Deck 10: Ventilation

Question 1

During each cycle of normal resting ventilation, a volume of gas is moved into and out of the respiratory tract. This cyclical volume is called the:

A)inspiratory reserve volume (IRV)
B)vital capacity (VC)
C)residual volume (RV)
D)tidal volume (V_T)

Answer 1

D

Question 2

Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?

A)transcanadian pressure gradient (P_pc - P_ks)
B)transpulmonary pressure gradient (P_alv - P_pl)
C)transrespiratory pressure gradient (P_alv - P_ao)
D)transthoracic pressure gradient (P_pl - P_bs)

Answer 2

C

Question 3

What is the effect of surface tension forces in the air-filled lung?
I.It increases the elastic recoil of the lung (promoting collapse).
II.It makes the lung harder to inflate than if it were filled with fluid.
III.It decreases the lung's elasticity as volume increases.

A)I and II
B)II
C)I and III
D)I, II, and III

Answer 3

I and II

Question 4

What occurs at a lung volume equivalent to the functional residual capacity (FRC)?
I.The forces of the chest wall and lungs are in balance.
II.Chest wall expansion is offset by lung contraction.
III.Opposing chest wall-lung forces generate negative P_pl.

A)I, II, and III
B)I and II
C)I and III
D)II and III

Question 5

During normal tidal ventilation, the transpulmonary pressure gradient (P_alv - P_pl) reaches its maximum value at what point in the cycle?

A)mid-inspiration
B)end-expiration
C)end-inspiration
D)mid-expiration

Question 6

Which of the following statements about alveolar pressure (P_alv) during normal quiet breathing is true?

A)It is positive during inspiration and negative during expiration.
B)It is the same as intrapleural pressure (P_pl).
C)It is negative during inspiration and positive during expiration.
D)It always remains less than atmospheric pressure.

Question 7

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

A)transpulmonary pressure gradient (P_alv - P_pl)
B)transthoracic pressure gradient (P_pl -P_bs)
C)transcanadian pressure gradient (P_ca - P_ks)
D)transrespiratory pressure gradient (P_alv - P_ao)

Question 8

What happens during normal inspiration?
I.The P_pl decreases further below atmospheric.
II.The transpulmonary pressure gradient widens.
III.P_alv drops below that at the airway opening.

A)I, II, and III
B)II and III
C)I only
D)I and III

Question 9

Which of the following pressures vary throughout the normal breathing cycle?
I.alveolar pressure (P_alv)
II.body surface pressure (P_bs)
III.mouth pressure (P_ao)
IV.pleural pressure (P_pl)

A)I, II, III, and IV
B)II, III, and IV
C)II and IV
D)I and IV

Question 10

What term is used to note the difference between inspiratory lung volume and expiratory lung volume at any given pressure?

A)alveolar aphasia
B)hysteresis
C)pleural pressure variance
D)transpulmonary pressures

Question 11

What is the primary function of the lungs?

A)convert angiotensin I to angiotensin II
B)filter pulmonary blood
C)gas exchange
D)remove carbon monoxide (CO)

Question 12

Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?

A)P_alv
B)P_pl
C)P_ao
D)P_bs

Question 13

How is compliance computed?

A)change in pressure/change in flow
B)change in pressure/change in volume
C)change in volume/change in flow
D)change in volume/change in pressure

Question 14

During expiration, why does gas flow out from the lungs to the atmosphere?

A)P_alv is less than at the airway opening.
B)P_alv is the same as at the airway opening.
C)P_alv is greater than at the airway opening.
D)Airway pressure is greater than P_alv.

Question 15

The presence of surfactant in the alveoli tends to do which of the following?

A)decrease compliance
B)decrease surface tension
C)increase elastance
D)increase resistance

Question 16

A fibrotic lung would exhibit which of the following characteristics?

A)decreased airway resistance
B)decreased lung compliance
C)decreased PVR
D)decreased surface tension

Question 17

Normal lung compliance is approximately which of the following?

A)0.01 L/cm H₂O
B)0.20 L/cm H₂O
C)2.00 L/cm H₂O
D)10.00 L/cm H₂O

Question 18

A lung that loses elastic fibers (as in emphysema) would exhibit which of the following characteristics?

A)decreased airways resistance
B)decreased pulmonary vascular resistance
C)increased airway resistance
D)increased pulmonary compliance

Question 19

At approximately what point during a maximum inspiration does the chest wall reach its natural resting level?

A)about 30% of the VC
B)about 40% of the total lung capacity (TLC)
C)about 70% of the VC
D)about 90% of the VC

Question 20

What forces must be overcome to move air into the respiratory system?
I)tissue movement
II)elastic forces of lung tissue
III)airway resistance
IV)surface tension forces

A)I, II, and III
B)II and IV
C)IV only
D)I, II, III, and IV

Question 21

Which of the following factors would tend to increase the elastic component of the work of breathing?
I)decreased compliance of the lungs or thorax
II)high frequencies of breathing
III)increased V_T

A)I and III
B)I, II, and III
C)II and III
D)I and II

Question 22

Most of the drop in pressure due to frictional resistance to gas flow occurs in what region?

A)nose, mouth, and large airways
B)respiratory bronchioles
C)terminal bronchioles
D)terminal respiratory unit

Question 23

Exhalation below the resting level requires active muscular effort in order to overcome what tendency?

A)the airways to collapse
B)the alveoli to expand
C)the chest wall to expand
D)the lungs to expand

Question 24

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find?
I)decrease in the slope of the volume-pressure curve
II)increase in the area of the volume-pressure curve
III)positive P_pl during exhalation

A)II only
B)I, II, and III
C)I and II
D)I and III

Question 25

In health, about what proportion of the total work of breathing is attributable to frictional resistance to gas and tissue movement?

A) $1 / 3$
B) $1 / 2$
C) $2 / 3$
D) $3 / 4$

Question 26

In traditional physical terms, how is work defined?

A)force * distance
B)force * time
C)mass * acceleration
D)mass * force

Question 27

Which of the following statements about Raw is true?

A)The greater the lung volume, the greater is the Raw.
B)The greater the lung volume, the less is the Raw.
C)As lung volume decreases toward RV, the Raw drops.
D)As lung volume increases toward TLC, the Raw rises.

Question 28

Total lung-thorax compliance in normal subjects is about what level?

A)0.1 L/cm H₂O
B)0.2 L/cm H₂O
C)1.0 L/cm H₂O
D)2.0 L/cm H₂O

Question 29

Which of the following statements about the equal pressure point (EPP) is true?

A)As gas travels from the EPP to the mouth, greater expiratory effort increases flow.
B)At the EPP, pressure inside the airway exceeds P_pl.
C)The EPP normally occurs at volumes greatly below the FRC.
D)Upstream from the EPP (toward the alveoli), P_pl exceeds pressure in the airway.

Question 30

How is airway resistance (Raw) computed?

A)change in pressure/change in volume
B)change in pressure/flow
C)change in volume / change in pressure
D)change in volume/change in pressure

Question 31

Which of the following factors affects Raw?
I)pattern of gas flow (e.g., laminar versus turbulent)II.characteristics of the gas being breathed
III)diameter and length of the airways
IV)variations in lung compliance

A)I, II, and III
B)II and IV
C)IV only
D)I, II, III, and IV

Question 32

A patient in the pulmonary lab has the following test results: compliance of the lung (C_L) = 0.20 L/cm H₂O; compliance of the lung and thorax = 0.04 L/cm H₂O. What is the patient's chest wall compliance?

A)0.05 L/cm H₂O
B)0.08 L/cm H₂O
C)0.24 L/cm H₂O
D)0.70 L/cm H₂O

Question 33

Why is the total mechanical work of breathing difficult to assess during spontaneous breathing?

A)Most volunteer subjects cannot understand the procedure used.
B)Respiratory muscle activity contributes to inflation resistance.
C)The respiratory muscles (diaphragm, etc.) must be paralyzed.
D)The subjects used to make the measurements must be unconscious.

Question 34

Normal Raw is approximately which of the following?

A)0.1 to 0.2 cm H₂O/L/sec
B)0.5 to 2.5 cm H₂O/L/sec
C)15.0 to 20.0 cm H₂O/L/sec
D)20.0 to 25.0 cm H₂O/L/sec

Question 35

For healthy individuals at rest, which of the following statements about exhalation is true?

A)Exhalation will be passive, due to inspiratory stored potential energy.
B)Exhalation will only require 40% of the energy expended for inspiration.
C)Exhalation will be the result of accessory respiratory muscle use.
D)Exhalation will generally take half the time of inspiration.

Question 36

Which of the following formulas is used to compute the mechanical work of breathing?

A)change in pressure/flow
B)change in pressure * change in flow
C)change in pressure * change in volume
D)change in volume/change in pressure

Question 37

What is the term for the impedance to ventilation caused by the movement of gas through the conducting system of the lungs?

A)airway resistance
B)lung compliance
C)surface tension
D)tissue elastance

Question 38

On inspecting a volume-pressure curve of the lungs and thorax, an increase in the mechanical work of breathing above normal would always be indicated by which of the following?

A)decrease in the area of the volume-pressure curve
B)decrease in the slope of the volume-pressure curve
C)increase in the area of the volume-pressure curve
D)Increase in the slope of the volume-pressure curve

Question 39

In healthy individuals, what may lead to airway collapse?

A)increased lung recoil
B)significantly decreased surfactant
C)maximal inspiration to TLC
D)forced exhalation to RV

Question 40

According to Poiseuille's law, which of the following statements are true if we wish to maintain a constant flow of gases?

A)Alveolar recruitment has its greatest affect on flow.
B)Halving the tube radius will require a 16-time increase in driving pressure.
C)Large jumps in driving pressure are needed to overcome airway narrowing.
D)The driving pressure varies directly with the airway circumference.

Question 41

Which of the following statements apply to a lung unit with higher resistance than normal?

A)A given volume change will require less of a pressure change.
B)It will fill and empty more rapidly than a normal lung unit.
C)There will be less volume change for a given pressure change.
D)Volume to this area will remain the same under all conditions.

Question 42

For a given transpulmonary pressure gradient and inflation time, which of the following lung units would exhibit the greatest change in volume?

A)a unit with high resistance and low compliance
B)a unit with high resistance and normal compliance
C)a unit with normal resistance and low compliance
D)a unit with normal resistance and normal compliance

Question 43

What is gas that is wasted during normal ventilation called?

A)alveolar ventilation
B)bronchial ventilation
C)conducting ventilation
D)dead space ventilation

Question 44

A patient has a V_T of 625 ml and a physiological dead space of 275 ml and is breathing at a frequency of 16 per minute. What is the alveolar ventilation (V_A)?

A)3000 ml/min
B)4400 ml/min
C)5600 ml/min
D)7000 ml/min

Question 45

During normal inspiration, which of the following occurs?

A)Alveoli at the apexes expand less than those at the bases.
B)Alveoli at the apexes expand more than those at the bases.
C)Alveoli at the bases expand less than those at the apexes.
D)Central alveoli expand more than those at the periphery.

Question 46

In a normal individual, what is the oxygen cost of breathing as a percentage of the body's total oxygen consumption?

A)5%
B)10%
C)20%
D)35%

Question 47

All of the following will cause an increase in the pressure energy required for inspiration EXCEPT which one?

A)increased compliance
B)increased flow
C)increased resistance
D)increased volume

Question 48

In patients with small-airway disease breathing at higher than normal frequencies, what will NOT happen?

A)Dynamic compliance drops.
B)Oxygen consumption decreases.
C)The distribution of ventilation worsens.
D)The work of breathing increases.

Question 49

Given a constant resistance, how will increasing the compliance of a lung unit alter gas movement into and out of the alveolus?

A)Both filling and emptying will be slower.
B)The alveolus will fill and empty more quickly.
C)The alveolus will fill more quickly but empty more slowly.
D)The alveolus will fill more slowly but empty more quickly.

Question 50

Which of the following statements are true about pressure differences in the upright lung?
I.P_pl increases from lung apex to base.
II.The apical alveoli resting volume is less than at the base.
III.The transpulmonary pressure gradient is greatest at the apex.

A)I and III
B)I, II, and III
C)II and III
D)I and II

Question 51

Which of the following lung units would empty and fill most slowly?

A)a unit with high resistance and high compliance
B)a unit with high resistance and low compliance
C)a unit with low resistance and high compliance
D)a unit with low resistance and low compliance

Question 52

In a normal individual lying on the right side (right side down), which of the following conditions would be true?

A)Both lungs would receive nearly equal ventilation.
B)The left lung would receive the most ventilation.
C)The right lung would receive the most ventilation.
D)There is inadequate information to make a decision.

Question 53

Compared to a normal individual, when a patient with a severe obstructive impairment such as emphysema increases ventilation, which of the following occurs?

A)Carbon dioxide production falls as anaerobic metabolism increases.
B)Oxygen consumption increases at a faster rate than normal.
C)Oxygen consumption rises faster than carbon dioxide production.
D)The anaerobic threshold is reached later than normal.

Question 54

If a patient has a V_T of 370 ml and a respiratory rate of 20 breaths per minute, what is the minute ventilation?

A)2.40 L/min
B)3.70 L/min
C)6.45 L/min
D)7.40 L/min

Question 55

A normal 150-lb man is breathing at a rate of 17 with a tidal volume of 450 ml. By estimation, what is his approximate alveolar ventilation?

A)7.65 L/min
B)5.10 L/min
C)3.85 L/min
D)2.60 L/min

Question 56

Which of the following factors would tend to increase the frictional component of the work of breathing?
I)decreased compliance of the lungs or thorax
II)high frequencies of breathing
III)increased Raw

A)I and II
B)I, II, and III
C)I and III
D)II and III

Question 57

Which of the following formulas are used to compute the time constant of a lung unit?

A)change in pressure * flow
B)compliance/resistance
C)resistance/elastance
D)resistance * compliance

Question 58

Blockage of the pulmonary arterial circulation to a portion of the lung would cause which of the following?

A)decrease in anatomical dead space
B)decrease in physiologic dead space
C)increase in alveolar dead space
D)increase in anatomical dead space

Question 59

Regional factors affecting the distribution of gas in the normal lung result in which of the following?

A)More ventilation goes to the apexes and lung periphery.
B)More ventilation goes to the apexes and lung core.
C)More ventilation goes to the bases and lung core.
D)More ventilation goes to the bases and lung periphery.

Question 60

In individuals with disorders characterized by an increased frictional work of breathing, such as emphysema, which of the following breathing patterns results in the minimum work?

A)rapid and deep breathing
B)rapid and shallow breathing
C)slow and deep breathing
D)slow and shallow breathing

Question 61

Given a constant carbon dioxide production, how will changing the level of V_A affect the PaCO₂?

A)A decrease in $\dot { V }$ _A will decrease PaCO₂.
B)An increase in $\dot { V }$ _A will decrease PaCO₂.
C)An increase in $\dot { V }$ _A will increase PaCO₂.
D)PaCO₂ is unaffected by changes in $\dot { V }$ _A.

Question 62

What is ventilation in excess of metabolic needs called?

A)hyperpnea
B)hyperventilation
C)hypopnea
D)hypoventilation

Question 63

How can the body effectively compensate for an increased V_Dphy?

A)decreased drive to breath
B)decreased respiratory rate
C)increased respiratory rate
D)increased tidal volume

Question 64

Which is the correct formula to calculate the alveolar minute ventilation of a spontaneously breathing subject?

A)f * V_DS/V_T
B)f * V_T
C)f * (V_T - V_DSphys)
D)f * (V_T + V_DSphys)

Question 65

In clinical practice measuring the physiologic dead space ventilation is achieved by using which formula?

A)Bernoulli's equation
B)modified Bohr equation
C)modified Shunt equation
D)Reynold's equation

Question 66

What is ventilation that is insufficient to meet metabolic needs called?

A)hypoventilation
B)hyperventilation
C)hyperpnea
D)hypopnea

Question 67

In what portion of the lungs does alveolar dead space normally occur?

A)apices
B)bases
C)middle portions of the lungs
D)terminal respiratory units

Question 68

Which of the following ventilatory patterns would result in the greatest $\dot { V }$ _A per minute (assume constant dead space)? $\underline {Frequency}~~~~ \underline { { Tidal~ Volume } }$
$\begin{array}{lll}\text { A. } 8 &&& 840 \\\text { B. } 18 &&& 220 \\\text { C. } 24 &&& 250 \\\text { D. } 30 &&& 160\end{array}$

Question 69

Which of the following ventilatory patterns would result in the MOST wasted ventilation per minute (assume constant physiologic dead space)? Frequency
Tidal Volume

A) $8 \quad 800$
B) $16 \quad 220$
C) $25 \quad 200$
D) $30 \quad 170$

Question 70

Under resting metabolic conditions, how much carbon dioxide does a normal adult produce per minute?

A)150 ml/min
B)200 ml/min
C)250 ml/min
D)300 ml/min

Question 71

Which of the following diseases or disorders is most likely to result in an increased V_D/V_T ratio?

A)atelectasis
B)pneumonia
C)pulmonary embolus
D)pulmonary fibrosis

Question 72

For carbon dioxide levels to remain constant during exercise, which of the following factors must be elevated?

A)alveolar ventilation
B)dead space ventilation
C)hemoglobin
D) $\dot { V }$ / $\dot { Q }$ ratio

Question 73

What will happen if the rate of breathing increases without any change in total minute ventilation ( $\dot { V }$ _Econstant)?

A)The dead space ventilation per minute will decrease.
B)The $\dot { V }$ _A per minute will decrease.
C)The $\dot { V }$ _A per minute will increase.
D)The $\dot { V }$ _A per minute will remain constant.

Question 74

What is the normal increase in ventilation that occurs with increased metabolic rates called?

A)hyperpnea
B)hyperventilation
C)hypopnea
D)hypoventilation

Question 75

In normal individuals, approximately what fraction of the V_T is wasted ventilation (does not participate in gas exchange)?

A) $1 / 4$
B) $1 / 3$
C) $1 / 2$
D) $2 / 3$

Question 76

What is the single best indicator of the adequacy or effectiveness of $\dot { V }$ _A?

A)PaO₂
B)PAO₂
C)PaCO₂
D)V_T

Question 77

Hypoventilation is defined as:

A)decreased tidal volume
B)low blood oxygen level
C)very slow respiratory rate
D)elevated blood carbon dioxide level

Question 78

A patient has a PCO₂ of 56 mm Hg. Based on this information, what can be concluded?

A)The patient is hyperventilating.
B)The patient is hypoventilating.
C)The patient's breathing rate is fast.
D)The patient's V_T is low.