Practice exercise (made-up values, not clinical guidance). An 80 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 85 mL/h for 24 hours a day. A protein powder supplies 5 g of protein per scoop. How many scoops n a day are needed to cover the shortfall? Round up to a whole scoop.
80 kg1.8 g/kg/day44 g/L85 mL/h · 24 h5 g/scoop
n =
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 2400 mL of parenteral nutrition with final concentrations of 12.5% dextrose and 5% amino acids, plus 500 mL of 20% lipid emulsion (2 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
2400 mLdextrose 12.5%amino acids 5%lipid 500 mL · 2 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 8-hour shift. The IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL.
soup: 180 mLtea: 240 mLIV infusion: 50 mL/h × 8 hIV antibiotic: 1 × 50 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL infusion starts at 12:00 at 100 mL/h. After 2 hours the rate is changed to 200 mL/h and is not changed again. How many hours t after the start will the bag be empty? Round to one decimal place.
500 mL100 mL/h · 2 h200 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: n = 11
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
1.8·80 = 144 g/day
Protein from the feed
85·24 = 2040 mL = 2.04 L
2.04·44 = 89.76 g/day
Shortfall
ΔP = 144 − 89.76 = 54.24 g
Scoops
54.24/5 = 10.85 → n = 11
Answer
n = 11
2.Enteral & parenteral nutrition calculations
Answer: E = 2500 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: 12.5·2400/100 = 300 g
amino acids: 5·2400/100 = 120 g
Kilocalories per component
dextrose: 300·3.4 = 1020 kcal
amino acids: 120·4 = 480 kcal
lipid: 500·2 = 1000 kcal
Total energy
E = 1020 + 480 + 1000 = 2500 kcal/day
Answer
E = 2500 kcal/day
3.IV fluids & fluid balance
Answer: I = 870 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: 180 + 240 = 420 mL
IV infusion: 50·8 = 400 mL
IV antibiotic: 1·50 = 50 mL
I = 870 mL
Answer
I = 870 mL
4.IV fluids & fluid balance
Answer: t = 3.5 h
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.
First part
100·2 = 200 mL
500 − 200 = 300 mL left
Second part
300/200 = 1.5 h
Total time
t = 2 + 1.5 = 3.5 h
Answer
t = 3.5 h
That is about 3 h 30 min, so the bag runs out at about 15:30.