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How to Write TPN. 1. Start by determining energy needs 2. Determine calories from protein 3. Determine calories from fat 4. Make up the remainder of energy needs from carbohydrates 5. Calculate the amount of fluid the patient needs 6. Add electrolytes, vitamins, trace elements.
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1. Start by determining energy needs2. Determine calories from protein 3. Determine calories from fat4. Make up the remainder of energy needs from carbohydrates5. Calculate the amount of fluid the patient needs6. Add electrolytes, vitamins, trace elements CALCULATING TPN
1. START BY DETERMINING ENERGY NEEDS Use Kcal/Kg based on the following scale: • Normal need: 25-30 Kcal/kg/day • Elective surgery: 28-30 kcal/kg/day • Severe injury: 30-40 kcal/kg/day • Extensive trauma/burn: 45-55 kcal/kg/day Example: 70 Kg male with elective surgery X 30 Kcal/Kg = 2,100 Kcal/day • May use Harris-Benedict + activity + infection/fever factor + etc = Energy (Kcal)
2. DETERMINE CALORIES FROM PROTEIN • Usually start with 0.83 gm/Kg and add stress and other factors as needed • May need up to 2.5 g/Kg due to loss and other factors For example: Malnourished 70 Kg man X 1.2 gm/kg/day = 84 gm protein per day Calories from protein: 84 gm protein * 4 Kcal/gm protein = 336 Kcal
3. DETERMINE CALORIES FROM FAT At LVH 0.6 gm fat/kg/day is used: Example: 0.6 gm fat/kg/day * 70 kg = 42 gm fat/day Calories from fat: 42 gm fat * 9 Kcal/gm fat = 378 Kcal
4. MAKE UP THE REST OF CALORIES FROM CARBOHYDRATES Energy needed in 1 day for a 70 kg pt. = 2100 Kcal/day 2100 Kcal/day – 336 Kcal from protein – 378 Kcal from fat = 1386 Kcal Dextrose = 3.4 Kcal/gram; available in 50 to 70% solution (D50W, D70W) To calculate the amount of Dextrose needed in grams: 1386 Kcal * (1 gm Dextrose/3.4 Kcal) = 408 gm Dextrose
5. NEXT CALCULATE THE AMOUNT OF FLUIDS THE PATIENT NEEDS: 100 cc/Kg for first 10 Kg + 50 cc/Kg for the second 10 Kg + 20 cc/Kg for each additional Kg: Example for 70 kg pt.: 100 cc/Kg X 10 Kg = 1000 cc 50 cc/Kg X 10 Kg = 500 cc 20 cc/Kg X 50 Kg = 1000 cc total: 1000 + 500 + 1500 = 2,500 cc/day
Determine how much volume will be taken up by protein in the TPN solution: 85 gm of protein using a 10% amino acid solution; 10% solution = 10 gm protein/100 cc Example: 85 gm / X mL = 10 gm/100 mL X mL * 10 gm = 8500 gm ml X = 8500 gm ml/10 gm = 850 ml 10% protein solution Determine how much volume will be taken up by fat: 42 gm of fat using a 15% amino acid solution; 15% solution = 15 gm fat/100 cc Example: 42 gm / X mL = 15 mg/100 mL X mL * 15 gm = 4200 gm mL X = 4200 gm mL/15 gm = 280 mL 15% fat solution Determine how much volume will be taken up by carbohydrates: 408 mg Dextrose using a D50W solution; 50% solution = 50 gm Dextrose/100 cc Example: 408 gm / X mL = 50 gm/100 mL X mL * 50 gm = 40800 gm mL X = 40800 gm mL/50 gm = 816 mL D50W
Total cc/day for 70 kg pt. = 2500 cc/day 850 cc 10% protein solution + 280 cc 15% protein solution + 816 cc D50W = 1946 cc TPN 2500 cc/day – 1946 cc TPN = 554 cc Need to add 554 cc of fluid for electrolytes, vitamins, and trace elements (or drips that pt. is already on) Calculate rate/hr: 2500 ml/24 hr = 105 ml/hr
6. ADD ELECTROLYTES, VITAMINS, AND TRACE ELEMENTS (ASPEN GUIDELINES) Vitamins Vitamin A: 3300 IU Vitamin D: 200 IU Vitamin E: 10 IU Vitamin K: 150 mcg Thiamine (B1): 6 mg Pyridoxine (B6): 6 mg Cyanocobalamin (B12): 5 mcg Pantothenic acid: 15 mg Biotin: 60 mcg Vitamin C: 200 mg Folic Acid: 600 mcg Niacin: 40 mg Riboflavin (B2): 3.6mg Electrolytes Sodium: 1–2 mEq/kg Potassium: 1–2 mEq/kg Phosphorus: 20–40 mmol Magnesium: 8–20 mEq Calcium: 10-15 mEq Chloride and Acetate: adjusted by acid-base balance Trace Elements Zinc: 2.5 – 5.0 mg Copper: 0.3 – 0.5 mg Chromium: 10 – 15 mcg Manganese: 60 – 100 mcg Selenium: 20 – 60 mcg