October 21 2015 Introduction

Sam Smith

Pulmonary Function Lab

Moyer

October 21 2015

Introduction

For pulmonary function and the breathing process to occur, the lungs are used to exchange the gasses O₂ and CO₂. The lungs will transfer oxygen from the air to the blood and carbon dioxide from the blood to the air. The passing of air occurs through the airways of the body, and the actual gas exchange occurs through the thin walls of the alveoli at the ends of the bronchioles. The actual breathing process contains two key actions: inhalation and exhalation. During inhalation, muscles of the diaphragm and the rib cage contract and expand the size of the chest causing negative pressure within the airways and alveoli. As a result, air is pulled through the airways and into the alveoli and the chest wall is enlarged. During exhalation, the same muscles relax and the chest wall springs back to its resting positions, shrinking the chest and creating positive pressure within the airways and alveoli. As a result, air is expelled from the lungs.

There are some known diseases that interfere with the way air is both taken in and released from the lungs. These diseases can be tricky to understand if a person does not have one himself/herself, because it is difficult to gain an understanding of how it affects those that do have the disease. There are two large categories of diseases of this nature, and they are restrictive diseases and obstructive diseases. Restrictive lung diseases are chronic disorders that decrease the ability to expand the lungs during inhalation. This category of diseases also makes it difficult to get enough oxygen in to meet the body's needs. With obstructive lung diseases, on the other hand, there is a chronic obstruction of the flow of air through the airways and out of the lungs, and the obstruction is usually permanent and may be progressive over time. The chronic lung conditions are generally classified as COPD - chronic obstructive pulmonary disease. COPD is most often characterized by the symptoms at the time of an aggravation of the disease. Some examples of these diseases may be chronic bronchitis, chronic asthma, and emphysema. The purpose of this lab is to try and gain a better understanding of how both restrictive and obstructive diseases affect the breathing process of a person by simulating the symptoms of the disease.

Methods

To complete the lab, a spirometer was used to measure the breathing rate, Forced expiratory volume (FEV₁), mean tidal volume, and a variety of other lung volumes. The subject would be seated comfortably, and was asked to breathe normally. Once the testing began, the subject was asked to breathe into the flowhead. While the machine was recording, the subject was to take three normal breaths, followed by a large breath (this 3normal:1Large pattern will be completed three times). During the large breath, the subject should inhale as quickly and completely as possible, and should exhale for as long as possible, i.e., until the lungs are completely empty. The tester and subject should be able to see the waves of their breaths on the screen. With a restrictive disease, it is difficult for a person to get air into the lungs. To simulate this, the subject would wear a corset to place pressure on the rib cage, not allowing it to expand as much. Once the subject was seated with the corset tight around the ribcage, the subject would complete the same small breaths/big breath routine as before. With an obstructive disease, it is difficult to get air out of the lungs, which in turn will make it difficult to get into the lungs, and so forth. To simulate such a disease, we taped a standard straw to the mouthpiece, to make it more difficult to get air out from the lungs. After the straw was taped on and the corset was removed, the subject would complete the same breathing routine as the first two other tests (note: when taping the straw onto the mouthpiece, be sure to cover the rest of the mouthpiece completely, to ensure that all air passing through is coming from the subject’s straw).

Results and Graphs

Forced Expiration Lung Volumes

As you can see in the graph above, my obstructive FEV was much higher than both normal and restrictive. I believe this occurred because the mouthpiece was smaller, and so I was forced to push air out slower than before. By pushing the air out slower, my lungs did not feel as empty as quickly, and I was able to push out more air before my lungs felt empty. I believe that the normal and Restrictive FEVs were so similar because the corset was not as tight as it could have been, so there was not much restriction actually occurring. This graph may actually be misleading when compared to the other results, however, because the FEV1s were drastically different. The FEV1s for normal, restrictive, and obstructive were 3.989, 2.498, and 1.899, respectively. Though the total FEV volumes were similar or misleading, the FEV1s show the true effect these diseases have on breathing. This effect is most clearly shown by the FEV1 of the obstructive test. Obstructive diseases inhibit air from being expelled from the lungs, and this is most evident in the fact that there was a 2L difference in FEV1 when comparing normal breathing to obstructive breathing.

The other results from the test show exactly what could be expected. The forced air flow rates of normal breathing were higher than those of the restrictive and obstructive tests (5.346 compared to 4.441 and 1.367). Another example of the simulated diseases affecting the breathing process is the Inspiratory Reserve Volume (IRV). The IRVs were lower in both restrictive and obstructive (1.573 and .288) when compared to normal breathing (1.86), which shows that these diseases hinder the body’s ability to intake air into the lungs.

Discussion

The forced Vital Capacity of the restrictive breathing test was nearly equal to that of the normal breathing test (4.874 to 4.891), but there was evidence of restricted breathing in both the IRV and ERV. Both the IRV and ERV of the restricted breathing were .3L lower than that of the normal breathing, showing the inability to intake and then release breaths with a restrictive disease.

From a physiological standpoint, the results were mostly what I was expecting, but there were a few standouts points that intrigued me. As mentioned in the results section, the FVC and FEV of the obstructed disease were far higher than expected. An obstructive disease should, in theory, be the most inhibitory to all aspects of breathing, since air has trouble coming both in and out. I would also say that the restrictive results could have been more drastic, but I feel that that was due to the corset not being as tight as it could have been. The results were different from the normal breathing results, and the results did show negative effects of restrictive diseases on breathing, but I would have expected the effects to be more drastic.

It could be argued that these results would be different between genders, but it could also be argued that the results would not be different. Men are generally bigger than women, which would mean they have a larger chest, and thus, a larger FVC. At the same time, however, men generally have more mass surrounding their rib cage, which could result in some restrictive-type effects on the breathing. The opposite situation could be true for females, where they may not have restrictions on their rib cages, but they may not have very large rib cages to begin with, which would lower the FVC. Since men generally have more muscle, they also may be able to force a larger inhalation and expiration, pushing their bodies to the limit. With this though, they again could be restricting themselves by having such muscles. This argument could go back and forth forever, and I feel that since there is so much back-and-forth that the results would not be dependent on gender.

This lab helped provide an understanding of these diseases and how they affected the breathing process to people who do not have those diseases. Though some of the results were odd, I felt that most of the results were an accurate representation of the diseases, and how the breathing process is affected by them. I would like to see a comparison between men and women’s results to better answer the back-and-forth argument mentioned earlier. Overall, I felt like this lab yielded accurate results that provided an accurate representation of how these diseases affect the breathing process.

Questions:

1. 
   Did tidal volume change while the subject had on the corset? What about while the subject was breathing through the narrowed opening?
   

Tidal volume was lowered while wearing the corset and breathing through the narrowed opening, but the corset did not have a large effect on the tidal volume. This effect may have been affected by the tightness of the corset; if the corset was not that tight, the tidal volume would be very similar to the resting breathing.

2. 
   Did inspiratory and expiratory reserves change while the subject was wearing the corset? While the subject was breathing through the narrowed opening?
   

While the subject was wearing the corset, both the IRV and ERV dropped, showing the body’s inability to fully expand the lungs/ribs. While the subject was breathing through the narrowed opening, the IRV and ERV dropped significantly, showing the body’s inability to intake and release air.

3. 
   Did chest restriction influence the time taken for each breathing cycle?
   

Chest restriction increased the amount of time take for each breathing cycle, because the chest could not quickly expand as it could without the restriction.

4. 
   Did the rate of air flow during the inhalation phase increase or decrease with restriction or obstruction of the chest? How can you account for the change(s) (be sure to address both factors)?
   

The rate of air flow decreased with both obstruction and restriction of the chest. With obstruction, air has a difficult time exiting the lungs, would make it difficult to get a substantial breath in, which would slow the breathing rate. With restrictive breathing, the body has a difficult time getting a full breath in, which would force the breathing rate to slow down and take deeper breaths to get an adequate amount of air in the lungs.

5. 
   Did the rate of air flow during the exhalation phase increase or decrease with restriction or obstruction of the chest? How can you account for the change(s) (be sure to address both factors)?
   

Obstructive breathing makes it difficult to get air out of the lungs, so the rate of air flow would decrease significantly. Restrictive breathing would slow down the inhalation process, and in order to keep smooth, balanced breaths the exhalation rate would need to slow down to match it.

6. 
   Did the volume of air passing in and out of the resting subject’s lungs each minute increase or decrease while the subject’s chest was restricted? When the subject was breathing through the narrowed opening?
   

While the subject was restricted, the subject’s volume of air passing in and out of the lungs was mostly unaffected, but the rate was slowed slightly. When the subject was obstructed, the subject’s volume of air passing in and out of the lungs was decreased greatly, because there was an inability to both get air into the lungs out of the lungs.