e-FIGURE 21.3 Blue dye causing localized cyanosis of the face and scalp of an infant Note the difference in color on the upper forehead which appears pink after wiping off the dye This dye originated from a blue blanket that the infant had been lying on (Photo courtesy of David Lowe.) CHAPTER 22 ■ DEHYDRATION SARAH D MESKILL, ASHA T V MORROW Dehydration is not a disease itself, rather a symptom of another process Infants have higher morbidity and mortality from dehydration and are more susceptible to it because of their larger water content, three times higher metabolic turnover rate of water than adults, renal immaturity, and inability to meet their own needs independently Children with various illnesses and circumstances will present to the emergency department (ED) with signs of dehydration ( Table 22.1 ) Gastroenteritis is the most common cause of dehydration in infants and children and is the leading cause of death worldwide in children younger than years of age In the United States, an average of 300 children younger than years of age die each year, and an additional 200,000 are hospitalized, secondary to diarrheal illnesses with dehydration PATHOPHYSIOLOGY In pediatrics, dehydration and hypovolemia are used interchangeably to describe a reduction in the water content of the body Over two-thirds of the total body water is intracellular and one-third is in the extracellular space Early in the process of dehydration, the majority of the water loss is from the extracellular compartment, which contains 135 mEq/L of sodium and negligible potassium However, with time, there is an equilibration between the extracellular compartment and the intracellular compartment, which has 150 mEq/L of potassium and negligible sodium As the electrolyte composition of extracellular fluid and intracellular fluid varies greatly, an understanding of this process helps the clinician gauge the optimal composition and rate of fluid deficit correction (see Chapter 100 Renal and Electrolyte Emergencies ) Dehydration is often categorized by severity or degree of fluid deficit, severity is judged by the amount of body fluid lost or the percentage of weight loss, and is typically characterized as minimal (less than 3% of total body weight), mild to moderate (3% to 10% of total body weight), or severe (greater than 10% of total body weight) Most children have isotonic dehydration (with normal sodium content) however both hyponatremic and hypernatremic dehydration can occur TABLE 22.1 CAUSES OF DEHYDRATION Decreased intake Physical restriction Infant Central nervous system depression Anorexia Voluntary or imposed cessation of drinking Pharyngitis, stomatitis a Respiratory distress a Child abuse Hypothalamic hypodipsia Increased output Insensible losses Fever a Sweating Heat prostration High ambient temperature/low humidity Hyperventilation Cystic fibrosis Thyrotoxicosis Renal losses Osmotic Diabetic ketoacidosis a Acute tubular necrosis High protein feeds Mannitol usage Nonosmotic Diabetes insipidus Sustained hypokalemia–hypercalcemia Sickle cell disease Chronic renal disease ... their own needs independently Children with various illnesses and circumstances will present to the emergency department (ED) with signs of dehydration ( Table 22.1 ) Gastroenteritis is the most common... 200,000 are hospitalized, secondary to diarrheal illnesses with dehydration PATHOPHYSIOLOGY In pediatrics, dehydration and hypovolemia are used interchangeably to describe a reduction in the