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  Dehydration is not a disease; the underlying cause must be identified and treated.

  
  
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  Severity of dehydration can be classified using clinical assessment.

  
  
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  Management priorities in the emergency department are stabilization of vital signs, replacement of intravascular volume deficit and ongoing losses, and correction of electrolyte abnormalities.

  
  
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  Frequent reassessment of clinical status is necessary to monitor the response to treatment.

Acute evaluation and treatment of children presenting with dehydration represents one of the most common situations in the pediatric emergency department (ED). Dehydration in sick children is often a combination of refusing to eat or drink and losing fluid from vomiting, diarrhea, or fever. In children with vomiting and diarrhea, the underlying problem is actually intravascular volume depletion, not dehydration. Volume depletion represents an equal loss of water and solutes (mainly sodium) from the blood plasma, whereas dehydration denotes a disproportional loss of plasma free water.

Children have higher morbidity and mortality rates associated with dehydration than adults due to a higher turnover of fluids and solutes (higher metabolic rates, increased body surface area/mass index, larger total body water content, immature kidneys with relative inability to produce concentrated urine, reliance on caregivers for basic needs). In clinical practice, the clinician attempts to determine the degree of volume depletion and the underlying cause of dehydration to initiate proper treatment.

Gastroenteritis is the most common cause of dehydration and is due to viruses in 80% of cases (rotavirus 30–50%). The clinical diagnosis of gastroenteritis by definition requires the presence of diarrhea. However, many infants with viral gastroenteritis present with isolated diarrhea or isolated vomiting. Rotavirus infections are responsible for approximately 3 million cases of diarrhea and 55,000 hospitalizations for diarrhea and dehydration in children <5 years of age each year in the United States. The majority of children with dehydration presenting to the ED have a benign etiology; however, there are serious causes for dehydration that should be considered.

Consider appendicitis, intussusception, volvulus, pyloric stenosis, urinary tract infection, hydrocephalus, brain tumors, and diabetes mellitus as potential underlying conditions in the pediatric patient who presents with dehydration. Other causes of dehydration include gastrointestinal (hepatitis, liver failure, drug toxicity), endocrine (congenital adrenal hyperplasia, Addisonian crisis), renal (pyelonephritis, renal tubular acidosis, thyrotoxicosis), poor oral intake (pharyngitis, stomatitis), and insensible losses (fever, burns, sweating, pulmonary processes).

History

A complete history is necessary to determine the severity of illness and to identify the type of dehydration present. Obtain as much information from the child, and elicit further details and clarifications from the parent or caregiver. Obtain a detailed description of intake (types of liquids and solids, volume, frequency) and output of urine (frequency, amount, color, odor, hematuria), stool (number, consistency, presence of blood or mucous), and emesis (frequency, volume, bilious or nonbilious, hematemesis). Estimate urine output by the number and saturation of wet diapers in infants and young children. Note the presence of abdominal pain (duration, location, intensity, quality, and radiation). Inquire about weight loss and activity level. Note the time interval of symptoms. The last episode of vomiting is important in determining when the initiation of an oral trial is advisable.

Ask about associated symptoms (fever, headache, neck pain, throat pain, dysuria, urinary frequency, rash). Travel and recent antibiotic use are also pertinent.

Note underlying diseases that could contribute to dehydration (kidney disease, diabetes mellitus, cystic fibrosis, hyperthyroidism). Contact with ill people and daycare attendance should be considered. Important elements of the past medical history include immunocompromise and malignancy.

Physical Examination

The examination begins with assessment of the general appearance of the child. Lethargy or listlessness can warn of impending circulatory collapse. Examine the throat for erythema, ulcerations, or tonsillar exudates. Assess the abdomen for tenderness, rebound, or guarding. Neurologic exam should include mental status, cranial nerves, strength, and reflexes. Altered mental status or focal neurologic findings can indicate increased intracranial pressure. Capillary refill and skin turgor should be noted. The gold standard for the diagnosis of dehydration is measurement of acute weight loss. True pre-illness weight is rarely known in the acute care setting. An estimate of the fluid deficit is thus made based on clinical assessment (Table 51-1). Any of the two following findings are predictive of clinically significant dehydration in children: ill appearance, absence of tears, dry mucous membranes, and delayed capillary refill (>2 seconds). Other important considerations are abnormal respiratory pattern and skin tenting.