Lung Volumes

Question 1

*** Resistance in the airways of the lungs decreases:

Answer 1

in response to parasympathetic nerve stimulation

Question 2

*** Resistance in the airways of the lungs increases

Answer 2

in response to sympathetic nerve stimulation

Question 3

*** A 12-year old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial P O2 is 60 mm Hg and P CO2 is 30 mm Hg. To treat this patient the physician should administer

Answer 3

β2-adrenergic agonist

Question 4

*** An infant born prematurely in gestational week 25 has neonatal respiratory distress syndrome. Which of the following would be expected in this infant?

Answer 4

Collapse of the small alveoli

Question 5

Tidal volume (TV)

Answer 5

normal breath

Normal value: 500ml

Question 6

Inspiratory reserve volume (IRV)

Answer 6

maximal inspiratory effort

3000-3500 ml

Question 7

Expiratory reserve volume (ERV)

Answer 7

air expired after tidal expiration

1200-1500ml

Question 8

Residual volume (RV)

Answer 8

never be expelled from the lungs

1200 ml

Question 9

Inspiratory capacity (IC)

Answer 9

(TV +IRV)

= 500 + (3000-3500)
= 3500-4000 mL

Question 10

Functional residual capacity (FRC)

Answer 10

( ERV + RV )

= (1200 -1500)+ 1200
= 2400-2700 mL

Question 11

Vital capacity (VC) / Forced vital capacity (FVC)

Answer 11

( TV + IRV + ERV )

Question 12

Total lung capacity (TLC)

Answer 12

(TV + IRV + ERV + RV)

Question 13

Can NOT be measured by spirometry

Answer 13

Residual volume (RV) & any capacity containing RV ie; TLC, FRC

Question 14

Forced Expiratory Volume (FEV)

Answer 14

83% FVC in 1st sec - FEV1
94% in 2nd sec – FEV2
97% by 3rd sec - FEV3

Question 15

Obstructive Lung Diseases

Answer 15

difficulty in moving gas out

↑ airway resistance
↓elastic recoil
↓ alveolar pressure
↓ transmural pressure

Question 16

Restrictive Lung Diseases

Answer 16

difficulty in moving gas into

↓ lung compliance

Question 17

emphysema

Answer 17

↑ TLC
↑ RV
↓ VC

Question 18

chronic bronchitis

Answer 18

↑ TLC
↑ RV
↓ VC

Question 19

asthma

Answer 19

↑ TLC
↑ RV
↓ VC

Question 20

pulmonary fibrosis

Answer 20

↓ TLC
↓ IRV
↓ ERV
↓ RV
↓ FEV1
↓ FEV1/FVC

Question 21

Respiratory minute volume (RMV)

Answer 21

TV * RR
[tidal volume (TV) and respiratory rate (RR)]

Normal RMV = 6 L

Question 22

Maximum ventilation volume (MVV) or Maximum breathing capacity (MBC)

Answer 22

Liters per minute

ex. MBC in 12 seconds = 32 L
so, MBC per minute
= 32/12 * 60 L
= 160 L

Question 23

ALVEOLAR VENTILATION

Answer 23

(TIDAL VOLUME – DEAD SPACE ) X Breaths/min

Question 24

*** A 40-year-old male, who is a chronic smoker, presents to the physician with chronic cough & difficulty in breathing. On examination, his respiratory rate was 26/min. He appeared bluish. Lung function tests revealed:

• Tidal volume = 310 ml
• Vital capacity = 3.0 Lts
• FEV1 = 1.50 Lts
• FEV1/FVC = 50%

Which of the following is the patient‘s respiratory minute volume?

Answer 24

RMV = TV * RR
= 310 * 26
= 8060 ml/min

Question 25

*** A 40-year-old male, who is a chronic smoker, presents to the physician with chronic cough & difficulty in breathing. On examination, his respiratory rate was 26/min. He appeared bluish. Lung function tests revealed:

• Tidal volume = 280 ml
• VD=150 ml
• Vital capacity = 3.0 Lts
• FEV1 = 1.50 Lts
• FEV1/FVC = 50%

Which of the following is the patient‘s alveolar ventilation volume?

Answer 25

= (TD - DS) * RR
= (280 - 150) * 26
= (130) * 26
= 3380 mL/min

Question 26

*** A 35-year-old male presents to the physician with cough & difficulty in breathing. On examination, his respiratory rate was 12/min. Lung function tests revealed: • Tidal volume = 500 ml •Vital capacity = 3.0 Lts •FEV1/FVC = 75% • The Pco2 in his arterial blood is 40 mm Hg, and the Pco2 in his expired air is 30 mm Hg. Which of the following is the patient‘s alveolar ventilation volume?

Answer 26

DS = TD * [(Pa-PE)/Pa]
= 500 * [(40-30)/40]
= 500 * (0.25)
= 125mL

AV = (TD - DS) * RR
= (500 - 125) * 12
= 375 * 12
= 4500mL

Question 27

A 55-year-old man with a history of a chronic lung disease presents to his primary care physician with worsening shortness of breath. He was diagnosed about 1 year ago. He gives a history of smoking cigarettes (one pack a day for 30 years) but has no other medical problems. His general appearance is that of a thin male who appears to be in mild distress. His cardiac examination is normal, but he is noted to have an expanded anterior-posterior diameter of the chest with expiratory wheezes and breathing through pursed lips. A chest xray reveals hyperinflated lung fields bilaterally and no infiltrates. Which of the following is the most probable diagnosis?

Answer 27

Emphysema