Introduction / Background

In this interrupted case study, students read about an older woman named Barbara who becomes ill after driving with her husband 19 hours from Florida to visit their son’s family. Barbara experiences an asthma attack and then more serious breathing problems, which result in her admission to the hospital. Students are presented with a variety of signs, symptoms, and medical data relating to Barbara’s health, which they must interpret to solve this case in circulatory and respiratory physiology.

The case was developed for use in a one-semester animal physiology course taken by sophomore and junior science majors. It could also be used in an anatomy and physiology course, as well as a course in general biology. I find that the case is best performed when I am covering pulmonary physiology, and after I have covered circulation.

Objectives

Upon completion of this case, students will be able to:

• Describe what initiates an asthmatic episode.
• Relate airway diameter to air flow.
• Describe microcirculation at the capillaries as a balance between filtration and reabsorption, and explain how an edema is formed.
• Understand how blood clots formed in one part of the body can be dislodged, enter the circulation as an embolism, and block blood flow to other parts of the body.
• Demonstrate that changes in pulmonary blood flow can influence arterial blood gas levels, blood pressure, and heart rate.
• Synthesize medical data and form a hypothesis to diagnose the problem.

Classroom Management

The case takes 75 minutes to fully develop. Students work on the case in class in groups of five to six students. It can be taught in a single class period or presented over a number of classes. I prefer to do the case in one session because students seem to stay up-to-speed and become more engaged and involved if they perform all components at the same time.

Board Management

In my class I have a large white board that is divided into four areas. Erasable markers are used to enter student input and ideas as follows:

• The first area is used to list Barbara’s symptoms (from Part II of the case study).
• The second area is used for diagrams, such as the two graphs (Part II), the airways (Part II), and microcirculation at the capillaries (Part III).
• The third area is used to list the students’ suggestions for tests (Part III).
• The fourth area is used to list student speculations of Barbara’s problems (Parts II and III).

Entries are made throughout the case as information is provided. Speculations are entered in the fourth area from Part II onwards. If a certain speculation loses favor, the original group is asked if it is reasonable to delete their entry. If they (and the class) agree, an “x” is placed next to the entry. The entry is not erased because it may be reconsidered at a later date.

Case Management

Students are given each part of the case in sequence and instructed to read and discuss the material and answer the questions associated with it. Students are told how much time they have for each part of the case, and are permitted to use books, the Internet, and notes for reference. After the prescribed time period (5 to 15 minutes), the class is called together to share ideas; the questions are used as a basis for discussion. Groups take turns going first, and different members of each group are called upon for input. In this way, all of the students participate in the case study.

Each group is given a two-sided mini-whiteboard. Groups draw diagrams on these boards and are asked to hold them up so that everyone can see. In this case, the diagrams are the two graphs (Part I), the airways (Part I), and the capillary microcirculation (Part III).

Part I—The Grandparents Arrive

The grandparents drive 1200 miles in 19 hours, which means they probably stopped only for meals and gas. The afternoon of their arrival, the grandmother, Barbara, has an asthma attack, which is probably brought on by the allergens in the baby’s old teddy bear.

Part II—That Night

That night, Barbara has difficulty breathing. It becomes clear that she is experiencing something more than an asthma attack. She has pain in her chest, neck, and left arm. Students are asked to speculate what is wrong with Barbara, and many suggest a heart attack.

Part III—The Hospital

Barbara is taken to the Emergency Room, and students are given data for heart rate and blood pressure. The doctor examines Barbara, and students are asked about factors that influence capillary microcirculation. This section is rounded off by students suggesting tests to determine what is wrong with Barbara.

Part IV—Test, Tests, and More Tests

Two tests (V/Q scan and ultrasound) are described and some data are given from Barbara’s chart. The values include a low arterial PO₂, and a low blood pH and high PCO₂. At this stage, students should be able to determine that gas exchange at the lungs is not optimal. Students are asked to use the observations and the nature of the tests performed to speculate about what is wrong with Barbara.

Part V—A Few Days Later

Students are told that Barbara suffered a pulmonary embolism. She had blood clots in the veins in her thighs, and one probably dislodged to form an embolism, which traveled to her lung. Heparin dissolved the clots, and daily Warfarin tablets maintain blood clotting times within normal limits. Jen’s cat Muffy ate Warfarin and is now bleeding from an old cut. Students are asked to find out the mode of Warfarin’s action and the treatment that must be given to the cat.

Answer Key

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Acknowledgements: This case was published with support from the National Science Foundation under CCLI Award #0341279. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Date Posted: December 30, 2008.

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