Respiratory Air Flow and Volume
Exercise 1: Lung volumes and capacities Using the Horizontal Compression buttons and the scroll bar, display the data you wish to include in your report.
The predicted values are based on the Goldman and Becklake equations for Pulmonary Function (cited from the John Hopkins Pulmonary Laboratory)
1. Comment on the differences between the experimental and predicted values for VC, FRC and TLC in the table above. What could cause these differences, if any? The experimental values for VC, FRC and TLC are substantially lower than the predicted values which is based on the datas of heights and ages. The differences in the results could possibly be due to the subject having a smaller chest cavity, a lower level of fitness, and the subject having a habit of smoking which decreases FRC. Psychological effects such as self-consciousness of the subject could have also cause the differences in the values. The structure of the equipment having a long connection tube also adds on to the dead space, hence increasing the level of CO2 over time which affects the results.
Study Questions 2. In quiet breathing, muscular effort is used mainly in inspiration, and expiration is largely passive, due to elastic recoil of the lung. Can you relate this fact to the pattern of expiratory and inspiratory flow? Hint: the normal pattern of breathing is efficient in that it requires muscular effort for only a short time. The time period between the expiration peaks in flow pattern is shorter than that of the inspiration peaks. This reflects exhalation being a passive action, because it does not require effort and hence air flows out faster and expiration occurs over a shorter time compared to inspiration. During inspiration, muscular effort is needed and the pattern of the flow shows that the period of inspiration is longer that expiration.
3. Explain why RV cannot be determined by ordinary spirometry? RV cannot be deteremined by ordinary spirometry because it is physically impossible to exhale the RV.( The RV is there because during inspiration, a low pressure is created in our lungs. If the RV is not present, our lungs would collapse.) Special techniques are needed to determine RV such as nitrogen washout.
Exercise 2: Pulmonary function tests Using the Horizontal Compression controls and the scroll bar, display the data you wish to include in your report.
Study Questions 4. Comment on the differences between the experimental and predicted values for FVC, FEV1 and the FEV1/FVC ratio in the table above. What could cause these differences, if any? The experimental values are much lower than the predicted values. This could be due to the subject having weak lung muscles as the subject smokes regularly.
5. In you own words describe the physiological significance of the FEV1/FVC ratio? The ratio tells us the maximum amount of air that can be forcefully pushed out by the lungs, and how efficient the lungs are at exhaling forcefully as quckly as possible. This procedure is helpful in showing any possible obstructive lung disease that the person has, such as asthma or bronchitis.
6. Were your results for forced breathing consistent across all three trials? If not, why not? The results for forced breathing were more or less consistent across all three trials.
Exercise 3: Simulated airway obstruction Using the Horizontal Compression controls and the scroll bar, display the data for both normal pulmonary function tests (Exercise 2) and the simulated obstructed airway (Exercise 3) for inclusion in your report.
Study Questions 7. Based on your data, what values have been affected by simulated airway obstruction and why? Respiratory parameters PIF,PEF,FEV1 and FVE1/FVC ratio decreased substantially due to the simulated airway obstruction, while FVC was not affected as much as the former parameters. The airway obstruction causes an increase in the resistance of airflow. Hence, the values decrease because the subject has to put in more effort to overcome the airflow resistance, and airflow through the flowhead per unit time is decreased. FVC is not affected as much as the other parameters because the total inspired volume is almost the same as the unobstructed airway, just that the subject takes a longer time to inhale.
8. In your own words explain the physiological events that occurred during this simulated asthma attack. Hint: Think about what it felt like and how that would affect your general state of well being and activity level. Reduction in the airflow may be caused by the narrowing of the airways such as the bronchus and the trachea. This would make respiration alot harder and requires more effort from the person. The person would not be able to do strenous activity because the restricted airflow would not be able to accommodate a faster gas exchange of carbon dioxide and oxygen needed during exercise. However, under normal conditions, the person would just have an increased rate of respiration but they would still be able to function normally.
Exercise 4: Pulmonary function tests in different volunteers Using the Horizontal Compression controls and the scroll bar, display the data for Exercise 4 you wish to include in your report.
Study Questions 9. Comment on the range of results shown in the table for Exercise 4. The respiratory parameters PIF, PEF, FVC and FEV1 do not have a large range. However, the FEV1/FVC ratio has a very large range, 60% to 91%, and differs greatly for volunteer 1 compared to volunteers 2 & 3.
10. What factors do you think could contribute to differences in pulmonary parameters between the volunteers? The contributing factors could be gender, height differences ,fitness levels, structure of the chest cavity, and the extent of their effort during forced breathing.
11. General discussion In conclusion, the lung volumes and capacities vary from person to person and are affected by various factors. The smoking factor can also have a substantial effect on lung function and this is reflected in volunteer 1 having a much lower percentage of FVC expired in 1second compared to volunteers 2&3, also taking into account that volunteer 1 is a male and volunteers 2&3 are females. As seen in the experiments, obstructive respiration has a very large effect on the respiratory parameters and can greatly decrease the lung function of a person. By comparing the values tested for the subjects to the predicted parameters, we are able to detect any defects or abnormalties present in the lungs or respiratory tract of the subject.
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