Question 1

Which of the following conditions is characterized by a loss of elastic lung tissue?

Accepted Answer

Emphysema is characterized by a loss of elastic lung tissue, which meAnswer the lungs can be easily distended and have an abnormally low recoil force.

Question 2

What is the minimum MIP required to confirm adequacy of ventilatory muscle strength?

Accepted Answer

Severe compromise of ventilatory muscle strength is evident when no more than -20 cm H₂O MIP can be generated.

Question 3

The change in lung volume resulting from a unit of pressure change is known as:

Accepted Answer

Lung compliance (CL) is defined as the change in lung volume resulting from a unit of pressure change and is measured in liters per centimeter of water pressure (L/cm H₂O).

Question 4

What is the normal C_LT?

Accepted Answer

The normal value is 0.1 L/cm H₂O for C_LT.

Question 5

Which of the following is the function of the surfactant?

Accepted Answer

Dipalmitoyl phosphatidylcholine (DPPC) composes approximately 50% of surfactant's phospholipid content and is primarily responsible for surfactant's surface tension-lowering properties.

Question 6

According to Laplace's law, if surface tension remains constant, what will happen to small alveoli?

Accepted Answer

If surface tension remains constant, small alveoli require higher distending pressure than large alveoli; the equation thus predicts that the smaller alveoli should empty into larger alveoli-assuming that all alveoli have the same surface tension.

Question 7

What is the normal composition of the surfactant?

Accepted Answer

Pulmonary surfactant is a complex substance composed of 90% phospholipid and 10% protein.

Question 8

What causes air to move in or out of the lungs?

Accepted Answer

A pressure gradient is simply a pressure difference between two points that causes air to move in or out of the lungs. It is the force responsible for keeping the lungs in an inflated state.

Question 9

Which of the following are true physiological benefits of surfactant?
I.It reduces the work of breathing.
II.It reduces the distending pressure required to keep small alveoli open.
III.It provides a stabilizing influence to alveoli of different sizes.
IV.It enhances the elastic properties of the lung.

Accepted Answer

In summary, the physiological importance of pulmonary surfactant is that 
(1) it reduces the work of breathing, 
(2) it reduces the distending pressure required to keep small alveoli open, and 
(3) it provides a stabilizing influence, allowing alveoli of different sizes to coexist at the same distending pressure.

Question 10

What is the normal lung compliance (CL)?

Accepted Answer

The more elastic the lung, the less its compliance. Elastance can be conceptualized as recoil force; highly elastic lungs are stiff and difficult to inflate and exhibit a high recoil force.

Question 11

At the end of a spontaneous 500 mL inspiration, the PA is 0 mm Hg, and at the end of a positive pressure lung inflation to 500 mL, PA is 10 mm Hg.Why does the lung contain the same volume at these two different alveolar pressures?

Accepted Answer

Figure 3-4 compares PPV and SB. The lung diagrams illustrate conditions at the end of an inspiration. Although the trAnswerpulmonary pressures were achieved by different meAnswer in SB and PPV, PL is 10 cm H₂O in both instances. This meAnswer that elastic lung fibers are stretched to the same extent in both instances. The PPV inspiration places no more stress on the lung than the SB inspiration, although PA is 10 cm H₂O greater in PPV than in SB. This fact has relevance to therapeutic lung expAnswerion techniques used in respiratory care. Given normal inspiratory muscle function, a mechanical positive pressure inspiration is not in some way superior to a spontaneous inspiration in expanding the lung, nor is a 500 mL positive pressure breath any more likely than a 500 mL spontaneous breath to injure the lungs.

Question 12

The presence of high lung elastance will produce which of the following effects on a quiet, passive exhalation?

Accepted Answer

The person with high lung compliance (low elastance) requires the longest passive exhalation time because of reduced elastic lung recoil forces. A lung with high elastance (low compliance) has a high recoil force and thus empties more quickly.

Question 13

Which of the following terms defines the amount of gas the lung contains after a maximal inspiratory effort?

Accepted Answer

The total lung capacity (TLC) is the amount of gas the lung contains after a maximal inspiratory effort.

Question 14

Which of the following statements explains why compliance is greater in the adult than the infant?

Accepted Answer

Clearly, compliance (L/cm H₂O) is greater in the adult than the infant because adult lungs are larger and accept more volume for a given pressure.

Question 15

What are the tests that are considered the "gold standard" for determining fetal lung maturity?
I.L/S ratio
II.DPPC measurement
III.PG in amniotic fluid
IV.Lamellar body count

Accepted Answer

The L/S ratio and the presence of PG in amniotic fluid continue to be the "gold standard" for determining fetal lung maturity.

Question 16

Which of the following statements are true of the lecithin-to-sphingomyelin ratio?
I.It is predictive of fetal lung maturation.
II.An L/S ratio greater than 2:1 indicates fetal lung maturity in nondiabetic pregnancies.
III.The L/S ratio is falsely high in diabetes.
IV.The L/S ratio is generally 2:1 at 35 weeks' gestation.

Accepted Answer

The ratio of lecithin to sphingomyelin (L/S ratio) in amniotic fluid is predictive of fetal lung maturation. An L/S ratio greater than 2:1 indicates fetal lung maturity in nondiabetic pregnancies. (The L/S ratio is falsely high in diabetes.) The L/S ratio is generally 1:1 at 31 to 32 weeks' gestation, and 2:1 at 35 weeks.

Question 17

Which of the following conditions is characterized by high lung recoil forces?

Accepted Answer

Pulmonary fibrosis is characterized by high lung recoil forces.

Question 18

Which of the following mechanisms is responsible for the creation of the subatmospheric pressure between the lung and chest wall?
I.Both lungs and chest wall pull outward.
II.The lung has a tendency to recoil inward and pull away from the chest wall.
III.The thorax has a tendency to recoil outward, away from the lung.

Accepted Answer

The healthy lung has a tendency to recoil inward and pull away from the chest wall. At the same time, the thorax has a tendency to recoil outward, away from the lung. These two oppositely directed recoil forces create a subatmospheric pressure between the lung and the chest wall.

Question 19

When lung inflation pressure is increased from 10 cm H₂O to 20 cm H₂O, what happens to the alveolar size?

Accepted Answer

When lung inflation pressure was increased from 10 cm H₂O to 20 cm H₂O, and then from 20 cm H₂O to 30 cm H₂O, the alveolar size did not change but the number of recruited alveoli changed in direct proportion to the applied pressure.

Question 20

What is the best word to define elastance?

Accepted Answer

The more elastic the lung, the less its compliance. Elastance can be conceptualized as recoil force; highly elastic lungs are stiff and difficult to inflate and exhibit a high recoil force.

Quiz 3: Mechanics of Ventilation

Which of the following conditions is characterized by a loss of elastic lung tissue?

What is the minimum MIP required to confirm adequacy of ventilatory muscle strength?

The change in lung volume resulting from a unit of pressure change is known as:

What is the normal C_LT?

Which of the following is the function of the surfactant?

According to Laplace's law, if surface tension remains constant, what will happen to small alveoli?

What is the normal composition of the surfactant?

What causes air to move in or out of the lungs?

What is the normal lung compliance (CL) ?

At the end of a spontaneous 500 mL inspiration, the PA is 0 mm Hg, and at the end of a positive pressure lung inflation to 500 mL, PA is 10 mm Hg.Why does the lung contain the same volume at these two different alveolar pressures?

The presence of high lung elastance will produce which of the following effects on a quiet, passive exhalation?

Which of the following terms defines the amount of gas the lung contains after a maximal inspiratory effort?

Which of the following statements explains why compliance is greater in the adult than the infant?

What are the tests that are considered the "gold standard" for determining fetal lung maturity? I.L/S ratio II.DPPC measurement III.PG in amniotic fluid IV.Lamellar body count

Which of the following conditions is characterized by high lung recoil forces?

When lung inflation pressure is increased from 10 cm H₂O to 20 cm H₂O, what happens to the alveolar size?

What is the best word to define elastance?

Quiz 3: Mechanics of Ventilation

Which of the following conditions is characterized by a loss of elastic lung tissue?

What is the minimum MIP required to confirm adequacy of ventilatory muscle strength?

The change in lung volume resulting from a unit of pressure change is known as:

What is the normal CLT?

Which of the following is the function of the surfactant?

According to Laplace's law, if surface tension remains constant, what will happen to small alveoli?

What is the normal composition of the surfactant?

What causes air to move in or out of the lungs?

What is the normal lung compliance (CL) ?

At the end of a spontaneous 500 mL inspiration, the PA is 0 mm Hg, and at the end of a positive pressure lung inflation to 500 mL, PA is 10 mm Hg.Why does the lung contain the same volume at these two different alveolar pressures?

The presence of high lung elastance will produce which of the following effects on a quiet, passive exhalation?

Which of the following terms defines the amount of gas the lung contains after a maximal inspiratory effort?

Which of the following statements explains why compliance is greater in the adult than the infant?

What are the tests that are considered the "gold standard" for determining fetal lung maturity? I.L/S ratio II.DPPC measurement III.PG in amniotic fluid IV.Lamellar body count

Which of the following conditions is characterized by high lung recoil forces?

When lung inflation pressure is increased from 10 cm H2O to 20 cm H2O, what happens to the alveolar size?

What is the best word to define elastance?

What is the normal C_LT?

When lung inflation pressure is increased from 10 cm H₂O to 20 cm H₂O, what happens to the alveolar size?