Exam 2 Lange & Guyton questions

Question 1

A woman inspires 500 mL from a spirometer. The intrapleural pressure, determined using an esophageal balloon, was –5 cm H2O before the inspiratory effort and –10 cm H2O at the end of the inspiration.

• What is the pulmonary compliance?

Answer 1

See picture

Question 2

A postoperative patient whose respiratory muscles have been paralyzed with pancuronium bromide, a curare-like drug, is maintained by a positive-pressure respirator. At end expiration (when alveolar pressure equals 0), intrapleural pressure, as measured by an esophageal balloon, is equal to –3 cm H2O. At the peak of inspiration, alveolar pressure is +20 cm H2O and intrapleural pressure is +10 cm H2O. Tidal volume is 500 mL.

• a. What is the patient’s pulmonary compliance?
• b. What is the patient’s total compliance?
• c. What is the patient’s chest wall compliance?

Answer 2

See picture

Question 3

Which of the following conditions are reasonable explanations for a patient’s decreased static pulmonary compliance (the pressure-volume curve for the lungs shifted to the right)?

a. Decreased functional pulmonary surfactant
b. Fibrosis of the lungs
c. Surgical removal of one lobe
d. Pulmonary vascular congestion
e. All of the above

Answer 3

The correct answer is e.
All of the conditions lead to decreased compliance. Surgical removal of one lobe would decrease pulmonary compliance because the lobes of the lung are in parallel and compliances in parallel add directly.

Question 4

Which of the following tend to increase airways resistance?

a. Stimulation of the parasympathetic postganglionic fibers innervating the bronchial and bronchiolar smooth muscle
b. Low lung volumes
c. Forced expirations
d. Breathing through the nose instead of the mouth
e. All of the above

Answer 4

E

Question 5

Which of the following statements concerning alveolar pressure is/are correct?

a. Alveolar pressure is lower than atmospheric pressure during a normal negative-pressure inspiration.
b. Alveolar pressure is greater than atmospheric pressure during a forced expiration.
c. Alveolar pressure equals the sum of the intrapleural pressure plus the alveolar elastic recoil pressure.
d. Alveolar pressure equals atmospheric pressure at the end of a normal tidal expiration.
e. All of the above.

Answer 5

E

Question 6

Which of the following statements concerning small airways is/are true?

a. The total resistance to airflow decreases with successive generations of airways because there are increasing numbers of units arranged in parallel.
b. The linear velocity of airflow decreases as the airways decrease in size because their total cross-sectional area increases.
c. Alveolar elastic recoil plays an important role in determining the resistance to airflow in small airways because alveolar septal traction helps to oppose dynamic compression.
d. Airflow in small airways is usually laminar.
e. All of the above.

Answer 6

E

Question 7

Which of the following statements concerning pulmonary mechanics during the early portion of a forced expiration, when lung volume is still high, is/are correct?

a. There is less alveolar elastic recoil at high lung volumes than there is at low lung volumes.
b. Airways resistance is greater at high lung volumes than it is at low lung volumes.
c. There is more dynamic compression of airways at high lung volumes than there is at low lung volumes.
d. The effective pressure gradient for airflow is greater at high lung volumes than it is at low lung volumes.

Answer 7

The correct answer is d.

Alveolar elastic recoil is greater at high lung volumes, which helps oppose dynamic compression and decrease airways resistance by traction on small airways. During a forced expiration, as soon as dynamic compression occurs the effective driving pressure for airflow becomes alveolar pressure minus intrapleural pressure (instead of alveolar pressure minus atmospheric pressure). However, alveolar pressure minus intrapleural pressure equals the alveolar elastic recoil pressure.

Question 8

The above figure shows three different compliance curves (S, T, and U) for isolated lungs subjected to various transpulmonary pressures. Which of the following best describes the relative compliances for the three curves?

A) S < T < U
B) S < T > U
C) S − T − U
D) S > T < U
E) S > T > U

Answer 8

E

Question 9

Assuming a respiratory rate of 12 breaths/min, calculate the minute ventilation.

A) 1 l/min
B) 2 l/min
C) 4 l/min
D) 5 l/min
E) 6 l/min

Answer 9

E

Question 10

A 22-year-old woman inhales as much air as possible and exhales as much air as she can, producing the spirogram shown in the figure. A residual volume of 1.0 liter is determined using the helium dilution technique. What is her FRC (in liters)?

A) 2.0
B) 2.5
C) 3.0
D) 3.5
E) 4.0
F) 5.0

Answer 10

C

Question 11

A 22-year-old woman has a pulmonary compliance of 0.2 l/cm H2O
and a pleural pressure of −4 cm H2O. What is the pleural pressure (in cm H2O) when the woman inhales 1.0 l of air?

A) −6
B) −7
C) −8
D) −9
E) −10

Answer 11

D

Question 12

A preterm infant has a surfactant deficiency. Without surfactant, many of the alveoli collapse at the end of each expiration, which in turn leads to pulmonary failure. Which set of changes is present in the preterm infant compared with a normal infant?

  Alveolar Surface Tension     Pulmonary Compliance A).        Decreased                                Decreased B)         Decreased                                Increased C)         Decreased                                No change D)         Increased                                 Decreased E)          Increased                                 Increased F)          Increased                                 No change G)         No change                               No change

Answer 12

D

Question 13

A patient has a dead space of 150 ml, FRC of 3 liters, tidal volume (VT) of 650 ml, expiratory reserve volume (ERV) of 1.5 l, total lung capacity (TLC) of 8 l, and respiratory rate of 15 breaths/min. What is the residual volume (RV)?

A) 500 ml
B) 1000 ml
C) 1500 ml
D) 2500 ml
E) 6500 ml

Answer 13

C

Question 14

The various lung volumes and capacities include the total lung capacity (TLC), vital capacity (VC), inspiratory capacity (IC), tidal volume (VT), expiratory capacity (EC), expiratory reserve volume (ERV), inspiratory reserve volume (IRV), functional residual capacity (FRC), and residual volume (RV). Which of the following lung volumes and capacities can be measured using direct spirometry without additional methods?

Answer 14

B

Question 15

A 22-year-old woman has a pulmonary compliance of 0.2 l/cm H2O
and a pleural pressure of −4 cm H2O. What is the pleural pressure (in cm H2O) when the woman inhales 1.0 l of air?

A) −6
B) −7
C) −8
D) −9
E) −10

Answer 15

D

Question 16

An experiment is conducted in two persons (subjects T and V) with identical VTs (1000 ml), dead space volumes (200 ml), and ventilation frequencies (20 breaths/min). Subject T doubles his VT and reduces his ventilation frequency by 50%. Subject V doubles his ventilation frequency and reduces his VT by 50%. What best describes the total ventilation (also called minute ventilation) and VA of subjects T and V?

Answer 16

E

Question 17

Which diagram in the above figure best illustrates the pulmonary vasculature when the cardiac output has increased to a maximum extent?

A) A
B) B
C) C
D) D
E) E

Answer 17

A

Question 18

A child who is eating round candies approximately 1.5 cm in diameter inhales one down his airway, blocking his left bronchiole. How are his Left Lung PAO2, Left Lung PCO2 & systemic PO2 affected?

Answer 18

Increased PACO2
Decreased PAO2
Decreased SPO2

Question 19

A person’s normal VT is 400 ml with a dead space of 100 ml. The respiratory rate is 12 breaths/min. The person undergoes ventilation during surgery, and the VT is 700 with a rate of 12. What is the approximate alveolar PCO 2 for this person?

A) 10
B) 20
C) 30
D) 40
E) 45

Answer 19

B
Double minute ventilation –> halved PCO2

Question 20

A 45-year-old man at sea level has an inspired O2 tension of 149
mm Hg, nitrogen tension of 563 mm Hg, and water vapor pressure of 47 mm Hg. A small tumor pushes against a pulmonary blood vessel, completely blocking the blood flow to a small group of alveoli. What are the O2 and carbon dioxide (CO2) tensions of the alveoli that are not perfused (in mm Hg)?

Answer 20

• CO2= 0
• PAO2= 149 mm Hg

Question 21

In which conditions is alveolar PO 2 increased and alveolar PCO 2
decreased?

A) Increased Va and unchanged metabolism
B) Decreased Va and unchanged metabolism C) Increased metabolism and unchanged Va
D) Proportional increase in metabolism and VA

Answer 21

A

Question 22

A 67-year-old man has a solid tumor that pushes against an airway, partially obstructing air flow to the distal alveoli. Which point on the line of the O2-CO2 diagram above corresponds to the alveolar gas of these distal alveoli?

A) A
B) B
C) C
D) D
E) E

Answer 22

B

Question 23

A 55-year-old man has a pulmonary embolism that completely blocks the blood flow to his right lung. Which point on the line of the O2-CO2 diagram above corresponds to the alveolar gas of his right lung?

A) A
B) B
C) C
D) D
E) E

Answer 23

E

Question 24

The volume–pressure curves in the above figure were obtained from a normal subject and patient with a pulmonary disease. Which abnormality is most likely present in the patient?

A) Asbestosis
B) Emphysema
C) Mitral obstruction
D) Rheumatic heart disease E) Silicosis
F) Tuberculosis

Answer 24

B

Question 25

Which of the following best describes comparison of the lung compliance and surfactant levels in a premature infant with respiratory distress syndrome versus a normal full-term infant?

Answer 25

C

Question 26

A patient’s mean arterial blood pressure is 100 mm Hg and his right atrial pressure is 2 mm Hg. His mean pulmonary artery pressure and pulmonary capillary wedge pressure (≈left atrial pressure) determined using a Swan-Ganz catheter, are 15 and 5 mm Hg, respectively.
- If his cardiac output is 5 L/min, calculate his pulmonary vascular resistance and systemic vascular resistance?

Answer 26

• PVR= 2 mm Hg/L/min
• SVR= 19.6 mmHg/L/min

Question 27

Which of the following situations would be expected to lead to an increase amount of the lung under zone 1 conditions?

a. Ascent to 15,000 ft above sea level
b. Blood loss secondary to trauma
c. Moderate exercise
d. Positive-pressure ventilation with positive end-expiratory pressure (PEEP)
e. Changing from the standing to the supine position.

Answer 27

Answer is B & D.
- Blood loss secondary to trauma lowers venous return and cardiac output. As a result, pulmonary artery pressure is likely to fall, increasing the likelihood of zone 1 conditions in the lung.
- Positive-pressure ventilation with PEEP (positive airway pressure during expiration, often used on patients at risk for atelectasis, causes positive alveolar and pleural pressures throughout the respiratory cycle) would also increase the likelihood of zone 1 conditions in the lung.

Question 28

Which of the following circumstances might be expected to contribute to the formation of pulmonary edema?

a. Overtransfusion with saline
b. Occlusion of the lymphatic drainage of an area of the lung
c. Left ventricular failure
d. Low concentration of plasma proteins
e. Destruction of portions of the pulmonary capillary endothelium by toxins
f. All of the above

Answer 28

Answer is F all of the above

Question 29

Which of the following situations would be expected to decrease PVR?

a. Ascent to 15,000 ft above sea level
b. Inspiration to the total lung capacity
c. Expiration to the residual volume
d. Moderate exercise
e. Blood loss secondary to trauma

Answer 29

Answer is D Moderate exercise decreases PVR

Question 30

Relative to atmospheric pressure the pleural pressure at rest is −5 cm H2O. What would alveolar pressure be at the end of an
inhalation?

A) −5 cm H2O
B) −2 cm H2O
C) 0 cm H2O
D) +2 cm H2O
E) 5 cm H2O

Answer 30

C

Question 31

Which of the following would be increase airway conductance?

A) Stimulation of parasympathetic nerves to the lungs
B) Low lung volumes
C) Release of histamine by mast cells
D) Inhalation to TLC

Answer 31

D

Question 32

In a normal subject at sea level breathing 50% O2, which compartment has the lowest CO2 partial pressure?

A) Pulmonary vein in the basal region of lung
B) Alveolar air in zone II
C) Pulmonary arterial blood
D) Anatomic dead space at the end of inspiration

Answer 32

D

Question 33

What is the effect on each of the following standard lung volumes and capacities of changing from a supine to an upright position?

a. Functional residual capacity (FRC)
b. Residual volume (RV)
c. Expiratory reserve volume (ERV)
d. Total lung capacity (TLC)
e. Tidal volume (VT)
f. Inspiratory reserve volume (IRV)
g. Inspiratory capacity (IC)
h. Vital capacity (VC)

Answer 33

As a person stands up, the effects of gravity alter the mechanics of breathing (and also decrease venous return). The contents of the abdomen are pulled away from the diaphragm, thus increasing the outward elastic recoil of the chest wall.
- The inward recoil of the lungs is not affected, and so the functional residual capacity (FRC) is increased.
- The residual volume (RV) is relatively unaffected.
- The expiratory reserve volume (ERV) increases because the FRC is increased and the RV is relatively unchanged.
- The total lung capacity (TLC) may increase slightly because of the slightly decreased inward elastic recoil of the chest wall at high lung volumes and because the abdominal contents are pulled away from the diaphragm.
- The tidal volume (VT) is probably unchanged.
- The higher FRC and similar TLC and VT lead to a decrease in the inspiratory reserve volume (IRV) and a decrease in the inspiratory capacity (IC).
- The vital capacity (VC) is also relatively unchanged, although it may be slightly increased because of the slight increase in TLC and the decreased intrathoracic blood volume.

Question 34

A subject starts at her FRC and breathes 100% O2 through a 1-way valve. The expired air is collected in a very large spirometer (called a Tissot spirometer). The test is continued until the expired N2 concentration, as measured by a nitrogen analyzer, is virtually zero. At this time, there are 36 L of gas in the spirometer, of which 5.6% is N2.

What is the subject’s FRC?

Answer 34

2.5 L

• The volume of N2 in the spirometer is 0.056 × 36 L, or 2.0 L. This is the volume of N2 in the subject’s lungs when the test began (at her FRC). Since N2 constituted 80% of her FRC, her FRC is equal to 100 ÷ 80 × 2.0 L, or 1.25 × 2.0 L, which is equal to 2.5 L.

Question 35

A 63-year-old woman who is 5 ft 5 in. tall and weighs 100 lb complains of dyspnea. During the determination of her lung volumes, she rebreathes the gas in a 20-L-capacity spirometer that originally contained 10 L of 15% helium. After a number of breaths, the concentration of helium in her lungs is equal to that now in the spirometer, which is 11% helium. (During the equilibration period, the expired CO2 was absorbed by an absorbent chemical in the spirometer and O2 was added to the spirometer at the subject’s O2.) At the end of a normal expiration, the spirometer contains 10.64 L when corrected to BTPS.

What is her FRC?

Answer 35

FHEi × Vspi = FHEf (Vspf + VLf)

Because the test was ended at the end of a normal expiration, VLf equals the subject’s FRC.

• 0.15 x 10 L= 0.11(10.64 L + FRC)
  –> 1.5 L = 1.17 L + (0.11 x FRC)
  –> 0.11 x FRC = 1.5 L - 1.17 L
  –> FRC = 0.33 L / 0.11
  – FRC = 3.0L

Question 36

A patient on a ventilator has a rate of 10 breaths per minute and a tidal volume (VT) of 500 mL.

a. What is the patient’s VE?
b. If the patient’s anatomic dead space is estimated to be 150 mL, what is his VA?
c. If his rate is increased to 15 breaths per minute with VT remaining at 500 mL, what will his new VE and VA be?
d. If his VT is increased to 750 mL, with his rate remaining at 10 breaths per minute, what will his new VE and VA be?

Answer 36

a) VE= 10bpm x 500mL= 5L/min

b) VA= VE= VA + VD –> VA= VE - VD –> 10bpm x (500 mL - 150 mL)= 3,500 mL/min

c) VE= 15bpm x 500 mL= 7,500 mL/min
VA= 15bpm x (500 mL - 150mL)= 5,250 mL/min

d) VE= 10bpm x 750 mL= 7,500 mL/min
VA= 10bpm x (750 mL - 150 mL)= 6,000 mL/min

Question 37

A normal person, seated upright, begins to inspire from the residual volume. The first 100 mL of inspired gas is labeled with xenon 133. Most of this radioactive gas (ie, the first 100 mL of gas inspired after the dead space) will probably be found:

a. in alveoli in lower portions of the lung
b. in alveoli in upper portions of the lung
c. uniformly distributed to all alveoli

Answer 37

The correct answer is b.
At the residual volume, airways in gravity-dependent portions of the lungs are likely to be collapsed. Alveoli in upper regions of the lung are on the steep portion of their pressure-volume curves (ie, they are more compliant than they are at higher lung volumes), and so most of the labeled gas will enter the alveoli in the upper portions of the lung.