PFTs Flashcards

1
Q

What are the 5 components of the respiratory unit?

A
  • Airways
  • Alveoli
  • Interstitium
  • Capillary
  • RBCs
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2
Q

When is it appropriate to order PFTs? (5)

A
  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
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3
Q

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

A

True

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4
Q

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

A

Flow
Volume
Gas exchange

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5
Q

What is the normal Tidal Volume?

A

500 mL

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6
Q

What is the functional residual capacity?

A

Residual volume + expiratory reserve

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7
Q

What is the vital capacity?

A

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

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8
Q

What is inspiratory capacity?

A

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

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9
Q

What is the expiratory reserve volume?

A

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

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10
Q

Which lung volume cannot be measured with an inspirometer?

A

Residual volume

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11
Q

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

A

Name and date

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12
Q

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

A

Flow

Dynamic

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13
Q

What do capacities measure?

A

Volume

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14
Q

What is used to determine gas exchange?

A

Carbon monoxide

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15
Q

What is body plethysmography?

A

Static measurement of lung volumes

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16
Q

What is DLCO? What is it used to assess?

A

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

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17
Q

Can spirometry be used to definitively diagnose restrictive lung disease?

A

No, but can aid in diagnosis

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18
Q

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

A
  • Inability to follow instructions
  • Muscular weakness
  • Poor oral seal
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19
Q

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

A

Age
Gender
Height
Race

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20
Q

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

A

Seated

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21
Q

What happens to the lungs as we age?

A

Lose elasticity

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22
Q

What is FEV1?

A

Change in expiratory volume in the 1st second

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23
Q

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

A

max of dV/dt

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24
Q

What is FEV25-75?

A

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

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25
Q

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?

A

FEV1/FVC

Less than the 5th percentile or a value less than 0.7

26
Q

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

A
FEV1:
Mild = greater than 70%
Mod = 50% to 69%
Severe = 35-50%
Very Severe = less than 35%
27
Q

What are the obstructive pathologies to airflow? (6)

A
  • Asthma
  • COPD
  • Bronchiectasis
  • CF
  • Upper airway obstruction
  • Extrinsic airway narrowing
  • FBs
28
Q

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

A

Earlier outflow peak, with a sudden dropoff of flow

29
Q

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

A

Lower plateau, with a lower FEV1 value

30
Q

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

A

Lower plateau, with a lower FEV1 value

31
Q

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

A

Within 5%

32
Q

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

A

Morphology of the graph

33
Q

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

A

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

34
Q

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

A

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

35
Q

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

A

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

36
Q

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

A

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
Q

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

A

Reduced flows throughout inspiration and expiration

38
Q

What is the indication for a bronchoprovocation test?

A

Evaluate airway hyperresponsiveness

39
Q

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

A

Methacholine
Mannitol
Hypertonic saline

40
Q

What indicated a positive bronchoprovocation test?

A

If FEV1 decreases by more than 20% after drug administration

41
Q

What is the PD20 for a bronchoprovocation test?

A

Dose required to lower the FEV1 by 20%

42
Q

What are the three techniques to measure lung capacities?

A
  • Body plethysmography
  • Nitrogen wash out
  • He technique
43
Q

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

A

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

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

44
Q

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

A

Less than 80% of normal

45
Q

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

A

Greater than 120% of normal

46
Q

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

A

Myasthenia gravis
Guillain-barre
Spinal cord injury

47
Q

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

A

Kyphosis

Scoliosis

48
Q

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

A

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

If decreases, then it is affected.

49
Q

What can cause abnormal DLCO? (3)

A
  • Alveolar abnormalities
  • Interstitial space process
  • Capillary/circulation probs
50
Q

What is the MIP? A low value indicates what?

A

Maximum inhalation against an occluded airway

Lower value indicates breathing problems are neuromuscular in origin

51
Q

What is MEP?

A

Maximal exhalation against an occluded airway

52
Q

What are the 8 steps of PFT interpretation?

A
  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
Q

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

A

FEV1/FVC

54
Q

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

A

FEV1 compared to reference

55
Q

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

A

Variation of FEV1 and/or FVC on prebronchodilator and post

56
Q

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

A

Obstructive

57
Q

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

A

Restrictive

58
Q

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

A

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

59
Q

What is the treatment for paradoxical vocal cord dysfunction?

A

Speech pathology exercises

60
Q

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

A

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

61
Q

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

A

Lower flows and volumes throughout

62
Q

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

A

12%

200 mL