What is the recommended total parenteral nutrition (TPN) volume in ml/kg/day and dextrose concentration for a 26-week unstable infant?

TPN Management for a 26-Week Unstable Preterm Infant

Immediate Recommendations

For this 26-week unstable infant, start with 140-160 ml/kg/day total fluid volume on day 1, using a dextrose concentration of 5-8% (providing 4-8 mg/kg/min glucose), and begin amino acids immediately at 1.5 g/kg/day. 1

Fluid Volume Strategy

Day 1 Approach

• Total fluid: 140-160 ml/kg/day for preterm infants <1500g during the stabilization phase 1
• This accounts for the high insensible water losses in extremely premature infants while avoiding fluid overload in an unstable patient 1

Progression Beyond Day 1

• Maintain 140-160 ml/kg/day during the stable growth phase (Phase III) 1
• Critical caveat: Because this infant is "very unstable," you must adjust based on clinical status—if requiring vasopressors, mechanical ventilation, or fluid resuscitation, consider the lower end of this range 1

Dextrose Concentration and Glucose Delivery

Day 1 Glucose Strategy

• Start with 5-8% dextrose concentration to deliver 4-8 mg/kg/min (5.8-11.5 g/kg/day) 1
• For a 1 kg infant receiving 150 ml/kg/day: 5% dextrose = 7.5g glucose = ~5.2 mg/kg/min
• For a 1 kg infant receiving 150 ml/kg/day: 8% dextrose = 12g glucose = ~8.3 mg/kg/min

Day 2 Onwards (Once Stabilized)

• Target 8-10 mg/kg/min glucose (11.5-14.4 g/kg/day), which typically requires 10-12% dextrose concentration 1
• Maximum: 12 mg/kg/min (17.3 g/kg/day)—do not exceed this as it surpasses the maximum rate of glucose oxidation in preterm infants 1

Critical Adjustment for Instability

• If the infant has sepsis, infection, or acute critical illness requiring organ support, temporarily reduce to day 1 glucose rates (4-8 mg/kg/min) guided by blood glucose monitoring 1
• The PEPaNIC trial demonstrated that lower carbohydrate/energy delivery during acute critical illness reduces infections, ventilator time, and kidney failure 1

Amino Acid Delivery

Day 1 Protocol

• Start immediately with at least 1.5 g/kg/day amino acids to achieve anabolic state and prevent metabolic shock from interruption of placental nutrition 1, 2
• This is a strong recommendation (Grade A evidence) even in unstable infants 1

Day 2 Onwards

• Advance to 2.5-3.5 g/kg/day amino acids accompanied by non-protein energy >65 kcal/kg/day 1, 2
• Do not exceed 3.5 g/kg/day outside of clinical trials 1

Practical Calculation Example

For a 1.0 kg infant at 26 weeks:

Day 1:

• Total volume: 150 ml/kg/day = 150 ml
• 7% dextrose solution = 10.5g glucose = ~7.3 mg/kg/min ✓
• Amino acids: 1.5 g/kg/day = 1.5g
• This provides ~42 kcal/kg/day from dextrose + amino acids

Day 2-3 (if stabilizing):

• Total volume: 150 ml/kg/day = 150 ml
• 10% dextrose solution = 15g glucose = ~10.4 mg/kg/min ✓
• Amino acids: 2.5-3.0 g/kg/day = 2.5-3.0g
• Add lipids to reach >65 kcal/kg/day total non-protein energy 1

Essential Monitoring

• Blood glucose every 4-6 hours initially to detect hypo/hyperglycemia 1
• Daily weights to assess fluid balance and avoid overload 1
• Serum sodium, potassium, chloride at least daily during unstable phase 1
• Electrolyte supplementation: Sodium 3-5 mmol/kg/day, Potassium 2-5 mmol/kg/day, Chloride 3-5 mmol/kg/day for preterm <1500g 1

Critical Pitfalls to Avoid

• Never delay amino acids beyond the first day—this causes protein catabolism and negative nitrogen balance 1, 2
• Never exceed 12 mg/kg/min glucose (17.3 g/kg/day)—this surpasses oxidation capacity and increases lipogenesis without benefit 1
• Never use hypotonic maintenance fluids—use isotonic solutions (Na 140 mmol/L) if supplementing beyond TPN to avoid hyponatremia 1
• Never provide amino acids without adequate non-protein calories—minimum 30-40 kcal per 1g amino acids is required for utilization 1
• Never continue high glucose rates during acute sepsis/instability—reduce to day 1 rates temporarily 1

Nuance Regarding "Unstable" Status

The term "very unstable" is crucial here. If this infant requires:

• Mechanical ventilation with high settings
• Vasopressor support
• Active sepsis/infection

Then maintain the conservative day 1 glucose approach (4-8 mg/kg/min) until stabilization occurs, as the acute phase of critical illness benefits from lower carbohydrate delivery 1. However, do not reduce amino acids below 1.5 g/kg/day even during instability, as this strong recommendation applies to all preterm infants 1, 2.