Chapter 43: Physiology of Ventilatory Support

Chapter 43: Physiology of Ventilatory Support

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. In which of the following types of ventilation is alveolar expansion during inspiration due to a decrease in pleural pressure?
2. positive-pressure ventilation (PPV)
3. negative-pressure ventilation (NPV)
4. spontaneous ventilation

a.	1 and 2
b.	1 and 3
c.	2 and 3
d.	1, 2, and 3

 

 

ANS:  C

NPV decreases pleural pressure (P_p1) during inspiration by exposing the chest to subatmospheric pressure.

 

DIF:    Recall             REF:   p. 1045          OBJ:   1

 

2. Which of the following statements are TRUE about negative-pressure ventilation (NPV)?
3. NPV is similar to spontaneous breathing.
4. Airway (mouth) pressure during NPV is zero.
5. Expiration during NPV is by passive recoil.
6. NPV decreases pressure at the body surface.

a.	2 and 4
b.	1, 2, 3, and 4
c.	3 and 4
d.	1, 3, and 4

 

 

ANS:  B

Mechanical NPV is similar to spontaneous breathing. NPV decreases pleural pressure (P_pl) during inspiration by exposing the chest to subatmospheric pressure. Negative pressure at the body surface (P_bs) is transmitted first to the pleural space and then to the alveoli (P_alv). Because the airway opening remains exposed to atmospheric pressure during NPV, a transairway pressure gradient is created. Thus, gas flows from the relatively high pressure at the airway opening (zero) to the relatively low pressure in the alveoli (negative).

 

DIF:    Recall             REF:   p. 1045          OBJ:   1

 

3. In which of the following types of ventilation is alveolar expansion during inspiration due to an increase in alveolar pressure?
4. negative-pressure ventilation
5. positive-pressure ventilation
6. spontaneous ventilation

a.	1 and 2
b.	2 and 3
c.	2
d.	1, 2, and 3

 

 

ANS:  C

Gas flows into the lungs because pressure at the airway opening (P_awo) is positive and alveolar pressure (P_alv) is initially zero or less positive.

 

DIF:    Recall             REF:   p. 1046          OBJ:   1

 

4. All of the following occur with positive-pressure ventilation (PPV), except?

a.	During inspiration, pleural pressure decreases.
b.	During inspiration, pressure in the alveoli increases.
c.	The pressure gradients of normal breathing are reversed.
d.	During inspiration, alveolar pressure exceeds pleural pressure.

 

 

ANS:  A

Because alveolar pressure is greater than pleural pressure (P_pl) during PPV, positive pressure is transmitted from the alveoli to the pleural space, causing pleural pressure to increase during inspiration.

 

DIF:    Recall             REF:   p. 1047          OBJ:   1

 

5. In which of the following types of ventilation can pleural pressure become positive during inspiration?
6. positive-pressure ventilation
7. spontaneous ventilation
8. negative-pressure ventilation

a.	2 and 3
b.	1 and 2
c.	1, 2, and 3
d.	1

 

 

ANS:  D

Because alveolar pressure is greater than pleural pressure (P_pl) during PPV, positive pressure is transmitted from the alveoli to the pleural space, causing pleural pressure to increase during inspiration.

 

DIF:    Recall             REF:   p. 1047          OBJ:   1