Using Oral Rehydration Salts with Appropriate Osmolarity!

Using Oral Rehydration Salts with Appropriate Osmolarity!

by Mohanta, Professor, Annamalai University

Oral Rehydration Salts (ORS) has been recognized as one of the remarkable medical discoveries of the 20^th century and has been used as main therapy for reducing diarrhoeal deaths over the years.  The genesis of this discovery goes to Bangladesh liberation war of 1971. When intravenous fluids were out of stock, the ORS were tried in the refugee camps to treat cholera. Surprisingly over 96 percent cholera victims treated with ORS survived that convinced the world. Cholera Research Laboratory, Dhaka; and Infectious Diseases Hospital, Calcutta (now Kolkata) contributed significantly in the development of modern ORS.

The principle of ORS therapy is based on basic concepts of physiology. When glucose is present within the intestinal lumen, sodium and water absorption increases. The concentration of glucose is crucial in absorption of water. Water is transported paracelluarly as a result of osmotic ingredient. The development of ORS has undergone several transformation. The earlier version of ORS when dissolved in required quantity of water provided a solution containing 90 mEq/l of sodium with a total osmolarity of 311 mOsm/l. However, this high osmolarity caused hypertonic environment in the digestive tract leading to adverse effects such as reverse loss of more fluids. This is the principle of osmosis where fluid moves from a lower concentration to higher concentration. The research and clinical testing has proved that low osmolarity salt solutions are preferable and accordingly WHO recommended the reduced osmolarity ORS containing 75 mEq/l sodium, 75 mmol/l glucose (total osmolarity of 245 mOsm/l) as improved ORS for preventing dehydration in all types of diarrhoea.

The current formula; Sodium Chloride –   2.6 g, Sodium Citrate         – 2.9 g, Potassium Chloride –  1.5 g, and Glucose (anhydrous) – 13. 5 g; is required to be dissolved in one litre of recently boiled and cooled drinking water. Quantity of water is important to have the correct Osmolarity for water absorption and thus prevent dehydration, the main reason for deaths. Often people overlook this aspects believing concentrated solutions are better as patients sometimes refuse to take ORS solutions. The four points are important to remember to ensure the correct use of ORS:

• ORS treatment does not reduce frequency of stools. But it only prevents dehydration, the major cause of death in acute diarrhoea.
• Medical advice is needed if condition looks to be serious.
• ORS in sachets should be dissolved with recommended quantity of freshly boiled and cooled drinking water. The different sachets may have different quantity of powders.

·         The prepared solution is unfit for use after 24 hours of preparation and the left over unused solution needs to be thrown.