Practice exercise (made-up values, not clinical guidance). A 66 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 90 mL/h for 24 hours a day. The rest of the fluid is given as water flushes every 8 hours. What volume V is each flush? Round to the nearest whole number.
66 kg35 mL/kg/day84%90 mL/h · 24 hevery 8 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 25% dextrose and 6% amino acids, plus 100 mL of 20% lipid emulsion (2 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
1500 mLdextrose 25%amino acids 6%lipid 100 mL · 2 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 12-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).
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag runs by pump at 75 mL/h. At 09:30, 700 mL have already been infused. How many hours t until the bag is empty? Round to one decimal place.
1000 mL700 mL infused75 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 165 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
35·66 = 2310 mL/day
Free water from the formula
90·24 = 2160 mL
2160·0.84 = 1814 mL
Water still needed
2310 − 1814 = 495.6 mL/day
Volume per flush
24/8 = 3 flushes
V = 495.6/3 = 165.2 ≈ 165 mL
Answer
V = 165 mL
2.Enteral & parenteral nutrition calculations
Answer: E = 1835 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: 25·1500/100 = 375 g
amino acids: 6·1500/100 = 90 g
Kilocalories per component
dextrose: 375·3.4 = 1275 kcal
amino acids: 90·4 = 360 kcal
lipid: 100·2 = 200 kcal
Total energy
E = 1275 + 360 + 200 = 1835 kcal/day
Answer
E = 1835 kcal/day
3.IV fluids & fluid balance
Answer: B = 925 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: 200 + 240 + 150 = 590 mL
IV infusion: 80·12 = 960 mL
IV antibiotic: 1·100 = 100 mL
total intake = 1650 mL
Total output
200 + 225 + 300 = 725 mL
Balance
B = 1650 − 725 = 925 mL
Answer
B = 925 mL
Positive: more fluid went in than came out.
4.IV fluids & fluid balance
Answer: t = 4 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.
Volume left
1000 − 700 = 300 mL
Time
t = 300/75 = 4 h
Answer
t = 4 h
That is about 4 h 00 min, so the bag runs out at about 13:30.