Practice exercise (made-up values, not clinical guidance). A 66 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 76% free water and runs at 50 mL/h for 24 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.
66 kg35 mL/kg/day76%50 mL/h · 24 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). An 83 kg adult receives 1000 mL of parenteral nutrition containing 25% dextrose, infused over 24 hours. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
83 kg1000 mLdextrose 25%24 h
GIR = mg/kg/min
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.
jelly: 100 mLtea: 150 mLIV infusion: 100 mL/h × 12 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 15:30 at 125 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 mL125 mL/h · 2 h200 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 233 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
35·66 = 2310 mL/day
Free water from the formula
50·24 = 1200 mL
1200·0.76 = 912 mL
Water still needed
2310 − 912 = 1398 mL/day
Volume per flush
24/4 = 6 flushes
V = 1398/6 = 233 mL
Answer
V = 233 mL
2.Enteral & parenteral nutrition calculations
Answer: GIR = 2.09 mg/kg/min
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.
Dextrose in the bag
25·1000/100 = 250 g = 250 000 mg
Minutes of infusion
24·60 = 1440 min
Glucose infusion rate
GIR = 250 000/(83·1440) = 2.092 ≈ 2.09 mg/kg/min
Answer
GIR = 2.09 mg/kg/min
3.IV fluids & fluid balance
Answer: I = 1500 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 + 150 = 250 mL
IV infusion: 100·12 = 1200 mL
IV antibiotic: 1·50 = 50 mL
I = 1500 mL
Answer
I = 1500 mL
4.IV fluids & fluid balance
Answer: t = 3.3 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
125·2 = 250 mL
500 − 250 = 250 mL left
Second part
250/200 = 1.25 h
Total time
t = 2 + 1.25 = 3.25 ≈ 3.3 h
Answer
t = 3.3 h
That is about 3 h 15 min, so the bag runs out at about 18:45.