Practice exercise (made-up values, not clinical guidance). A 50 kg adult (BMI below 30) needs 30 kcal/kg/day. The tube feed provides 2 kcal/mL and runs by pump for 24 hours a day. At what rate R do you set the pump, in mL/h? Round to the nearest whole number.
50 kg30 kcal/kg/day2 kcal/mL24 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). An 80 kg adult receives 1200 mL of parenteral nutrition containing 20% dextrose, infused over 12 hours. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
80 kg1200 mLdextrose 20%12 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 patient weighs 109 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 09:30 at 120 mL/h. After 4 hours the rate is changed to 125 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 h125 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 31 mL/h
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.
Energy needed
E = 30·50 = 1500 kcal/day
Daily volume
V = 1500/2 = 750 mL/day
Pump rate
R = 750/24 = 31.25 ≈ 31 mL/h
Answer
R = 31 mL/h
2.Enteral & parenteral nutrition calculations
Answer: GIR = 4.17 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
20·1200/100 = 240 g = 240 000 mg
Minutes of infusion
12·60 = 720 min
Glucose infusion rate
GIR = 240 000/(80·720) = 4.167 ≈ 4.17 mg/kg/min
Answer
GIR = 4.17 mg/kg/min
3.IV fluids & fluid balance
Answer: U = 0.86 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 + 300 + 200 + 400 = 1125 mL
Per kilogram per hour
U = 1125/(109·12) = 0.8601 ≈ 0.86 mL/kg/h
Answer
U = 0.86 mL/kg/h
4.IV fluids & fluid balance
Answer: t = 8.2 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
520/125 = 4.16 h
Total time
t = 4 + 4.16 = 8.16 ≈ 8.2 h
Answer
t = 8.2 h
That is about 8 h 10 min, so the bag runs out at about 17:40.