Practice exercise (made-up values, not clinical guidance). An 85 kg adult (BMI below 30) needs 30 kcal/kg/day. The tube feed provides 1 kcal/mL and runs by pump for 16 hours a day. At what rate R do you set the pump, in mL/h? Round to the nearest whole number.
85 kg30 kcal/kg/day1 kcal/mL16 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A child who weighs 17 kg receives 7.5% dextrose at 52 mL/h. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
17 kg7.5%52 mL/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 8-hour shift. The IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL.
water: 350 mLjuice: 100 mLsoup: 180 mLIV infusion: 60 mL/h × 8 hIV antibiotic: 1 × 50 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 1000 mL infusion starts at 09:00 at 80 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.
1000 mL80 mL/h · 2 h200 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 159 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 = 30·85 = 2550 kcal/day
Daily volume
V = 2550/1 = 2550 mL/day
Pump rate
R = 2550/16 = 159.4 ≈ 159 mL/h
Answer
R = 159 mL/h
2.Enteral & parenteral nutrition calculations
Answer: GIR = 3.82 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 concentration
7.5% = 75 mg/mL
Dextrose per minute
75·52/60 = 65 mg/min
Per kilogram
GIR = 65/17 = 3.824 ≈ 3.82 mg/kg/min
Answer
GIR = 3.82 mg/kg/min
Shortcut: GIR = % dextrose × mL/h/(6 × kg).
3.IV fluids & fluid balance
Answer: I = 1160 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: 350 + 100 + 180 = 630 mL
IV infusion: 60·8 = 480 mL
IV antibiotic: 1·50 = 50 mL
I = 1160 mL
Answer
I = 1160 mL
4.IV fluids & fluid balance
Answer: t = 6.2 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
80·2 = 160 mL
1000 − 160 = 840 mL left
Second part
840/200 = 4.2 h
Total time
t = 2 + 4.2 = 6.2 h
Answer
t = 6.2 h
That is about 6 h 12 min, so the bag runs out at about 15:12.