Bartter syndrome Sodium-losing Congenital adrenal hypoplasia Diuretics Sodium-losing nephropathy Pseudohypoaldosteronism Gastrointestinal losses Gastroenteritis a Diarrhea (see Chapter 23 Diarrhea ) Secretory vs nonsecretory Vomiting (see Chapter 81 Vomiting ) Obstructive vs nonobstructive Translocation of fluids Burns Ascites (e.g., nephrotic syndrome) Intraintestinal Paralytic ileus Postabdominal surgery a Indicates common cause of dehydration in pediatrics TABLE 22.2 SYMPTOMS ASSOCIATED WITH DEHYDRATION Signs and symptoms Minimal or no dehydration (9% loss of body weight) Mental status Well; alert Thirst Apathetic, lethargic, unconscious Drinks poorly; unable to drink Heart rate Drinks normally; might refuse liquids Normal Normal, fatigued or restless, irritable Thirsty; eager to drink Normal to increased Quality of pulses Normal Breathing Eyes Tears Mouth and tongue Skin fold Capillary refill Normal Normal Present Moist Instant recoil Normal Normal to decreased Normal; fast Slightly sunken Decreased Dry Recoil in 2 sec Prolonged; minimal Cold, mottled; cyanotic Minimal CDC MMWR Managing acute gastroenteritis among children Nov 21, 2003 Vol 53 No RR-16 DIFFERENTIAL DIAGNOSIS Fluid imbalance in dehydration results from (i) decreased intake; (ii) increased output secondary to insensible, renal, or gastrointestinal (GI) losses; or (iii) translocation of fluid such as occurs with major burns or ascites ( Table 22.1 ) Many presentations of dehydration are a combination of different causes of fluid imbalance EVALUATION AND DECISION The first step in evaluating a child with dehydration is to assess the severity or degree of dehydration, regardless of the cause ( Table 22.2 ) Most children with clinically significant dehydration will have two of the following four clinical findings: (i) capillary refill greater than seconds, (ii) dry mucous membranes, (iii) no tears, and (iv) ill appearance The more dehydrated a patient is, the more hypovolemic they are and the more likely they are progressing toward shock Minimal, mild–moderate, and severe dehydration correspond to impending, compensated, and uncompensated states of shock, respectively (see Chapter 10 Shock ) If there is severe dehydration or uncompensated shock, the child must be treated immediately with isotonic fluids to restore intravascular volume, as detailed later in this chapter History A thorough history aids in assessing child’s degree and etiology of dehydration ( Fig 22.1 ) Attention should be paid to the child’s output and intake of fluids and electrolytes Overt GI losses from diarrhea and vomiting are the most common causes of dehydration in children (see Chapters 23 Diarrhea and 81 Vomiting ) However, other diagnoses with these symptoms should be considered, especially if the patient presents with only vomiting (i.e., diabetes ketoacidosis and urinary tract infections) ( Table 22.3 , Chapter 81 Vomiting ) Decreased oral intake may occur for various reasons, including painful oral lesions, limited resources, or altered mental status Insensible losses can occur due to fever, high ambient temperatures, sweating, and hyperventilation It is important to note whether there is any underlying disease that would contribute to dehydration (e.g., cystic fibrosis, diabetes insipidus, hyperthyroidism, renal disease) Asking the parents about documented weight loss, amount of urine output, and the presence or absence of tears is helpful in determining the severity of the dehydration Although decreased urine output is an early sign of dehydration, only 20% of patients with the complaint of decreased urine output will be dehydrated With dehydration, one expects to find oliguria or anuria if normal renal concentrating function remains intact Severe oliguria or anuria may also, however, be manifested if severe dehydration and shock has led to acute renal failure (see Chapter 100 Renal and Electrolyte Emergencies ) The unexpected discovery of polyuria points to diabetes mellitus or insipidus, adrenal insufficiency, diuretic use, or renal injury or disease with resultant loss of concentrating ability ( Fig 22.1 ) Fluid intake should be recorded A detailed fluid history may reveal potential risk for electrolyte abnormalities For example, diluted juice or excessive water intake can lead to hyponatremic dehydration, while improperly prepared infant formula can cause hypernatremic dehydration Physical Examination The physical examination, including vital signs, is an important and objective assessment of dehydration ( Table 22.2 ) Unfortunately, multiple studies have demonstrated that using scales are not useful in assessing all degrees in dehydration so these signs are most useful as a starting point for treatment The first sign of mild dehydration is tachycardia, whereas hypotension is a very late sign of severe dehydration In mild to moderate dehydration, the respiratory rate is usually normal As a child becomes more acidotic and fluid is depleted, the respiratory rate increases and the breathing pattern becomes hyperpneic Vital signs alone are not always reliable Tachycardia also may be caused by fever, agitation, or pain; respiratory illness affects respiratory rates; and orthostatic signs are difficult to obtain in babies and young children