Chapter 40: The Child With a Fluid and Electrolyte Alteration

The distinctive features of pediatric fluid physiology include proportionally greater extracellular fluid volume, elevated metabolic demands, larger surface area relative to body mass, and kidneys that have not yet reached full concentrating capacity, all of which combine to increase insensible fluid losses and susceptibility to acute dehydration. The chapter explores acid-base homeostasis and disturbances in the pediatric context, explaining how metabolic and respiratory forms of acidosis and alkalosis develop and how the body's buffering systems, respiratory compensation, and renal mechanisms work to restore balance. Assessment of dehydration requires careful classification based on serum sodium concentration—distinguishing between isonatremic, hyponatremic, and hypernatremic dehydration—and severity stratification from mild to severe using clinical indicators such as weight loss percentage, skin turgor elasticity, fontanel appearance, and capillary refill time. Management strategies are tailored to dehydration severity, with oral rehydration therapy serving as the preferred approach for mild-to-moderate cases and intravenous fluid administration using isotonic solutions reserved for severe dehydration or when shock threatens. The chapter addresses important electrolyte imbalances, particularly elevated potassium levels and diminished calcium levels, with critical nursing considerations for safe potassium replacement. A substantial portion focuses on gastrointestinal causes of fluid loss, notably acute infectious diarrhea and vomiting from pathogens such as rotavirus and norovirus, along with corresponding nursing interventions for wound care, infection prevention, nutritional support, and family education regarding appropriate fluid selection and avoidance of hyperosmolar beverages.