Practice exercise (made-up values, not clinical guidance). A 94 kg adult (BMI below 30) needs 25 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.
94 kg25 kcal/kg/day2 kcal/mL24 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A critically ill woman is 169 cm tall and weighs 156 kg. The practice protocol gives 11 kcal/kg of actual body weight per day if the BMI is 30–50 kg/m², and 22 kcal/kg of ideal body weight (Devine) per day if the BMI is above 50 kg/m². Find the energy goal E in kcal/day. Round to the nearest whole number.
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 80 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
80 kg12 hurine: 475 mLurine: 450 mL
U = mL/kg/h
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL infusion starts at 15:30 at 80 mL/h. After 4 hours the rate is changed to 150 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 mL80 mL/h · 4 h150 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 49 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 = 25·94 = 2350 kcal/day
Daily volume
V = 2350/2 = 1175 mL/day
Pump rate
R = 1175/24 = 48.96 ≈ 49 mL/h
Answer
R = 49 mL/h
2.Enteral & parenteral nutrition calculations
Answer: E = 1332 kcal/day
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. Obesity in critical illness (ASPEN/SCCM 2016): BMI = weight/height² (kg/m²). For BMI 30–50 the energy goal is 11–14 kcal/kg of actual body weight per day; above 50 it is 22–25 kcal/kg of ideal body weight per day. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Body mass index
BMI = 156/1.69² = 54.62 kg/m²
Ideal body weight (Devine)
169 cm/2.54 = 66.54 in
IBW = 45.5 + 2.3·(66.54 − 60) = 60.53 kg
Energy goal
BMI above 50: kcal per kg of ideal body weight.
E = 22·60.53 = 1332 kcal/day
Answer
E = 1332 kcal/day
3.IV fluids & fluid balance
Answer: U = 0.96 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
475 + 450 = 925 mL
Per kilogram per hour
U = 925/(80·12) = 0.9635 ≈ 0.96 mL/kg/h
Answer
U = 0.96 mL/kg/h
4.IV fluids & fluid balance
Answer: t = 5.2 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
80·4 = 320 mL
500 − 320 = 180 mL left
Second part
180/150 = 1.2 h
Total time
t = 4 + 1.2 = 5.2 h
Answer
t = 5.2 h
That is about 5 h 12 min, so the bag runs out at about 20:42.