Practice exercise (made-up values, not clinical guidance). A 90 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.
90 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 174 cm tall and weighs 144 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 8-hour shift. The IV infusion ran at the rate shown for the whole shift. Find the fluid balance B = intake − output in mL (a negative answer means a net loss). Count ice chips as half their volume.
Practice exercise (made-up values, not clinical guidance). A 1000 mL infusion starts at 16:00 at 100 mL/h. After 3 hours the rate is changed to 60 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 mL100 mL/h · 3 h60 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 94 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 = 30·90 = 2700 kcal/day
Daily volume
V = 2700/1.2 = 2250 mL/day
Pump rate
R = 2250/24 = 93.75 ≈ 94 mL/h
Answer
R = 94 mL/h
2.Enteral & parenteral nutrition calculations
Answer: E = 2016 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 = 144/1.74² = 47.56 kg/m²
Energy goal
BMI 30–50: kcal per kg of actual body weight.
E = 14·144 = 2016 kcal/day
Answer
E = 2016 kcal/day
3.IV fluids & fluid balance
Answer: B = 80 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.
Total intake
oral: 240 + 150 = 390 mL
ice chips: 100/2 = 50 mL
IV infusion: 50·8 = 400 mL
IV antibiotic: 1·100 = 100 mL
total intake = 940 mL
Total output
425 + 325 + 110 = 860 mL
Balance
B = 940 − 860 = 80 mL
Answer
B = 80 mL
Positive: more fluid went in than came out.
4.IV fluids & fluid balance
Answer: t = 14.7 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
100·3 = 300 mL
1000 − 300 = 700 mL left
Second part
700/60 = 11.67 h
Total time
t = 3 + 11.67 = 14.67 ≈ 14.7 h
Answer
t = 14.7 h
That is about 14 h 40 min, so the bag runs out at about 06:40.