Practice exercise (made-up values, not clinical guidance). An 88 kg patient needs 1.2 g of protein per kg a day. The tube feed contains 63 g of protein per litre and runs at 75 mL/h for 16 hours a day. How many grams of extra protein ΔP a day are still needed? Round to one decimal place.
88 kg1.2 g/kg/day63 g/L75 mL/h · 16 h
ΔP = g/day
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 2000 mL of parenteral nutrition with final concentrations of 15% dextrose and 4.25% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
2000 mLdextrose 15%amino acids 4.25%lipid 500 mL · 1.1 kcal/mL
E = kcal/day
3.IV fluids & fluid balanceMedium
Practice exercise (made-up values, not clinical guidance). The record shows a patient's intake and output for one 12-hour shift. The patient weighs 94 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A 500 mL bag was started at 09:00 and runs by pump at 100 mL/h. How many mL V are left in the bag at 11:30?
500 mL100 mL/h09:00 → 11:30
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: ΔP = 30 g/day
Needs and free water: energy needs are often estimated as kcal/kg/day × weight and protein needs as g/kg/day × weight. A formula is only partly water, so its free water = volume × water fraction; water flushes make up the rest of the daily fluid goal. Ideal body weight (Devine): IBW = 50 kg + 2.3 kg for every inch over 5 feet (60 in) for men, and 45.5 kg + 2.3 kg per inch over 60 in for women; 1 in = 2.54 cm. The formula is meant for adults at least 152.4 cm (5 ft) tall. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Protein needed
1.2·88 = 105.6 g/day
Protein from the feed
75·16 = 1200 mL = 1.2 L
1.2·63 = 75.6 g/day
Shortfall
ΔP = 105.6 − 75.6 = 30 g/day
Answer
ΔP = 30 g/day
2.Enteral & parenteral nutrition calculations
Answer: E = 1910 kcal/day
Parenteral nutrition: dextrose provides 3.4 kcal/g, amino acids 4 kcal/g and lipid emulsion the kcal/mL stated (2 kcal/mL for 20%, 1.1 kcal/mL for 10%). Grams = % × mL/100. Non-protein kcal (NPC) = dextrose + lipid kcal; nitrogen = protein/6.25. The glucose infusion rate (GIR) in mg/kg/min = dextrose mg/(kg × minutes). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Grams of dextrose and amino acids
dextrose: 15·2000/100 = 300 g
amino acids: 4.25·2000/100 = 85 g
Kilocalories per component
dextrose: 300·3.4 = 1020 kcal
amino acids: 85·4 = 340 kcal
lipid: 500·1.1 = 550 kcal
Total energy
E = 1020 + 340 + 550 = 1910 kcal/day
Answer
E = 1910 kcal/day
3.IV fluids & fluid balance
Answer: U = 0.66 mL/kg/h
Intake and output: intake counts everything that goes in (oral fluids, IV infusions, IV medications and flushes, tube feeds); ice chips count as half their volume. Output counts urine, drains, vomit and other losses. Balance = total intake − total output; a negative balance is a net loss. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Total urine
225 + 175 + 150 + 200 = 750 mL
Per kilogram per hour
U = 750/(94·12) = 0.6649 ≈ 0.66 mL/kg/h
Answer
U = 0.66 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 250 mL
Infusion time: time (h) = volume to infuse (mL)/rate (mL/h); use the volume still left in the bag, not the bag size. Volume infused = rate × time. Convert decimal hours to hours and minutes with the fraction × 60 (0.5 h = 30 min, not 50 min). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.