Deck 3: Mechanics of Ventilation

Question 1

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

A) Chronic bronchitis
B) Acute respiratory distress syndrome
C) Emphysema
D) Pneumonia

Answer 1

Emphysema

Question 2

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

A) More than -20 cm H₂O
B) Less than -20 cm H₂O
C) More than -40 cm H₂O
D) Less than 50 cm H₂O

Answer 2

More than -20 cm H₂O

Question 3

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

A) Elastance
B) Lung compliance
C) Airway resistance
D) Lung recoil

Answer 3

Lung compliance

Question 4

What is the normal CLT?

A)0.1 L/cm H₂O
B)0.2 L/cm H₂O
C)0.3 L/cm H₂O
D)0.4 L/cm H₂O

Question 5

Which of the following is the function of the surfactant?

A) To feed alveolar cell type I
B) To lower surface tension
C) To increase surface tension
D) To lubricate alveoli

Question 6

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

A) They will receive volume from larger alveoli.
B) They will retain the same volume even at the end of an exhalation.
C) They will require a lower distending pressure.
D) They will empty into larger alveoli.

Question 7

What is the normal composition of the surfactant?

A) 90% phospholipid and 10% protein
B) 50% phospholipid and 50% protein
C) 10% phospholipid and 90% protein
D) 30% phospholipid and 70% protein

Question 8

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

A) Volume gradients
B) Pressure gradients
C) Temperature gradients
D) Flow gradients

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.

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

Question 10

What is the normal lung compliance (CL)?

A)0.1 L/cm H₂O
B)0.2 L/cm H₂O
C)0.3 L/cm H₂O
D)0.4 L/cm H₂O

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?

A) The volume is the same regardless of the type of breath.
B) That is the lung capacity.
C) The pressure gradient is the same.
D) The flow gradient is the same.

Question 12

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

A) The expiratory time will be shorter.
B) The inspiratory time will be shorter.
C) The expiratory time will be longer.
D) The inspiratory time will be longer.

Question 13

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

A) TLC
B) RV
C) FRC
D) IC

Question 14

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

A) Infant lungs are smaller and accept less volume for a given pressure.
B) Adult lungs are larger and accept less volume for a given pressure.
C) The infant lung is more elastic.
D) The adult lung is more elastic.

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

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

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.

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

Question 17

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

A) Pulmonary fibrosis
B) Pleural effusion
C) Emphysema
D) Pneumonia

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.

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

Question 19

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

A) Increases by 50%
B) Increases by 100%
C) Does not change but more alveoli are recruited
D) Increases by 50% and more alveoli are recruited

Question 20

What is the best word to define elastance?

A) Compliance
B) Recoil
C) Airway resistance
D) Inflation

Question 21

Which of the following ventilatory strategies is useful in managing a patient with status asthmaticus?

A) Decreasing inspiratory flow rates
B) Increasing inspiratory flow rates
C) Shortening the expiratory time
D) Lengthening the inspiratory time

Question 22

A female approximately 25 years old was thrown from a vehicle and sustained a penetrating wound to her left chest.The wound is deep and emits a sucking sound with each inspiration.The woman is complaining of severe left chest pain and has no breath sounds over the left side of the chest.Her trachea is in the midline position.What is the most probable diagnosis?

A) Left-sided pulmonary contusion
B) Right-sided atelectasis
C) Left-sided non-tension pneumothorax
D) Left-sided tension pneumothorax

Question 23

With normal values for total compliance (0.1 L/cm H₂O) and Raw (1.0 cm H₂O/L/sec), one TC should be approximately:

A) 0.1 sec
B)0.2 sec
C)0.3 sec
D)0.4 sec

Question 24

In order to determine the ventilator parameter that reflects both elastic and flow resistive opposition to lung inflation, the respiratory therapist should assess which of the following pressures?

A) P_peak
B) P_mouth
C) P_pl
D) P_plat

Question 25

Which of the following structures accounts for almost 50% of total Raw at FRC?

A) Upper airways
B) Airways less than 3 mm in diameter
C) Main bronchi
D) Trachea

Question 26

A patient who is critically ill and endotracheally intubated is admitted to the ICU for ventilatory management.Which of the following lung conditions explains the patient's having short time constants?

A) Decreased CL
B) Increased Raw
C) Normal CL and normal Raw
D) Normal CL and high Raw

Question 27

The respiratory system equation of motion is the theoretical basis for what kind of mechanical ventilation?

A) Inverse ratio ventilation
B) Proportional assist ventilation
C) High-frequency ventilation
D) Negative pressure ventilation

Question 28

Which of the following parameters is the most relevant in assessing the potential for pressure-induced alveolar injury during positive pressure mechanical ventilation?

A) P_peak
B) P_mouth
C) P_pl
D) P_plat

Question 29

What is the normal airway resistance?

A)4.0 to 4.5 cm H₂O/L/sec
B)3.0 to 3.5 cm H₂O/L/sec
C)2.0 to 2.5 cm H₂O/L/sec
D)0.5 to 1.5 cm H₂O/L/sec

Question 30

What is considered the "gold standard" index of diaphragmatic fatigue?

A) Tension-time index of the diaphragm
B) Plateau pressure
C) Low inflection determination
D) Duty cycle

Question 31

A patient's PIP has increased significantly since the last measurement 2 hours ago.It is noticed that the P_plat has not changed.What is the most probable explanation for the increased PIP?

A) Increased lung compliance
B) Increased airway resistance
C) Decreased lung compliance
D) Decreased airway resistance

Question 32

Which of the following conditions are associated with the presence of air trapping and auto-PEEP?
I.High airway resistance
II.Weak lung recoil force
III.High breathing rates
IV.Short expiratory times

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

Question 33

The point at which intraairway pressure equals the surrounding P_pl is knows as:

A) Dynamic airway compression
B) Equal pressure point
C) Lower inflection point
D) Critical opening pressure

Question 34

A time constant determines how rapidly the source pressure and lung pressure equalize.Which of the following parameters determine the time constant?
I.CL
II.Raw
III.TLC
IV.FRC

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

Question 35

Patients with pulmonary fibrosis tend to have rapid and shallow respiration.Which of the following lung conditions explains their breathing pattern?

A) High compliance
B) High elastance
C) High airway resistance
D) High peak airway pressures

Question 36

Auto-PEEP is known to increase WOB in spontaneously breathing and mechanically ventilated patients.Which of the following maneuvers will reduce auto-PEEP in both types of patients?

A) Increasing CL
B) Promoting a breath hold
C) Shortening the expiratory time
D) Lengthening the expiratory time

Question 37

According to Poiseuille's law, if an airway's radius decreases to one-half of its original size, what pressure will be required to maintain the original flow through the airway?

A) 2 times more pressure
B) 4 times more pressure
C) 8 times more pressure
D) 16 times more pressure

Question 38

Helium is sometimes used in patients with severe airway obstruction to reduce the work of breathing.Which of the following properties of helium allows better airflow in these patients?

A) Density
B) Viscosity
C) Velocity
D) Molecular weight

Question 39

If the calculated time constant is 0.1 sec, what time will be required to achieve 99.3% equilibrium of pressure or volume?

A)0.3 sec
B)0.4 sec
C)0.5 sec
D)0.6 sec

Question 40

People with emphysema have an increased work of breathing (WOB) as a result of their high expiratory Raw.In order to keep their airways open during exhalation, they perform which of the following maneuvers?

A) Deep inhalation
B) Rapid exhalation
C) Breath hold
D) Pursed-lip breathing

Question 41

Although an increased use of accessory ventilatory muscles coupled with rapid, shallow breathing may signal impending diaphragmatic fatigue, which of the following signs is typically seen in critically ill patients with ventilatory failure and diaphragmatic fatigue?

A) Retractions
B) Cyanosis
C) Abdominal paradox
D) Stridor