Practice exercise (made-up values, not clinical guidance). Use the Devine formula to find the ideal body weight IBW of a woman who is 183 cm tall (1 in = 2.54 cm). Round to one decimal place.
183 cmwoman1 in = 2.54 cm
IBW = kg
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 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.
1500 mLdextrose 25%amino acids 6%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 total intake I in mL.
jelly: 100 mLsoup: 150 mLIV infusion: 60 mL/h × 8 hIV antibiotic: 1 × 50 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL infusion starts at 10:00 at 80 mL/h. After 3 hours the rate is changed to 75 mL/h and is not changed again. How many hours t after the start will the bag be empty? Round to one decimal place.
500 mL80 mL/h · 3 h75 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: IBW = 73.2 kg
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.
Height in inches
183 cm/2.54 = 72.05 in
Ideal body weight (Devine)
IBW = 45.5 + 2.3·(72.05 − 60) = 73.21 ≈ 73.2 kg
Answer
IBW = 73.2 kg
2.Enteral & parenteral nutrition calculations
Answer: E = 2135 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: 250·2 = 500 kcal
Total energy
E = 1275 + 360 + 500 = 2135 kcal/day
Answer
E = 2135 kcal/day
3.IV fluids & fluid balance
Answer: I = 780 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: 100 + 150 = 250 mL
IV infusion: 60·8 = 480 mL
IV antibiotic: 1·50 = 50 mL
I = 780 mL
Answer
I = 780 mL
4.IV fluids & fluid balance
Answer: t = 6.5 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.
First part
80·3 = 240 mL
500 − 240 = 260 mL left
Second part
260/75 = 3.467 h
Total time
t = 3 + 3.467 = 6.467 ≈ 6.5 h
Answer
t = 6.5 h
That is about 6 h 28 min, so the bag runs out at about 16:28.