A broad understanding of the principles of fluid and electrolyte homeostasis is essential for ensuring safe and effective prescribing of fluids. Inappropriate prescribing can lead to unnecessarily prolonged hospital stays and, in extreme cases, can lead to morbidity and mortality. Generally, infants have a much higher surface area to body mass ratio than older children and adults. This combined with the fact that they have a relatively higher proportion of extracellular water, means that they are more likely to become dehydrated. Hence stopping fluid intake for more than short periods of time will affect the body's ability to maintain fluid homeostasis. In such patients, drinking water may not be sufficient to replace deficits within a safe time frame, and intravenous (IV) fluid administration may become essential to correct acute losses.
Intravenous fluid therapy can be divided into two categories depending on the aim of treatment: to correct existing fluid deficits (fluid replacement/resuscitation) or to replace normal losses (routine maintenance). Most indications for IV fluid replacement are the same for children as for adults. The amount of IV fluid required by a child will depend on the current level of dehydration, the indication and any comorbidity. Another important factor is age; neonates require relatively more fluid intake than infants or older children
