Fluid and Electrolyte Therapy in Infants and Children

Fluid and Electrolyte Therapy in Infants and ChildrenDehydration

caused by a negative fluid balance resulting from decreased intake, increased output from systemic responses to specific disease states such as burns or sepsis.

Infants and children are particularly susceptible to dehydration

Hypermetabolic states increase the need for free water. (e.g. fever and increased sweating)

Dehydration

often described in relation to serum sodium concentrations as

hyponatremic dehydration (sodium level of 150 mEq/L). - occurs when the fluid lost contains less sodium than the blood, which causes ECF free water to move into the ICF spaceClinical Features

HistoryQuantify the child's intake and output. Ask about intakethe amount, frequency, and types of fluids taken (including orally, via gastrostomy tube, or parenterally). For breastfed infants, ask if the infant is feeding or merely sucking. Assess potential fluid losses by asking about vomiting and diarrhea (including frequency, volume, and composition) and amount of urine output. Ask about level of activity and mental status, skin color (pallor, cyanosis, mottling), and temperature, and, in infants, whether parents or other caretakers have noticed a sunken fontanelle. Weight loss, if accurately known, is the most reliable way to quantify the degree of dehydration4Clinical FeaturesPhysical ExaminationVital sign tachycardia and tachypnea are compensatory signs characteristic of moderate dehydration, hypotension - is the sine qua non of hypovolemic shock. Additional signs of dehydration include listlessness, lethargy, and decreased tone; a sunken fontanelle; sunken eyes or absent or diminished tears; dry or sticky mucous membranes; a scaphoid or distended abdomen; skin that is cool or mottled with delayed capillary refill time; decreased elastic recoil of the skin; diminished pulses; or evidence of neurologic dysfunction such as lethargy and seizures.

Clinical FeaturesThe gold standard remains pre-illness and post-illness weight, either at the end of a hospital admission or a weight obtained during a follow up visit.

Clinical criteria are inconsistent and unreliable, because many signs of dehydration are subjective or confounded by other physiologic stressors (e.g., tachycardia may indicate dehydration, pain, anxiety, or feverLaboratory Evaluation

Routine laboratory testing for dehydration is controversial, and results do not predict the degree of dehydration based on the gold standard of weight.

routine measurement of serum electrolytes is not necessary for most cases of dehydration due to gastroenteritis.

perform laboratory testing when clinically indicated based on the findings of a thorough history and physical examination, or when underlying conditions suggest the likelihood of metabolic abnormalities.

Discharge or admission decisions should be based on the response to rehydration in the EDTreatment of Dehydration

Rehydration MethodsMild and moderate dehydration oral rehydrationFor moderate and severely dehydrated children unable to tolerate oral rehydration, the treatment strategy emerging from more recent clinical trials emphasizes large volumes of fluid over a short period of time.

when IV access is difficult to obtain or based on clinician preference, nasogastric hydration (NG), is an effective strategy for rehydration.

Treatment of DehydrationModerate and Severe DehydrationThe child with moderate to severe or severe dehydration unable to tolerate oral rehydration therapy requires prompt fluid resuscitation. Give 20 mL/kg boluses over 5 to 10 minutes repetitively until hemodynamics stabilize. Give a minimum of 60 mL/kg or more in the first hour, unless contraindicated based on the patient's disease.

Maintenance Fluid and Electrolyte Requirementsfluid requirements can be estimated from body surface area, in the ED, weight is a sufficiently accurate and more easily obtained value for calculating fluid requirements. For the first 10 kg: 100 mL/kg/dFor the second 10 kg: 50 mL/kg/dFor each kg >20 kg: 20 mL/kg/dElectrolyte requirements remain constant throughout childhood and can be estimated by body weight. All infant formulas contain sufficient electrolytes to satisfy these requirements, as do the oral rehydration solutions Ricelyte and Pedialyte. The requirement for sodium is 2 to 3 mEq/kg/d and for potassium is 2 mEq/kg/d Hyponatremiaserum sodium level of 150 mEq/LDiarrhea is the most common cause of hypotonic fluid losses in children causing a hypernatremic dehydration. Other diseases renal disease and diabetes insipidus. sodium levels of >160 mEq/L associated with permanent neurologic sequelae, sodium level of