DEHYDRATION
It is a negative water balance leading to a decrease in water content of the body. This occurs when the output of water is more than intake.
Dehydration may occur due to -
Water depletion
Salt depletion
Both salt and water depletion
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Water depletion (primary dehydration) : It occurs due to inadequate water intake. It may occur in -
Illness like difficulty in swallowing or coma
Non -availability of water as in desert or ocean
As a result of water depletion, the concentration of electrolytes increases in extracellular compartment. To, compensate this, water is drawn from intracellular compartment to extracellular compartment. So intracellular water decreases causing dehydration. The symptoms are thirst, dry tongue, dry skin and increased body temperature.
Salt depletion (Secondary dehydration) : It occurs when fluids with high Na+ or Cl - content are lost from the body. In this case, the significant ion that is lost is Na+. So it must be called ‘Sodium depletion’ rather than salt depletion. The causes are -
Loss of Na+ due to excessive sweating
Use of diuretics with a low sodium or salt free diet
Both salt and water depletion : It is a mixed type of depletion causing dehydration. In this case, there is excessive loss of water. A long with this, there is excessive loss of Na+ and Cl -. It is further aggravated by no free intake of water (e.g - water restriction). This results in a decrease in both extracellular and intracellular fluid volume. Ultimately, BP is lowered. Also urine volume decreases.
Effects of dehydration :
Dryness of mouth and increased thirst
Dryness, wrinkling and loosening of skin
Rise in body temperature
Loss of weight due to reduction in tissue water
Increased pulse rate and decreased cardiac output
Muscle weakness and cramps due to loss of electrolytes
Exhaustion and collapse
Oral rehydration therapy
Oral Rehydration Salt (ORS)
It has the following composition -
Sodium chloride 2.6 g
Potassium chloride 1.5 g
Trisodium citrate 13.5 g
Dextrose 20g
Water 1 litre
(WHO formula 2002)
The solution is freshly prepared and patient is given to drink at ½ to 1 hourly intervals. ORS stops diarrhoea and also corrects dehydration.
