Dehydration in children

Dehydration is a significant loss of water and, as a rule, electrolytes. Symptoms of dehydration in children include thirst, inhibition, dry mucous membranes, decreased diuresis and with progression of the degree of dehydration - tachycardia, hypotension and shock. The diagnosis is based on anamnesis and physical examination. Treatment of dehydration in children is performed by oral or intravenous fluid and electrolyte reimbursement.

Dehydration, usually as a result of diarrhea, remains the leading cause of morbidity and mortality in children under the age of 1 and early in the world. Children of the first year of life are particularly susceptible to dehydration and its negative effects, because they have a higher fluid demand (due to a higher rate of metabolic processes), higher fluid loss (due to a higher body surface-to-volume ratio), and inability to report about thirst or independently to find a liquid.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

What causes dehydration in children?

Dehydration develops as a result of increased fluid loss, reduced fluid intake, or a combination of these causes.

The most frequent increase in fluid loss occurs through the gastrointestinal tract during vomiting, diarrhea, or a combination of them (gastroenteritis). Other sources of fluid loss include kidneys (diabetic ketoacidosis), skin (excessive sweating, burns) and fluid loss in the cavity (into the intestinal lumen with intestinal obstruction). With all these options, the liquid that the body loses at various concentrations contains electrolytes, so fluid loss is always accompanied by loss of electrolytes.

Reduction of fluid intake is often found during any serious illness and most seriously in the presence of vomiting and in hot weather. This may also be a sign of a lack of care for the child.

Symptoms of dehydration in children

Symptoms of dehydration in children may differ depending on the degree of fluid deficiency and depend on the concentration of sodium in the blood serum: the effect on the hemodynamics of the child increases with hyponatremia and decreases with hypernatremia. In general, dehydration without hemodynamic disorders is considered to be mild (approximately 5% of body weight in children in the first years of life and 3% in adolescents); tachycardia occurs with an average degree of severity of dehydration (approximately 10% of body weight in children in the first years of life and 6% in adolescents); hypotension with a violation of microcirculation indicates severe dehydration (approximately 15% of body weight in children of the first years of life and 9% in adolescents). A more accurate method for assessing the degree of dehydration is to determine the change in body weight; believe that in any case, the loss of more than 1% of body weight per day is associated with a fluid deficit. At the same time, this method depends on knowing the exact weight of the child before the disease. Parents' assessments, as a rule, are not true; an error of 1 kg in a 10-kilogram child leads to a 10% error in calculating the degree of dehydration - this is the difference between mild and severe.

Laboratory tests, as a rule, are necessary for patients in the middle or severe condition, which often develop electrolyte disorders (hypernatremia, hypokalemia, metabolic acidosis). Other changes in the assays include relative polycythemia due to hemoconcentration, increased urea nitrogen, an increase in the specific gravity of urine.

Treatment of dehydration in children

The best approach in treatment is the separation of liquid for rehydration into liquid for emergency correction, compensation of deficiency, continuing pathological losses and physiological needs. The volume (amount of liquid), the composition of the solutions and the rate of replenishment may differ. Formulas and evaluation tables give only initial data, but therapy requires continued monitoring of the child: assessment of hemodynamics, appearance, urine output, urine specific gravity, body weight, and sometimes the level of blood electrolytes. Children with severe dehydration are parenteral rehydration. Children who can not or refuse to drink, as well as children with repeated vomiting, are given intravenous rehydration, the introduction of fluid through the nasogastric tube, and sometimes use oral rehydration - frequent fractional drinking.

Emergency correction of newborn dehydration

Patients with signs of hypoperfusion should be urgently corrected for fluid deficiency by bolus administration of saline (0.9% sodium chloride solution). The goal is to restore adequate BCC to maintain blood pressure and microcirculation. The phase of emergency correction should reduce the degree of dehydration with an average or severe to deficit of approximately 8% of body weight. If dehydration is moderate, intravenously inject 20 ml / kg (2% body weight) of the solution in 20-30 minutes, reducing the fluid deficit from 10% to 8%. With severe dehydration, you will probably need 2-3 bolus injections at a rate of 20 ml / kg (2% of body weight). The result of the emergency correction phase is the restoration of peripheral blood circulation and blood pressure, normalization of the increased heart rate. Compensation of fluid deficiency.

The total fluid deficit is determined from clinical data, as described above. The sodium deficiency is usually 80 meq / l of the missing liquid, and the potassium deficiency is about 30 meq / l of the missing liquid. In the phase of emergency correction of severe or moderate dehydration, the fluid deficit should be reduced to 8% of body weight; this persistent deficit should be compensated in the amount of 10 ml / kg (1% body weight) / hour for 8 hours. Since a 0.45% solution of sodium chloride contains 77 mEq of sodium per liter, it is usually the solution of choice. Compensation for potassium losses (usually by adding 20-40 mEq of potassium per liter of solution) should not be performed until a sufficient diuresis is established.

Dehydration with significant hypernatremia (serum sodium level above 160 meq / l) or hyponatremia (serum sodium level below 120 meq / l) requires special attention to prevent complications.

[10], [11], [12], [13], [14], [15], [16], [17]

Continuing losses

The volume of continuing losses should be determined directly (using a nasogastric tube, catheter, fecal volume measurement) or evaluated (for example, 10 ml / kg with a stool for diarrhea). The replacement should be up to a milliliter corresponding to the losses and be conducted in a time corresponding to the rate of continuing losses. The continuing loss of electrolytes can be estimated from a source or cause. Renal losses of electrolytes vary depending on their intake and the disease itself, but can be measured if the deficit can not be replenished with replacement therapy.

[18], [19], [20], [21], [22], [23]

Physiological need

The physiological need for liquids and electrolytes should also be taken into account. The physiological need depends on the basal metabolism and body temperature. Physiological losses (loss of water through the skin and breathing in a ratio of 2: 1) are approximately 1/2 physiological needs.

Rarely accurate calculation is required, but usually the volume should be sufficient to prevent the kidney from significantly concentrating or diluting the urine. The most common method takes into account the weight of the patient to determine the energy costs in kcal / day, which approximately correspond to the physiological need for fluid in ml / day.

An easier calculation method (Holiday-Segar formula) uses 3 weight classes. You can also use the calculation on the child's body surface, determined with the help of nomograms, the physiological need for the liquid will be 1500-2000 ml / (m2 x day). More complex calculations are rarely used. The calculated volume can be administered as a separate infusion simultaneously with those already described, so that the infusion rate of fluid deficit recovery and continuing pathological losses can be set and changed regardless of the speed of the maintenance infusion.

The calculated volume of physiological needs can vary with fever (increasing by 12% per degree above 37.8 ° C), hypothermia, physical activity (increases with hyperthyroidism and epileptic status, decreases with coma).

The composition of the solutions differs from those used to compensate for fluid deficiency and continuing pathological losses. The patient needs 3 meq / 100 kcal / day sodium (meq / 100 ml / day) and 2 meq / 100 kcal / day potassium (meq / 100 ml / day). This requirement corresponds to a 0.2-0.3% solution of sodium chloride with 20 mEq / L potassium in a 5% glucose solution (5% H / V). Other electrolytes (magnesium, calcium) are not routinely assigned. It is incorrect to compensate for fluid deficiency and continuing pathological losses, only increasing the volume and speed of infusion of the supporting solution.