nutrition in ICU part 2. (Total parenteral nutrition)

nutrition in icu

1. Nutrition in ICU - II By Dr Charul Jakhwal

2. Parenteral nutrition Definition: Pharmacological therapies where nutrients, vitamins, electrolytes and medications are delivered via venous route to those patients whose GIT is not functioning and are unable to tolerate enteral nutrition. ▪

3. Indications When patient gastrointestinal tract is paralysed and nonfunctional , as in the case of complete bowel obstruction, bowel ischemia, ileus, Circulatory shock with high-dose vasopressor requirements When >7 days of nothing-by-mouth (NPO) status is anticipated, as in the case of inflammatory bowel disease, patients with an acute exacerbation, critically ill patients and so on When the baby’s gut is too immature or has congenital malformations When the patient is suffering from chronic diarrhoea and vomiting or is extremely undernourished and needs to have surgery, chemotherapy and so on When patients with bowel anastomoses develop anastomotic leaks in the early postoperative period Nevertheless, the aim in all patients fed intravenously should be to revert to enteral feeding as this becomes possible. WHO?

4. Parenteral feeding solutions may be prepared from their component parts under sterile conditions. ▪ Readymade solutions also exist, but any necessary additions must be made in the same way. ▪ In ICU patients the daily requirements are infused continuously over 24 hours. Careful biochemical and clinical monitoring is important, particularly at the outset HOW?

5. Access Solutions for peripheral  parenteral nutrition  are hypertonic to blood, and their  osmolality  should not exceed 900  mOsm /L. osmolality > 900  mOsm /L, the incidence of  phlebitis inflammation, and pain Adding 5000 units of heparin to a peripheral parenteral nutrition solution may prolong the duration of the peripheral line. The major concern with central venous access for TPN is prevention of infection . Subclavian lines have lower infection rates than internal jugular or femoral lines. Tunnelling may reduce infection rates in internal jugular lines but apparently not in short-term subclavian lines. It is not recommended for routine use. a multi-lumen catheter is used, one lumen should be dedicated to administration of TPN and not used for any other purpose. Three-way taps should be avoided and infusion set changes carried out daily under sterile conditions Central venous catheter PICC Peripheral line

6. Peripherally inserted catheters are inserted through a peripheral, usually  antecubital, vein  and then advanced into a  central vein . They can be placed if the intended duration of parenteral nutrition is more than 2 weeks, and they can be used for up to 6 months in stable patients. Advantage: avoidance of the risks associated with the puncture of a central vein. D isadvantage: lead to a higher rate of phlebitis.

7. • Peripheral (partial or supplemental) parenteral nutrition: – Minimizes cost and complications of the central catheter – Can provide supplemental calories and protein not met by enteral route – Phlebitis, requires frequent site rotations and fluid overload

8. SUBSTRATE SOLUTIONS Dextrose Solutions Standard nutrition support regimens use carbohydrates to supply approximately 70% of the daily (nonprotein) caloric requirements. The carbohydrate source for total parenteral nutrition (TPN) is dextrose (glucose), which is available as solutions. Hyperosmolar must be infused through large central veins D50

9. Amino Acid Solutions Protein is provided as amino acid solutions that contain varying mixtures of essential (N=9), semi-essential (N=4), and nonessential (N=10) amino acids. These solutions are mixed with dextrose solutions in a 1:1 volume ratio. Standard Solutions: (e.g., Aminosyn ) balanced mixtures of 50% essential amino acids and 50% nonessential and semi-essential amino acids. Available concentrations range- 3.5%, 5%, 7%, 8.5%, 10%, but 7% solutions (70 g/L) are used most often. Glutamine, tyrosine and cysteine are absent from many because of instability

10. Specialty Solutions Metabolic stress (e.g., Aminosyn -HBC ) are enriched with branched chain amino acids (iso-leucine, leucine, and valine), which are preferred fuels in skeletal muscle when metabolic demands are high. Renal failure solutions (e.g., Aminosyn RF) are rich in essential amino acids, because the nitrogen in essential amino acids is partially recycled to produce nonessential amino acids, which results in smaller increments in blood urea nitrogen (BUN) when compared with breakdown of nonessential amino acids. Hepatic failure (e.g., HepaticAid ) are en-riched with branched chain amino acids, which block the transport of aromatic amino acids across the bloodbrain barrier (which is implicated in hepatic encephalopathy). .

11. Lipid Emulsions Lipids are provided as emulsions composed of submicron droplets of cholesterol, phospholipids, and triglycerides. The triglycerides are derived from vegetable oils (safflower or soybean oils) and are rich in linoleic acid, an essential fatty acid. 30% of daily caloric requirements, and 4% of the daily calories should be provided as linoleic acid to prevent essential fatty acid deficiency. Available in 10% and 20% strengths (the percentage refers to grams of triglyceride per 100 mL of solution). 10% emulsions 1 kcal/ mL. 20% emulsions 2 kcal/ mL. Isotonic to plasma and can be infused through peripheral veins. The lipid emulsions are available in unit volumes of 50 to 500 mL, and can be infused separately (at a maximum rate of 50 mL/hour) or added to the dextrose–amino acid mixtures.

12. ▪ Intralipid with PN is controversial because past studies have shown that long-chain fats can cause immune suppression. It can promote dysfunction of the reticuloendothelial system, enhance formation of prostanoids and leukotrienes, increase generation of ROS, and adversely affect the composition of cell membranes. ▪ Among trauma patients, the use of PN without lipids versus with lipids was associated with a significant reduction in pneumonia (48% versus 73%; P =0.05), catheter-related sepsis (19% versus 43%; P =0.04), length of ICU stay (18 versus 29 days; P =0.02), and length of hospital stay (27 versus 39 days; P =0.03). ▪ However, some fat—at least 5% of total calories—has to be provided as lipid emulsion to prevent essential fatty acid deficiency, although this issue is usually not important until after the first 10 days of hospitalization.

13. Vitamin and trace element preparations are added to TPN solutions in appropriate amounts. Thiamine, folic acid and vitamin K are particularly vulnerable to depletion and additional doses may be necessary. .

14. Parenteral Nutrition Delivery as separate solutions for carbohydrates, amino acids, and lipids; as a primary amino acid and glucose solution (two-in-one) with the lipid component as piggyback; as a three-in-one admixture (all-in-one infusion).

15. CREATING A TPN REGIMEN Step 1 The first step is to determine the daily requirement for calories and protein. The daily requirement for calories is 25 kcal/kg, and the daily protein requirement is 1.2–1.6 g/kg. For the 70 kg patient, we’ll use actual body weight, and a daily protein requirement of 1.4 g/kg. Therefore, the daily requirement for calories and protein will be:

16. Step 2 Take a standard mixture of 10% amino acids (500 mL) and 50% dextrose (500 mL) and determine the volume of this mixture that is needed to deliver the estimated daily protein requirement. Final A10-D50 mixture ====> 5% amino acids (50 grams of protein per liter ) and 25% dextrose (250 grams of dextrose per liter ) The volume of the that will provide the daily protein requirement Rate-

17. Step 3 Determine how much dextrose is in 1.9 liters of A10-D50:

18. Step 4 The next step is to use lipid calories to make up the difference between the calories supplied by dextrose and the daily requirement for calories. will be provided by lipids. If a 10% lipid emulsion (1 kcal/mL) is used, the volume will be 135 mL/day.

19. Step 5 The TPN orders for this example can be written as follows: 1. A10-D50 to run at 80 mL/hour. 2. 10% Intralipid, 150 mL, to infuse over 3 hours. 3. Add standard electrolytes, multivitamins, and trace elements. TPN orders are rewritten each day. Specific electrolytes, vitamins, and trace elements are added to the daily orders when needed

20. Calculation of daily requirement ▪ Sample calculation for 60 kg, stable, euvolemic patient with good urine output and moderate stress ▪ Fluid requirement : 35ml/kg = 2100 ml/day ▪ Calories : 25kcal/kg = 1500 kcal/day ▪ Proteins : 1g/kg = 60 g/day = 240 kcal/day (4kcal/g) ▪ Fats : 30% of total calories = 450 kcal/day = 50g fat (9kcal/g) ▪ Carbohydrates : 1500 – (240+450) = 810kcal = 202.5g of dextrose (4kcal/g)

21. Convert requirements into prescription Fluid volume reqd. = Amt. of substance(gm) X 100 Conc. Of substance(%) Determine volume of lipid emulsion : 10% lipid emulsion Volume of lipid emulsion = 50/10 x 100 = 500 ml Determine volume of amino acid infusion : 10 % solution Volume of amino acids = 60/10 X 100 = 600 ml

22. Selection of dextrose infusion : in remaining 1000 ml volume, 202.5g dextrose needs to be infused. 1000 = 202.5 X 100 Conc. of subst. ▪ Concentration of substance = 202.5/1000 X 100 = 20.25% = 20% approx. ▪ Prescription : Pt. needs 500ml of 10% lipid emulsion 600ml of 10% amino acid and 1000 ml of 20% dextrose

23. Termination of parenteral nutrition ▪ Goal : restart oral/enteral food intake as soon as GI function improves. ▪ Gradual transition from PN to oral/enteral nutrition. ▪ Reduce infusion rate to 50% for 1-2 hrs before stopping PN (minimizes risk of rebound hypoglycemia ). ▪ When 60% of total energy and protein requirements are taken orally/enterally, PN may be stopped. ▪ Oral or iv electrolytes supplementation may be needed.

24. COMPLICATIONS Mechanical complications: Related to vascular access technique: Misdirected Catheter Venous thrombosis Catheter occlusion Metabolic complications: Hyper-/hypoglycemia Hypercapnia Electrolyte abnormalities : Hypophosphatemia, Hypokalemia Acid–base disorders Hyperlipidemia , acute respiratory distress syndrome (ARDS) Steatosis Hepatobiliary Complications Hepatic Steatosis, Cholestasis Infectious complications Bowel Sepsis

25. PERIPHERAL PARENTERAL NUTRITION Peripheral parenteral nutrition (PPN) is a truncated form of TPN that can be used to provide nonprotein calories in amounts that will spare the breakdown of proteins to provide energy (i.e., protein-sparing nutrition support). Peripheral parenteral nutrition (PPN) is meant to act as a supplement and is used when the patient has another source of nutrition. Uses as a supplement to enteral feeding as a source of calories during brief periods of inadequate nutrition. Not intended for hypercatabolic or malnourished patients, who need full nutritional support The osmolarity of peripheral vein infusates should be kept below 900 mosm /L, with a pH between 7.2 and 7.4, to slow the rate of osmotic damage to vessels. This requires dilute amino acid and dextrose solutions, which limits nutrient intake. Lipids (isotonic) can be used to provide a considerable portion of the nonprotein calories in PPN. A mixture of 3% amino acids and 20% dextrose (final concentration of 1.5% amino acids and 10% dextrose), which has an osmolarity of 500 mosm /L.

26. SETPWISE APPROACH

27. Step 1: Initial resuscitation Nutrition should be started as soon as the patient is resuscitated. Step 2: Assess nutritional status (A) History 1. Weight change 2. Dietary intake change relative to normal 3. Gastrointestinal symptoms (persisting for more than 2 weeks) 4. Functional capacity 5. Disease and its relationship to nutritional requirements (B) Physical examination Loss of subcutaneous fat (triceps, chest) Muscle wasting (quadriceps, deltoids) Ankle edema/sacral edema/ascites (C) Subjective global assessment rating Well nourished Moderately malnourished Severely malnourished

28. Step 3: Calculate ideal (predicted) body weight Step 4: Estimate energy (calories) requirement Rule of the “thumb”: 25–30 kcal/kg IBW meets most patients’ needs. In undernourished patients, initial calorie should be 25% less than IBW to prevent refeeding, and in overweight patients, initial calorie should be 25% more than IBW to meet requirement. Step 5: Estimate protein (nitrogen) requirement Rule of the “thumb”: 1.5–2 g of protein/kg IBW meets most patients’ needs 6.25 g of protein is equal to 1 g of nitrogen. Step 6: Supplement micronutrients Step 7: Estimate fluid and electrolyte requirement Step 8: Select route of delivering nutrition Step 9: Select the type of enteral feed - Blenderized diets / Polymeric diets/ Predigested diets/ Disease-specific diets/ Immunonutrition Step 10: Look for tolerance to enteral feed Step 11: Select candidates for parenteral nutrition Step 12: Select the route of total parenteral nutrition (TPN) Step 13: Monitor patients on parenteral nutrition Step 14: Look for complications of TPN

29. Thank you