Exam 3: 6 Mar Basic Pulmonary Function Testing And Gas Exchange Flashcards
What is dead space in the context of pulmonary function?
Dead space refers to the air in the upper airways and conducting zones that does not participate in gas exchange
In healthy individuals, dead space is limited to chemical death rates.
How much of a normal tidal breath (500 cc) typically reaches the alveoli?
About 350 cc of the tidal breath reaches the alveoli, while the remaining 150 cc is dead space air.
What is the formula for calculating the partial pressure of a gas?
The partial pressure of a gas is equal to the fractional concentration of the gas multiplied by the total pressure
Commonly used total pressures are 760 mmHg or 713 mmHg after accounting for vapor pressure of water.
What is the normal alveolar pressure of nitrogen in millimeters of mercury?
569 millimeters of mercury.
Fill in the blank: The concentration of nitrogen in lung air is approximately ______.
75%.
What happens to the concentration of nitrogen in lung air compared to dry atmospheric air?
It decreases from about 80% in dry atmospheric air to about 75% in lung air due to water vapor.
True or False: The total pressure of all gases at sea level is 760 mmHg.
True.
What is Fowler’s test used for?
Fowler’s test analyzes the nitrogen content in expired air to assess pulmonary function.
What is the expected expired nitrogen concentration when a healthy person breathes room air?
About 75% to 80% nitrogen concentration.
What is the significance of using a source of 100% oxygen in pulmonary function tests?
It allows for the measurement of nitrogen coming from the lungs, as the inspired air contains no nitrogen.
Fill in the blank: To find the nitrogen concentration in lung air, divide the alveolar pressure of nitrogen by ______.
760.
What does a nitrogen meter measure during a pulmonary function test?
The concentration of nitrogen in the expired gas.
What is the role of water vapor in gas exchange within the lungs?
Water vapor displaces some of the gas in the lungs, affecting the concentration measurements.
What is the formula to find the concentration of a gas in the lungs if the partial pressure and total pressure are known?
Fractional concentration = Partial pressure / Total pressure.
What does the term ‘anatomical dead space’ refer to?
The volume of air in the conducting zones where no gas exchange occurs.
What is the significance of the transitional zone between dead space air and alveolar air?
It allows for some mixing and minor gas exchange between dead space air and alveolar air.
In pulmonary function tests, why is it important to account for water vapor?
To accurately determine the concentration of gases in the lungs, as water vapor displaces some of the gas volume.
What is the expected partial pressure of nitrogen when inspiring 100% oxygen?
569 millimeters of mercury
What is the composition of the first part of the inspired breath when breathing 100% oxygen?
Contains no nitrogen
What is anatomical dead space?
The portion of the respiratory system where no gas exchange occurs
What should be expected in the first portion of expired breath after inhaling 100% oxygen?
0% nitrogen
What is the alveolar plateau in expired breath?
A phase where the expired nitrogen concentration stabilizes
How much anatomical dead space is expected in a healthy 20-year-old?
About 150 CC’s
What is the nitrogen washout test used for?
To analyze ventilation distribution in the lungs
What is the expected nitrogen concentration in expired air from a healthy individual after breathing normally?
Dilution of nitrogen concentration occurs with each breath
What is the normal endpoint for the nitrogen washout test in a healthy individual?
2.5% nitrogen concentration
What is an abnormal result in the nitrogen washout test?
Taking greater than seven minutes to reach 2.5% nitrogen concentration
What indicates uneven ventilation in the nitrogen washout test?
Scattered data points and irregular nitrogen dilution
What can cause a delay in nitrogen washout besides uneven ventilation?
Large lung capacity in individuals with COPD
What does the flow-volume graph represent?
Air flow rates during maximal inspiration and expiration
What happens to air flow rate during expiration as lung volume decreases?
The air flow rate slows down
What is the maximum expected peak air flow rate during expiration?
About 10 liters per second
What is the significance of the vital capacity in respiratory function?
It represents the maximum amount of air that can be expelled from the lungs
Fill in the blank: The anatomical dead space should have ______% nitrogen in it after inhaling 100% oxygen.
0
True or False: The first breath after inhaling 100% oxygen should have a higher nitrogen concentration than subsequent breaths.
False
What happens to the nitrogen concentration in the lungs after multiple breaths of 100% oxygen?
It continues to dilute with each breath
What does a normal nitrogen washout test result look like on a graph?
A smooth, orderly reduction in nitrogen concentration
In a nitrogen washout test, what is indicated by a longer time to reach the endpoint?
Potentially unhealthy lung function
What is the relationship between lung size and nitrogen washout test results?
Larger lungs may require longer to wash out nitrogen due to increased volume
What should be monitored during the nitrogen washout test?
Expired gas nitrogen content over time
What happens to the air flow rate as lung volumes decrease?
The air flow rate slows down as we get towards lower lung volumes.
What is the total lung capacity?
The total lung capacity is the maximum amount of air that the lungs can hold.
What is vital capacity?
The vital capacity is the difference between total lung capacity and residual volume.
Describe the relationship between effort and expired air flow.
At high lung volumes, expired air flow is effort dependent; at low lung volumes, it becomes effort independent.
What is effort dependence in the context of lung function?
Effort dependence refers to the degree to which expiratory flow rate is affected by the effort applied.
What is effort independence in the context of lung function?
Effort independence occurs when the maximum expired flow rate is capped and does not increase with additional effort.
What happens to the expiratory flow rate during maximal effort?
The expired air flow picks up quickly, peaks, and then tapers off throughout expiration.
What muscle groups are primarily involved in forced expiration?
- Internal intercostal muscles
- Abdominal muscles
What is elastic recoil pressure?
Elastic recoil pressure is the pressure generated when the lungs are stretched to total lung capacity.
How does a patient’s health affect their expiratory flow rate?
The more unhealthy a patient is, the slower they are able to expel air.
What is the typical pleural pressure during maximal effort expiration?
Pleural pressure is usually positive during maximal effort expiration.
What is the significance of the flow volume loop?
The flow volume loop helps visualize the relationship between lung volume and flow rate during expiration and inspiration.
What is FVC?
FVC stands for forced vital capacity, referring to the maximum amount of air that can be forcibly exhaled.
What does a lower residual volume indicate in restrictive lung disease?
Lower residual volume indicates less air remaining in the lungs after expiration due to increased elastic tissue.
What does a higher residual volume indicate in obstructive lung disease?
Higher residual volume indicates that the lungs are fuller at higher pleural pressures, making it difficult to expel air.
How does vital capacity differ between restrictive and obstructive lung diseases?
- Restrictive lung disease: lower vital capacity
- Obstructive lung disease: smaller vital capacity due to increased lung fullness
What is the typical shape of the expiratory flow rate curve in healthy lungs?
The curve resembles an upside-down ice cream cone.
True or False: The inspiratory flow rate is usually prioritized over the expiratory flow rate in pulmonary function tests.
False
Fill in the blank: The maximum expiratory flow rate is affected by _______ and _______.
elastic recoil pressure and pleural pressure
What happens to the time required for expiration in patients with low elastic recoil?
More time is needed for expiration due to slower passive forces.
What is the significance of the peak inspiratory flow rate?
The peak inspiratory flow rate occurs at the halfway point of the inspiration loop.
What is vital capacity?
The maximum amount of air a person can exhale after a maximum inhalation.
What is the typical vital capacity for a healthy individual?
Approximately four and a half liters.
How does vital capacity differ in restrictive lung disease?
It is lower than normal, approximately three liters.
In obstructive lung disease, what happens to vital capacity?
It is smaller due to increased residual volume.
What is the relationship between airflow rate and disease severity?
Lower airflow rate usually indicates worse disease.
What is FBC an abbreviation for?
Forced Vital Capacity maneuver.
What does a flow volume loop typically not provide?
Specific values for residual volume.
What is the significance of residual volume in lung disease?
A large residual volume may indicate severe disease.
What is the role of positive pleural pressure during forced expiratory maneuvers?
It affects the ability of airways to stay open.
What happens to airway pressure as air moves up the respiratory tree?
Airway pressure decreases.
What supports the structure of the conducting zones in the respiratory system?
Cartilage.
What is a vulnerable point in the small airways?
The area just before cartilage support begins.
What occurs if alveolar pressure is low but pleural pressure is high?
Small airway collapse may happen.
True or False: The shape of the flow volume loop can provide information about lung disease.
True.
Fill in the blank: The lower the vital capacity, the ______ the disease.
worse.
What is the significance of expiratory flow rate in lung function tests?
It indicates how well air can be expelled from the lungs.
What can be inferred from a maximal forced expiratory flow rate?
It provides insight into airway obstruction.
What is typically not plotted in flow volume loops from pulmonary function labs?
Specific residual volume values.
What is the relationship between vital capacity and disease severity?
Typically, the sicker you are, the smaller your vital capacity.
