Practice exercise (made-up values, not clinical guidance). A 71 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 85 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.
71 kg35 mL/kg/day84%85 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 2400 mL of parenteral nutrition with final concentrations of 20% dextrose and 3.5% amino acids, plus 250 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.
2400 mLdextrose 20%amino acids 3.5%lipid 250 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 8-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 80 mL/h. At 15:00, 600 mL have already been infused. How many hours t until the bag is empty? Round to one decimal place.
1000 mL600 mL infused80 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 200 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
35·71 = 2485 mL/day
Free water from the formula
85·18 = 1530 mL
1530·0.84 = 1285 mL
Water still needed
2485 − 1285 = 1200 mL/day
Volume per flush
24/4 = 6 flushes
V = 1200/6 = 200 mL
Answer
V = 200 mL
2.Enteral & parenteral nutrition calculations
Answer: E = 2468 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: 20·2400/100 = 480 g
amino acids: 3.5·2400/100 = 84 g
Kilocalories per component
dextrose: 480·3.4 = 1632 kcal
amino acids: 84·4 = 336 kcal
lipid: 250·2 = 500 kcal
Total energy
E = 1632 + 336 + 500 = 2468 kcal/day
Answer
E = 2468 kcal/day
3.IV fluids & fluid balance
Answer: B = 195 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: 120 + 200 + 250 = 570 mL
IV infusion: 50·8 = 400 mL
IV antibiotic: 2·50 = 100 mL
total intake = 1070 mL
Total output
300 + 225 + 350 = 875 mL
Balance
B = 1070 − 875 = 195 mL
Answer
B = 195 mL
Positive: more fluid went in than came out.
4.IV fluids & fluid balance
Answer: t = 5 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 − 600 = 400 mL
Time
t = 400/80 = 5 h
Answer
t = 5 h
That is about 5 h 00 min, so the bag runs out at about 20:00.