PFTs

Question 1

What are the types of PFTs?

Answer 1

Spirometry
Lung Volumes
Diffusion Capacity

Question 2

What is spirometry?

What is the primary measurement?

Answer 2

measures how an individual inhales or exhales volume of air as a function of time

Primary measurement in spirometry is either volume or flow

Question 3

What are the indications for spirometry?

Answer 3

Detecting & quantifying pulmonary impairment in cardiopulmonary diseases

Following the evolution of diseases & monitoring response to therapy

Monitoring the effects of environmental, occupational & drug exposures associated with lung injury

Assess preoperative risk

Assessing disability & impairment

Question 4

What are the primary spirometric indices?

What else can be found with spirometry?

Answer 4

Forced Vital Capacity (FVC)
Forced Expiratory volume in 1 sec (FEV1)
Ratio FEV1/FVC

Flow-Volume Loop

Question 5

How is the FVC test performed

Answer 5

having patient inhale to TLC & make a maximally forced exhalation into a spirometer

Question 6

How is Exhaled volume measured in spirometry?

How is flow measured?

Answer 6

exhaled volume is measured as a function of time (volume-time curve)

Flow is also measured & displayed as function of exhaled volume (flow-volume loop)

Question 7

How are patients classifed with spirometry?

Answer 7

Normal
Airflow obstruction
Restriction

Question 8

What are the three types of ventilatory defects?

Answer 8

Obstructive Ventilatory Defects
Restrictive Ventilatory Defects
Mixed Ventilatory Defects

Question 9

what are obstructive ventilatory defect?

Answer 9

decreased expiratory flows compared with a healthy persons

Early airway obstruction begins in the small airways & tends to reduce flows at lower lung volumes

Progressive slowing of expiratory flow is reflected in the concave shape on flow-volume curve

Question 10

What is the primary marker for presence of airway obstruction?

Answer 10

FEV1/FVC ratio

FEV1/FVC<70% predicted

Question 11

How is airway obstruction classified?

Answer 11

using the FEV1%

Question 12

What is FEF25-75?
How is it useful?
How can it be used to diagnose airflow obstruction?

Answer 12

average forced expiratory flow rate over the mid 50% of FVC

helpful in diagnosing obstruction, but dependent on FVC

, a reduced FEF25-75 <60% & FEV1/FVC in low-normal range can confirm airflow obstruction

Question 13

What is the degree o severity in obstructive defects using FEV1% pred?

Answer 13

mild= FEV1% > 80%
moderate = FEV1% 50-79%
severe = FEV1% 30-49%
very severe <35%

Question 14

What is bronchodilator response?

How is the test performed?

Answer 14

used for patients with obsructive lung disease

obtaining baseline spirometry
administering SABA, waiting 15 mins
then repeat the spirometry

Question 15

What is an improvement when administering a bronchodialtor response?

Answer 15

An improvement in FEV1 or FVC of 12% & 200ml from baseline is considered a positive response

Lack of response does not preclude a clinical response

Question 16

What are restrictive defect characterized by?
why?
What is suggestive of a restrictive defect?

Answer 16

reduced FVC

reduced because of the smaller absolute lung volumes

FVC < 80% predicted is suggestive of a restrictive defect

Question 17

When would you obtain lung volume to confirm restrictive defect?

Answer 17

If airway obstruction is present & FVC is low, a defect maybe present

Would recommend obtaining lung volumes to confirm the restrictive defect

Question 18

What are differentials for restrictive lung disease?

Answer 18

Pleural Disease
Parenchymal Lung Disease
Chest Wall Disease
Neuromuscular Disorders

Question 19

When are lung volume test used?

Answer 19

diagnose a restrictive lung disease & to determine the severity of the impairment

To help clarify whether a decrease in FVC is due to restriction or a consequence of air trapping due to airflow obstruction

Question 20

What is restrictive lung disease defined as in lung volume test?

Answer 20

Restrictive lung disease is defined as a reduction in lung volumes, particularly VC & TLC

Question 21

What are TLC ranges in normal restrictive lung diseases and obstructive lung diseases?

Answer 21

TLC Normal Range is 80-120% predicted

Restrictive Defect
TLC < 80% predicted

Obstructive Defect
TLC > 120% predicted

Question 22

What does diffusion capacity represent and measure?

Answer 22

Represents the gas exchange capabilities of the lung

Measures the ability of gas to diffuse across the alveolar-capillary membrane using carbon monoxide (DLCO)

Question 23

What does diffusion capacity depend upon?

Answer 23

Alveolar-capillary membrane
Hemoglobin concentration
Cardiac output

Question 24

What is a decreased DLCO<80% predictive of?

Answer 24

Obstructive Lung Disease
Parenchymal Lung Disease
Pulmonary Vascular Disease
Anemia

Question 25

What is a increased DLCO> 120% predictive of?

Answer 25

Asthma (maybe also normal)
Pulmonary Hemorrhage
Polycythemia
Left to Right Shunt

Question 26

What is a systematic way to interpret spirometry?

Answer 26

Look at the Force Vital Capacity (FVC) to see if its within normal limits

Look at the FEV1 & determine if it is within normal limits

If both FVC & FEV1 are normal, then you do not have to go any further

If the FEV1/FVC is <70%, you probably have an obstructive defect
Severity can be determined by the FEV1%

If FEV1/FVC is >88% and/or FVC <80%, you probably have a restrictive defect & would consider obtaining lung volumes and/or diffusion capacity

Question 27

What is a systematic way to determine Lung volume testing?

Answer 27

If the TLC < 80% predicted, then there is a restrictive ventilatory defect

If the TLC >80% predicted, but the FVC <80%, the patient does not have a restrictive defect

If the TLC >120% predicted, then there is a an obstructive ventilatory defect

Question 28

when would you order DLCO?

Answer 28

To help differentiate asthma from emphysema

To help in the evaluation & determine, the severity of interstitial lung disease or restrictive lung disease

Evaluate cardiovascular disease