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Flashcards in PFTs Deck (62):
1

What are the 5 components of the respiratory unit?

-Airways
-Alveoli
-Interstitium
-Capillary
-RBCs

2

When is it appropriate to order PFTs? (5)

1. Evaluation of pts with suspected respiratory disease
2. Eval of severity of respiratory disease
3. Preop
4. Eval of persons at risk for pulmonary disease
5. Assessment of therapeutic response

3

True or false: you should never order PFTs in the acute setting

True

4

What are the three factors of respiration that are measured with PFTs?

Flow
Volume
Gas exchange

5

What is the normal Tidal Volume?

500 mL

6

What is the functional residual capacity?

Residual volume + expiratory reserve

7

What is the vital capacity?

TLC - residual volume (total volume that you can move)

8

What is inspiratory capacity?

Tidal volume + inspiratory reserve (total amount of air that you can move into your lungs, not including the residual volume)

9

What is the expiratory reserve volume?

Difference between the end of tidal volume expiration, and residual volume

10

Which lung volume cannot be measured with an inspirometer?

Residual volume

11

What is the first thing to check with a PFT result?

Name and date

12

What does spirometry measure? Is this a static or dynamic measure?

Flow
Dynamic

13

What do capacities measure?

Volume

14

What is used to determine gas exchange?

Carbon monoxide

15

What is body plethysmography?

Static measurement of lung volumes

16

What is DLCO? What is it used to assess?

Diffusion capacity of the lungs for CO. Used to evaluate gas exchange capacity of the lungs

17

Can spirometry be used to definitively diagnose restrictive lung disease?

No, but can aid in diagnosis

18

What are the three major factors that may affect the accuracy of spirometry?

-Inability to follow instructions
-Muscular weakness
-Poor oral seal

19

What is the reference population for PFTs based on? (4)

Age
Gender
Height
Race

20

What position must the patient be in to properly evaluate PFTs?

Seated

21

What happens to the lungs as we age?

Lose elasticity

22

What is FEV1?

Change in expiratory volume in the 1st second

23

Where is the FEV1 on a normal time-volume curve?

max of dV/dt

24

What is FEV25-75?

Forced expiratory volume in the 25-75% of the curve

25

What part of a PFT is used to assess whether or not there is an obstruction to airflow? What value of this is characteristic of an obstruction to airflow?

FEV1/FVC
Less than the 5th percentile or a value less than 0.7

26

What value of a PFT determines the severity of an obstruction to airflow? What values indicate mild, moderate, and severe?

FEV1:
Mild = greater than 70%
Mod = 50% to 69%
Severe = 35-50%
Very Severe = less than 35%

27

What are the obstructive pathologies to airflow? (6)

-Asthma
-COPD
-Bronchiectasis
-CF
-Upper airway obstruction
-Extrinsic airway narrowing
-FBs

28

What happens to the flow volume loop with an obstructive disease?

Earlier outflow peak, with a sudden dropoff of flow

29

What happens to the FVC plateau on the time-volume exhaled curve with an obstructive disease? What about the FEV1?

Lower plateau, with a lower FEV1 value

30

What happens to the FVC plateau on the time-volume exhaled curve with an restrictive disease? What about the FEV1?

Lower plateau, with a lower FEV1 value

31

Sequential FVC measurements should be within what value of each other to be considered good quality?

Within 5%

32

How can you determine that quality of the breath in a PFT (time vs volume exhaled curve)?

Morphology of the graph

33

What are the characteristics of the flow-volume curve pattern with restrictive lung diseases?

Lower volumes and flow rates, but normal morphology of the curve

34

What happens to the volume vs flow curve with an obstructive disease?

Indentation of the normal curve, with a lower PEF (flow drops off more quickly than usual after peak reached)

35

What happens to the time-volume expired curve with obstructive diseases?

Slow rise, reduce volume expired, prolonged time to full expiration

36

What is the morphology of the flow-volume loop with a large lower airway obstructive disease? Why?

Inflow is normal, but expiratory flow plateau is reduced, and prolonged

Expiration increases pressure inside the lungs, and puts pressure on a narrow airway

37

What is the morphology of the flow-volume loop with a fixed lower airway obstructive disease? (think concentric obstruction)

Reduced flows throughout inspiration and expiration

38

What is the indication for a bronchoprovocation test?

Evaluate airway hyperresponsiveness

39

What are the three drugs used to induce bronchospasm with a bronchoprovocation test?

Methacholine
Mannitol
Hypertonic saline

40

What indicated a positive bronchoprovocation test?

If FEV1 decreases by more than 20% after drug administration

41

What is the PD20 for a bronchoprovocation test?

Dose required to lower the FEV1 by 20%

42

What are the three techniques to measure lung capacities?

-Body plethysmography
-Nitrogen wash out
-He technique

43

What is Boyle's law? What is the simplification that is used with body plethysmography?

(V1)(P1)(T1) = (V2)(P2)(T2)

T1=T2, thus (V1)(P1) = (V2)(P2)

44

What is the range of TLC that indicates a restrive lung pathology?

Less than 80% of normal

45

What is the range of TLC that indicates a hyperinflated lung pathology?

Greater than 120% of normal

46

What are some examples of the neuromuscular pathologies that can cause restrictive lung diseases?

Myasthenia gravis
Guillain-barre
Spinal cord injury

47

What are the skeletal abnormalities that can cause restrictive lung disease?

Kyphosis
Scoliosis

48

How do you determine the cause of a restrictive lung disease?

DLCO normal = respiratory unit it fine, and the restriction is outside the lungs.

If decreases, then it is affected.

49

What can cause abnormal DLCO? (3)

-Alveolar abnormalities
-Interstitial space process
-Capillary/circulation probs

50

What is the MIP? A low value indicates what?

Maximum inhalation against an occluded airway

Lower value indicates breathing problems are neuromuscular in origin

51

What is MEP?

Maximal exhalation against an occluded airway

52

What are the 8 steps of PFT interpretation?

1. Ensure demographics
2. FEV1/FVC
3. How severe
4. Fixed or reversible
5. Large airway obstruction
6. Intra or extrathoracic
7. Restrictive process?
8. Parenchymal disease

53

What are the PFT values that are used to determine if there is an airway obstructive present?

FEV1/FVC

54

What are the PFT values that are used to determine the severity of an obstruction?

FEV1 compared to reference

55

What are the PFT values that are used to determine if there is an airway obstruction is fixed or reversible?

Variation of FEV1 and/or FVC on prebronchodilator and post

56

Obstructive or restrictive pattern on time vs volume expired curve: Slow rise, reduced volume expired; prolonged time to full expiration

Obstructive

57

Obstructive or restrictive pattern on time vs volume expired curve: fast rise to plateau at reduced max volume

Restrictive

58

Reduced inflow but normal outflow on a volume-flow curve indicates what? Why?

Upper airway obstruction d/t lower pressures in the airways are occluding the upper airways

59

What is the treatment for paradoxical vocal cord dysfunction?

Speech pathology exercises

60

What does the volume-flow curve look like with a fixed obstruction? Why?

low plateau on both inspiration and expiration, since the obstruction does not change with inspiration or expiration

61

What does the volume-flow curve look like with neuromuscular weakness?

Lower flows and volumes throughout

62

After giving bronchodilators, the FEV1 must improve by more than what percent and increase by how many mLs to diagnose an obstructive lung disorder

12%
200 mL