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Parenteral nutrition for sick and preterm infants – meeting nutritional needs in the NICU

Interview with Professor Nadja Haiden, Medical University of Vienna, Austria

Photo: © Prof. Nadja Haiden, Medical University of Vienna.

Babies with a healthy digestive tract usually get their nutrition by drinking breastmilk and digesting. This provides the body with the nutrients necessary for growth and development. However, babies who are born very preterm or have certain illnesses often cannot be fed by mouth or by a feeding tube. In this case, they require so-called parenteral nutrition, which means that nutrients are provided directly into a blood vessel. We spoke with Professor Nadja Haiden from the Medical University of Vienna about the process of parenteral feeding, its benefits and possible challenges. 

Question: Professor Haiden, for many people it is hard to imagine receiving nutrients directly into the bloodstream. How do such parenteral mixtures of nutrients for the preterm born babies look like and what kind of nutrients do they contain?

Professor Haiden: Parenteral nutrition is provided as clear or opaque solutions filled in syringes or bags. In some units ready- to- use multi-chamber bags are used.  To protect nutrients from destruction via sunlight these bags, syringes and lines are often coloured (e.g. orange). The solutions contain all essential nutrients such as carbohydrates, amino acids, fat, salts and vitamins. The nutrients are mixed in optimal concentrations according to the infant’s needs and are compounded under sterile conditions.  

Q: How do you decide if a baby needs parenteral nutrition and when to stop? Are other people involved in the decision?

Professor Haiden: There are various reasons why parenteral nutrition is applied. In premature babies, the most frequent cause is the immaturity of the gut. The gut isn’t ready to tolerate large quantities of food immediately after birth and has to get accustomed to it slowly. But there are other conditions when the digestive tract has to bypassed for a certain period of time such as malformations need to be fixed via surgery, heart defects or other causes of severe illness. Usually, parenteral nutrition is prescribed by a neonatologist during the daily round after discussion with the attending nurse of the infant. The nurse provides valuable information on the infant’s tolerance against enteral feedings and together they schedule the feeding plan for the next day. In addition, laboratory values help the physician to prescribe the optimal mixture of nutrients for the infant. In some units also dieticians and pharmacists are involved in the prescription process.

Q: Does receiving PN mean that the baby is not getting mother’s milk or formula, during that time?

Professor Haiden: No, the aim is to establish enteral nutrition as soon as possible after birth. Therefore, the infant receives so-called “minimal enteral feedings” in parallel to parenteral nutrition. Minimal enteral feedings are small amounts of mother’s own milk, donor milk or formula which are given every 2-3 hours. Mother’s own milk is the best and optimal nutrition for all babies even the most immature ones. Therefore, we strongly encourage the mother to provide breastmilk and we are happy with each millilitre the mother pumps. Initially, small meals of 0,5-1 ml should get the gut accustomed to enteral feedings and facilitate advancement of enteral nutrition. If these small amounts are well tolerated, the volume of the meals is increased every day and in parallel, the volume of the parenteral nutrition is reduced. The next goal is to achieve full enteral feedings as soon as possible and to end parenteral nutrition. Depending on the immaturity of the baby this period lasts 7 to 21 days.

Q: What difficulties can occur when applying parenteral nutrition to a preterm born baby?

Professor Haiden: Parenteral nutrition might be associated with certain side effects such as infection-related sepsis, thrombosis, parenteral nutrition-related liver disease and failure to thrive.

Q: How can these difficulties be avoided?

Professor Haiden: Hygienic measures such as strict hand hygiene or wearing surgical masks in case anyone is suffering from a cold are important to avoid infections and infection-related sepsis. Failure to thrive can be avoided by reassessment and optimizing the parenteral and enteral nutritional intake. In general, parenteral nutrition should be given as short as possible but as long as necessary- this approach avoids side effects and parenteral nutrition-associated problems.

Q: Is there anything, in particular, you would like the parents to know?

Professor Haiden: The parents are the most important persons for our little patients- it is essential for us to include them in all processes and to provide accurate and reliable information for them. If parents have any questions concerning the local process of parenteral and enteral nutrition please do not hesitate to ask us, physicians or nurses.       

Special thanks to Assoc. Prof. Dr Nadja Haiden, MD. MSc. is head of the Neonatal Nutrition Research Team of the Medical University of Vienna.