TPN solutions vary depending on other disorders present and patient age, as for the following: For renal insufficiency not being treated with dialysis or for liver failure: Reduced protein content and a high percentage of essential amino acids For heart or kidney failure: Limited volume (liquid) intake For respiratory failure: A lipid emulsion that provides most of nonprotein calories to minimize carbon dioxide production by carbohydrate metabolism For neonates: Lower dextrose concentrations (17 to 18%) Beginning TPN administration Because the central venous catheter needs to remain in place for a long time, strict sterile technique must be used during insertion and maintenance of the TPN line.