Question 1

A patient's lung compliance was measured with the use of an intraesophageal balloon (a measure of pleural pressure).When he has inspired 500 mL,his intraesophageal pressure decreases from -3 cm H₂O at FRC to -7 cm H₂O.What is his lung compliance?

A)1.67 L/cm H₂O
B)0.71 L/cm H₂O
C)0.500 L/cm H₂O
D)0.125 L/cm H₂O

Accepted Answer

D

Question 2

If the compliance of the lung is 0.2 L/cm H₂O and the compliance of the chest wall is 0.2 L/cm H₂O,what is the compliance across the respiratory system (C_rs)? A)0.1 L/cm H₂O B)0.4 L/cm H₂O C)1.0 L/cm H₂O D)4.0 L/cm H₂O

Accepted Answer

The compliance of the respiratory system is calculated by taking the reciprocal of the sum of the reciprocals of the lung compliance and the chest wall compliance. Given both compliances as 0.2 L/cm H2O, the calculation is 1 / (1/0.2 + 1/0.2) = 0.1 L/cm H2O.

Question 3

What is the pressure in the alveolus when the translung pressure is 3.5 cm H₂O and the pleural pressure is -8.5 cm H₂O? A)-5 cm H₂O B)0 cm H₂O C)5 cm H₂O D)-12 cm H₂O

Accepted Answer

Translung pressure = Alveolar pressure - Pleural pressure3.5 cm H₂O = Alveolar pressure - (-8.5 cm H₂O)Alveolar pressure = 3.5 cm H₂O + 8.5 cm H₂OAlveolar pressure = 12 cm H₂O

Question 4

When the pressure across the respiratory system (P_rs)is 0,which of the following statements is true? A)The individual is at total lung capacity (TLC). B)The individual is at FRC. C)The individual is at residual volume (RV). D)The transpulmonary (translung)pressure is 0.

Accepted Answer

When the pressure across the respiratory system is 0, it means there is no pressure gradient between the lungs and the atmosphere. This occurs at functional residual capacity (FRC), which is the equilibrium point between the inward recoil of the lungs and the outward recoil of the chest wall. At FRC, the transpulmonary pressure (PL - PIP) is also 0. Therefore, the best choice is B - the individual is at FRC.

Question 5

If pleural pressure changes from -3 cm H₂O to -7 cm H₂O as a subject breathes,and if the functional residual capacity (FRC)increases by 1 L,what is the compliance of the lung? A)0.1 L/cm H₂O B)4 cm H₂O/L C)0.25 L/cm H₂O D)10 cm H₂O/L

Accepted Answer

Compliance is calculated as the change in volume (ΔV) divided by the change in pressure (ΔP). Here, ΔV = 1 L and ΔP = -7 - (-3) = -4 cm H2O. Thus, compliance = 1 L / 4 cm H2O = 0.25 L/cm H2O.

Question 6

An individual with an increase in lung compliance will demonstrate which of the following changes in TLC and the ratio of the total lung capacity to the RV?&#10;A)An increase in TLC and a decrease in RV/TLC&#10;B)A decrease in TLC and a decrease in RV/TLC&#10;C)An increase in TLC and an increase in RV/TLC&#10;D)A decrease in TLC and an increase in RV/TLC&#10;E)No change in TLC or in RV/TLC

Accepted Answer

The answer of An individual with an increase in lung...

Question 7

An individual with respiratory symptoms undergoes pulmonary function testing.The RV measured by helium dilution is increased but is lower than the RV measured by body plethysmography.Which of the following is the most likely explanation for this difference?

A)There is a problem with one of the machines.
B)The individual has severe air trapping.
C)The individual did not keep his mouth pressed tightly around the mouthpiece,and air leaked out during the helium dilution testing.
D)The individual held his breath during body plethysmography.
E)The individual has a loss of lung compliance.

Accepted Answer

The increased RV measured by body plethysmography suggests severe air trapping, which could explain the difference between the RV measured by helium dilution and body plethysmography. Option A is less likely as it is less probable that there is an issue with both machines. Option C is possible but the difference is unlikely to be significant. Option D is less probable unless the instructions were misunderstood. Option E is less likely, as loss of compliance is associated with lower lung volume.

Question 8

Which of the following statements about the effect of surfactant on chest wall compliance is correct?&#10;A)Increased surfactant production is associated with an increase in chest wall compliance.&#10;B)Increased surfactant production is associated with a decrease in chest wall compliance.&#10;C)Decreased surfactant production is associated with an increase in chest wall compliance.&#10;D)Decreased surfactant production is associated with a decrease in chest wall compliance.&#10;E)Surfactant has no effect on chest wall compliance.

Accepted Answer

Surfactant primarily affects the compliance of the lungs by reducing surface tension, not the compliance of the chest wall. The chest wall compliance is influenced by factors such as the rib cage and muscles, not surfactant.

Question 9

An individual with pulmonary fibrosis will demonstrate&#10;A)An increase in lung compliance.&#10;B)A decrease in lung compliance.&#10;C)No change in lung compliance.&#10;D)An increase in chest wall compliance.&#10;E)A decrease in chest wall compliance.

Accepted Answer

Pulmonary fibrosis is characterized by the formation of scar tissue in the lungs, which reduces the compliance or stretchiness of the lung tissue. As a result, the lungs become stiffer and less able to expand and contract during breathing. This can lead to difficulty breathing and reduced oxygenation of the blood. Therefore, the correct choice is B, a decrease in lung compliance.

Question 10

An individual with increased mucus production and airway inflammation will demonstrate what changes in the residual volume (RV)and FRC?&#10;A)An increase in RV and an increase in FRC&#10;B)An increase in RV and a decrease in FRC&#10;C)A decrease in RV and an increase in FRC&#10;D)A decrease in RV and a decrease in FRC&#10;E)No change in RV or FRC

Accepted Answer

Increased mucus production and airway inflammation can lead to air trapping and reduced airway clearance, resulting in an increase in residual volume (RV) as more air remains in the lungs after expiration. This also leads to an increase in functional residual capacity (FRC), which is the volume of air present in the lungs at the end of passive expiration, as RV is a component of FRC.

Deck 21: Static Lung and Chest Wall Mechanics