Principles of nutrition in the preterm infant. Importance of nutrition: Undernutrition is very common in VLBW infants

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1 Principles of nutrition in the preterm infant Dr. S. Navarro-Psihas Pädiatrie IV, Klinik für Neonatologie Medizinische Universität Innsbruck Importance of nutrition: Undernutrition is very common in VLBW infants 20 % of ELBW infants have a weight below the 10th percentile ELBW infants reach the birth weight only after 2-3 weeks At 36 weeks almost all are undernourished 1

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3 Typical feeding schedule in preterm infants Start with glucose 10% without aminoacids or fat Initiate with aminoacids on day 3 and with fat on day 3-4 Initiate oral feedings when the baby is stable Acute interruption of the nutritional supplementation Interruption of the administration of key aminoacids (arginine, leucine) ) after clamping the placenta metabolic shock Starvation reaction: endogenous glucose, insulin Hyperglycaemia and undernutrition Consequences of malnutrition: The most critical development period of brain growth occurs during the last trimester and the first 2 years Animal studies: Alteration of structure and function of brain Loss of brain cells 3

4 Short-term consequences: Lucas A: Lancet 1990 Prospective study comparing motor and mental function at 18 months in 377 preterm infants fed with preterm formula or normal formula: Results: Better motor and mental function evaluations with preterm formula Changes were more evident in SGA infants and in males Breast milk improved the scores even more Long-term consequences: Lucas A: BMJ 1998 Analysis at 8 years showed: Correlation of breast milk and IQ More pronounced in males Correlation between preterm formula and less cerebral palsy and better verbal IQ Consequences in adult life: SGA patients have an increased risk to develop: Type II diabetes mellitus Hyperlipidemia Hypertension Ischemic heart disease Catching up growth could be an independent factor for these disorders SGA infants remain small It is common to administer lots of calories to get more growth Catch up growth may reflect deposition of fat instead of real growth 4

5 Physiologic basis Physiologic differences: Glycogen storage is very low Fast predisposition to hypoglycaemia Fat transport through the placenta takes place only in the 3th trimester No fat reserves Aminoacids are transported actively by the placenta 50% of the aminoacids are used as source of energy The goal of nutrition: In the first two weeks of life weight reflects the hydration state More realistic goal would be the body composition of the fetus Protein would be the best parameter 5

6 Metabolism of proteins: Protein accretion in fetus weeks is about 2 g/kg/day In the absence of aminoacid administration, protein loss relates inversely to GA At 26 weeks GA about 1.5% of the total protein reserves are lost every day (1.3 g/kg/day) Only 70% is utilized! Are only a few days of TPN really dangerous? Example: Preterm 26 weeks GA G with a weight of 1000g, fed with glucose only Protein reserves are 88g Protein loss: 1.3 g/kg/day Initially Preterm Fetus Reserves: 80g 80g After 3 days Reserves: 76g 86g Deficit: (5%) from initially (10%) of the fetus 6

7 Background for recommendations: g/kg/die are necessary to stop catabolism About 50 Kcal/kg/die are enough for stopping the protein losses Accretion increases with protein intake up to 4 g/kg/day The effect of the intake of calories on protein accretion is curvilinear! Protein accretion Protein accretion and caloric intake 80 Caloric intake Practical recommendations: Initiate with (1)-2 g/kg/day protein on day one Initiate with at least 30 Cal/kg/day and increase to 50 in 1-2 days Increase protein to a maximum of 4 g/kg/day Keep the caloric intake at Kcal/kg/day 7

8 Can aggressive parenteral nutrition be dangerous? Toxicity: Most studies were performed in the 70 s s with casein hydrolisates Urea levels: Relate with the hydration Protein brake down No short-term detrimental effects Metabolic acidosis Ammonia levels Scarce long-term studies Better growth Better outcome Recommendations for glucose: Initiate with 6 mg/kg/min Increase daily 1-2 mg/kg/min to a maximum of Amino acids stimulate the insulin production and secretion! 8

9 Recommendation for fat: Linoleic and linolenic fat acids are essential for the brain development! Initiate with g/kg/day on day one Increase 0.5 g/kg every day to a maximum of g/kg/day Monitor triglyceride levels (<150) 0.5 g/kg/day is enough to avoid the deficiency of essential fatty acids Exemple: Preterm infant 1000g First day: 70 ml/kg glucose 10% = 28 Kcal/kg 1g fat/kg = 9 Kcal/kg 1g protein/kg 37Kcal/g Second day: 90 ml/kg glucose 10% = 36 Kcal/kg 1.5g fat/kg = 14 Kcal 1.5g protein/kg 50 Kcal Minimal enteral feeding (MEN) 9

10 Victoria Smallpeice 1964 Early feeding of preterm infants g with breast milk Controled study with 111 patients Advancing the feedings: 30 ml/kg/day Results: More weight gain Meconium passage earlier Lower bilirubin levels The background The amniotic fluid has growth factors that stimulate the intestinal cells The volume swallowed by a term fetus is the same as in a term baby breast fed! The amniotic fluid provides about 25% of the protein intake of a term baby Minimal enteral feeding: Administration of 5-25 ml/kg/day 1 ml/kg/day is enough to stimulate the intestine Increase in the intestinal mass and enhances DNA synthesis (trophic factors) Release of hormones and intestinal peptides Trophic properties Digestive and motile functions 10

11 Minimal enteral nutrition (MEN): Advantages: Less time to full feedings Less phototherapy and less cholestasis Less feeding intolerance More weight gain Less incidence of NEC in some studies Less days in the hospital Wilson DC. Arch Dis Chil 1997 Prospective study in 125 VLBW infants with two feeding protocols: Aggressive Conservative 11

12 Practical recommendations: Initiate on the first day of life (10-20 ml/kg/day) Advance ml/kg/day Do not dilute formula! Do not advance in unstable patients Contraindication: Intestinal ischemia 12