Supportive interventions in acute diarrhoea

Fluid requirements change dramatically during the early neonatal period and through childhood into adult life (Fig. 1). Fluid requirements (related to body weight) are greatest during infancy and thus it is this period when the child is most susceptible to fluid losses.

Dehydration is a state in which total body water is decreased and in acute diarrhoeal illnesses results from both (i) increased fluid losses from the gastrointestinal tract and when there is fever, increased insensible losses through the skin, and (ii) inadequate intake which may occur concurrently with diarrhoea when accompanied by nausea and vomiting. Whatever the mechanisms of fluid and electrolyte depletion it is vital that these are replaced promptly before large, potentially fatal deficits occur.

FIG. 1. Fluid requirements in the neonate, infant and throughout childhood.

Assessment of dehydration. During the initial clinical assessment of an infant or child with acute diarrhoea, it is essential to make an estimate of the degree of dehydration. This assessment guides the choice of the approach to rehydration (oral or intravenous) and allows an estimate to be made of the rate at which fluid should be replaced. The World Health Organization (WHO) devised a comprehensive scheme for classifying dehydration as mild, moderate and severe based on clinical parameters (Table 1). Paediatricians at Queen Elizabeth Hospital for Children in the UK developed a simplified version that enabled the severity of dehydration to be graded into four categories (Table 2).

If dehydration is severe with 10% or more body weight loss then fluid replacement should be at least 100 ml/kg, which almost inevitably must be delivered intravenously. When dehydration is mild and body weight loss does not exceed 5% fluid replacement is usually required at 50 ml/kg and can almost always be delivered orally. In the intermediate category when dehydration exceeds 5%, intravenous rehydration may be required initially, although if the infant or young child is alert and able to take oral fluid and urine output recovers rapidly then it is reasonable to pursue the oral route.


Oral fluid replacement remedies have been used by mothers and grandmothers for many centuries (Farthing 1988). Naturally occurring fluids such as coconut milk and other preparations containing rock salt and molasses have been described in ancient manuscripts. Formal oral rehydration therapy (ORT) began to evolve in

TABLE 1 WHO guidelines for assessment of dehydration and fluid deficit

Signs and symptoms Mild dehydration Moderate dehydration Severe dehydration

General appearance and condition Infants & young Thirsty, alert, children

Older children & adults

Radial pulse1


♦Anterior fontanelle2

♦Systolic blood pressure3


Thirsty, alert, restless

Normal rate and volume




*Skin elasticity4 Pinch retracts immediately

*Eyes Normal

Tears Present

Mucous membranes5 Moist

*Urine flow Normal6

Body weight loss (%%) Estimated fluid deficit

Thirsty, restless, or lethargic but irritable when touched

Thirsty, alert, giddiness with postural changes

Rapid and weak

Deep, may be rapid



Pinch retracts slowly Sunken Absent Dry

Reduced amount and dark

60-90 ml/kg

Drowsy, limp, cold, sweaty, cyanotic extremities, may be comatose

Usually conscious, apprehensive, cold, sweaty cyanotic extremities, wrinkled skin of fingers and toes, muscle cramps

Rapid, feeble, sometimes impalpable

Deep and rapid

Very sunken

Less than 10.7 kPa (80 mmHg), may be unrecordable Pinch retracts very slowly

(> 2 seconds) Deeply sunken Absent Very dry

None passed for several hours, empty bladder

10% or more 100-110ml/kg

^Particularly useful in infants for assessment of dehydration and monitoring of rehydration JIf radial pulse cannot be felt, listen to heart with stethoscope.

2Useful in infants until fontanelle closes at 6-18 months or age. After closure there is a slight depression in some children.

3Difficult to assess in infants.

4Not useful in marasmic malnutrition or obesity.

5Dryness of mouth can be palpated with a clean finger. Mouth may always be dry in a child who habitually breaths by mouth. Mouth may be wet in a dehydrated patient due to vomiting or drinking.

6A marasmic baby or one receiving hypotonic fluids may pass good urine volumes in the presence of dehydration.

the 1940s largely due to the initiatives of Harold Harrison at the Baltimore City Hospital and Daniel Darrow at Yale (Darrow 1946, Harrison 1954). Chatterjee (1953) first showed that an oral rehydration solution (ORS) could rehydrate patients with cholera without the need to resort to intravenous fluids. Thus, the

TABLE 2 Simplified guidelines for assessing the severity of dehydration

% dehydration

Clinical signs


Thirst, mild oliguria.


Discernible alteration in skin tone, slightly sunken eyes, some

loss of intraocular tension, thirst, oliguria. Sunken fontanelle

in infants.


Very obvious loss of skin tone and tissue turgor, sunken eyes,

loss of intraocular tension, marked thirst and oliguria. Often

some restlessness or apathy.


All the foregoing, plus peripheral vasoconstriction,

hypotension, cyanosis, and sometimes hyperpyrexia. Thirst

may be lost at this stage.

practice of ORT was established but the true scientific rationale remained to be discovered.

Scientific rationale for oral rehydration therapy. Fisher (1955) showed that glucose promoted intestinal ion transport and this observation was soon followed by the finding that sodium and glucose transport was coupled in the small intestine (Schedl & Clifton 1963). It also became evident that other solutes, such as amino acids were also absorbed by active transport, again coupled with transport of sodium ions (Fig. 2).

At the same time that these basic laboratory studies were being pursued, a US Navy Captain, Robert Phillips, working in Egypt and subsequently in the Philippines, was performing clinical rehydration studies in human cholera using glucose—electrolyte solutions. In 1961, as the seventh cholera pandemic began in the Philippines, Phillips and his team clearly showed that oral administration of glucose—salt solutions could reduce stool output in cholera and thus, could be used for oral replacement of water and electrolytes. Phillips' observations were confirmed in Dhaka (Hirschhorn et al 1968) and Calcutta (Pierce et al 1968).

Clinical developments in ORT. ORTsoon became widely used for other dehydrating diarrhoeal diseases with similar success (Farthing 1988). The WHO began a major campaign throughout the 1970s and 1980s which has successfully implemented ORT in most countries in the developing world. Subsequently, many clinical trials have been performed confirming the efficacy and feasibility of using ORT in preference to intravenous rehydration in the field setting and in particular during cholera epidemics. ORT was successfully used in cholera outbreaks in Bangladesh in 1971 (Mahalanabis et al 1973); mortality was reduced from 30% to

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