Practice exercise (made-up values, not clinical guidance). A 54 kg patient needs 1.8 g of protein per kg a day. The tube feed contains 44 g of protein per litre and runs at 65 mL/h for 24 hours a day. How many grams of extra protein ΔP a day are still needed? Round to one decimal place.
54 kg1.8 g/kg/day44 g/L65 mL/h · 24 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 10% dextrose and 3.5% amino acids, plus 100 mL of 20% lipid emulsion (2 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
2000 mLdextrose 10%amino acids 3.5%lipid 100 mL · 2 kcal/mL
NPC : N =
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 IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL. Count ice chips as half their volume.
Practice exercise (made-up values, not clinical guidance). A 500 mL bag was started at 11:00 and runs by pump at 60 mL/h. How many mL V are left in the bag at 14:30?
500 mL60 mL/h11:00 → 14:30
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: ΔP = 28.6 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
1.8·54 = 97.2 g/day
Protein from the feed
65·24 = 1560 mL = 1.56 L
1.56·44 = 68.64 g/day
Shortfall
ΔP = 97.2 − 68.64 = 28.56 ≈ 28.6 g/day
Answer
ΔP = 28.6 g/day
2.Enteral & parenteral nutrition calculations
Answer: NPC : N = 79
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: 10·2000/100 = 200 g
amino acids: 3.5·2000/100 = 70 g
Kilocalories per component
dextrose: 200·3.4 = 680 kcal
amino acids: 70·4 = 280 kcal
lipid: 100·2 = 200 kcal
Non-protein kcal and nitrogen
NPC = 680 + 200 = 880 kcal
N = 70/6.25 = 11.2 g
Ratio
NPC : N = 880/11.2 = 78.57 ≈ 79 : 1
Answer
NPC : N = 79
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
3.IV fluids & fluid balance
Answer: I = 1820 mL
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.
Add the intake
oral: 100 + 120 + 180 = 400 mL
ice chips: 240/2 = 120 mL
IV infusion: 100·12 = 1200 mL
IV antibiotic: 1·100 = 100 mL
I = 1820 mL
Answer
I = 1820 mL
4.IV fluids & fluid balance
Answer: V = 290 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.