Practice exercise (made-up values, not clinical guidance). A man is 187 cm tall and weighs 112 kg. Find the actual weight as a percentage of the ideal body weight, %IBW, using the Devine formula (1 in = 2.54 cm). Round to the nearest whole number.
187 cm112 kgman
%IBW = %
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 17.5% dextrose and 3.5% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
1500 mLdextrose 17.5%amino acids 3.5%lipid 500 mL · 1.1 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 patient weighs 110 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
110 kg8 hurine: 400 mLurine: 250 mLwound drain: 140 mL
U = mL/kg/h
4.IV fluids & fluid balanceHard
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 13:30 and runs by pump at 80 mL/h. How many mL V are left in the bag at 20:30?
1000 mL80 mL/h13:30 → 20:30
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: %IBW = 138 %
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.
Ideal body weight (Devine)
187 cm/2.54 = 73.62 in
IBW = 50 + 2.3·(73.62 − 60) = 81.33 kg
Percentage of ideal body weight
%IBW = 112/81.33·100 = 137.7 ≈ 138%
Answer
%IBW = 138%
2.Enteral & parenteral nutrition calculations
Answer: E = 1653 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: 17.5·1500/100 = 262.5 g
amino acids: 3.5·1500/100 = 52.5 g
Kilocalories per component
dextrose: 262.5·3.4 = 892.5 kcal
amino acids: 52.5·4 = 210 kcal
lipid: 500·1.1 = 550 kcal
Total energy
E = 892.5 + 210 + 550 = 1653 kcal/day
Answer
E = 1653 kcal/day
3.IV fluids & fluid balance
Answer: U = 0.74 mL/kg/h
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 urine
400 + 250 = 650 mL
Per kilogram per hour
U = 650/(110·8) = 0.7386 ≈ 0.74 mL/kg/h
Answer
U = 0.74 mL/kg/h
4.IV fluids & fluid balance
Answer: V = 440 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.