Questions from Book Flashcards
Asthma is a disease that affects primarily the peripheral airways. Which of the following would best characterize pulmonary function in a patient diagnosed with asthma compared to normal predicted values?
A. FEV1/FVC ratio is increased.
B. Residual volume is increased.
C. Total lung capacity is decreased.
D. Resistance to airflow is decreased.
E. Both airway resistance and total lung capacity are decreased.
- The correct answer is B. Asthma is one of the diseases that falls under chronic obstructive pulmonary disease (COPD). COPD is characterized by high static lung volumes and low airflow. This means total lung capacity and residual volumes are increased. Airflow is restricted due to the increase in airway resistance. FEV1, FVC, and FEV1/FVC ratio are also decreased because of the increase in airway resistance.
Residual volume: volume of air that is remaining in the lungs after the most forceful expiration (about 1200ml)
A 48-year-old patient undergoes a pulmonary function test. At which lung volume would her pleural pressure be most negative?
A. Residual volume
B. Functional residual capacity
C. End of tidal volume
D. Total lung capacity
E. Middle of forced vital capacity
The correct answer is D.
During inspiration, pleural pressure becomes more negative.
Pleural pressure would be the most negative at maximal inspiration (total lung capacity).
Pleural pressure is the least negative at residual volume. During forced vital capacity, pleural pressure is positive. FRC and end-tidal volume are distracters.
If alveolar ventilation is doubled while breathing room air, and if CO2 production remains unchanged, then the most likely effect (increase, decrease, or no change) on alveolar CO2 tension (Paco2), alveolar O2 tension (Pao2), arterial O2 tension (Pao2), and arterial CO2 tension (Paco2) will be that:
The correct answer is decreased PACo2
increased PAo2
little effect on Pao2
decreased Paco2
If carbon production remains unchanged and one hyperventilates for 2 minutes, both alveolar and arterial carbon tensions decrease. Hyperventilation increases oxygen tension in the alveolar but has little effect on arterial oxygen tension.
The following measurements were made on a normal subject:
Arterial Pco2 = 36 mm Hg; arterial PO2 = 100 mm Hg; minute ventilation = 9 L/min
Alveolar ventilation = 6 L/min; frequency = 15 breaths/min
Which one of the following breathing patterns would result in the highest alveolar ventilation?
- The correct answer is B. The key to measuring alveolar ventilation is to determine the dead space volume.
Dead space ventilation = minute ventilation – alveolar ventilation (9 L/min – 6 L/min = 3 L/min).
Dead space volume equals dead space ventilation/breathing frequency (3 L/min/15 breaths/min = 200 mL).
Alveolar ventilation = tidal volume − dead space volume × frequency.
- In a healthy individual, which of the following combination of changes from normal values in chest wall and lung compliance would result in the greatest decrease in functional residual capacity?
A. A 10% increase in lung compliance and a 10% decrease in chest wall compliance
B. A 10% decrease in lung compliance and a 10% decrease in chest wall compliance
C. A 10% decrease in lung compliance and a 10% increase in chest wall compliance
D. A 10% increase in lung compliance and a 10% increase in chest wall compliance
E. A 5% increase in lung compliance and a 5% increase in chest wall compliance
The correct answer is C. Since the lung elastic recoil and chest wall elastic recoil are in equal but opposite directions, an increase in lung elastic recoil (decreased lung compliance) and a decrease in chest wall elastic recoil will favor the greatest decrease in functional residual capacity (FRC). Options A and E would result in an increase in FRC. Options B and D would essentially result in no change in FRC.
Compared to an individual with normal lung capacities and compliance, a patient with a restrictive disorder would exhibit
A. increased functional residual capacity and increased lung compliance.
B. increased functional residual capacity and decreased lung compliance.
C. decreased functional residual capacity and increased lung compliance.
D. decreased functional residual capacity and decreased lung compliance.
E. normal functional residual capacity and decreased lung compliance.
The correct answer is D. A restrictive disorder is characterized by lungs with increased stiffness (decreased compliance) and smaller static lung volumes (decreased functional residual capacity).
A 13-year-old girl suffers from asthma. She inhales a bronchodilator drug that causes a threefold increase in the radius of her small peripheral airways. Which of the following pulmonary function tests would show the greatest improvement?
A. Total lung capacity
B. Tidal volume
C. Inspiratory capacity
D. Forced vital capacity
E. Functional residual capacity
he correct answer is D. Asthma is an obstructive disorder with the primary effect of obstructing airflow out of the lungs. Although all would improve with the bronchodilator, the greatest improvement of the pulmonary function tests would be forced vital capacity
A 52-year-old patient has a frequency = 10 breaths/min, vital capacity = 6 L, minute ventilation = 8 L/min, and functional residual capacity = 3 L. His tidal volume is
A. 0.3 L
B. 0.5 L
C. 0.6 L
D. 0.8 L
E. 0.9 L
The correct answer is D. Minute ventilation (Inline Image) = tidal volume (VT) × breathing rate (f). Thus, Inline Image = VT × f, and therefore, VT = Inline Image/f.
. What are the common spirometry findings associated with emphysema?
The hallmark of emphysema is the limitation of airflow out of the lungs. In emphysema, expiratory flow rates (FVC, FEV1, and FEV1/FVC ratio) are significantly decreased. However, some lung volumes (TLC, FRC, and RV) are increased, and the increase is a result of the loss of lung elastic recoil (increased compliance).
. What are the mechanisms of airflow limitation in emphysema?
The mechanisms that limit expiratory airflow in emphysema include hypersensitivity of airway smooth muscle, mucus hypersecretion, and bronchial wall inflammation and increased dynamic airway compression as a result of increased compliance.
. What is the most commonly held theory explaining the development of emphysema?
loss of lung elastic recoil and destruction of the alveolar–capillary membrane. In emphysema, excess proteolytic activity destroys elastin and collagen.
Cigarette smoke increases proteolytic activity, which may arise through an increase in protease levels, a decrease in antiprotease activity, or a combination of the two.
The main cause for a normal A–aO2 gradient in a healthy individual is:
A. a low diffusing capacity for oxygen compared with that for carbon dioxide.
B. a high Inline Image ratio in the apex of the lungs.
C. an over ventilation in the base of the lung.
D. a small shunt from bronchial circulation.
E. a right-to-left shunt in the heart.
The correct answer is D. The A–aO2 gradient in a healthy person is due to both a low Inline Image ratio at the base of the lungs and a small shunt from the bronchial circulation.
Which of the following will not cause a low lung diffusing capacity (Dl)?
A. Decreased diffusion distance
B. Decreased capillary blood volume
C. Decreased surface area
D. Decreased cardiac output
E. Decreased hemoglobin concentration in the blood
The correct answer is A. A decrease in the diffusion distance will lead to an increase in Dl. A decrease in capillary blood volume, surface area, cardiac output, and blood hemoglobin concentration will decrease Dl.
- Which of the following parameters would best reflect adequate oxygenation to the tissues?
A. Arterial oxygen tension
B. Arterial oxygen saturation
C. Arterial oxygen tension required to make the blood 50% saturated (P50)
D. Arterial–venous O2 tension difference
E. Arterial O2 content
The correct answer is E. Arterial oxygen content provides the best index to tissue oxygenation. Arterial oxygen tension and arterial oxygen saturation can be normal in situations like anemia. Arterial–venous oxygen tension difference can also be unchanged in anemic patients. The P50 reflects the ability of the hemoglobin-binding affinity for oxygen and provides little information about tissue oxygenation.
- During light to moderate exercise, pulmonary vascular resistance in a healthy individual will:
A. increase because cardiac output increases.
B. decrease because pulmonary arterial pressure decreases.
C. increase due to the increase in venous admixture.
D. decrease due to pulmonary capillary recruitment.
E. not change because of the compensatory mechanism of the increased lung compliance with exercise
The correct answer is D. With increase in exercise, cardiac output increases. The increase flow results in opening up more capillaries (capillary recruitment), which results in a decrease in pulmonary vascular resistance.
- In a healthy individual, which of the following changes in hemodynamics would favor the formation of pulmonary edema?
A. Decreased hydrostatic interstitial pressure around alveoli
B. Decreased pulmonary arterial pressure
C. Decreased pulmonary wedge pressure
D. Increased oncotic pressure in the pulmonary capillaries
E. Increased pulmonary blood flow
A
In a healthy individual, an increase in blood flow will open up more capillaries (capillary recruitment) which lowers pulmonary arterial pressure with increased cardiac output
- A 65-year-old patient has a lung region that is well ventilated but poorly perfused. This situation will cause alveoli in this region to have:
A. high Po2 and a low Pco2 with increased O2 uptake.
B. high Po2 and a low Pco2 with decreased O2 uptake.
C. low Po2 and a high Pco2 with decreased O2 uptake.
D. high Po2 and a high Pco2 with increased O2 uptake.
E. low Po2 and a low Pco2 with decreased O2 uptake.
The correct answer is B. A lung region that is over ventilated with respect to blood flow will have an alveolar gas tension in which the Po2 is greater than normal and the Pco2 is less than normal.
- Following surgery, a patient develops a pulmonary embolism in the left lung. Which of the following will most likely occur in the left lung?
A. A high ventilation/perfusion ratio, with an alveolar Pco2 below normal and a Po2 above normal.
B. A high ventilation/perfusion ratio with a high alveolar Pco2 and Po2 that is above normal
C. A high ventilation/perfusion ratio with a low alveolar Po2 and Pco2 that is below normal
D. A low ventilation/perfusion ratio with an alveolar Pco2 below normal and a Po2 above normal.
E. A low ventilation/perfusion ratio with an alveolar Pco2 above normal and Po2 that is below normal.
The correct answer is A. The embolism creates an abnormal high ventilation/perfusion which results in the region that is over ventilated with respect to blood flow. This causes a high alveolar Po2 and a low Pco2 in the over ventilated region. Option E is correct for a lung region that has results in a low ventilation/perfusion ratio (e.g., a blocked airway).
- Which of the following best characterizes alveolar ventilation and blood flow at the apex, compared to the base of the lungs of a healthy standing individual?
A. Blood flow, ventilation, and the ventilation/perfusion ratio are lower at the apex of the lung.
B. Blood flow, ventilation, and the ventilation/perfusion ratio are higher at the apex of the lung.
C. Blood flow is higher at the apex, but ventilation and the ventilation/perfusion ratio is lower.
D. Blood flow and ventilation are lower at the apex, but the ventilation perfusion ratio is higher.
E. Blood flow and ventilation are higher at the apex, but the ventilation/perfusion ratio is lower.
The correct answer is D. Compared to the base of the lung, the apex is being underperfused and under ventilated. Although both are lower at the apex, blood flow is proportionally lower than ventilation, which results in a higher ventilation/perfusion ratio
what best characterizes pulmonary circulation? (flow, pressure, resistance, compliance)
Flow - high
pressure - low
resistance - low
compliance - high
