Practice exercise (made-up values, not clinical guidance). A 60 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 84% free water and runs at 65 mL/h for 18 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.
60 kg35 mL/kg/day84%65 mL/h · 18 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 2000 mL of parenteral nutrition with final concentrations of 12.5% dextrose and 5% amino acids, plus 250 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
2000 mLdextrose 12.5%amino acids 5%lipid 250 mL · 1.1 kcal/mL
NPC : N =
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 59 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
59 kg8 hurine: 200 mLurine: 225 mL
U = mL/kg/h
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 09:45 and runs by pump at 80 mL/h. How many mL V are left in the bag at 11:15?
1000 mL80 mL/h09:45 → 11:15
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 186 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
35·60 = 2100 mL/day
Free water from the formula
65·18 = 1170 mL
1170·0.84 = 982.8 mL
Water still needed
2100 − 982.8 = 1117 mL/day
Volume per flush
24/4 = 6 flushes
V = 1117/6 = 186.2 ≈ 186 mL
Answer
V = 186 mL
2.Enteral & parenteral nutrition calculations
Answer: NPC : N = 70
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: 12.5·2000/100 = 250 g
amino acids: 5·2000/100 = 100 g
Kilocalories per component
dextrose: 250·3.4 = 850 kcal
amino acids: 100·4 = 400 kcal
lipid: 250·1.1 = 275 kcal
Non-protein kcal and nitrogen
NPC = 850 + 275 = 1125 kcal
N = 100/6.25 = 16 g
Ratio
NPC : N = 1125/16 = 70.31 ≈ 70 : 1
Answer
NPC : N = 70
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
3.IV fluids & fluid balance
Answer: U = 0.9 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
200 + 225 = 425 mL
Per kilogram per hour
U = 425/(59·8) = 0.9004 ≈ 0.9 mL/kg/h
Answer
U = 0.9 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 880 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.