Practice exercise (made-up values, not clinical guidance). A 97 kg patient needs 1.2 g of protein per kg a day. The tube feed contains 40 g of protein per litre and runs at 70 mL/h for 18 hours a day. How many grams of extra protein ΔP a day are still needed? Round to one decimal place.
97 kg1.2 g/kg/day40 g/L70 mL/h · 18 h
ΔP = g/day
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 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 25%amino acids 6%lipid 250 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 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). Count ice chips as half their volume.
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 06:15 and runs by pump at 60 mL/h. How many mL V are left in the bag at 13:45?
1000 mL60 mL/h06:15 → 13:45
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: ΔP = 66 g/day
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.
Protein needed
1.2·97 = 116.4 g/day
Protein from the feed
70·18 = 1260 mL = 1.26 L
1.26·40 = 50.4 g/day
Shortfall
ΔP = 116.4 − 50.4 = 66 g/day
Answer
ΔP = 66 g/day
2.Enteral & parenteral nutrition calculations
Answer: E = 1910 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: 250·1.1 = 275 kcal
Total energy
E = 1275 + 360 + 275 = 1910 kcal/day
Answer
E = 1910 kcal/day
3.IV fluids & fluid balance
Answer: B = 1610 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: 240 + 120 + 250 = 610 mL
ice chips: 100/2 = 50 mL
IV infusion: 125·12 = 1500 mL
IV antibiotic: 2·50 = 100 mL
total intake = 2260 mL
Total output
425 + 225 = 650 mL
Balance
B = 2260 − 650 = 1610 mL
Answer
B = 1610 mL
Positive: more fluid went in than came out.
4.IV fluids & fluid balance
Answer: V = 550 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.