Potential subjects will be pre-screened and informed consent/assent will be obtained from the subject and/or subject's parents or guardians prior to surgery. Post-surgery, the subject will be admitted to the Surgical, Neonatal, or Pediatric Intensive Care Unit (SICU/NICU/PICU) for postoperative recovery and care management. Subjects who show signs of hypovolemia as judged by the Principal Investigator (PI) will be screened to determine their eligibility to participate in this trial. Subjects will then be randomized to receive treatment with Kedbumin 25% or the comparator, normal saline (sodium chloride 0.9%).