Table of Contents
Understanding Total Parenteral Nutrition (TPN) involves mastering concepts like volume, rate, and osmolarity. Practice problems can help reinforce these concepts, ensuring safe and effective patient care. Below are some practice problems with detailed answers to enhance your learning.
Practice Problems on TPN Volume
Problem 1: A patient requires 1500 mL of TPN solution over 24 hours. What is the hourly infusion rate?
Answer: To find the hourly rate, divide the total volume by the number of hours:
Rate = 1500 mL / 24 hours = 62.5 mL/hour
Practice Problems on TPN Rate
Problem 2: A nurse administers TPN at a rate of 80 mL/hour. How much TPN will the patient receive in 12 hours?
Answer: Multiply the rate by the number of hours:
Volume = 80 mL/hour × 12 hours = 960 mL
Practice Problems on Osmolarity
Problem 3: A TPN solution contains 20 grams of dextrose in 100 mL of solution. What is the osmolarity contribution of dextrose in mOsmol/L? (Dextrose’s molecular weight is 180 g/mol, and it dissociates into particles in solution.)
Answer: First, calculate the molarity:
Moles of dextrose = 20 g / 180 g/mol ≈ 0.111 mol
Molarity = 0.111 mol / 0.1 L = 1.11 mol/L
Since dextrose does not dissociate, osmolarity = molarity × 1 = 1110 mOsmol/L
Additional Practice Problems
Problem 4: A TPN solution has a total osmolarity of 900 mOsmol/L. If the total volume to be infused is 1500 mL over 24 hours, what is the osmolarity per liter?
Answer: Since the total osmolarity is given per liter, it remains 900 mOsmol/L.
Problem 5: Calculate the infusion rate in mL/hour for a TPN solution that needs to deliver 1200 mOsmol over 24 hours with a solution osmolarity of 900 mOsmol/L.
Answer: First, find the total volume needed:
Volume = Total osmoles / Osmolarity per liter = 1200 mOsmol / 900 mOsmol/L ≈ 1.33 L = 1333 mL
Then, calculate the hourly rate:
Rate = 1333 mL / 24 hours ≈ 55.5 mL/hour