Fluid and Electrolyte Therapy in Low Birth Weight Infants

Abstract

Infants with respiratory distress syndrome (RDS) often require parenteral fluid therapy during the course of acute respiratory illness due to difficulty giving oral feedings. Errors in prescribing the fluid treatment may lead to either dehydration or fluid overload, partly due to the limitations in renal compensatory mechanism in these infants. Therefore, inappropriate fluid and electrolyte management in infants with RDS may lead to metabolic complications, dehydration, poor nutritional support, and additional cardiopulmonary complications because of the fluid overload. This article provides a brief review on the principles of fluid and electrolyte management in infants with RDS with the aim of minimizing the complications of such therapy. MAINTENANCE FLUID REQUIREMENT The maintenance fluid requirement should consist of allowances for (1) insensible water loss, (2) water for urine formation, (3) water loss through the stool, and (4) in a growing infant, water required for tissue growth. In low birth weight infants, insensible water loss is higher than in term infants.1,2 The water required for urine formation is dependent on solute excretion which in turn is dependent on the amount of solute given exogenously (primarily electrolytes and protein) and those endogenously derived from normal body metabolism. The amount of water excreted through the stool is minimal in the first days of life particularly in low birth weight infants simply because of smaller amounts of stool in these subjects during the first week of life.