Practice exercise (made-up values, not clinical guidance). An 87 kg patient has a fluid goal of 30 mL/kg/day and receives all fluid through a feeding tube. The formula is 84% free water and runs at 80 mL/h for 24 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.
87 kg30 mL/kg/day84%80 mL/h · 24 hevery 4 h
V = mL
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1200 mL of parenteral nutrition with final concentrations of 25% dextrose and 5% amino acids, plus 250 mL of 20% lipid emulsion (2 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
1200 mLdextrose 25%amino acids 5%lipid 250 mL · 2 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 IV infusion ran at the rate shown for the whole shift. Find the total intake I in mL. Count ice chips as half their volume.
milk: 200 mLtea: 240 mLice chips: 120 mLIV infusion: 125 mL/h × 8 hIV antibiotic: 1 × 50 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 13:00 and runs by pump at 80 mL/h. How many mL V are left in the bag at 16:30?
1000 mL80 mL/h13:00 → 16:30
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 166 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
30·87 = 2610 mL/day
Free water from the formula
80·24 = 1920 mL
1920·0.84 = 1613 mL
Water still needed
2610 − 1613 = 997.2 mL/day
Volume per flush
24/4 = 6 flushes
V = 997.2/6 = 166.2 ≈ 166 mL
Answer
V = 166 mL
2.Enteral & parenteral nutrition calculations
Answer: NPC : N = 158
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: 25·1200/100 = 300 g
amino acids: 5·1200/100 = 60 g
Kilocalories per component
dextrose: 300·3.4 = 1020 kcal
amino acids: 60·4 = 240 kcal
lipid: 250·2 = 500 kcal
Non-protein kcal and nitrogen
NPC = 1020 + 500 = 1520 kcal
N = 60/6.25 = 9.6 g
Ratio
NPC : N = 1520/9.6 = 158.3 ≈ 158 : 1
Answer
NPC : N = 158
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
3.IV fluids & fluid balance
Answer: I = 1550 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.
Add the intake
oral: 200 + 240 = 440 mL
ice chips: 120/2 = 60 mL
IV infusion: 125·8 = 1000 mL
IV antibiotic: 1·50 = 50 mL
I = 1550 mL
Answer
I = 1550 mL
4.IV fluids & fluid balance
Answer: V = 720 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.