Practice exercise (made-up values, not clinical guidance). A 54 kg patient has a fluid goal of 30 mL/kg/day and receives all fluid through a feeding tube. The formula is 76% free water and runs at 40 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.
54 kg30 mL/kg/day76%40 mL/h · 20 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A critically ill man is 182 cm tall and weighs 179 kg. The practice protocol gives 14 kcal/kg of actual body weight per day if the BMI is 30–50 kg/m², and 25 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 83 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 bag was started at 08:00 and runs by pump at 150 mL/h. How many mL V are left in the bag at 13:00?
1000 mL150 mL/h08:00 → 13:00
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 169 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
30·54 = 1620 mL/day
Free water from the formula
40·20 = 800 mL
800·0.76 = 608 mL
Water still needed
1620 − 608 = 1012 mL/day
Volume per flush
24/4 = 6 flushes
V = 1012/6 = 168.7 ≈ 169 mL
Answer
V = 169 mL
2.Enteral & parenteral nutrition calculations
Answer: E = 1920 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 = 179/1.82² = 54.04 kg/m²
Ideal body weight (Devine)
182 cm/2.54 = 71.65 in
IBW = 50 + 2.3·(71.65 − 60) = 76.8 kg
Energy goal
BMI above 50: kcal per kg of ideal body weight.
E = 25·76.8 = 1920 kcal/day
Answer
E = 1920 kcal/day
3.IV fluids & fluid balance
Answer: U = 1.33 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
175 + 275 + 425 + 450 = 1325 mL
Per kilogram per hour
U = 1325/(83·12) = 1.33 mL/kg/h
Answer
U = 1.33 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 250 mL
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.