2. Pulmonary Function Tests

Question 1

the rate at which the lung deflates (exhales) is a function of what?

Answer 1

resistance, and elastic recoil.

Question 2

elastic recoil is determined by what?

Answer 2

properties of the tissue, and the volume to which it is inflated

Question 3

stiff balloon will empty more or less air in one sec than floppy?

Answer 3

more

Question 4

balloon that is inflated to a higher volume will empty more or less air in one sec than a less-volume balloon?

Answer 4

more

Question 5

low FEV1 comes from what 3 things/

Answer 5

• incr in airway resistance
• decr in recoil
• decr in volume
• any combo of these

Question 6

diseases in which airway resistance is incr

Answer 6

asthma, bronchitis, tracheal tumor, aspiration

Question 7

diseases in which recoil is decr

Answer 7

emphysema

Question 8

diseases in which lung vol decr

Answer 8

restrictive disease

Question 9

in restrictive disease, is the VC incr or decr?

Answer 9

decr

Question 10

in obstructive disease, is the VC incr or decr?

Answer 10

normal or decr

Question 11

how does pulm fibrosis have opposing effects on the FEV1?

Answer 11

elastic recoil incr -> incr FEV1

stiff lungs cannot be inflated very much -> decr FEV1

Question 12

what measure distinguishes between obstructive and restrictive disease?

Answer 12

RATION of FEV1 to FVC.

Question 13

PFTs in obstructive disease

Answer 13

FEV1 decr, FVC normal or decr, ratio decr

Question 14

PFTs in restrictive disease

Answer 14

FEV1 decr, FV decr, ration normal or incr

Question 15

since we can’t measure FRC or RV with spirometry, how do we measure them?

Answer 15

plethysmography (like Inyang did?)

Question 16

VC + RV = what?

Answer 16

TLC.

Question 17

what is FRC?

Answer 17

point at which the elastic recoil of lungs exactly balances the recoil of the chest wall

Question 18

what is RV when does it increase?

Answer 18

RV = amt of gas left in lungs after max expiratory effort. incr in obstructive disease (air trapping)

Question 19

what is a restrictive ventilatory defect?

Answer 19

expansion of the lungs is restricted. reduction in TLC. NOT a reduction in VC. caused by insp muscles being unable to fully inflate the lungs and rib cage.

Question 20

examples of restrictive defect?

Answer 20

neuromuscular disease, chest wall problems, pleural disease, loss of lung, interstitial lung disease

Question 21

when is the flow-volume loop most useful?

Answer 21

in dx problems with inspiration, exp extra-thoracic airflow obstruction.

Question 22

what affects the diffusing capacity?

Answer 22

• partial pressure gradient of CO between alveolus and blood.
• total surface area avail for gas exchange
• hemoglobin
• thickness of diffusing surface
• lung vol (if can’t take deep breath, DLCO decr)

Question 23

what happens to diff capacity in smokers?

Answer 23

in smokers, there is incr CO in blood, which decr the partial pressure gradient, and decr measured DLCO

Question 24

combination of obstructive pattern and low DLCO suggests what disease?

Answer 24

emphysema

Question 25

combination of restrictive pattern, incr ratio, and low DLCO suggests what disease?

Answer 25

interstitial lung disease