Practice exercise (made-up values, not clinical guidance). A 57 kg adult (BMI below 30) needs 30 kcal/kg/day. The tube feed provides 1.2 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.
57 kg30 kcal/kg/day1.2 kcal/mL24 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A critically ill man is 189 cm tall and weighs 188 kg. The practice protocol gives 2 g of protein per kg of ideal body weight (Devine) per day if the BMI is 30 to under 40 kg/m², and 2.5 g/kg of ideal body weight per day if the BMI is 40 kg/m² or more. Find the protein goal P in g/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 IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL.
milk: 200 mLjuice: 150 mLIV infusion: 75 mL/h × 12 hIV antibiotic: 1 × 100 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL bag runs by pump at 80 mL/h. At 16:30, 200 mL have already been infused. How many hours t until the bag is empty? Round to one decimal place.
500 mL200 mL infused80 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 59 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 = 30·57 = 1710 kcal/day
Daily volume
V = 1710/1.2 = 1425 mL/day
Pump rate
R = 1425/24 = 59.38 ≈ 59 mL/h
Answer
R = 59 mL/h
2.Enteral & parenteral nutrition calculations
Answer: P = 208 g/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). The protein goal is 2 g/kg of ideal body weight per day for BMI 30–40 and up to 2.5 g/kg of ideal body weight per day for BMI 40 and above. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Body mass index
BMI = 188/1.89² = 52.63 kg/m²
Ideal body weight (Devine)
189 cm/2.54 = 74.41 in
IBW = 50 + 2.3·(74.41 − 60) = 83.14 kg
Protein goal
BMI 40 or more: 2.5 g per kg of ideal body weight.
P = 2.5·83.14 = 207.9 ≈ 208 g/day
Answer
P = 208 g/day
3.IV fluids & fluid balance
Answer: I = 1350 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: 200 + 150 = 350 mL
IV infusion: 75·12 = 900 mL
IV antibiotic: 1·100 = 100 mL
I = 1350 mL
Answer
I = 1350 mL
4.IV fluids & fluid balance
Answer: t = 3.8 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.
Volume left
500 − 200 = 300 mL
Time
t = 300/80 = 3.75 ≈ 3.8 h
Answer
t = 3.8 h
That is about 3 h 45 min, so the bag runs out at about 20:15.