Abnormal lung function tests

Question 1

How would you instruct the patient to carry out spirometry

Answer 1

Inhale as much as possible then exhale rapidly and forcefully for as long as flow can be maintained - at least 6s. At the end of this patient should again fully inhale as rapidly as possible.

Question 2

What does spirometry measure?

Answer 2

total volume of air exhaled from full lung - TLC to maximal expiration - RV, = FVC
FEV1- forced expiratory volume in the the 1st second of forceful exhalation.

Question 3

How would you interpret spirometry results?

Answer 3

Calculate the FEV1/FVC ratio:

normal = 75-80%
restrictive = >70% normal
obstructive = 70% predicted

Question 4

Differentiate the causes of abnormal lung function tests suggesting obstructive lung disease

Answer 4

COPD
Asthma
Bronchiectasis
Cystic fibrosis

Question 5

Differentiate the causes of abnormal lung function tests suggesting restrictive lung disease

Answer 5

Fibrosis
Sarcoidosis
Pneumoconiosis
Interstitial pneumonias
Connective tissue diseases
Pleural effusion
Obesity
Kyphoscoliosis
Neuromuscular problems

Question 6

Recall the investigations you would carry out for abnormal lung function tests

Answer 6

Sputum sample
Peak expiratory flow
Pulse oximetry
ABG 
CXR