Practice exercise (made-up values, not clinical guidance). A 58 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.
58 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 180 cm tall and weighs 109 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 patient weighs 71 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
71 kg12 hurine: 425 mLurine: 425 mLwound drain: 80 mL
U = mL/kg/h
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL bag was started at 13:30 and runs by pump at 80 mL/h. How many mL V are left in the bag at 18:30?
500 mL80 mL/h13:30 → 18:30
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 60 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 = 30·58 = 1740 kcal/day
Daily volume
V = 1740/1.2 = 1450 mL/day
Pump rate
R = 1450/24 = 60.42 ≈ 60 mL/h
Answer
R = 60 mL/h
2.Enteral & parenteral nutrition calculations
Answer: P = 150 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 = 109/1.8² = 33.64 kg/m²
Ideal body weight (Devine)
180 cm/2.54 = 70.87 in
IBW = 50 + 2.3·(70.87 − 60) = 74.99 kg
Protein goal
BMI 30 to under 40: 2 g per kg of ideal body weight.
P = 2·74.99 = 150 g/day
Answer
P = 150 g/day
3.IV fluids & fluid balance
Answer: U = 1 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
425 + 425 = 850 mL
Per kilogram per hour
U = 850/(71·12) = 0.9977 ≈ 1 mL/kg/h
Answer
U = 1 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 100 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.