Practice exercise (made-up values, not clinical guidance). A 51 kg patient needs 1.3 g of protein per kg a day. The tube feed contains 40 g of protein per litre and runs at 70 mL/h for 16 hours a day. A protein powder supplies 10 g of protein per scoop. How many scoops n a day are needed to cover the shortfall? Round up to a whole scoop.
51 kg1.3 g/kg/day40 g/L70 mL/h · 16 h10 g/scoop
n =
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1000 mL of parenteral nutrition with final concentrations of 12.5% 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.
1000 mLdextrose 12.5%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 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 500 mL bag runs by pump at 60 mL/h. At 13:30, 300 mL have already been infused. How many hours t until the bag is empty? Round to one decimal place.
500 mL300 mL infused60 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: n = 3
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
1.3·51 = 66.3 g/day
Protein from the feed
70·16 = 1120 mL = 1.12 L
1.12·40 = 44.8 g/day
Shortfall
ΔP = 66.3 − 44.8 = 21.5 g
Scoops
21.5/10 = 2.15 → n = 3
Answer
n = 3
2.Enteral & parenteral nutrition calculations
Answer: E = 1115 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: 12.5·1000/100 = 125 g
amino acids: 3.5·1000/100 = 35 g
Kilocalories per component
dextrose: 125·3.4 = 425 kcal
amino acids: 35·4 = 140 kcal
lipid: 500·1.1 = 550 kcal
Total energy
E = 425 + 140 + 550 = 1115 kcal/day
Answer
E = 1115 kcal/day
3.IV fluids & fluid balance
Answer: B = 790 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 + 240 = 480 mL
ice chips: 240/2 = 120 mL
IV infusion: 60·12 = 720 mL
IV antibiotic: 1·50 = 50 mL
total intake = 1370 mL
Total output
250 + 200 + 30 + 100 = 580 mL
Balance
B = 1370 − 580 = 790 mL
Answer
B = 790 mL
Positive: more fluid went in than came out.
4.IV fluids & fluid balance
Answer: t = 3.3 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
500 − 300 = 200 mL
Time
t = 200/60 = 3.333 ≈ 3.3 h
Answer
t = 3.3 h
That is about 3 h 20 min, so the bag runs out at about 16:50.