Total Parenteral Nutrition

Role of Total Parenteral Nutrition in Hospitalized Patients

Enteral feeding is the preferred means of nutritional support. Without any specific surgical contraindication, all patients should  receive enteral feeding  as soon as possible, preferably within 24 hours of admission. Enteral feeding provides nutrition and helps to maintain gastrointestinal tract integrity and function. However, not all patients can receive enteral nutritional support due to some contraindications. This requires the assistance of some extraneous source of energy and nutrients to support the body during times of stress.

Total parenteral nutrition (TPN) support is an important component  of supportive therapy in hospitalized patients, particularly ICU patients. It is generally not necessary if the patient is likely to be able to recommence enteral feeding within a few days, unless the patient is already severely wasted or malnourished.

Typical Composition of  Standard Total Parenteral Nutrition

Volume – 2.5 Litres

Nitrogen Source (9-14 g nitrogen) – L-amino acid solution

Energy Source (1500-2000 kcal) – Glucose and Lipid emulsion

Additives – Electrolytes, Trace Elements, Vitamins

Other Additives – Insulin and H2 blockers may be added if required

Practical Aspects of Parenteral Nutrition

TPN should be customized to a person’s requirements. Advice should be sought from dietitians or a parenteral nutrition team for specialized scenarios but a standard feed will suffice for most. Standard adult feeds are typically 2.5 litres a day, but smaller  volume feeds are available for fluid-restricted patients.

Parenteral feeds are hypertonic and cause thrombophlebitis. Hence, they are preferentially given via central venous lines. However, high volume lower-osmolality feeds are now developed that can be given via peripherally inserted feeding lines called “Peripheral TPN”. It is a good practice to keep one lumen clean and dedicated for TPN.

Parenteral nutrition mixtures make good culture mediums for bacteria, so make sure not to break the line to give anything else. TPN is given by constant infusion over 24 hours and delivered by volumetric infusion pumps.

Monitoring Total Parenteral Nutrition

Advice should be sought from the nutrition team and dietitian. The following should be assessed on a daily basis to provide a well-tailored TPN to the patient.

  • Fluid balance
  • Urea, Electrolytes, Phosphate
  • Glucose: An insulin infusion might need to be instituted to maintain blood sugar levels to an acceptable level. Close control of blood sugar levels have recently been shown to improve the outcome of critically ill patients.
  • Adequate energy requirements: Clinical acumen is required to assess adequate energy requirements by degree of catabolism.
  • Liver function (albumin, transferrin and enzymes) indicate adequate protein synthesis and give an early indication of TPN-related complications.

Complications of Total Parenteral Nutrition

  • All complications of central venous access are an accompaniment of TPN.
  • Metabolic derangement, particularly hyper- or hypoglycaemia, hypophosphataemia and hypercalcaemia, are quite common and require adequate adjustment of the feed.
  • Hepatobiliary dysfunction, including elevation of liver enzymes, jaundice and fatty infiltration of the liver may occur. This is usually a consequence of the patient’s underlying disease processes and overfeeding. Reduce the volume of TPN and/or energy content in the feed to correct the same. If the serum becomes very lipaemic it may be necessary to reduce the fat content.

• Meet the Author • Dr. Lawrence Kindo

I am a Medical Professional with a passion for writing, blogging, playing, computers, and of course patient care. My writing in this medical blog will reflect my passion, and you are welcome to be a part of this venture. This medical blog is a tribute to all the great medical pioneers, and to the ultimate source of wisdom, God.

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