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Ovid: Oxford Handbook of Tropical Medicine

Editors: Eddleston, Michael; Pierini, Stephen; Wilkinson, Robert; Davidson, Robert Title: Oxford Handbook of Tropical Medicine, 2nd Edition Copyright ©2005 Oxford University Press (Copyright 2005 by M. Eddleston, S. Pierini, R. Wilkinson, and R. Davidson) > Table of Contents > Chapter 2 > Chapter 2D – Diarrhoeal diseases > General management of dehydration General management of dehydration The volume of fluid lost in the stool in 24 hrs can vary from 5 ml/kg to 200 ml/kg or more. The loss of electrolytes also varies. The total body sodium defect in young children with severe dehydration owing to diarrhoea is usually about 70–110 mmol per litre of water lost. The degree of dehydration is graded according to the signs and symptoms that reflect the amount of fluid lost. In the early stages of dehydration, there are no signs or symptoms. As dehydration increases, these develop, including thirst, restless or irritable behaviour, decreased skin turgor, dry mucous membranes, sunken eyes, sunken fontanelle (in infants), and absence of tears when crying. In severe dehydration, these effects become more pronounced and the patient may develop signs of hypovolaemic shock, including decreased consciousness, anuria, cool moist extremities, rapid and feeble pulse, low blood pressure, and peripheral cyanosis. Death may follow swiftly if rehydration is not started at once. Types of dehydration

  • Isotonic dehydration: is the most frequently encountered type of dehydration and occurs when the net losses of water and sodium are in the same proportion as is normally found in the extracellular fluid (ECF). The principal features of isotonic dehydration are: a balanced deficit of water and sodium; normal serum sodium concentration (130–150 mmol/l); normal serum osmolality (275–295 mOsmol/l); hypovolaemia because of excess ECF losses. Clinical features are those of hypovolaemic shock (i.e. thirst, reduced skin turgor, dry mucous membranes, sunken eyes, oliguria, and a sunken fontanelle in infants). This progresses to anuria, hypotension, a weak pulse, cool extremities, and eventually coma and death.
  • Hypertonic (hypernatraemic) dehydration: reflects a net loss of water in excess of sodium and tends to occur in infants only. It usually results from attempted treatment of diarrhoea with fluids that are hypertonic (e.g. sweetened fruit juices/soft drinks, glucose solution) combined with insufficient intake of water and other hypotonic solutes. Hypertonic solutions cause water to flow from the ECF into the intestine, leading to decreased ECF volume and hypernatraemia. The principal features are: a deficit of water; hypernatraemia (>150 mmol/l); serum osmolality >295 mOsmol/l; severe thirst; irritability; and convulsions (especially if serum Na+ is >165 mmol/l).
  • Hypotonic (hyponatraemic) dehydration: occurs in patients with diarrhoea who drink large amounts of water or other hypotonic fluids containing very low quantities of salt and other solutes. It also occurs in patients who receive IV infusions of 5% glucose in water. It occurs because water is absorbed from the gut while the loss of salt continues, producing a net excess of water and hyponatraemia. The features are: dehydration with hyponatraemia (serum Na+ <130 mmol/l); low serum osmolality (<275 mOsmol/l); lethargy; and, rarely, convulsions.

Assessment of dehydration in patients with diarrhoea

1. Look at:
ConditionWell, alertRestless, irritableLethargic1 or unconscious
ThirstNoneDrinks eagerly, very thirstyDrinks poorly, unable to drink
2. Pinch the skin3:
 Goes backGoes backGoes back
 immediatelyslowlyvery slowly
3. Decide:
4. Treat:
 Plan APlan BPlan C
 (see p. 156)(see p. 158)(see p. 160)
 Plans B and C require at least two of the four signs to be positive
1. A lethargic patient is not simply asleep; the patient’s mental state is dull and the patient cannot be fully awakened. The patient may appear to be drifting into unconsciousness.
2. In some infants, the eyes normally appear a little sunken, so ask the mother if the child’s eyes appear normal to her.
3. Pinch the abdominal skin in a longitudinal manner with thumb and bent forefinger. ‘Goes back slowly’ means that it is visible for more than 2 seconds.

Estimation of fluid deficit Children with dehydration should be weighed without clothing, as an aid to estimating their fluid requirements. If weighing is not possible, the child’s age may be used to estimate the weight. Treatment should never be delayed because scales are not readily available. A child’s fluid deficit may be estimated as follows:

AssessmentFluid deficit as % of body weightFluid deficit ml/kg body weight
No signs of dehydration<5%<50 ml/kg
Some dehydration5–10%50–100 ml/kg
Severe dehydration>10%>100 ml/kg>

Suitable fluids Many countries have designated recommended home fluids which should be used in the prevention of dehydration only (i.e. treatment plan A – see p. 156). Whenever possible, these should include at least one fluid that normally contains salt (e.g. oral rehydration solution — ORS; salted drinks such as salted rice water or salted yoghurt; vegetable or chicken soup with salt). Other fluids should be recommended that are frequently given to children in the area, that mothers consider acceptable for children with diarrhoea, and that the mothers would likely give in increased amounts if advised to do so. Such fluids should be safe and easy to prepare. If there are signs of dehydration, ORS should be used as per treatment plans B and C (see pp. 158, 160)

  • Teaching mother to add salt (about 3g/l) to unsalted drinks or soups during diarrhoea is beneficial, but requires education and (initially) supervision.
  • A home-made solution containing 3 g/l salt and 18 g/l of common sugar (sucrose) is effective, but the recipe is often forgotten and/or the ingredients hard to obtain.

Unsuitable fluids A few fluids are potentially dangerous and should be avoided during episodes of diarrhoea. Especially important are drinks sweetened with sugar that can cause osmotic diarrhoea and hypernatraemia (e.g. soft drinks, sweetened fruit drinks, sweetened tea). Oral rehydration solution (ORS) The formula for ORS recommended by WHO and UNICEF is given in the box opposite. Where bulk preparation is required, multiply the amounts shown by however many litres of solution you wish to make. ORS should be used within 24 hrs of preparation. When given correctly, ORS provides sufficient water and electrolytes to correct the deficits associated with acute diarrhoea. For children with severe malnutrition a solution containing 45–60 mMol sodium is preferred. P.155
To make a litre of ORS solution from bulk ingredients

1. Sodium chloride
2.6 g
2. Glucose
13.5 g
3. Trisodium citrate, dihydrate
2.9 g
4. Potassium chloride1.5 g

If glucose and trisodium citrate are not available; use:

Sucrose27 g
Sodium2.5 g
  • Completely dissolve the sugar and salts in one litre of clean water — boiled or chlorinated water is best.
  • ORS solution should be used within 24 hrs, after which time it should be discarded and fresh solution prepared.
  • To make 1 litre of rice-based ORS, boil 50 g of rice powder in 1.1 litres of water. Mix in sugar and salt in the quantities stated above. Use within 12 hrs

Treatment plan A To treat diarrhoea without signs of dehydration at home Use this plan to teach the mother to:

  • Continue to treat her child’s current episode of diarrhoea at home
  • Give early treatment for future episodes of diarrhoea

Explain the 3 rules for treating diarrhoea at home

  • Give the child more fluids than usual to prevent dehydration Use recommended home fluids (see above) and ORS as described below. Note: if the child is <6 months old and not yet taking solid foods, give ORS solution rather than a food-based fluid. Give as much of these fluids as the child will take. Use the amounts shown below for ORS as a guide. Continue giving these fluids until the diarrhoea stops.
  • Give the child plenty of food to prevent malnutrition Continue to breastfeed frequently. If the child is not breastfed, give the usual milk. If the child is >6 months, or already taking solid foods, also give cereal or another starchy food mixed, if possible, with pulses, vegetables, meat, or fish. Add 1 teaspoon (5 ml) of vegetable oil to each serving. Give fresh fruit juice or mashed banana to provide potassium. Give freshly prepared foods. Cook and mash/grind food well. Encourage the child to eat; offer food >5 times per day. Give the same foods after diarrhoea stops and give an extra meal each day for 2 weeks.
  • Take the child to a health worker if the diarrhoea does not improve within 3 days or the child develops any of the following:
    • Many watery stools
    • Fever
    • Repeated vomiting
    • Eating/drinking poorly
    • Marked thirst
    • Blood in the stool

Children should be given ORS at home if:

  • They have been on treatment plans B or C.
  • They cannot return to the health worker, but the diarrhoea gets worse.
  • It is national policy to give ORS to all children who see a health worker for diarrhoea.

How to give ORS

  • Give a teaspoon every 1–2 mins for a child <2 yrs.
  • Give frequent sips from a cup to older children.
  • If the child vomits, wait 10 mins then give fluid more slowly.
  • If diarrhoea persists after all ORS is used, use food-based fluids (see above), or return to the health care centre with the child

Amount of ORS to give according to child’s age

AgeAfter each loose stoolAt home
<2 yrs50–100 ml500 ml/day
2–10 yrs100–200 ml1 litre/day
>10 yrsAs much as tolerated2 litres/day

When oral rehydration therapy fails or is inappropriate In about 5% of patients the signs of dehydration do not improve or worsen after starting treatment with ORS. The usual causes are:

  • Continuing rapid stool loss (>15–20 ml/kg/hr), as may occur in cholera
  • Insufficient intake of ORS due to fatigue, lethargy, or lack of supervision
  • Frequent severe vomiting.

Such patients should be admitted to hospital and given ORS by NG tube or Ringer’s lactate solution 75 ml/kg IV over 4 hrs. Look for other signs of cholera infection and take necessary precautions. In most instances, it will not be cholera and the patient will improve. When not to give ORS Rarely, ORS should not be given. This is true for children with:

  • Abdominal distension due to paralytic ileus (often owing to opiate drugs such as codeine or loperamide, or to hypokalaemia).
  • Glucose malabsorption, indicated by a marked increase in stool output as ORS is started. There is no improvement and the stool contains large amounts of glucose.

In these situations, rehydration should be given intravenously until diarrhoea subsides P.158
Treatment plan B To treat some dehydration Approximate amounts of ORS to give in the first 4 hrs of treatment

AgeWeight (kg)ORS (mls)
<4 mths<5200–400
4–11 mths5–8400–600
1–2 yrs8–11600–800
2–4 yrs11–16800–1200
5–14 yrs16–301200–2200
>14 yrs>302200–4000
  • Use the patient’s age only when you do not know the weight. The required amount of ORS in ml can also be calculated approximately by multiplying the patient’s weight by 75.
  • If the patient wants more ORS than the dose shown, give more.
  • Encourage the mother to continue breastfeeding the child.
  • For infants <6 months who are not breastfed, give 100–200 ml of clean water in addition to these ORS amounts within these 4 hrs.

N.B. During the initial stages of therapy, whilst still dehydrated, adults can consume up to 750 ml per hour if necessary and children up to 20 ml per kg body weight per hour. Observe the patient carefully and help mothers to give ORS

  • Show the mother how much solution to give to her child.
  • Show the mother how to give it — a teaspoon every 1–2 mins for a child under 2 years, frequent sips from a cup for an older child.
  • Check from time to time to see if there are problems.
  • If a patient vomits, wait 10 mins and then continue giving ORS.
  • If the child’s eyelids become oedematous, stop ORS and give plain water or breast milk. Give ORS according to plan A once the oedema has subsided.

After 4 hours, reassess the patient using the chart on p. 153 and continue plan A, B, or C as appropriate

  • If there are no signs of dehydration, shift to plan A. When dehydration has been corrected, urine will start to be passed and children may become less irritable and fall asleep.
  • If signs indicating some dehydration are still present, repeat plan B, but start to offer food, milk, and juice as in plan A.
  • If signs indicating severe dehydration are present, treat according to plan C.

If the mother must leave the health post or hospital before completing treatment plan B

  • Show her how much ORS to give to finish the 4-hr treatment period at home.
  • Give her enough ORS packets to complete rehydration and for 3 more days, as in plan A.
  • Show her how to prepare ORS.
  • Explain to her the 3 rules in plan A for treating her child at home: (i) give ORS until diarrhoea stops; (ii) feed the child more to prevent malnutrition; and (iii) bring the child back to the health post/hospital if symptoms persist.
  • Make sure that children receive breastmilk or if >6 months are given some food before being sent home. Emphasize to the mother the importance of continuing feeding throughout the diarrhoeal episode.

Monitoring signs of oral rehydration therapy Check the patient from time to time during rehydration to ensure that ORS is being taken satisfactorily and that signs of dehydration are not worsening. If at any time the patient develops severe dehydration, switch to treatment plan C. After 4 hrs, reassess the patient following the guidelines in the box on p. 153. Decide what treatment to give next.

  • If signs of severe dehydration have appeared, IV therapy should be started immediately, following plan C. This is very unusual, however. It tends to occur in children who drink ORS poorly and continue to pass large volumes of watery stool during the rehydration period.
  • If the patient still has signs of mild dehydration, continue oral rehydration therapy following plan B. At the same time start to offer food, milk, and other fluids as described in treatment plan A. Reassess the patient frequently.
  • If there are no signs of dehydration, the patient should be considered fully rehydrated. If this is the case: the skin pinch is normal; the thirst has subsided; urine is passed normally; and the child is no longer irritable and may fall asleep.

Teach the mother to treat her child at home using ORS following plan A. Give her enough ORS sachets for 3 days and teach her the signs that indicate she must bring her child back to the health post. Meeting normal fluid needs While treatment to replace the existing water and electrolyte deficit is in progress the child’s normal daily fluid requirements must also be met. This may be done as follows:

  • Breastfed infants: continue to breastfeed as often and as long as the infant wants to, even during oral rehydration therapy.
  • Non-breastfed infants <6 months of age: during rehydration with ORS, give 100–200 ml of plain water by mouth. After completing rehydration, resume full-strength milk or formula feeds. Give water and other fluids normally taken by the infant.
  • Older children and adults: throughout rehydration treatment, offer as much plain water, milk, or juice as is accepted, in addition to ORS.

Treatment plan C For patients with severe dehydration in hospital Can you give IV fluids immediately? If not, see below.

  • Patients who can drink, however poorly, should be given ORS until the IV drip is running. In addition, all children should begin to receive some ORS (5 ml/kg/hr) as soon as they can drink without difficulty, which is usually within 3–4 hrs. This provides additional base and potassium which may not be adequately supplied by the IV fluid.
  • Start IV infusion of 100 ml/kg of Ringer’s lactate (Hartmann’s solution) as soon as possible. Divide the dose as follows:
    AgeFirst giveThen give
    <12 mths30 ml/kg in 1 hr70 ml/kg in 5 hrs
    >12 mths30 ml/kg in 30 mins70 ml/kg in 2.5 hrs>
  • Reassess the patient every 1–2 hrs. If the state of hydration is not improving, give the IV fluid more rapidly.
  • After 6 hours (infants <12 months) or 3 hours (>12 months), evaluate the patient using the assessment chart (see p. 153). Follow the appropriate treatment plan to continue treatment.


  • If Ringer’s lactate solution is not available, isotonic saline is an acceptable substitute — see box.
  • Repeat once if radial pulse is weak or not detectable.

Monitoring IV rehydration therapy

  • Patients should be reassessed every 15–20 mins until a strong radial pulse is present.
  • Thereafter, they should be assessed hourly to confirm that hydration is improving. If it is not, the IV fluid may be run at a faster rate.
  • When the planned amount of IV fluid bas been given (6 hrs for infants, 3 hrs for older patients), the patient’s state of hydration should be reassessed using the chart on p. 153.
    • If there are still signs of severe dehydration, repeat plan C. This is unusual, but may occur in cases of cholera and children who pass frequent, watery stools during the rehydration period.
    • If the patient shows signs of mild dehydration, discontinue IV fluid replacement and commence oral rehydration with ORS for 4 hrs according to plan B.
    • If there are no signs of dehydration, discontinue IV therapy and commence ORS treatment according to plan A.
  • Observe the patient for at least 6 hrs before discharging.
  • For children, ensure that the mother is able to continue giving ORS at home and is aware of the signs that indicate she must bring the child back.

Alternative solutions for IV rehydration

  • Ringer’s lactate solution with 5% dextrose — provides glucose to help prevent hypoglycaemia. If available, it is preferred to Ringer’s lactate solution without dextrose.
  • Physiological saline (0.9% NaCl, also called normal saline) — widely available, it is an acceptable alternative to Ringer’s lactate solution, but contains neither a base to correct acidosis nor potassium to correct K+ losses. Sodium bicarbonate or sodium lactate (20–30 mmol /l) and potassium chloride (5–15 mmol/l) may be added.
  • Half-strength Darrow’s solution — is made by diluting full-strength Darrow’s solution with an equal volume of glucose solution (50 g/l or 100 g/l). Note that it contains less sodium than is required to replace the sodium lost in diarrhoea.

Plain glucose (dextrose) solution should not be used since it does not contain any sodium, base, or potassium and does not correct hypovolaemia effectively When no IV fluid is available

  • Is there the facility for IV infusions within 30 mins’ travelling time? If so, transfer the patient, giving ORS as frequently as tolerated. If not:
  • Is there the facility for nasogastric intubation? If so, insert a NG tube and start rehydration with ORS 20 ml/kg/hr for 6 hrs (total 120 ml/kg). Reassess the patient q2h. If there is repeated vomiting or abdominal distension, give the fluid more slowly. If there is no improvement after 3 hrs, send the patient for IV therapy, continuing NG tube rehydration throughout the journey. After 6 hrs, reassess the patient and follow the appropriate treatment plan. If not:
  • Can the patient drink? If yes, start rehydration using ORS, giving 20 ml/kg/hr for 6 hrs (total 120 ml/kg). Reassess the patient every 1–2 hrs. If there is repeated vomiting, give the fluid more slowly. If the patient has not improved after 3 hrs, send for IV therapy, giving oral ORS throughout the journey. After 6 hrs, reassess the patient and follow the appropriate treatment plan. If not:
  • Refer the patient as urgently as possible for IV/nasogastric rehydration.

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