Perioperative fluid therapy in pediatrics

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Perioperative Fluid Therapy in Pediatrics

Overview

Pediatric perioperative fluid management cannot simply extrapolate adult guidelines. Age-specific differences in metabolism, extracellular fluid volume, renal maturity, and body surface area all demand a tailored approach. The three major goals are:

Meet maintenance requirements
Replace preoperative deficits
Compensate for ongoing perioperative losses

Hypovolemia is the most common cause of perioperative cardiac arrest in children, making fluid management a patient safety priority.

Miller's Anesthesia, 10e, p. 10616

1. Maintenance Fluid Requirements - The 4-2-1 Rule

The most widely used formula for hourly maintenance fluid rate is the Holliday-Segar "4-2-1" rule:

Body Weight	Hourly Rate
First 10 kg	4 mL/kg/h
10-20 kg	+ 2 mL/kg/h
Each kg > 20 kg	+ 1 mL/kg/h

This formula was originally based on metabolic activity and the electrolyte composition of milk (Holliday & Segar, 1957). It remains the starting point but is being actively reexamined.

Miller's Anesthesia, 10e, p. 10616

2. Preoperative Deficit

Traditional approach

Replace fasting deficit using the 4-2-1 rule multiplied by hours fasted, or a bolus of 25 mL/kg (for children both under and over 3 years in some protocols).

Modern revision

Contemporary liberal fasting guidelines allowing clear fluids up to 1-2 hours before surgery significantly reduce clinically significant preoperative dehydration. This has led to questioning the routine need for large preoperative deficit replacement.

German guidelines suggest initiating a background infusion at 10 mL/kg/h and adjusting to actual need; 10 mL/kg boluses are recommended for each estimated percent of clinical dehydration.

Miller's Anesthesia, 10e, pp. 10616-10617

3. Neonatal Considerations

Neonates require special attention due to:

Increased skin permeability and high body surface area-to-weight ratio (especially preterm)
Immature kidneys unable to excrete large water or electrolyte loads
Relatively large extracellular fluid volume

Daily requirements for term newborns:

Day of Life	Requirement
Day 1	70 mL/kg
Day 3	80 mL/kg
Day 5	90 mL/kg
Day 7	120 mL/kg

Preterm infants have slightly higher requirements. Ongoing losses vary widely by procedure - from 10-15 mL/kg/h for routine surgeries up to >50 mL/kg/h for burns or extensive neonatal abdominal surgery.

Miller's Anesthesia, 10e, p. 10617

4. Fluid Composition

Isotonic crystalloids - the current standard

The shift away from hypotonic fluids is one of the most important modern developments. The original 4-2-1 approach used hypotonic glucose-containing solutions, but this led to hospital-acquired hyponatremia, seizures, cerebral edema, and death. Children are particularly vulnerable to acute hyponatremia because of greater susceptibility to cerebral edema.

A meta-analysis of large randomized trials demonstrates that isotonic IV maintenance fluids (sodium concentration similar to plasma) significantly reduce the risk of hyponatremia compared to hypotonic fluids.

Current recommendation: isotonic crystalloid solutions for intraoperative use.

Miller's Anesthesia, 10e, pp. 10617-10618

Balanced crystalloids vs. normal saline

While isotonic saline (0.9% NaCl) has been advocated as "safer," it carries the risk of sodium overload and hyperchloremic metabolic acidosis. Balanced isotonic crystalloids (e.g., Lactated Ringer's, Plasma-Lyte) are generally preferred.

Postoperative fluids

Proposed strategies to prevent postoperative hyponatremia include:

Use one-half to two-thirds of the calculated 4-2-1 rate
Avoid the most hypotonic solutions (e.g., 4% dextrose with 0.18% NaCl)
Use balanced isotonic crystalloids (with glucose if available)
Return to oral fluids as early as possible
Ensure euvolemia to minimize the ADH (SIADH) response from surgical stress, pain, and hypovolemia
Check electrolytes at least daily in children still receiving IV fluids
Miller's Anesthesia, 10e, p. 6409

5. Glucose Management

Intraoperative glucose-containing fluids are not routinely recommended in healthy children.

Preoperative hypoglycemia incidence is low (<2.5%) and mainly occurs with inappropriately prolonged fasting or special risk factors (prematurity, small for gestational age, poor nutrition)
Intraoperative 5% dextrose infusions consistently cause hyperglycemia, which risks osmotic diuresis, electrolyte abnormalities, and potential adverse neurologic outcomes if ischemia/hypoxia occurs

High-risk groups who do need glucose supplementation:

Neonates and infants (especially preterm, SGA)
Patients on hyperalimentation
Diabetes mellitus

For these patients: 1%-2.5% dextrose in isotonic solution, with serial blood glucose monitoring to maintain levels in the optimal range.

Miller's Anesthesia, 10e, pp. 10618, 6409

6. Colloids

No well-controlled studies clearly define the role of crystalloids vs. colloids for perioperative loss replacement and volume expansion in neonates and children.

Albumin remains the most commonly used plasma expander in neonates/infants (historically the gold standard for colloid osmotic pressure maintenance), but general evidence for its use in routine fluid resuscitation is lacking
Hydroxyethyl starch (HES): A third-generation HES showed no serious adverse reactions (anaphylaxis, renal failure, coagulopathy) in children with normal renal and clotting function; efficacy and safety were comparable to albumin in pediatric cardiac surgery. However, further studies are needed before use in renal failure or high bleeding-risk patients
Gelatins: No short- or long-term adverse effects in a recent trial, though older formulations had high rates of hypersensitivity
Dextrans: Not recommended due to negative coagulation effects and high anaphylactic potential
Miller's Anesthesia, 10e, pp. 10618-10619

7. Blood Volume and Transfusion

Estimated Blood Volume (EBV) by age

Age Group	EBV
Preterm infant	100-120 mL/kg
Full-term infant	90 mL/kg
Infant 3-12 months	70-80 mL/kg
Child > 1 year	70 mL/kg

Maximum Allowable Blood Loss (MABL)

$$\text{MABL} = \frac{EBV \times (\text{Starting Hct} - \text{Desired Hct})}{\text{Starting Hct}}$$

Example: A 15 kg, 3-year-old child with starting Hct 38%, desired Hct 25%:

MABL = (15 × 70) × (38 - 25) / 38 = 360 mL

Blood losses up to MABL are replaced with 3 mL of isotonic crystalloid (e.g., Lactated Ringer's) per 1 mL of blood lost.

Transfusion thresholds

Non-neonatal pediatric transfusion guidelines are similar to adults
Special precautions apply for massive transfusion
Miller's Anesthesia, 10e, pp. 10619-10620

8. Goal-Directed Fluid Therapy (GDFT)

GDFT remains largely unexplored in the pediatric population. The evidence base for GDFT benefits seen in adults has not been reproduced in children, and current practice largely relies on clinical assessment rather than advanced hemodynamic monitoring.

Miller's Anesthesia, 10e, p. 6409

Key Takeaways

Issue	Old Practice	Current Recommendation
Maintenance formula	4-2-1 with hypotonic fluids	4-2-1 rate, but with isotonic crystalloids
Glucose	Routine dextrose 5% intraoperatively	Avoid routine glucose; use 1-2.5% dextrose only in high-risk patients
Preoperative deficit	Aggressive replacement by fasting formula	Minimize fasting; modern guidelines reduce need for large deficit replacement
Postoperative maintenance	Full 4-2-1 with hypotonic saline	Reduced rate (1/2 to 2/3 of 4-2-1) with isotonic solutions
Colloid of choice	Albumin broadly used	No clear evidence; albumin for COP support in neonates; avoid dextrans

Recent literature note: A 2025 narrative review (Lorente et al., Front Med, PMID 40823584) covers perioperative fluid therapy in both adults and children, and a 2023 review (Lee & Kim, Korean J Anesthesiol, PMID 37073521) specifically addresses pediatric perioperative fluid management - these are current resources for updated clinical perspectives.

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