DEHYDRATION
Professor Shahenaz M. Hussien
OBJECTIVES
At the end of this lecture you will able to know
the followings:
*What is dehydration?
*What are the causes of dehydration?
*The clinical manifestaions of dehydration.
*The investigations required.
*Management of dehydration.
DEHYDRATION
Fluid and electrolytes requirements
Water: : Constitutes about 70% of infant's body weight as
compared to 60% in adults.
Most of the water is found within the cells of
the body (intracellular space). The rest is found in
the extracellular space, which consists of the
blood vessels (intravascular space) and the spaces
between cells (interstitial space).
Total body water = intracellular space +
intravascular space + interstitial space
Average daily requirement of water (ml/kg):
-First year: 130 – 150.
-2 to 4 years: 100 – 130.
-4 to 10 years: 70 – 100.
-10 to 18 years: 50- 70.
Dietary Reference Intakes (DRI) of electrolytes:
Sodium (mg/day): 120 in the 1st 6months,
200 in the age 7-12 months,
225 in the age 1-3 years, and 300 from 4-8 years of age.
Potassium (mg/day): 500 in the 1st 6 months,
700 from7-12 months,
1000 from1-3 years, and 1400 from 4-8 years of age.
What is dehydration?
Dehydration occurs when the amount of water leaving the body is
greater than the amount being taken in.
We lose water routinely when:
• We breathe and humidified air leaves the body;
• We sweat to cool the body; and,
• We urinate or have a bowel movement to get rid the body waste
products.
Hyponatremia ;
Is a condition in which the body's stores of sodium are too low, and
this condition can result from drinking extreme amounts of water.
Hyponatremia can lead to confusion, lethargy, agitation, seizures,
and in extreme cases, even death.
Early symptoms are nonspecific may include disorientation, nausea,
or muscle cramps. The symptoms of hyponatremia may also mimic
those of dehydration, so athletes experiencing these symptoms
drinking more water that result in further worsening the condition.
CONSERVATION OF BODY WATER
• In a normal day, a person has to drink a significant amount of water to
replace the routine losses.
• If intravascular water is lost, the body can compensate by shifting
water from cells into the blood vessels, but this is a very short-term
solution. Signs and symptoms of dehydration will occur quickly if the
water is not replenished.
• The thirst mechanism signals the body to drink water when the body
is dry. As well, hormones like anti-diuretic hormone (ADH) work
within the kidney to limit the amount of water lost in the urine.
• The electrolytes in our body include sodium, potassium, chloride,
calcium and phosphate, but sodium is the substance of most concern
when replacing fluids lost through exercising.
Hypernatremic dehydration
• Dehydration,characterized by increased concentrations of sodium and
chloride in the extracellular fluid, it results from diarrhea in infants.
• The occurance of the hypernatremia and hyperchloremia lies in the
relatively greater expenditure of water than electrolyte via skin, lungs,
stool and urine. The water deficit in these infants is primarily
intracellular.
• The majority of infants with this type of dehydration show varying
degrees of depression of central nervous system varying from
lethargy to coma. Convulsions are frequently observed.
• Dilute solutions of electrolyte are indicated in rehydration. Rapid
adjustment, however, appears to accentuate the CNS disturbance.
Rehydration is best carried out slowly over a 2- to 3-day period.
What causes dehydration?
• Diarrhea: is the most common reason for loss of excess water. Worldwide,
more than four million children die each year because of dehydration
from diarrhea. -Vomiting: can also be a cause of fluid loss .
• Sweat: The body can lose significant amounts of water when it tries to
cool itself by sweating whatever the cause of hotness of the body such as
intense exercising in a hot environment, or presence of fever .
• Diabetes: In people with diabetes, elevated blood sugar levels cause
sugar to spill into the urine and water then follows. For this reason,
frequent urination and excessive thirst are among the symptoms of
diabetes.
• Chronic renal failure: dehydration occurs due to polyuria.
• Burns: dehydration occur because water moves into the damaged skin.
Other inflammatory diseases of the skin are also associated with fluid
loss.
• Inability to drink fluids: The inability to drink adequately is the other
potential cause of dehydration.
Clinical picture:
Examination.
- Body weight. - Temperature.- Signs of
dehydration. - Systemic examination.
General manifestations:
- Dry skin and mucous membrane.
- Decrease all body secretions (urine, sweats,
tears, saliva)
- Depressed fontanel, sunken eyes, thirst,
irritability, lately hypotension, acidosis and
coma.
DEGREES OF DEHYDRATION:
Degree of dehydration Plan A: Plan B: Some Plan C: Severe
No dehydration dehydration dehydration
General condition Calm, alert Restless Lethargic,
irritable unconscious
Eye manifestation Normal Sunken Sunken
Ability to drink Normal Thirsty, eager Poor
to drink
Skin pinch Goes back Slowly Very slowly
quickly
IMCI MANAGEMENT: Integrated
management of childhood illness ( WHO)
* Plan A: Give fluid and food to treat diarrhea at home
• If child is 2 years or older and there is Cholera in your area, give
antibiotic for cholera.
• Advise mother when to return immediately
• Follow-up in 5 days if not improving.
* Plan B: Give fluid and food for some dehydration.
• If child has also a severe classification:
• Refer URGENTLY to hospital with mother giving frequent sips of
ORS on the way
• Advise the mother to continue breast-feeding
• If child is 2 years or older and there is Cholera in your area, give
antibiotic for cholera.
• Advise mother when to return immediately
• Follow-up in 5 days if not improving.
IMCI MANAGEMENT: Integrated management
of childhood illness ( WHO)
* Plan C: - Give fluids for severe dehydration or If child has also
another severe classification:
• Refer URGENTLY to hospital with mother giving frequent
sips of ORS on the way
• Advise the mother to continue breast-feeding
• If child is 2 years or older and there is Cholera in your area,
give antibiotic for cholera.
MANAGEMENT OF DEHYDRATION
-Replace Phase 1: Acute Resuscitation :
– Give Lactated Ringer OR Normal Saline at 10-20 ml/kg IV over 30-60
minutes.
– May repeat bolus until circulation stable
-Calculate 24 hour maintenance requirements
– Formula:
• First 10 kg: (100 cc/kg/24 hours)
• Second 10 kg: (50 cc/kg/24 hours)
• Remainder: (20 cc/kg/24 hours)
Example: 35 Kilogram Child
• Daily: 1000 cc + 500 cc + 300 cc = 1800 cc/day
-Calculate Deficit:
– Mild Dehydration: (40 ml/kg)
– Moderate Dehydration: (80 ml/kg)
– Severe Dehydration: (120 ml/kg)
MANAGEMENT Continue ---------
-Calculate remaining deficit:
– Substract fluid resuscitation given in Phase 1
-Calculate Replacement over 24 hours:
– First 8 hours: 50% Deficit + Maintenance
– Next 16 hours: 50% Deficit + Maintenance
• Determine Serum Sodium Concentration
– Hypertonic Dehydration (Serum Sodium > 150)
– Isotonic Dehydration
– Hypotonic Dehydration (Serum Sodium 10 Kilograms: 20 meq KCl /liter glucose