Paediatric Perioperative Fluid Management

Paediatric Perioperative Fluid Management

• Fluid Needs in Minor Surgery: Fit children undergoing minor surgery usually do not need IV fluids. Clear fluids permitted up to 2 hours before surgery; breast milk up to 3 hours. All other food/fluids withheld 6 hours pre-op.

• Fluid Administration Indications: IV fluids used for resuscitation, maintenance, or replacing ongoing losses. Resuscitation of dehydrated/hypovolemic patients should happen pre-surgery if possible; isotonic saline (0.9%), colloids, or blood used to correct hypovolemia rapidly.

• Maintenance Fluids: Clear fluids can be used for maintenance, however some (hypotonic) may cause hyponatremia if given in large amounts. Isotonic fluids (0.9% saline, Hartmann's) have the same solute concentration as plasma. Dextrose (5%) is initially isosmolar to plasma, but metabolizes into free water. Solutions like 0.45% or 0.18% saline, and dextrose solutions are hypotonic.

• Fluid Management and Hyponatremia: Stress (surgery, pain, nausea, hypovolemia) causes increased ADH (antidiuretic hormone), leading to water retention and lower plasma sodium. Rapid/large sodium drops cause cell swelling and edema, potentially leading to raised intracranial pressure and death. Avoid hypotonic fluids if sodium levels are below 140 mmol/l and give 0.9% saline as a safer initial choice if plasma electrolytes are unknown.

• Fluid Replacement (Ongoing Losses): Replace ongoing losses (e.g., pyrexia, open wounds, breathing dry gases) with isotonic fluids, colloids, or blood. Monitoring of heart rate, capillary refill, and blood pressure is essential for identifying and managing these losses.

• Dextrose Use: Dextrose needed to prevent hypoglycemia during fasting for surgery, but perioperative hypoglycemia is rare in most children--only exceptions are neonates (less than 48 hours old, dextrose infusion stopped, or below 3rd weight centile).

• Neonate Fluid Requirements: Babies up to 44 weeks post-conception have different needs due to initial "waterlogging," followed by fluid loss in the first week. Premature/small babies have higher fluid needs due to larger surface area to weight ratio, and require 10% dextrose, potentially with or without 0.45% saline.

• Fluid Calculation Guide: There are different formulas for calculating maintenance fluid rates based on the child's weight. Rates are based on 1-kg, 10-kg, and >20-kg categories. Neonate rates are provided in a separate table, taking into account the varying fluid requirements based on postnatal age.

• Postoperative Fluid Management: Post-op monitoring for fluid status continues until oral intake is adequate. Ongoing losses need measurement and replacement. Symptoms (nausea, vomiting, reduced consciousness, respiratory depression, seizures) can indicate raised intracranial pressure – but these symptoms can be masked by surgical / anesthetic/ analgesic side effects. A careful strategy using calculated maintenance infusion of 0.9% or 0.45% saline is advised.

• Additional Fluids: Additional fluids to correct deficits or replace ongoing losses can be administered in 0.9% saline, colloids, or blood; use dextrose for neonates, malnourished patients, or if blood glucose is low.