Resp - Physio (Lung volume, Ventilation, & Lung and chest wall)

Question 1

What defines inspiratory reserve volume (IRV)?

Answer 1

Air that can still be breathed in after normal inspiration

Question 2

What defines tidal volume (TV)? What is its typical value?

Answer 2

Air that moves into lung with each quiet inspiration, typically 500 mL

Question 3

What defines expiratory reserve volume (ERV)?

Answer 3

Air that can still be breathed out after normal expiration

Question 4

What defines residual volume (RV)? What is its clinical limitation?

Answer 4

Air in lung after maximal expiration; cannot be measured on spirometry

Question 5

What lung volumes equal the inspiratory capacity (IC)?

Answer 5

IC = IRV + TV

Question 6

What lung volumes equal the functional residual capacity (FRC)?

Answer 6

FRC = RV + ERV (volume in lungs after normal expiration)

Question 7

What lung volumes equal the vital capacity (VC)? What defines the VC?

Answer 7

VC = TV + IRV + ERV; Maximum volume of gas that can be expired after a maximal inspiration

Question 8

What lung volumes equal the total lung capacity (TLC)? What defines TLC?

Answer 8

TLC = IRV + TV + ERV + RV; Volume of gas present in lungs after a maximal inspiration

Question 9

What is the equation for the physiologic dead space?

Answer 9

Vd = Vt x (PaCO2 - PeCO2)/PaCO2; Vd = physiologic dead space, Vt = tidal volume, PaCO2 = arterial PCO2, PeCO2 = expired air PCO2; Think: “Taco, PAco, PEco, PAco (refers to order of variables in equation)”

Question 10

What does physiologic dead space include? What is another way to define this?

Answer 10

Anatomic dead space of conducting airways plus functional dead space in alveoli; Volume of inspired air that does not take part in gas exchange

Question 11

What is the largest contributor of functional dead space?

Answer 11

Apex of healthy lung is largest contributor of functional dead space

Question 12

What are the 2 types of ventilation?

Answer 12

(1) Minute ventilation (Ve) (2) Alveolar ventilation (Va)

Question 13

What defines minute ventilation? What is its equation?

Answer 13

Total volume of gas entering the lungs per minute; Ve = Vt x respiratory rate (RR)

Question 14

What defines alveolar ventilation? What is its equation?

Answer 14

Volume of gas per unit time that reaches the alveoli; Va = (Vt - Vd) x RR

Question 15

What is the natural tendency of lungs versus chest wall?

Answer 15

Tendency for lungs to collapse inward and chest wall to spring outward

Question 16

At what point does inward pull of lung balance the outward pull of chest wall? What is also the system pressure at this point?

Answer 16

At FRC, inward pull of lung is balanced by outward pull of chest, and system pressure is atmospheric

Question 17

What determines the combined volume of the chest wall and lungs?

Answer 17

Elastic properties of both chest wall and lungs determine their combined volume

Question 18

Describe the following measures at FRC: (1) airway pressure (2) alveolar pressure (3) intrapleural pressure (4) PVR?

Answer 18

At FRC, (1) airway and (2) alveolar pressures are 0, and (3) intrapleural pressure is negative (prevents pneumothorax). (4) PVR is at minimum.

Question 19

What defines compliance?

Answer 19

Compliance - change in lung volume for a given change in pressure

Question 20

What are 3 examples of conditions in which lung compliance is decreased?

Answer 20

Decreased in pulmonary fibrosis, pneumonia, and pulmonary edema

Question 21

What are 2 examples of conditions in which lung compliance is increased?

Answer 21

Increased in emphysema and normal aging

Question 22

Draw of graph of transorgan static pressure in cmH2O (x) and volume in L (y), graphing (1) chest wall (2) lung-chest wall system (3) lung.

Answer 22

See p. 597 in First Aid 2014 for graph at top right