Title III
Erie Community College
Algebra Skills Assignment
Health Sciences - Respiratory Care
Interdisciplinary Course Materials (ICM)
Course:
MT 006
Course Outline Topic:
Ratio, Proportion, Linear Inequalities
Project Title:
Oxygen Flow
Project description:
Students will be given several scenarios in which they will use
Air:Oxygen ratios provided to setup and solve proportions or linear
inequalities to find solutions to the problems posed.
Author:
Gail Butler (North Campus Mathematics/C.S. Department)
Curriculum Expert:
James Bierl (North Campus Respiratory Care Department)
Semester Created:
Fall 2008
A.
Essential Question
What is the total flow of oxygen being delivered by an air entrainment mask delivering a
certain percentage of oxygen?
B.
Introduction
An air entrainment oxygen mask mixes room air with pure oxygen so as to deliver a
precise amount of oxygen to a patient. In this project, you will investigate several
scenarios involving the use of air entrainment masks in respiratory therapy. You will use
your knowledge of ratios and proportions to solve the problems.
C.
Basic Directions
All work is to be shown in an organized fashion on separate paper. Your work should be
clearly labeled. In addition to correct answers, neatness and legibility are required for
full credit.
You may use a calculator for the computations. If necessary, follow the problem specific
directions for rounding your answers.
You are to complete this project on your own. It will count toward your final grade as
indicated in your instructor’s syllabus.
Erie Community College
Title III Grant
D.
Things to Learn Before Starting the Project
1. Know how to write and simplify ratios.
2. Know how to use ratios to write a proportion.
3. Know how to solve proportions.
4. Know how to solve word problems algebraically.
5. Know how to solve linear inequalities.
E.
The Project Assignment
The following Air: Oxygen ratios will be used in the problems you will be asked to solve.
What do these numbers mean? For example, in the first ratio (24% O2 ) for every 1 liter
of pure oxygen flow to the mask, the mask entrains (“sucks in”) 25 liters of room air (the
air already has some oxygen in it but the mask is adding 1 liter of pure oxygen to it.)
Air : Oxygen Ratios
24% O2
30% O2
35% O2
40% O2
50% O2
60% O2
=
=
=
=
=
=
Air: Oxygen (pure)
25 : 1
8:1
5:1
3:1
1.7 : 1
1:1
Problem #1
A respiratory therapist is setting up an air entrainment mask to deliver 40% oxygen to a
patient. If the therapist runs the mask with 9 Liters of oxygen (per minute), how many
Liters of air (per minute) are entrained? You must set up and solve a proportion that
includes a word plan in your solution.
Problem #2
A patient is wearing a 24% air entrainment mask running at 3 L/M (3 liters of oxygen per
minute). What is the total flow of gas per minute being delivered? You must set up and
solve a proportion that includes a word plan in your solution. Also, keep in mind that
total flow will be the amount of air plus the amount of pure oxygen that is being added by
the mask.
Erie Community College
Title III Grant
Problem #3
A patient wearing a 35% air entrainment mask has its oxygen flow increased from 4 L/M
to 8 L/M.
a. Set up and solve a proportion (including a word plan) to find the total flow of gas per
minute that was being delivered when the oxygen flow was 4 L/M.
b. Set up and solve a proportion (including a word plan) to find the total flow of gas per
minute that was being delivered when the oxygen flow is 8 L/M.
c. What is the change in total flow?
Problem #4
A respiratory therapist is setting up a 30% air entrainment mask at 6 L/M (the oxygen
flow). Calculate the total flow of gas. You must set up and solve a proportion that
includes a word plan in your solution.
Use the following problem as an example to help you complete problems 5 and 6.
A patient requires a total flow of 50 L/M from his oxygen mask which is set to deliver
40% oxygen. What should be the minimum oxygen flow set to meet the patient’s
inspiratory flow rate demands? Round your answer to the nearest integer.
Explanation: At 40%, the air:oxygen ratio is 3:1 (remember this means 3 parts air and 1
part pure oxygen, making the total flow 3parts + 1part = 4parts). Recall that other ratios are
3 6 9 12
equivalent to this simplified ratio:    etc . The numerator and denominator can be
1 2 3 4
multiplied by any integer to obtain an equivalent ratio. Our goal is to find what number to
multiply both numbers in the ratio by to achieve a total flow of 50 L/M.
Let x = minimum oxygen flow set.
3x + x  50 (Remember the numbers in the ratio are 3 and 1)
4x  50 (Divide both sides by 4)
x  12.4
Since the answer must be greater than 12.4, we must go up to the next integer.
x= 13 L/min
Erie Community College
Title III Grant
Problem #5
A patient requires a total flow of 72 L/M from his oxygen mask which is set to deliver
24% oxygen. What should be the minimum oxygen flow set to meet the patient’s
inspiratory flow rate demands? Round your answer to the nearest integer.
Problem #6
A patient requires a total flow of 62 L/M from his oxygen mask which is set to deliver
35% oxygen. What should be the minimum oxygen flow set to meet the patient’s
inspiratory flow rate demands? Round your answer to the nearest integer.
F.
Student Resources (websites, books, technology, etc.)
Textbook; Class notes (to review ratios and proportions)
G.
Faculty Resources (teacher notes, websites, books, technology, etc.)
H.
Suggested Grading Rubric
Problems 1 - 6: 7.5 points each
Neatness and Legibility: 5 points
Total: 50 points
Erie Community College
Title III Grant
Answer Key
Problem 1:
3 x

1 9
air
oxygen
x = 27 L/min
Problem #2:
air
oxygen
25 x

1
3
x = 75 L/min (this is the amount of air). To find the total flow, it must be
added to the number of liters of oxygen that the mask is adding” 75 + 3 = 78L/min.
Problem #3:
a.
air
oxygen
5 x

1 4
x = 20 L/min ( amount of air). Total flow = 20 + 4 = 24 L/min.
b.
air
oxygen
5 x

1 8
x = 40 L/min (amount of air). Total flow = 40 + 8 = 48 L/min.
c. Change in total flow = 48 – 24 = 24 L/min.
Problem #4:
air
oxygen
8 x

1 6
x = 48 L/min (the amount of air). Total flow = 48 + 6 = 54 L/min.
Problem #5:
Let x = minimum oxygen flow set.
25x + x  72
26x  72
x  2.77
x = 3 L/min
Problem #6:
Let x = minimum oxygen flow set.
5x + x  62
6x  62
x  10.33
x = 11 L/min
Erie Community College
Title III Grant
Erie Community College
Title III Grant