PFTs

Question 1

Indications for performing PFT

Answer 1

dyspnea, cough
pre-op
occupational exposure, disability 
severity
Treatment response

Question 2

in spirometery, expiratory effort must be maintained for ___ seconds

Answer 2

6

Question 3

What is MVV?

Answer 3

maximal voluntary ventilation: maximum amount of air that can be inhaled and exhaled within one minute

Question 4

What is the clinical use of MVV?

Answer 4

1. used to determine if person is a candidate for lung resection
2. look for weakness/fatigue that would suggest neuromuscular disorder
3. determine breathing reserve

Question 5

MVV > 55%

Answer 5

pneumonectomy candidate

Question 6

MVV > 45 %

Answer 6

lobectomy candidate

Question 7

FEV1/FVC pattern for
normal lungs
restrictive lung disease
restrictive lung disease

Answer 7

nlm: 80%
obt: < 80%
rest: > 80%

Question 8

WHy is the FEV1/FVC > normal in restrictive lung disease?

Answer 8

fibrosis increases the elasticity/recoil of the lung and since expiration is passive and depends on the recoil, inc recoil = inc expiration

Question 9

What is the gold std for measuring TLC?

Answer 9

body plethymograph (sit in the box and breathe, use PV=PV to calculate volume changes)

Question 10

Describe the effects exercise on hyperinflated lungs

Answer 10

hyper-inflated lungs = air trapping = inc FRC = raises TV baseline

this means that there is a smaller inspiratory reserve volume left n, so when this person will have decreased exercise tolerance because they are unable to take in enough fresh air to meet their needs

Question 11

air trapping inc or dec in COPD pts that are exercising

Answer 11

increases

**called dynamic inflation

Question 12

How does lung compliance change in asthma

Answer 12

no change

Question 13

How does lung compliance change in emphysema?

Answer 13

increased

*can hold more volume with a smaller change in pressure

Question 14

How does lung compliance change in (what should be here?)?

Answer 14

decreased

*can hold less volume with inc pressure

Question 15

normal compliance
increased TLC
increased VC 
increased FRC
decreased FEV1/FRC but reversible

Answer 15

asthma

Question 16

inc compliance
increased TLC
increased VC 
increased FRC
decreased FEV1/FRC and not reversible

Answer 16

emphysema

Question 17

dec compliance
dec TLC
dec VC 
dec FRC
inc FEV1/FRC

Answer 17

fibrosis

Question 18

How is the diffusing capacity of the lung measured?

What is the problem with this test?

Answer 18

CO has a higher affinity for Hb than O2 so pt breathes it in and back out and the amt that diffused can be measured
**but it requires the pt to inhale > 1L anf hold it for 10 s

Question 19

What is the normal DLCO?

Answer 19

81-140%

Question 20

increased TLC
increased VC 
increased FRC
decreased FEV1/FRC and not reversible 
Low DLCO

Answer 20

emphysema

Question 21

increased TLC
increased VC 
increased FRC
decreased FEV1/FRC and not reversible 
nml DLCO

Answer 21

chronic bronchitis

Question 22

dec TLC
dec VC 
dec FRC
inc FEV1/FRC 
normal DLCO

Answer 22

kyphosis, muscle weakness, obesity, pregnancy

Question 23

nml compliance
normal lung volumes/capacities
dec DLCO

Answer 23

PE

PAH

Question 24

What are predictors of airflow?

Answer 24

sex, age, height