Practice exercise (made-up values, not clinical guidance). A 93 kg adult (BMI below 30) needs 25 kcal/kg/day. The tube feed provides 1 kcal/mL and runs by pump for 20 hours a day. At what rate R do you set the pump, in mL/h? Round to the nearest whole number.
93 kg25 kcal/kg/day1 kcal/mL20 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). A 100 kg adult receives 1800 mL of parenteral nutrition containing 15% dextrose, infused over 12 hours. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
100 kg1800 mLdextrose 15%12 h
GIR = mg/kg/min
3.IV fluids & fluid balanceMedium
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 51 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 500 mL bag was started at 09:15 and runs by pump at 120 mL/h. How many mL V are left in the bag at 10:15?
500 mL120 mL/h09:15 → 10:15
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 116 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 = 25·93 = 2325 kcal/day
Daily volume
V = 2325/1 = 2325 mL/day
Pump rate
R = 2325/20 = 116.3 ≈ 116 mL/h
Answer
R = 116 mL/h
2.Enteral & parenteral nutrition calculations
Answer: GIR = 3.75 mg/kg/min
Parenteral nutrition: dextrose provides 3.4 kcal/g, amino acids 4 kcal/g and lipid emulsion the kcal/mL stated (2 kcal/mL for 20%, 1.1 kcal/mL for 10%). Grams = % × mL/100. Non-protein kcal (NPC) = dextrose + lipid kcal; nitrogen = protein/6.25. The glucose infusion rate (GIR) in mg/kg/min = dextrose mg/(kg × minutes). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Dextrose in the bag
15·1800/100 = 270 g = 270 000 mg
Minutes of infusion
12·60 = 720 min
Glucose infusion rate
GIR = 270 000/(100·720) = 3.75 mg/kg/min
Answer
GIR = 3.75 mg/kg/min
3.IV fluids & fluid balance
Answer: U = 2.7 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 + 400 + 350 + 425 = 1650 mL
Per kilogram per hour
U = 1650/(51·12) = 2.696 ≈ 2.7 mL/kg/h
Answer
U = 2.7 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 380 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.