**2. Body water distribution**

In newborn babies, 75–80% of the total body weight constitutes the total body water (TBW) (varies with the gestational age), which decreases to 67% of body weight (2/3) after the neonatal period. There is a further decrease that reaches 60% by the end of the first year, and this percentage remains the same during the rest of life. After puberty and in adulthood, TBW is 60% in males and 55% in females. The TBW is divided into two components throughout the body: intracellular fluid compartment (ICF), which constitutes 40% of TBW, and extracellular fluid (ECF), which forms the remaining 20%. The ECF comprises interstitial fluid (IF) (15% of the TBW), and the remaining 5% of the TBW comprises intravascular plasma (**Figures 1** and **2**) [2–4]. This distribution of body fluids can have an impact on the management of pediatric gastroenteritis, as most of the fluid loss in AGE comes from the ECF. This matters because ECF contains a lot of sodium (135–145 mEq), and ICF contains a lot of potassium (150 mEq). In a brief duration of illness

**Figure 1.** *The percentage distribution of body fluids in the various compartments in a 1-year-old infant [2].*

**Figure 2.** *Body water compartments in relation to age [2–4].*

(<3 days), 80% of the deficit is typically from the ECF. After more than 3 days of illness, the deficit from the ECF decreases to 60%. Fluid losses for longer than 7 days are equally lost from ECF (50%) and ICF (50%) [5].

### **3. Assessment of dehydration**

Accurate and quick assessment of the degree of dehydration is important for proper treatment and disposition of infants and children with AGE [6]. The percentage of weight loss is the best measure to assess the degree of dehydration, as shown in Eq. (1). However, this method is impractical because in most patients the pre-illness weight is not known [7].

**39**

**Table 3.**

**Table 2.**

**Table 1.**

*Dehydration*

*DOI: http://dx.doi.org/10.5772/intechopen.83408*

**3.1 Clinical assessment of dehydration**

Scale (CDS) (**Table 3**) [8–10].

% *of dehydration* <sup>=</sup> [(*pre* <sup>−</sup> *illness weight in kg)* <sup>−</sup> (*illness weight in kg)*] <sup>×</sup> <sup>100</sup> \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ *pre* <sup>−</sup> *illness weight in kg* (1)

Current validated dehydration scales may help in assessing the versatile presentations of dehydration more objectively. Most of them illustrate clinical signs that can be assessed easily and rapidly, which can facilitate stratification of patients into dehydration categories. There are three clinical scales designed to estimate dehydration severity in children below 5 years of age: the World Health Organization (WHO) scale (**Table 1**), the Gorelick scale (**Table 2**), and the Clinical Dehydration

Using common tools to evaluate and assess dehydration would be more helpful in day-to-day practice. Consistent evidence supports the CDS which is more useful and easy to use in assessing dehydration. This scale in combination with other criteria should be used to guide the proper medical interventions in individual

**Characteristics No dehydration Some dehydration (>1 sign) Severe dehydration (>1 sign)** Alertness Well, alert Irritable or drowsy Lethargic or poorly responsive

**Characteristics No or minimal dehydration Moderate-to-severe dehydration** General appearance Alert Restless, lethargic, unconscious

Thirst Drinks normally Drinks eagerly Poor or weak drinking Skin turgor Goes back quickly Goes back slowly (<2 s) Return very slowly (>2 s)

*Gorelick (4-item) scale for dehydration in children aged 1 month–5 years. Scoring: ≥2 clinical signs indicates ≥ 5% loss of body weight from baseline (moderate dehydration), and ≥3 clinical signs indicates ≥ 10% loss of body weight from baseline (severe dehydration). The presence of two or more of these signs had a sensitivity of 79%* 

irritable when touched

*Clinical dehydration scale (CDS) for children aged 1 month–3 years. Scoring: ≥2 clinical signs indicates ≥ 5% loss of body weight from baseline (moderate dehydration), and ≥3 clinical signs indicates ≥ 10% loss of body weight from baseline (severe dehydration). The presence of two or more of these signs had a sensitivity of 79%* 

Drowsy, limp, cold, sweaty ±

comatose

Capillary refill Normal Prolonged or minimal

Eyes Normal Sunken Sunken

**Characteristics Score of 0 Score of 1 Score of 2**

Eyes Normal Slightly sunken Very sunken Mouth and tongue Moist Sticky Dry Tears Present Decreased Absent

General appearance Normal Thirsty, restless, or lethargic but

Tears Present Absent Mucous membranes Moist Dry, very dry

*WHO scale for dehydration in children aged 1 month–5 years old.*

*and a specificity of 87% in predicting 5% dehydration.*

*and a specificity of 87% in predicting 5% dehydration.*

% *of dehydration* <sup>=</sup> [(*pre* <sup>−</sup> *illness weight in kg)* <sup>−</sup> (*illness weight in kg)*] <sup>×</sup> <sup>100</sup> \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ *pre* <sup>−</sup> *illness weight in kg* (1)
