1. Parenteral Nutrition

2. NUTRITION
Human nutrition is the provision to obtain the essential nutrients necessary to support life and health
Nutrients are the substances that are not synthesized in sufficient quantity in the body and therefore must be supplied from diet
Macronutrients mainly carbohydrates, fats, protein, dietary fiber and water
Micronutrients: vitamins, minerals and trace elements

3. Essential Nutrients Protein (Amino acids) Fat Carbohydrate
Dietary fiber
Water and electrolytes
Vitamins
minerals
Trace elements

4. ENTERAL NUTRITION
Refers to feeding via a tube placed into the gut to deliver liquid formulas containing all essential nutrients
Preferred route because of benefits derived from maintaining the digestive, absorptive and immunological barrier function of GIT
Enteral/tube feeding is useful in pts who have functional GIT, but who cannot digest or ingest adequate amount of nutrients
Short term (<6 weeks) tube feeding can be achieved by nasogastric, nasoduodenal or nasojejunal tubes

5. ENTERAL Vs PARENTERAL
Enteral nutrition is associated with fewer complications than parenteral nutrition and is less expensive to administer.
However, the use of enteral nutrition alone often does not achieve caloric targets.
In addition, underfeeding is associated with weakness, infection, increased duration of mechanical ventilation, increased duration of hospital stay and death.
Combining parenteral nutrition with enteral nutrition constitutes a strategy to prevent nutritional deficit but may risk overfeeding which has been associated with liver dysfunction, infection, and prolonged ventilatory support.

6. PARENTERAL NUTRITION
The consequences of major surgeries and PEM can lead to hypermetabolism and subsequent malnutrition. A strong association exist between malnutrition and increased post operative morbidity and mortality.
The administration of TPN can prevent the effects of starvation in pts with non functional GIT
Parenteral nutrition should be considered if energy intake has been inadequate for more than days and enteral feeding is not feasible. (based on ICU focused meta- analysis discussed in 2009 ASPEN)

7. Parenteral nutrition
It involves the continuous infusion of a hyperosmolar solution containing carbohydrates, proteins, fat and other necessary electrolytes through an indwelling catheter inserted into (usually) SVC to meet the nutritional needs of the patient.
PN through a peripheral vein is limited by osmolality and volume constraints
Solutions that contain more than 3% aminoacid and 5% glucose are poorly tolerated peripherally

8. Types Peripheral parenteral nutrition (PPN)
administered through a peripheral intravenous catheter.
The osmolarity of PPN solutions generally is limited to 1,000 mOsm (approximately 12% dextrose solution) to avoid phlebitis.
Thus, large volumes (>2,500 mL) are needed.
Temporary nutritional supplementation with PPN may be useful
Generally intended as supplement to oral feeding and is not optimal for critically ill pts

9. Total parenteral nutrition (TPN)
provides complete nutritional support
The solution, volume of administration, and additives are individualized based on an assessment of the nutritional requirements.

10. Types of TPN formulations
TPN formulation without lipid (2-in-1 solution)
Calories from amino acids- 20 to 25%
Calories from dextrose %
TPN formulation with lipid ( 3-in-1 solution)
calories from amino acids- 20 to 25%
calories from lipids- 20%
calories from dextrose- 55 to 60 %

11. Special solutions that contain low, intermediate, or high nitrogen concentrations as well as varying amounts of fat and carbohydrate are available for pts with diabetes, renal or pulmonary failure, or hepatic dysfunction.

12. Additives:
Electrolytes (i.e., sodium, potassium, chloride, acetate, calcium, magnesium, phosphate) should be adjusted daily.
The number of cations and anions must balance; this is achieved by altering the concentrations of chloride and acetate.
If the serum bicarbonate is low, the solution should contain more acetate.
The calcium:phosphate ratio must be monitored to prevent salt precipitation.

13. Medications:
Albumin, H2-receptor antagonists, heparin, iron, dextran, insulin, and metoclopramide can be administered in TPN solutions. However, not all medications are compatible with 3-in-1 admixtures.
Regular insulin should initially be administered subcutaneously according to a sliding scale, based on a determination of the blood glucose level. After a stable insulin requirement has been established, insulin can be administered in the TPN solution, generally at two thirds of the daily subcutaneous insulin dose.

14. TPN- macronutrient solutions
Crystalline amino acid solutions containing % essential and 50-60% non essential amino acids are used to provide protein needs
Some amino acid solutions have been modified: rich in branched chain amino acids for hepatic encephalopathy, rich in essential amino acid for renal insufficiency pts
Glucose in IV solutions is hydrated; each gm of dextrose monohydrate provides 3.4 kcal. While there is no absolute requirement of glucose in most pts, providing >150g glucose/d maximizes protein balance

15. TPN- macronutrient solutions
Lipid emulsions are available as 10% (1.1kcal/ml) or 20% (2 kcal/ml) solutions and provide energy as well as source of essential fatty acids.
Rate of infusion should not exceed 1 kcal/kg/h

16. Some commercial available formulations
Climomel N5-800
Clinimix N9G-20E
Kabiven
Vitrimix
Celemix-G

17. Indications gastrointestinal cutaneous fistula Renal failure (ATN)
Short bowel syndrome
Severe burns
Hepatic failure
Crohn’s disease
Anorexia nervosa
Acute radiation enteritis
Acute chemotherapy toxicity
Prolonged ileus
Weight loss preliminary to major surgery

18. ADMINISTRATION OF TPN
Introduction of TPN should be gradual. For example, approximately 1,000 kcal is provided the first day. If there is metabolic stability (i.e., normoglycemia), this is increased to the caloric goal over 1 to 2 days.
TPN solutions are delivered most commonly as a continuous infusion. A new 3-in-1 admixture bag of TPN is administered daily at a constant infusion rate over 24 hours. Additional maintenance intravenous fluids are unnecessary, and total infused volume should be kept constant while nutritional content is increased.

19. Cyclic Administration
Cyclic administration of TPN solutions may be useful for
(1) those who will be discharged from the hospital and subsequently receive home TPN,
(2) those with limited intravenous access who require administration of other medications, and
(3) those who are metabolically stable and desire a period during the day when they can be free of an infusion pump.
Cyclic TPN is administered for 8 to 16 hours, most commonly at night. This should not be done until metabolic stability has been demonstrated for patients on standard, continuous TPN infusions.

21. ROUTES OF TPN: Central TPN: (usual osmolarity = 2000 mosmol/L)
Advantages
Can provide full nutritional support
(No limits in concentration of dextrose and amino acids)
No risk of thrombophlebitis
No risk of edema
No pain
Disadvantages
Requires surgery
More risk of sepsis than peripheral TPN
High risk of mechanical complications

22. Peripheral TPN: (maximum osmolarity in neonates = 1100/L,
Pediatrics = 1000/L, Adults = 900/L)
Advantages
Does not require surgery
Less risk of sepsis than central TPN
No risk of mechanical complications
Disadvantages
High risk of thrombophlebitis
Painful, and chance of edema
Does not require full nutrition support. Needs more fluids to provide more nutrition. (maximum dextrose = 7.5% and AA = 2.5%)

23. Monitoring of parenteral nutrition

26. Complications Of TPN
Mechanical
metabolic
infectious

27. Mechanical Complications
Air embolism
pneumothorax
hemothorax
Cardiac tamponade
Injuries to arteries and veins
Injury to thoracic duct
Brachial plexus injury

28. Metabolic complications
Early or nutrient related
hyperglycemia
hypoglycemia
hyperlipidemia
refeeding syndrome
late or related to long term administration
hepatic dysfunction
Steatosis, steatohepatitis, lipidosis, cholestasis, cirrhosis
biliary complications: acalculous cholecystitis, Gb sludge, cholelithiasis
Metabolic bone disease: osteomalaacia, osteopenia

29. Fluid overload
Hypo/hypernatremia
Hypercalcemia
Hypo/hyperkalemia
Infection :
Catheter related sepsis is most common life threatening complication
Causes: staph epidermidis and staph aureus, enterococcus, candida, E coli, psuedomonas, klebsiella etc in immunocompromised pts

30. Refeeding syndrome
Severe electrolyte and fluid shifts that may result from refeeding after severe weight loss (PEM)
Hypophosphatemia is the hallmark of refeeding syndrome due to shift from fat to glucose metabolism.
Hypokalemia and hypomagnesemia
↓K and ↓PO4→ ATP deficiency which can be life threatening.

31. Care of the parenteral nutrition (PN) mixture
Store reconstituted PN bags in a refrigerator until use
Always use aseptic techniques while connecting and infusing PN
Always use an infusion set with in-built air vent and 0.2 m filter
Never insert a needle for air venting in a PN bag
Never add any medication to the PN bag
Avoid frequent changes in the formulation of the PN solution
Infuse the prescribed volume and avoid wastage of PN solution