ORAL REHYDRATION SOLUTION – NOTES
ORS is a simple, cheap and effective treatment for diarrhea-related dehydration, e.g.
cholera or rotavirus. It consists of a solution of salts and other substances such as glucose, sucrose,
citrates or molasses, which is administered orally. It is used around the world, but is most important
in the Third World, where it saves millions of children from diarrhea, still their leading cause of
death.
WHO FORMULA (FOR 1 LITRE ORS)
Sodium chloride - 2.6 gm (Na+ : 75mM)
Trisodium citrate - 2.9 gm (K+ : 20mM)
Potassium chloride - 1.5 gm (Cl- : 65mM)
Glucose anhydrous - 13.5 gm (Citrate : 10mM & Glucose : 75mM)
Water - 1Litre (Total Osmolarity : 245mOsm/L)
In the human body, the plasma osmolality is about 285 mOsm/l.
(Earlier preparation contains Na+ rich 90mM – it is often produces periorbital edema in children
due to excess Na+ absorption)
OBJECTIVE OF ORS
• To prevent dehydration
-
Mild (5-7% BW)fluid loss
-
Moderate (7.5-10% BW) fluid loss
• To reduce mortality.
PRINCIPLES:
•
It should be isotonic or hypotonic (i.e. total osmolarity 200-310mOsm/L)
(Diarrhoea fluids are approximately isotonic, which is ~290mOsm/L)
•
The molar ratio of glucose should be equal to or somewhat higher than Na+ (but not exceed
110mM)
•
Enough K+ (15-25mM) and bicarbonate/ citrate should be provided to make up losses in stool
PROCEDURE
•
Get the ORS packet and check the information on the packet including expiry date
•
Get 1Litre of cooled, freshly boiled water or filtered water into a water jug
•
Cut the packet with clean scissors as depicted with cut lines on the packet
•
Pour the contents into the jug and mix well
•
Instruct the subjects to take it as frequently as needed. The frequency of sips will depend on
the level of dehydration
•
Do not add ORS to milk, soup, juice or any soft drinks and don’t add sugar
•
The prepared ORS solution should be covered and used within 24 hours, due to the risk of
bacterial contamination.
How much ORS to give
•
Encourage the child to drink as much as he/she can.
•
A child <2 years, give ¼ - ½ of a large (250mL) cup of the ORS drink after each watery stool
followed by 1-2 teaspoons every 2-3 minutes
•
A child 2 years or older, give ½ -1 whole large (250mL) cup of the ORS drink after each watery
stool
•
If the child vomits, wait for 10 minutes and then give a teaspoon every 2-3 minutes
•
If the child is on breastfeeding, continue to breastfeed along with ORS.
•
Initially, 5-7.5% BW volume equivalent is given in 2-4 hours (5ml/kg/hr in children)
•
Restoring hydration within 6hours should be aimed.
PHARMACOLOGICAL ACTIONS
In diarrhea, loss of water and electrolytes leads to dehydration. Hence, both water and electrolytes
are given for treatment of dehydration. If water alone is given it will dilute the salts present in body
and aggravates the condition.
PHARMACOLOGICAL ACTION OF SALTS
Sodium chloride
As you know, sodium is the main ion involved in various processes in the body, e.g. action
potential generation. It helps to maintain muscle tone. Symptoms associated with hyponatremia
are fatigue, muscle weakness, abdominal cramps, confusion, hypotension, weak pulse, cyanosis,
oliguria, tachycardia, loss of skin elasticity and dryness of mucous membranes.
Glucose
Glucose is the source of energy. Apart from that it helps in absorption of sodium. Molar ratio of
glucose is more than sodium in ORS. Sodium is absorbed through facilitated diffusion or
cotransport with the help of glucose.
Other contents provide sufficient amount of potassium, chloride and bicarbonate lost in diarrhea.
Sodium citrate is the source of HCO3– and also provides stability to the solution.
Potassium chloride influences the muscle action and ameliorates the cramps. Chloride helps to
maintain the fluid balance and production of gastric acid.
THERAPEUTIC USES
1. Diarrhoea
Oral rehydration therapy is widely considered to be the best method for combating the dehydration
caused by diarrhea and/or vomiting. Rehydration does not stop diarrhea, but keeps the body
hydrated and healthy until the diarrhea passes. ORS is recommended in mild to moderate cases of
diarrhea. Intravenous fluids are required in severe cases of dehydration.
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
The degree of dehydration can be assessed by following parameters:
— Pulse in dehydration has low volume and is thready.
— No tears, dry mouth in case of moderate to severe dehydration.
— Urine output is decreased in dehydration.
2. Heat stroke.
3. In patients of postburns/postsurgical and posttrauma to maintain hydration.
4. Change from parenetral to enteral therapy.
5. High grade fever.
TYPES OF ORS
1. HOME MADE ORS
In a glassful of water, add 1 teaspoonful of sugar and a pinch of salt. You can also add half a
lemon.
Rice water and dal water can also be used.
or
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.
2. SUPER-ORS
In this amino acids are added, e.g. alanine and glycine.
PRECAUTIONS
• Hot water should not be used as it may lead to breakdown of bicarbonate and alteration in flavor
• Do not use if the solution is coloured.
• Always use freshly prepared solution.
• The solution made should not be used 24 hours after its preparation.
• Use clean utensils to make solution.
Today, the total production is around 500 million ORS sachets per year, with the children's rights
agency UNICEF distributing them to children in around 60 developing countries. ORS represents
a cheap and effective way of reducing the millions of deaths caused each year by diarrhoea.
ORS day was celebrated every year on 29th July.