes,
especially sodium
and
potassium, so that
electrolyte disturbances may be avoided. Sugar is important to improve
absorption of electrolytes and water, but if too much is present in ORS
solutions,
diarrhea can be worsened. Oral rehydration does not stop diarrhea, but
keeps the body hydrated and healthy until the diarrhea passes.
There are several commercially available products but an inexpensive
home-made solution consists of 8 level
teaspoons
of sugar and 1
level teaspoon of
table
salt mixed in 1
liter of water. A half cup of
orange juice or half of a mashed
banana can be
added to each liter both to add potassium and to improve taste. If commercial
solutions are used, true rehydration solutions should be used and
sports drinks should be avoided (especially in younger children) as these
solutions contain too much sugar and not enough electrolytes.
The amount of rehydration that is needed depends on the size of the
individual and the degree of dehydration. Rehydration is generally adequate
when the person no longer feels thirsty and has a normal urine output. A rough
guide to the amount of ORS solution needed in the first 4-6 hours of treatment
for a mildly dehydrated person is:
- Up to 5 kg (11 lb): 200 – 400 ml
- 5-10 kg (11-22 lb): 400 – 600 ml
- 10-15 kg (22-33 lb): 600 – 800 ml
- 15-20 kg (33–44 lb): 800 – 1000 ml
- 20-30 kg (44-66 lb: 1000 – 1500 ml
- 30-40 kg (66-88 lb): 1500 – 2000 ml
- 40 plus kg (88 lb): 2000-4000 ml
Technique
Adults and children with dehydration who are not vomiting can be allowed to
drink these solutions in addition to their normal diet. People who are
vomiting should be fed small frequent amounts of ORS solution until
dehydration is resolved. Once they are rehydrated, they may resume eating
normal foods when nausea passes.
Vomiting itself does not mean that oral rehydration cannot be given. As
long as more fluid enters than exits, rehydration will be accomplished. It is
only when the volume of fluid and electrolyte loss in vomit and stool exceeds
what is taken in that dehydration will continue. When vomiting occurs, rest
the stomach for ten minutes and then offer small amounts of ORS solution.
Start with a teaspoonful every five minutes in children and a tablespoonful
every five minutes in older children and adults. If output exceeds intake or
signs of moderate to severe dehydration occur, medical assistance should be
sought.
