Oral Rehydration Therapy

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Oral Rehydration Therapy
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What is the main danger of diarrhoea and sickness?

• Dehydration
• Can be treated by ORT a mixture of glucose and
  salts in water
• Severe cases of dehydration intravenous drip
  may be necessary.

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What causes vomiting?

• Bacterial toxins that irritate the gut lining.
• In the intestine, the frequency of peristalsis
  increases and the contents move along the gut
  more rapidly than normal.
• This doesnt give the large intestine enough time
  to absorb water the result is diarrhoea.

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Why is vomiting and diarrhoea deadly if severe or
prolonged.

• The body loses water quicker than it gains it
  i.e. quicker than it can be replaced.
• How much fluid does the average person consume in
  a day?
• 2-3 litres

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Where else does fluid come from in our
intestines?

• About 8 litres of digestive juices
• Diarrhoea does not allow these fluids to be
  reabsorbed.

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What is lost along with the fluids?

• Vital ions such as sodium, potassium and chloride
  collectively known as electrolytes.

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What happens if left untreated?

• Muscle spasms, cramps, coma and heart failure.

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What is ORT?

• A mixture of salts and water
• If a person cannot keep anything down it can be
  given in a drip
• This simple treatment has saved millions of lives
  in places where dysentery and cholera are very
  common.

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GLOSSARY OF SOME OF THE TERMS USED

• METABOLITE
• Simple components into which food is broken down
  by digestion and which are subsequently built up
  into complex materials of body tissues e.g.
  proteins which are broken down into their
  component amino-acids by digestion and then
  metabolized back into further proteins in the
  body.

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GLOSSARY OF SOME OF THE TERMS USED

• IONA single electrically charged particle into
  which the atoms or molecules of some substances
  dissociate when in solution, e.g. sodium chloride
  in the solid state consists of molecules
  containing one atom of sodium Na and one atom of
  chlorine Cl bound together NaCl - in solution in
  water the molecule splits into two ions (Na) and
  (Cl-) each of which tends to be loosely bound to
  three or four molecules of watere.g.  (H8O4Na)
  and (H6O3Cl)-although for practical purposes
  they can be thought of as single ions Na and
  Cl-Positively charged ions e.g. Na are called
  CATIONS and Negatively charged ions e.g. Cl- are
  called ANIONS.The substances which show this
  dissociation into electrically charged ions are
  called ELECTROLYTES.

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GLOSSARY OF SOME OF THE TERMS USED

• SOLUTEA dissolved substance e.g. sodium chloride
  (the solute) dissolved in water (the solvent) to
  give a solution.MOLARITYIf two different
  substances are in a solution they are said to be
  equal in molarity (equimolar) if they have equal
  numbers of molecules per litre of solution. The
  mass or weight of each solute is then
  proportionate to their respective molecular
  weights.

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GLOSSARY OF SOME OF THE TERMS USED

• HYPERNATRAEMIAThe presence of an excess amount
  of sodium Na in the blood plasma (i.e. over 140
  mmol/l.) NORMONATRAEMIC - is the presence of a
  normal level of sodium and HYPONATRAEMIC - lower
  than normal sodium level in the plasma.
• UNICEF/WHO O.R.S
• Sodium Chloride 3.5 grams
• Sodium Bicarbonate 2.5 grams
• Potassium Chloride 1.5 grams
• Glucose 20 grams
• to be dissolved in one litre of clean drinking
  water

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THE PHYSIOLOGICAL PROCESS

• very nearly as much is reabsorbed every 24 hours
  - this mechanism allows the absorption into the
  bloodstream of soluble metabolites from digested
  food.

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• Simply giving a saline solution (water plus Na)
  by mouth has no beneficial effect because the
  normal mechanism by which Na is absorbed by the
  healthy intestinal wall is impaired in the
  diarrhoeal state and if the Na is not absorbed
  neither can the water be absorbed. In fact,
  excess Na in the lumen of the intestine causes
  increased secretion of water and the diarrhoea
  worsens.

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Sodium Glucose Transport

• If glucose (also called dextrose) is added to a
  saline solution a new mechanism comes into play.
  The glucose molecules are absorbed through the
  intestinal wall - unaffected by the diarrhoeal
  disease state - and in conjunction sodium is
  carried through by a co-transport coupling
  mechanism. This occurs in a 11 ratio, one
  molecule of glucose co-transporting one sodium
  ion (Na).

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• It was the discovery of this mechanism of
  co-transport of sodium and glucose which the
  Lancet described as "potentially the most
  important medical advance this century" ( ORT is
  in fact the practical realization of this
  potential).It should be noted that glucose does
  not co-transport water - rather it is the now
  increased relative concentration of Na across
  the intestinal wall which pulls water through
  after it.

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Several other molecules apart from glucose have a
similar capacity to co-transport Na including 

• aminoacids (e.g. glycine) 
• dipeptides 
• tripeptides
• and the absorption of these molecules may occur
  independently of each other at different sites -
  thus their effect can be additive. Research is
  currently being carried on to utilize these
  additive effects to develop a multi-component
  "Super ORS".

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• Starch is metabolized in the intestine to glucose
  and therefore it has the same properties of
  enhancing sodium absorption, however it has an
  added advantage that it has less osmotic effect,
  which would act to pull water back into the lumen
  of the intestine.

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• www.foodmuseum.com/exgutparts.html

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