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Parenteral Nutrition Formula Calculations and Monitoring Protocols

Parenteral Nutrition Formula Calculations and Monitoring Protocols. Macronutrient Concentrations in PN Solutions. Macronutrient concentrations (%) = the grams of solute/100 ml of fluid D70 has 70 grams of dextrose per 100 ml. 10% amino acid solution has 10 grams amino acids/100 ml of solution

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Parenteral Nutrition Formula Calculations and Monitoring Protocols

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  1. Parenteral Nutrition Formula Calculations and Monitoring Protocols

  2. Macronutrient Concentrations in PN Solutions • Macronutrient concentrations (%) = the grams of solute/100 ml of fluid • D70 has 70 grams of dextrose per 100 ml. • 10% amino acid solution has 10 grams amino acids/100 ml of solution • 20% lipids has 20 grams of lipid/100 ml of solution

  3. To calculate the grams of protein supplied by a TPN solution, multiply the total volume of amino acid solution (in ml*) supplied in a day by the amino acid concentration. Example Protein Calculation 1000 ml of 8% amino acids: 1000 ml x 8 g/100 ml = 80g Or 1000 x .08 = 80 g Protein Content Calculations

  4. Calculation of Dextrose Calories • Calculate grams of dextrose: • Multiply the total volume of dextrose soln (in ml) supplied in a day by the dextrose concentration. This gives you grams of dextrose supplied in a day. • Multiply the grams of dextrose by 3.4 (there are 3.4 kcal/g dextrose) to determine kcalories supplied by dextrose in a day.

  5. Sample Dextrose Calculation • 1000 ml of D50W (50% dextrose) • 1000 ml x 50g / 100 ml = 500g dextrose • OR 1000 ml x .50 = 500g dextrose • 500g dextrose x 3.4 kcal/g = 1700 kcal

  6. Calculation of Lipid Content • To determine kcalories supplied by lipid*, multiply the volume of 10% lipid (in ml) by 1.1; multiply the volume of 20% lipid (in ml) by 2.0. • If lipids are not given daily, divide total kcalories supplied by fat in one week by 7 to get an estimate of the average fat kcalories per day. *|Lipid emulsions contain glycerol, so lipid emulsion does not have 9 kcal per gram as it would if it were pure fat. Some use 10 kcal/gm for lipid emulsions. Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  7. Example Lipid Calculation for 2-in-1 • 500 ml of 10% lipid • 500 ml x 1.1 kcal/ml = 550 kcal • 500 ml 20% lipid • 500 ml x 2.0 kcal/ml = 1000 kcal • Or, alternatively, 500 ml of 10% lipid = 50 grams lipid x 10 kcal/g or 500 kcal Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  8. Calculation of Dextrose/AA with Piggyback Lipids (2-in-1) • Determine patient's kcalorie, protein, and fluid needs. • Determine lipid volume and rate for "piggy back" administration. • Determine kcals to be supplied from lipid. (Usually 30% of total kcals). • Divide lipid kcals by 1.1 kcal/cc if you are using 10% lipids; divide lipid kcals by 2 kcal/cc if you are using 20% lipids. This is the total volume. • Divide total volume of lipid by 24 hr to determine rate in cc/hr. Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  9. Determine protein concentration • Subtract volume of lipid from total fluid requirement to determine remaining fluid needs. • Divide protein requirement (in grams) by remaining fluid requirement and multiply by 100. This gives you the amino acid concentration in %. • Multiply protein requirement in grams x 4 to determine calories from protein Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  10. Determine dextrose concentration. • Subtract kcals of lipid + calories from protein from total kcals to determine remaining kcal needs. • Divide "remaining kcals" by 3.4 kcal/g to determine grams of dextrose. • Divide dextrose grams by remaining fluid needs (in protein calculations) and multiply by 100 to determine dextrose concentration. • Determine rate of AA/dex solution by dividing "remaining fluid needs” by 24 hr. Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  11. Example Calculation Nutrient Needs: Kcals: 1800. Protein: 88 g. Fluid: 2000 cc   1800 kcal x 30% = 540 kcal from lipid Lipid (10%): • 540 kcal/1.1 (kcal/cc) = 491 cc/24 hr = 20 cc/hr 10% lipid (round to 480 ml) • Remaining fluid needs: 2000cc - 480cc = 1520cc

  12. Protein Calculations Protein: 88 g / 1520 cc x 100 =5.8% amino acid solution 88 g. x 4 kcal/gm =352 kcals from protein • Remaining kcal needs: 1800 – (528 + 352) = 920 kcal

  13. Dextrose Concentration • 920 kcal/3.4 kcal/g = 270 g dextrose • 270 g / 1520 cc x 100 = 17.7% dextrose solution • Rate of Amino Acid / Dextrose: 1520 cc / 24hr = 63 cc/hr TPN recommendation: Suggest two-in-one PN 17.7% dextrose, 5.8% a.a. @ 63 cc/hr with 10% lipids piggyback @ 20 cc/hr

  14. Re-check calculations TPN recommendation: Suggest two-in-one PN 17.7% dextrose, 5.8% a.a. @ 63 cc/hr with 10% lipids piggyback @ 20 cc/hr 63 cc/hr x 24 = 1512 ml 1512 * (.177) = 268 g D X 3.4 kcals= 911 kcals 1512 * (.058) = 88 g a.a. x 4 kcals = 352 20 cc/hr lipids*24 = 480*1.1 kcals/cc = 528 1791

  15. 3 in 1 TNA Solutions | • Determine patient's kcalorie, protein, and fluid needs. • Divide daily fluid need by 24 to determine rate of administration. • Determine lipid concentration. • Determine kcals to be supplied from lipid. (Usually 30% of total kcals). • Determine grams of lipid by dividing kcal lipid by 10. * • Divide lipid grams by total daily volume (= fluid needs or final rate x 24) and multiply by 100 to determine % lipid.

  16. 3-in-1 TNA Solutions • Determine protein concentration by dividing protein needs (grams) by total daily volume and multiply by 100. • Multiply protein needs in grams x 4 kcal/gm = kcals from protein • Determine dextrose grams. • Subtract kcals of lipid andkcals from protein from total kcals to determine remaining kcal needs. • Divide "remaining kcals" by 3.4 kcal/g to determine grams of dextrose. • Determine dextrose concentration by dividing dextrose grams by total daily volume and multiply by 100

  17. Sample Calculation 3-in-1 • Nutrient Needs: • Kcals: 1800 Protein: 88 g Fluid: 2000 cc • Lipid : 1800 kcal x 30% = 540 kcal • 540 kcal / 10 kcal per gram = 54 g • 54 g / 2000 cc x 100 = 2.7% lipid • Protein: 88 g / 2000 cc x 100 =4.4% amino acids • 88 g x 4 = 352 kcals from protein

  18. Sample Calculation 3-in-1(cont) Dextrose: 908 kcal (1800 – 540 - 352) • 908/3.4 kcal/g = 267 g dextrose • 267 g / 2000 cc x 100 =13.4% dextrose solution • Rate of Amino Acid / Dextrose/Lipid: 2000 cc / 24hr = 83 cc/hr • TPN prescription: Suggest TNA 13.4% dextrose, 4.4% amino acids, 2.7% lipids at 83 cc/hour provides 88 g. protein, 1800 kcals, 2000 ml. fluid

  19. Evaluation of a TNA Order • PN 15% dextrose, 4.5% a.a., 3% lipid @ 100 cc/hour

  20. Evaluation of a PN Order PN 15% dextrose, 4.5% a.a., 3% lipid @ 100 cc/hour • Total volume = 2400 • Dextrose: 15g/100 ml * 2400 ml = 360 g • 360 g x 3.4 kcal/gram = 1224 kcals • Lipids 3 g/100 ml x 2400 ml = 72 g lipids • 72 x 10 kcals/gram = 720 kcals

  21. Evaluation of a PN Order • Amino acids: 4.5 grams/100 ml * 2400 ml = 108 grams protein • 108 x 4 = 432 kcals • 1224 + 720 + 432 = 2376 total kcals • Lipid is 30% of total calories • Dextrose is 51.5% of total calories • Protein is 18% of total calories

  22. Calculation of Nonprotein Calories • Some clinicians discriminate between protein and nonprotein calories although this is falling out of favor • This is more commonly used in critically ill patients

  23. Calculation of Non-Protein Calories • To determine the nonprotein kcalories (NPC) in a TPN prescription, add the dextrose calories to the lipid calories • In the last example, 1224 kcals (dextrose) + 720 kcals (lipid) = 1944 non-protein kcals • Dextrose is 63% of nonprotein kcals (1224/1944) • Lipid is 37% of nonprotein calories • In critically ill patients, some clinicians restrict lipid to 30% of nonprotein kcals

  24. Calculation of NPC:N Ratio | • Calculate grams of nitrogen supplied per day (1 g N = 6.25g protein) • Divide total nonprotein calories by grams of nitrogen • Desirable NPC:N Ratios: • 80:1 the most severely stressed patients • 100:1 severely stressed patients • 150:1 unstressed patient Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  25. Example NPC:N Calculation 80 grams protein2250 nonprotein kcalories per day 80g protein/ 6.25 = 12.82250/12.8 = 176NPC:N = 176:1 Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  26. Example %NPC Fat Calculation* 2250 nonprotein kcal550 lipid kcal 550/2250 x 100 = 24% fat kcals *Limit is 60% NPC

  27. Osmolarity in PPN • When a hypertonic solution is introduced into a small vein with a low blood flow, fluid from the surrounding tissue moves into the vein due to osmosis. The area can become inflamed, and thrombosis can occur.

  28. IV-Related Phlebitis

  29. Calculating the Osmolarity of a Parenteral Nutrition Solution • Multiply the grams of dextrose per liter by 5. Example: 100 g of dextrose x 5 = 500 mOsm/L • Multiply the grams of protein per liter by 10. Example: 30 g of protein x 10 = 300 mOsm/L • Multiply the grams of lipid per liter by 1.5. Example: 40 g lipid x 1.5 = 60. • Multiply the (mEq per L sodium + potassium + calcium + magnesium) X 2 Example: 80 X 2 = 160 • Total osmolarity = 500 + 300 + 60 + 160 = 1020 mOsm/L Source: K&M and PN Nutrition in ADA, Nutrition in Clinical Practice. P 626

  30. Osmolarity Quick Calculation To calculate solution osmolarity: • multiply grams of dextrose per liter by 5 • multiply grams of protein per liter by 10 • add a & b • add 300 to 400 to the answer from "c". (Vitamins and minerals contribute about 300 to 400 mOsm/L.) Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html

  31. Is the solution compoundable? • TPN is compounded using 10% or 15% amino acids, 70% dextrose, and 20% lipids • The TPN prescription must be compoundable using standard base solutions • This becomes an issue if the patient is on a fluid restriction

  32. Is the Solution Compoundable? What is the minimum volume to compound the PN prescription? Example: 75 g AA 350 g dextrose 50 g lipid 2000 ml fluid restriction AA: 10 g = 75 g = 750 ml using 10% AA 100 mlX ml OR divide 75 grams by the % base solution, 75 g/ .10

  33. Is the solution compoundable? Dextrose: 70 g = 350 g x = 500 ml 100 ml X ml Lipid: 20 g = 50g X = 250 ml 100 ml x ml Total volume = 750 ml AA + 500 ml D + 250 ml lipid + 100 ml (for electrolytes/trace) = 1600 ml (minimum volume to compound solution) Tip: Substrates should easily fit in 1 kcal/ml solutions

  34. Is this solution compoundable? PN prescription: AA 125 g D 350 g Lipid 50 g Fluid restriction 1800 ml/day

  35. Is this solution compoundable? AA: 10 g = 125 g = 1250 ml 10% AA 100 mlX ml Dextrose: 70 g = 350 g x = 500 ml (350/.70) 100 ml X ml Lipid: 20 g = 50g X = 250 ml (50/.20) 100 ml x ml Total volume = 1250 ml AA + 500 ml D + 250 ml lipid + 100 ml (for electrolytes/trace) = 2100 ml (minimum volume to compound solution) Verdict: not compoundable in 1800 ml. Action: reduce dextrose content or use 15% AA base solution if available (could deliver protein in 833 ml of 15%)

  36. Parenteral Nutrition Monitoring

  37. Monitoring for Complications • Malnourished patients at risk for refeeding syndrome should have serum phosphorus, magnesium, potassium, and glucose levels monitored closely at initiation of SNS. (B) • In patients with diabetes or risk factors for glucose intolerance, SNS should be initiated with a low dextrose infusion rate and blood and urine glucose monitored closely. (C) • Blood glucose should be monitored frequently upon initiation of SNS, upon any change in insulin dose, and until measurements are stable. (B) ASPEN BOD. Guidelines for the use of enteral and parenteral nutrition in adult and pediatric patients. JPEN 26;41SA, 2002

  38. Monitoring for Complications • Serum electrolytes (sodium, potassium, chloride, and bicarbonate) should be monitored frequently upon initiation of SNS until measurements are stable. (B) • Patients receiving intravenous fat emulsions should have serum triglyceride levels monitored until stable and when changes are made in the amount of fat administered. (C) • Liver function tests should be monitored periodically in patients receiving PN. (A) ASPEN BOD. Guidelines for the use of enteral and parenteral nutrition in adult and pediatric patients. JPEN 26;41SA, 2002

  39. Acute Inpatient PN Monitoring Adapted from K&M, p. 549

  40. Inpatient Monitoring PN

  41. Monitor—cont’d • Urine:Glucose and ketones (4-6/day)Specific gravity or osmolarity (2-4/day)Urinary urea nitrogen (weekly) • Other:Volume infusate (daily)Oral intake (daily) if applicableUrinary output (daily)Activity, temperature, respiration (daily)WBC and differential (as needed)Cultures (as needed)

  42. Monitoring: Nutrition Serum Hepatic Proteins Parameter t ½ Albumin 19 days Transferrin 9 days Prealbumin 2 – 3 days Retinol Binding Protein ~12 hours

  43. Complications of PN • Refeeding syndrome • Hyperglycemia • Acid-base disorders • Hypertriglyceridemia • Hepatobiliary complications (fatty liver, cholestasis) • Metabolic bone disease • Vascular access sepsis

  44. Refeeding Syndrome • Patients at risk are malnourished, particularly marasmic patients • Can occur with enteral or parenteral nutrition • Results from intracellular electrolyte shift

  45. Refeeding Syndrome Symptoms • Reduced serum levels of magnesium, potassium, and phosphorus • Hyperglycemia and hyperinsulinemia • Interstitial fluid retention • Cardiac decompensation and arrest

  46. Refeeding Syndrome Prevention/Treatment • Monitor and supplement electrolytes, vitamins and minerals prior to and during infusion of PN until levels remain stable • Initiate feedings with 15-20 kcal/kg or 1000 kcals/day and 1.2-1.5 g protein/kg/day • Limit fluid to 800 ml + insensible losses (adjust per patient fluid tolerance and status) Fuhrman MP. Defensive strategies for avoiding and managing parenteral nutrition complications. P. 102. In Sharpening your skills as a nutrition support dietitian. DNS, 2003.

  47. Glycemic Control in Critical Care • Until recently, BG<200 mg/dl was tolerated in critically ill patients. • Now greater attention is given to glycemic control due to evidence that glucose is associated with morbidity/mortality and risk of infection • New recommendation is to keep BG<150 mg/dl or as close to normal as possible Van den Berghe et al. NEJM, 2001

  48. Glycemic Control in PN • In critically ill patients, recommendation is to keep dextrose infusion <5 mg/kg/minute or <60% of total kcals. ASPEN Nutrition Support Practice Manual, 2005, p. 267

  49. Glycemic Control in PN For Patients Not Previously on Insulin • Monitor blood glucose levels prior to initiating PN • When therapy is initiated, monitor BG q 4-6 hours and use sliding scale or insulin drip as needed • Add a portion of the previous day’s insulin to TPN to maintain blood glucose levels Charney P. A Spoonful of Sugar: Glycemic Control in the ICU. In Sharpening your skills as a nutrition support dietitian. DNS, 2003.

  50. Glycemic Control in PN For Patients Previously on Insulin • Determine amount of insulin needed prior to illness • Determine amount of feedings to be given • Provide a portion of daily insulin needs in first PN along with sliding scale or insulin drip to maintain glucose levels (generally insulin needs will increase while on PN) Charney P. A Spoonful of Sugar: Glycemic Control in the ICU. In Sharpening your skills as a nutrition support dietitian. DNS, 2003.

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