LFTs

Question 1

What is FEV1?

Answer 1

• Forced expiratory volume in 1s (FEV1): the volume exhaled in the first second after deep inspiration and forced expiration, similar to PEFR.

Question 2

What is FVC?

Answer 2

• Forced vital capacity (FVC): the total volume of air that the patient can forcibly exhale in one breath.

Question 3

What does FEV1/FVC ratio of <0.7 show?

Answer 3

Obstructive disease

Question 4

What are the Spirometry findings in obstructive lung disease? (3)

Answer 4

• Reduced FEV1 (<80% of the predicted normal)
• Reduced FVC (but to a lesser extent than FEV1)
• FEV1/FVC ratio reduced (<0.7)

Question 5

What does a FEV1/FVC ratio of >0.7 show?

Answer 5

Restrictive lung disease

Question 6

What are the Spirometry findings in restrictive lung disease? (3)

Answer 6

• Reduced FEV1 (<80% of the predicted normal)
• Reduced FVC (<80% of the predicted normal)
• FEV1/FVC ratio normal (>0.7)

Question 7

What should be stopped before reversibility testing in Spirometry and for how long? (2)

Answer 7

• Short-acting beta-2-agonists should be stopped 6 hours prior to testing.
• Long-acting beta-2-agonists should be stopped 12 hours prior to testing.

Question 8

What does presence of reversibility in Spirometry suggest?

Answer 8

Asthma

Question 9

What does partial reversibility in Spirometry show?

Answer 9

Coexisting diagnosis of asthma and other obstructive disease

Question 10

What are 5 causes of obstructive lung disease?

Answer 10

• COPD
• Asthma
• Emphysema
• Bronchiectasis
• Cystic fibrosis

Question 11

What are the pulmonary (5) and non-pulmonary (4) causes of restrictive lung disease?

Answer 11

Pulmonary
• Pulmonary fibrosis
• Pneumoconiosis
• Pulmonary oedema
• Lobectomy/pneumonectomy
• Parenchymal lung tumours

Non-pulmonary
• Skeletal abnormalities (e.g. kyphoscoliosis)
• Neuromuscular diseases (e.g. motor neuron disease, myasthenia gravis, Guillan-Barre syndrome)
• Connective tissue diseases
• Obesity or pregnancy

Question 12

What is PEFR?

Answer 12

Peak expiratory flow rate
Measure peak expiratory flow out of the lungs to show obstruction

Question 13

When is pefr used?

Answer 13

To assess severity of asthma

Question 14

What is FeNo?

Answer 14

Fractional exhaled nitric oxide in breath of patients

Question 15

When is FeNO used?

Answer 15

Biomarker for asthma as it shows level of inflammation

Aids in diagnosis of asthma

Question 16

What is DLCO?

Answer 16

Lung diffusion test
Pulmonary function test that shows how much oxygen moves from lungs to blood by measureing carbon mono side

Question 17

What factors can determine oxygen transfer in a DLCO test? (5)

Answer 17

• The amount of surface area in your alveoli.
• The amount of blood in your capillaries.
• The concentration of hemoglobin (a protein that carries oxygen) in your blood.
• The thickness of the membrane between your alveoli and capillaries.
• Excess fluid in your alveoli.

Question 18

What can cause a low DLCO? (7)

Answer 18

• Smoking.
• Cystic fibrosis.
• COPD.
• Emphysema.
• Sarcoidosis and other interstitial lung diseases.
• Heart and blood conditions, like pulmonary embolism, pulmonary arterial hypertension, congestive heart failure and anaemia.
• Autoimmune disorders like mixed connective tissue disease, scleroderma and lupus (SLE).

Question 19

What can cause a high DLCO? (8)

Answer 19

○ Obesity.
○ Asthma.
○ Exercising before the test.
○ High altitude.
○ Bleeding in your lungs.
○ Cardiac shunt.
○ Heart failure.
○ Polycythemia vera.