Clin Med Selby - Interpreting PFTs Flashcards

1
Q

Who would get a PFT?

A
  1. Dyspnea at rest or on exertion
  2. Cough
  3. Asthma
  4. COPD
  5. Suspect bronchiectasis or bronchiolitis
  6. Suspect interstitial lung disease
  7. Suspect neuromuscular or chest wall disease
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2
Q

What is the FEV1/FVC ratio used for?

A

Normally about 0.80 and used to assess airway obstruction

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3
Q

What is the FEV1/FVC ratio in obstructive lung disease?

A

FEV1/FVC <0.70

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4
Q

What is diffusion capacity of lung for CO (DLCO)?

A
  • measure of gas exchange through alveolar wall
  • Pt inhales small amount of CO2, hold breath for 10 seconds and exhales quickly
  • concentration of CO2 in exhaled air is calculated
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5
Q

What are DDX of obstructive lung disease?

A
  1. COPD (chronic bronchitis/emphysema)
  2. Asthma
  3. Bronchiectasis
  4. Bronchiolitis
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6
Q

What are DDX for restrictive lung diseases?

A
  1. Abnormalitis of chest wall/ Pleura (kyphosis, scoliosis, obesity, chronic pleural effusions, ankylosing spondylitis)
  2. Drugs
  3. Interstitial lung disease
  4. Neuromuscular disease (amyotrophic lateral sclerosis [ALS], Guillain-Barre, Myasthenia Gravis
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7
Q

What is the spirometry PFT pattern for Obstructive lung disease?

A
  1. FEV1/FVC <0.70

2. Flow volume curve has “concave or scooped pattern” (expiratory)

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8
Q

What would you expect to see on PFT for TLC and RV on obstructive lung disease?

A
  1. Increased TLC from Air trapping

2. Increased residual volume from air trapping

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9
Q

What would you expect to see on PFT for DLCO in obstructive lung disease?

A

DLCO can be low or normal

  • Emphysema –> DLCO tends to be low causing destruction fo functional lung tissue
  • Astma and Bronchitis–> DLCO tends to be normal
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10
Q

What is the Bronchodialator response in a patient with Asthma? COPD?

A

Asthma with show an improvement with bronchodilator response

COPD/ other obstructive diseases will not show improvement with bronchodilator tx

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11
Q

What is bronchodilator response?

A

Determine if obstructive sx resolve with therapy.

  • positive response is >12% increase in FEV1 or FVC AND an absolute volume increase of >200ml
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12
Q

What would the FVC and FEV1/FVC numbers be on PFT in restrictive lung disease?

A

FVC in restrictive lung disease is <80% predicted

FEV1/FVC ration can be normal or >0.70

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13
Q

What does the flow volume curve look like in Restrictive lung pattern?

A

Peaked, steeple, or witch’s hat

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14
Q

How is the TLC and RV affected in restrictive lung disease?

A
  • TLC decreases

- RV decreases

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15
Q

What is the DLCO in restrictive lung disease?

A

DLCO will be normal or low in restrictive lung disease

in ILD it tends to be low

in neuromuscular or chest wall abnormalities it tends to be normal

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16
Q

What would you see on a mixed pattern PFT?

A

Low FEV1/FVC ratio

Low TLC <5 percentile