Practice exercise (made-up values, not clinical guidance). A 75 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 81% free water and runs at 60 mL/h for 20 hours a day. The rest of the fluid is given as water flushes every 4 hours. What volume V is each flush? Round to the nearest whole number.
75 kg35 mL/kg/day81%60 mL/h · 20 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1000 mL of parenteral nutrition with final concentrations of 10% dextrose and 5% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein energy NPC in kcal per day. Round to the nearest whole number.
1000 mLdextrose 10%amino acids 5%lipid 500 mL · 1.1 kcal/mL
NPC = 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 patient weighs 68 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 1000 mL infusion starts at 18:00 at 120 mL/h. After 4 hours the rate is changed to 75 mL/h and is not changed again. How many hours t after the start will the bag be empty? Round to one decimal place.
1000 mL120 mL/h · 4 h75 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 276 mL
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.
Fluid goal
35·75 = 2625 mL/day
Free water from the formula
60·20 = 1200 mL
1200·0.81 = 972 mL
Water still needed
2625 − 972 = 1653 mL/day
Volume per flush
24/4 = 6 flushes
V = 1653/6 = 275.5 ≈ 276 mL
Answer
V = 276 mL
2.Enteral & parenteral nutrition calculations
Answer: NPC = 890 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: 10·1000/100 = 100 g
amino acids: 5·1000/100 = 50 g
Kilocalories per component
dextrose: 100·3.4 = 340 kcal
amino acids: 50·4 = 200 kcal
lipid: 500·1.1 = 550 kcal
Non-protein energy
NPC = 340 + 550 = 890 kcal/day
Answer
NPC = 890 kcal/day
3.IV fluids & fluid balance
Answer: U = 1.42 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
250 + 375 + 150 = 775 mL
Per kilogram per hour
U = 775/(68·8) = 1.425 ≈ 1.42 mL/kg/h
Answer
U = 1.42 mL/kg/h
4.IV fluids & fluid balance
Answer: t = 10.9 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
120·4 = 480 mL
1000 − 480 = 520 mL left
Second part
520/75 = 6.933 h
Total time
t = 4 + 6.933 = 10.93 ≈ 10.9 h
Answer
t = 10.9 h
That is about 10 h 56 min, so the bag runs out at about 04:56.