Practice exercise (made-up values, not clinical guidance). A 68 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 76% free water and runs at 45 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.
68 kg35 mL/kg/day76%45 mL/h · 20 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1500 mL of parenteral nutrition with final concentrations of 12.5% dextrose and 4.25% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
1500 mLdextrose 12.5%amino acids 4.25%lipid 500 mL · 1.1 kcal/mL
E = kcal/day
3.IV fluids & fluid balanceMedium
Practice exercise (made-up values, not clinical guidance). The record shows a patient's intake and output for one 8-hour shift. The patient weighs 78 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 07:45 and runs by pump at 150 mL/h. How many mL V are left in the bag at 11:45?
1000 mL150 mL/h07:45 → 11:45
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 283 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
35·68 = 2380 mL/day
Free water from the formula
45·20 = 900 mL
900·0.76 = 684 mL
Water still needed
2380 − 684 = 1696 mL/day
Volume per flush
24/4 = 6 flushes
V = 1696/6 = 282.7 ≈ 283 mL
Answer
V = 283 mL
2.Enteral & parenteral nutrition calculations
Answer: E = 1443 kcal/day
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.
Grams of dextrose and amino acids
dextrose: 12.5·1500/100 = 187.5 g
amino acids: 4.25·1500/100 = 63.75 g
Kilocalories per component
dextrose: 187.5·3.4 = 637.5 kcal
amino acids: 63.75·4 = 255 kcal
lipid: 500·1.1 = 550 kcal
Total energy
E = 637.5 + 255 + 550 = 1443 kcal/day
Answer
E = 1443 kcal/day
3.IV fluids & fluid balance
Answer: U = 1.56 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
400 + 275 + 300 = 975 mL
Per kilogram per hour
U = 975/(78·8) = 1.563 ≈ 1.56 mL/kg/h
Answer
U = 1.56 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 400 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.