Practice exercise (made-up values, not clinical guidance). Use the Devine formula to find the ideal body weight IBW of a man who is 193 cm tall (1 in = 2.54 cm). Round to one decimal place.
193 cmman1 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 10% dextrose and 3.5% amino acids, plus 250 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein energy NPC in kcal per day. Round to the nearest whole number.
1500 mLdextrose 10%amino acids 3.5%lipid 250 mL · 1.1 kcal/mL
NPC = 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 total intake I in mL. Count ice chips as half their volume.
tea: 240 mLjuice: 100 mLice chips: 200 mLIV infusion: 125 mL/h × 12 hIV antibiotic: 1 × 100 mL
I = mL
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 500 mL infusion starts at 09:00 at 75 mL/h. After 4 hours the rate is changed to 100 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 mL75 mL/h · 4 h100 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: IBW = 86.8 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
193 cm/2.54 = 75.98 in
Ideal body weight (Devine)
IBW = 50 + 2.3·(75.98 − 60) = 86.76 ≈ 86.8 kg
Answer
IBW = 86.8 kg
2.Enteral & parenteral nutrition calculations
Answer: NPC = 785 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: 10·1500/100 = 150 g
amino acids: 3.5·1500/100 = 52.5 g
Kilocalories per component
dextrose: 150·3.4 = 510 kcal
amino acids: 52.5·4 = 210 kcal
lipid: 250·1.1 = 275 kcal
Non-protein energy
NPC = 510 + 275 = 785 kcal/day
Answer
NPC = 785 kcal/day
3.IV fluids & fluid balance
Answer: I = 2040 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: 240 + 100 = 340 mL
ice chips: 200/2 = 100 mL
IV infusion: 125·12 = 1500 mL
IV antibiotic: 1·100 = 100 mL
I = 2040 mL
Answer
I = 2040 mL
4.IV fluids & fluid balance
Answer: t = 6 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
75·4 = 300 mL
500 − 300 = 200 mL left
Second part
200/100 = 2 h
Total time
t = 4 + 2 = 6 h
Answer
t = 6 h
That is about 6 h 00 min, so the bag runs out at about 15:00.