Residency · Residency · Anesthesiology

Pediatric Fluid, Blood, and Glucose Management

Introduction

Fluid and transfusion management in pediatric patients requires precise weight-based calculations and an understanding of age-related physiological differences. Small errors in volume or glucose administration can have significant consequences in neonates and infants with limited physiologic reserve.

Body Fluid Composition by Age

Total body water as a percentage of body weight varies substantially with age. In premature neonates, total body water is approximately 80 to 85%. In term neonates it is 75 to 80%, in infants at one year approximately 65%, and in adults approximately 60%. Extracellular fluid constitutes a larger proportion in neonates (approximately 45%) compared to adults (approximately 20%), which affects the volume of distribution for water-soluble drugs. The transition from high extracellular fluid to a lower proportion occurs primarily in the first year of life.

Maintenance Fluid Requirements

Holliday-Segar Formula

The Holliday-Segar formula calculates maintenance fluid rates as follows: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg (added to the first 10 kg), and 1 mL/kg/hr for each kilogram above 20 kg. As an example, a 25 kg child requires 40 + 20 + 5 = 65 mL/hr.

Choice of Maintenance Fluid

Isotonic crystalloid (lactated Ringer's, Plasmalyte, or 0.9% NaCl) is now the standard for intraoperative maintenance fluid. Hypotonic solutions such as D5 1/4 NS or D5 1/2 NS should be avoided intraoperatively due to the risk of hyponatremia and cerebral edema. Addition of 1 to 2% dextrose to isotonic solutions may be appropriate for neonates and infants at risk of hypoglycemia.

Fasting Deficit and Replacement

The traditional approach of calculating fasting deficit (maintenance rate multiplied by hours of fasting) and replacing it in thirds has been largely abandoned. Current practice is to administer a 10 to 20 mL/kg bolus of isotonic crystalloid at induction to treat relative hypovolemia, then continue maintenance fluids. Liberal clear fluid policies permitting clear fluids until one hour before anesthesia reduce dehydration and fasting deficit.

Third-Space and Surgical Losses

Surgical replacement fluid estimates vary by case severity: 1 to 2 mL/kg/hr for minimal trauma procedures such as hernia repair, 4 to 7 mL/kg/hr for moderate trauma procedures such as bowel surgery, and 10 to 15 or more mL/kg/hr for major trauma procedures such as thoracoabdominal surgery. Replacement should be with isotonic crystalloid or balanced salt solution. Colloid (5% albumin) may be considered when crystalloid requirements exceed 40 to 50 mL/kg.

Blood Volume and Transfusion Thresholds

Estimated Blood Volume (EBV)

Estimated blood volume varies by age: approximately 90 to 100 mL/kg in premature neonates, 80 mL/kg in term neonates, 75 to 80 mL/kg in infants aged 3 to 12 months, 70 to 75 mL/kg in children aged 1 to 6 years, and 65 to 70 mL/kg in older children and adolescents.

Maximum Allowable Blood Loss (MABL)

The MABL is calculated as EBV multiplied by (starting Hct minus minimum Hct), divided by starting Hct. For example, in a 10 kg infant with an EBV of 800 mL, a starting hematocrit of 35%, and a minimum acceptable hematocrit of 25%, the MABL is 800 x (35 - 25) / 35 = 229 mL.

Transfusion Triggers

There is no universal transfusion threshold; the decision depends on clinical context, age, and cardiorespiratory status. General guidelines include a hemoglobin threshold of 10 to 13 g/dL for neonates under 4 months or critically ill patients, 7 to 8 g/dL for stable infants and children, and a higher hematocrit target for children with cyanotic heart disease to ensure adequate oxygen delivery.

Packed Red Blood Cell (pRBC) Transfusion

The standard dose of 10 to 15 mL/kg of pRBCs raises hemoglobin by approximately 2 to 3 g/dL. Leukoreduced, irradiated blood products should be used for neonates to prevent CMV transmission and transfusion-associated graft-versus-host disease. All blood products should be warmed to prevent hypothermia.

Other Blood Product Administration

Fresh Frozen Plasma (FFP)

FFP is dosed at 10 to 15 mL/kg and is indicated for coagulopathy with active bleeding, massive transfusion, and DIC. It contains all clotting factors at near-physiologic concentrations.

Platelets

Platelets are dosed at 5 to 10 mL/kg (or 1 unit per 10 kg) and increase the platelet count by approximately 50,000 to 100,000 per microliter. Transfusion is indicated for counts below 50,000 with active surgical bleeding or below 100,000 for neurosurgery.

Cryoprecipitate

Cryoprecipitate is dosed at 1 to 2 units per 10 kg and is rich in fibrinogen, factor VIII, factor XIII, and von Willebrand factor. The target fibrinogen level is above 150 to 200 mg/dL in the setting of active bleeding.

Tranexamic Acid (TXA)

TXA is an antifibrinolytic agent given as a loading dose of 10 to 30 mg/kg IV followed by a 5 to 10 mg/kg/hr infusion. It is widely used in pediatric cardiac surgery, scoliosis surgery, and craniofacial procedures and has been shown to reduce blood loss and transfusion requirements.

Glucose Management

Hypoglycemia Risk Factors

Risk factors for hypoglycemia include prematurity, small for gestational age, intrauterine growth restriction, infants of diabetic mothers (who have hyperinsulinism), prolonged fasting, hepatic disease, sepsis, glycogen storage disorders, and inborn errors of metabolism.

Monitoring and Treatment

Point-of-care glucose should be checked at induction and periodically during long cases. Normal neonatal blood glucose ranges from 45 to 100 mg/dL, and it should be maintained above 45 to 50 mg/dL. For documented hypoglycemia, a bolus of 2 to 4 mL/kg of D10W (delivering 0.2 to 0.4 g/kg of glucose) is administered. D25W and D50W should be avoided in neonates and infants due to hyperosmolarity and the risk of rebound hypoglycemia. A continuous dextrose infusion at a glucose infusion rate of 4 to 6 mg/kg/min should be considered for at-risk neonates.

Hyperglycemia

Glucose above 180 mg/dL in critically ill children is associated with worse outcomes. Stress hyperglycemia is common with surgical stimulus and steroid administration. Treatment involves reducing or stopping dextrose-containing fluids; insulin infusion is rarely needed intraoperatively.

Massive Transfusion in Children

Massive transfusion in children is defined as replacement of more than one total blood volume in 24 hours or more than 50% of the blood volume in 3 hours. A massive transfusion protocol should be activated early when massive hemorrhage is anticipated. The target ratio of pRBC to FFP to platelets is approximately 1:1:1 by volume.

Ionized calcium must be monitored because citrate toxicity causes hypocalcemia; treatment consists of calcium chloride 10 to 20 mg/kg or calcium gluconate 30 to 60 mg/kg. Potassium should also be monitored because stored blood is hyperkalemic. Magnesium and acid-base status require ongoing assessment. A rapid infusion device with a blood warmer should be used when transfusion volumes exceed 15 mL/kg/hr.

Clinical Pearls

Isotonic crystalloid should always be used for intraoperative fluid management in children because iatrogenic hyponatremia from hypotonic fluids is a preventable cause of morbidity and mortality. MABL should be calculated before every pediatric case and communicated to the surgical team. Neonates have minimal glycogen stores, so glucose should be checked early, especially in premature or small-for-gestational-age infants. Citrate toxicity from rapid transfusion manifests as hypotension, prolonged QT interval, and decreased contractility, and should be treated empirically with calcium. A 10 mL/kg bolus of pRBCs is a reasonable starting transfusion volume in a child who has exceeded MABL.

References

1. Sumpelmann R, Becke K, Brenner S, et al. Perioperative intravenous fluid therapy in children: guidelines from the Association of the Scientific Medical Societies in Germany. Paediatr Anaesth. 2017;27(1):10-18.
2. Chong MA, Wang Y, Berbenetz NM, McConachie I. Does goal-directed haemodynamic and fluid therapy improve peri-operative outcomes? A systematic review and meta-analysis. Eur J Anaesthesiol. 2018;35(7):469-483.
3. Goobie SM, Haas T. Bleeding management for pediatric hemorrhagic conditions. Br J Anaesth. 2014;113 Suppl 2:ii30-ii37.
4. Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832.

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