20 - Fluid, Electrolyte, and Acid-Base Balance

Abstract

Managing fluids, electrolytes, and acid–base status is arguably one of the most important skills of the neonatal clinician. First, this chapter describes the physiology and pathophysiology of fluid and electrolyte homeostasis from fetal through neonatal life, including the impact of the most relevant hormones and the changes that occur with maturation of the different organ systems. Next, the specific diagnostic approaches to assess the fluid and electrolyte status and its disturbances are discussed, followed by management guidelines. Since a number of clinical conditions are associated with fluid and electrolyte disturbances, the next section describes the relationship of fluid and electrolyte homeostasis with extreme prematurity, transient tachypnea of the newborn, respiratory distress syndrome, bronchopulmonary dysplasia, patent ductus arteriosus, the syndrome of inappropriate antidiuretic hormone, and selected surgical conditions. In the final section, the acid–base status in health and disease is discussed. Understanding the physiology of acid–base homeostasis and the changes taking place during development, particularly during the transition from fetal to neonatal life is critical. In the closing part of the final section, the different forms of acidosis and alkalosis associated with the most frequently encountered pathological conditions are reviewed and treatment guidelines are discussed.