Nitrogen Balance in Infants After Post Cardiothoracic Surgery

Postoperative neonates are susceptible to the adverse effects of surgery that is characterized by a breakdown of body stores. Without appropriate nutritional consideration this process can lead to increased physiological instability. It has been extensively documented that critically ill patients are typically catabolic. This results in body nitrogen losses from the breakdown of somatic protein to fuel metabolic processes such as, gluconeogenesis. The evaluation of this catabolic response is particularly crucial in infants due to their limited fat and lean body mass reserves. Quantifying the amount of protein needed to maintain body composition and to meet the demands of surgical stress is of clinical importance when considering factors associated with postoperative morbidity, such as delayed wound healing, impaired growth and prolonged hospital stay.

The results obtained from this study will assist with determining an appropriate level of protein for the development of optimal nutrition prescriptions that are aimed at reducing catabolism of body stores.

Inclusion criteria

• Clinical decision to initiate parenteral nutrition based on determination by medical team
• Gestational age ≥ 35 weeks
• Birth weight ≥ 2000 grams
• Indwelling urinary catheters for urine collection
• Central venous access for parenteral nutrition

Exclusion criteria

• Chromosomal abnormalities known to effect protein metabolism
• Hepatic failure defined as ALT and AST > 500 UL with an INR > 2.5, not accounted for by therapeutic anticoagulation
• Renal failure defined as creatinine 2x the upper limit of normal for age.
• Sepsis or suspected sepsis, defined as clinical suspicion or confirmation of a systemic infection treated with antibiotics
• Excessive blood loss from chest tubes (5 ml/kg/hr) that has not resolved within six hours following admission to the CCCU; as indicated by the need for frequent blood transfusion these subjects will be withdrawn from the study
• Requiring Extra Corporeal Membrane Oxygenation (ECMO) support