It is known that volatile anesthesia, such as sevoflurane, retain water and that this appears
more pronounced in children. However, the mechanisms for this effect is unknown and it is not
clear if the commonly used anesthetic propofol does the same. In this study the investigators
want to compare the fluid and electrolyte conserving effects of sevoflurane and propofol in a
pediatric setting and also investigate humoral changes induced by these anesthetics.