Practice exercise (made-up values, not clinical guidance). A 58 kg adult (BMI below 30) needs 35 kcal/kg/day. The tube feed provides 1.5 kcal/mL and runs by pump for 20 hours a day. At what rate R do you set the pump, in mL/h? Round to the nearest whole number.
58 kg35 kcal/kg/day1.5 kcal/mL20 h
R = mL/h
2.Enteral & parenteral nutrition calculationsHard
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1200 mL of parenteral nutrition with final concentrations of 12.5% dextrose and 4.25% amino acids, plus 250 mL of 20% lipid emulsion (2 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
1200 mLdextrose 12.5%amino acids 4.25%lipid 250 mL · 2 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 72 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 infusion starts at 16:00 at 120 mL/h. After 3 hours the rate is changed to 75 mL/h and is not changed again. How many hours t after the start will the bag be empty? Round to one decimal place.
1000 mL120 mL/h · 3 h75 mL/h
t = h
3Solutions
1.Enteral & parenteral nutrition calculations
Answer: R = 68 mL/h
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.
Energy needed
E = 35·58 = 2030 kcal/day
Daily volume
V = 2030/1.5 = 1353 mL/day
Pump rate
R = 1353/20 = 67.67 ≈ 68 mL/h
Answer
R = 68 mL/h
2.Enteral & parenteral nutrition calculations
Answer: NPC : N = 124
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: 12.5·1200/100 = 150 g
amino acids: 4.25·1200/100 = 51 g
Kilocalories per component
dextrose: 150·3.4 = 510 kcal
amino acids: 51·4 = 204 kcal
lipid: 250·2 = 500 kcal
Non-protein kcal and nitrogen
NPC = 510 + 500 = 1010 kcal
N = 51/6.25 = 8.16 g
Ratio
NPC : N = 1010/8.16 = 123.8 ≈ 124 : 1
Answer
NPC : N = 124
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
3.IV fluids & fluid balance
Answer: U = 1.3 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
350 + 200 + 200 + 375 = 1125 mL
Per kilogram per hour
U = 1125/(72·12) = 1.302 ≈ 1.3 mL/kg/h
Answer
U = 1.3 mL/kg/h
4.IV fluids & fluid balance
Answer: t = 11.5 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
120·3 = 360 mL
1000 − 360 = 640 mL left
Second part
640/75 = 8.533 h
Total time
t = 3 + 8.533 = 11.53 ≈ 11.5 h
Answer
t = 11.5 h
That is about 11 h 32 min, so the bag runs out at about 03:32.