Fluid and Electrolyte Balance

Abstract

The appropriate evaluation and maintenance of fluid and electrolyte balance in children with congenital heart disease are a fundamental aspect of everyday clinical practice. Fluids are continuously administered for the most reasons: nutrition, drug administration, and fluid resuscitation. Their amount and biochemical composition have been associated with several important outcomes in the pediatric and adult cardiac surgery populations. For example, even if human albumin and crystalloids remain the first choice for cardiopulmonary bypass priming and volume replacement, uncertainty currently concerns third-generation hydroxyethyl starches. Secondly, appropriate and timely fluid resuscitation may improve patients’ survival, but an incorrect fluid therapy in pediatric intensive care setting can significantly impact several organ functions. Hence, the fluid status assessment and management during perioperative period in pediatric cardiac surgery are a clinical challenge: there is no consensus regarding the optimal definition of fluid overload, which also varies by calculations and by the time frame during which fluid balance is assessed. Furthermore, the estimation of intravascular volume to guide fluid therapy is typically based on clinical assessment and on standard hemodynamic and perfusion parameters, but these parameters could be inadequate in children affected by congenital heart disease. Similarly, derangements of potassium, sodium, calcium, phosphate, and magnesium (both above and below the normal range) are extremely common in this population and require strict monitoring and careful intervention. This chapter will review the current evidence concerning perioperative fluid and electrolyte management, assessment, outcomes, and treatment in critically ill children undergoing congenital heart surgery.