Practice exercise (made-up values, not clinical guidance). A 60 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 84% free water and runs at 50 mL/h for 20 hours a day. The rest of the fluid is given as water flushes every 4 hours. What volume V is each flush? Round to the nearest whole number.
60 kg35 mL/kg/day84%50 mL/h · 20 hevery 4 h
V = mL
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 5% amino acids, plus 250 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
1500 mLdextrose 10%amino acids 5%lipid 250 mL · 1.1 kcal/mL
NPC : N =
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 patient weighs 97 kg. Find the average urine output U in mL/kg/h. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A 1000 mL bag was started at 12:15 and runs by pump at 60 mL/h. How many mL V are left in the bag at 19:45?
1000 mL60 mL/h12:15 → 19:45
V = mL
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: V = 210 mL
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.
Fluid goal
35·60 = 2100 mL/day
Free water from the formula
50·20 = 1000 mL
1000·0.84 = 840 mL
Water still needed
2100 − 840 = 1260 mL/day
Volume per flush
24/4 = 6 flushes
V = 1260/6 = 210 mL
Answer
V = 210 mL
2.Enteral & parenteral nutrition calculations
Answer: NPC : N = 65
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: 5·1500/100 = 75 g
Kilocalories per component
dextrose: 150·3.4 = 510 kcal
amino acids: 75·4 = 300 kcal
lipid: 250·1.1 = 275 kcal
Non-protein kcal and nitrogen
NPC = 510 + 275 = 785 kcal
N = 75/6.25 = 12 g
Ratio
NPC : N = 785/12 = 65.42 ≈ 65 : 1
Answer
NPC : N = 65
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
3.IV fluids & fluid balance
Answer: U = 1.18 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
450 + 325 + 400 + 200 = 1375 mL
Per kilogram per hour
U = 1375/(97·12) = 1.181 ≈ 1.18 mL/kg/h
Answer
U = 1.18 mL/kg/h
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.