Pulmonary Function Tests

Question 1

What are the two main types of respiratory disorders?

Answer 1

Obstructive and Restrictive

Question 2

What are restrictive disorders?

Answer 2

Extra-airways disorders which restrict the ability of the lungs to entirely fill with oxygen

Question 3

What are obstructive disorders?

Answer 3

Airways diseases which are associated with obstructed airflow

Question 4

what is FVC?

Answer 4

The forced vital capacity - the maximum amount of air which you can forcibly exhale from your lungs after fulling inhaling

Question 5

On a flow volume loop, which direction is exhalation and which direction is inhalation?

Answer 5

Expiration = going up
Inspiration = Going down

Question 6

How do you calculate the vital capacity from a flow volume loop?

Answer 6

The difference between the two places the looop croses the x axis

Question 7

what is the tidal volume?

Answer 7

The amount of air inhaled and exhaled per breath

Question 8

What is PEF?

Answer 8

Peak expiratory flow - the maximum flow rate - taken by the peak of the flow loop

Question 9

What are four reasons which spirometric pulmonary function tests might be undertaken?

Answer 9

1. Evaluate symptoms eg breathlessness
2. Monitor the progression of a lung disease over time
3. Monitor the efficacy of the treatment
4. Use it as a screening tool in the absence of sympoms

Question 10

Describe how a flow volume loop would look for a patient with Mild Obstructive disease?

Answer 10

Reduced FVC, Coving of the exhalation curve (indented)

Question 11

What are the major disadvantages of the spirometric pulmonary function tests?

Answer 11

Heavy reliance on technique and can be rather uncomfortable for patients which reduces their motivation to apply maximum effort

Question 12

What does a flow volume loop look like for a patient with severe obstructive disease?

Answer 12

Reduced FVC, Significantly Indented exhalation Curve, Reduced Peak Expiratory Flow

Question 13

What does a flow volume loop like for patients with a restrictive disease?

Answer 13

Reduced FVC, Narrow Curve

Question 14

What does the Flow Volume Curve loop like for someone with a variable extrathoracic obstruction?

Answer 14

Blunted inspiratory curve
Otherwise normal

Question 15

What does the Flow Volume Curve loop like for someone with a variable intrathoracic obstruction?

Answer 15

Blunted Expiratory Curve
Otherwise normal

Question 16

What does the Flow Volume Curve loop like for someone with a fixed airway obstruction?

Answer 16

Blunted inspiratory cure
Blunted expiratory curve
Otherwise normal

Question 17

How do you work out the PEF from a flow volume loop

Answer 17

Highest observed y value

Question 18

How to calculate the FEV1 from a spirometer pulmonary test?

Answer 18

Read the Y value from X=1 second

Question 19

How to calculate the Peak Expiratory Flow Rate on spirometer graph?

Answer 19

Read up from x=0.2 seconds and multiply by 300 for L/minute

Question 20

What does a spirometer curve look like in a obstructive disease?

Answer 20

Low Peak Expiratory Flow and FVC/FEV1 ratio, and small FVC

Question 21

Why does an obstructive condition result in a shallow spirometer curve?

Answer 21

Severe airflow limitation caused by narrowing of the medium and small airways
Respiratory muscle weakness and increased lung compliance may contribute to the reduced ability of the lungs to generate the pressure required to clear the lungs quickly

Question 22

Why might there be wavy airflow pattern after a certain period of time despite having normal airflow?

Answer 22

Patients may be unable to hold the expiration further - manifestation of the Hering-Breuer reflex where afferent signals from the airways lead to simulation of inspiration and cessation of expiratory muscle force

Question 23

What are some causes of extra-pulmonary restrictive diseases?

Answer 23

Obesity, Pneumoconiosis, Pulmonary fibrosis and severe burns