Spirometry

Question 1

Which of the following is NOT an expected change in pregnancy?
-Increase in total lung capacity
-Decrease in functional residual capacity
-Decrease in expiratory reserve volume
-Increase in tidal volume

Answer 1

Increase in total lung capacity

Decrease in FRC largely driven by decrease in ERV with enlarging uterus compressing diaphragm. Balanced with increase in thoracic / ribcage dimensions one sees an increase in inspiratory capacity hence net ‘equal’ TLC.

Question 2

What lung volume is most reduced by a rising BMI?

Answer 2

Expiratory reserve volume

BMI affects all of the lung volumes, but FRC and ERV decrease ‘exponentially’ with increasing BMI.

Question 3

Reduction in FVC signification ?

Answer 3

Restriction or gas trapping

Question 4

What is the definition of restriction ?

Answer 4

TLC < LLN
Parenchymal if reduced DLCO
Extra parenchymal if normal DLCO

Question 5

What is the definition of gas trapping?

Answer 5

RV/TLC > ULN

Question 6

What is the definition of hyperinflation?

Answer 6

TLC > ULN

Question 7

Cystic Fibrosis on spirometry ?

Answer 7

Obstruction without significant reversibility

Question 8

Sarcoidosis on spirometry?

Answer 8

Anything!

Question 9

Flattening of inspiratory curve: DDX?

Answer 9

• Extrapulmonary sacroidosis causing supraglottic obstruction
• VOCAL CORD PARALYSIS
  = anything that causes thoracic aneurysm or massive left atrial enlargement (severe mitral stenosis with Ortner’s syndrome)
  = iatrogenic lesions post op thyroid surgery
  = peripheral neuropathy
  = ALS
  = anxiety can cause paradoxical vocal cord movement

Question 10

PFT showing restriction with reduction in diffusion : wrong answer?
- asbestosis
- idiopathic pulmonary fibrosis
- methotrexate
- sarcoidosis
- cystic fibrosis

Answer 10

Cystic fibrosis as usually obstructive

Question 11

Obesity on spirometry ?

Answer 11

• Curve with low lung volumes
• FEV1 qnd FVC proportionately reduced with normal ratio
• TLC reduced on lung volumes
• DLCO normal
  = consistent with extraparenchymal restriction

Question 12

Fitness for lung surgery ?

Answer 12

FITNESS FOR SURGERY
Pneumonectomy - FEV1 >2L or 80% Predicted Lobectomy - FEV1>1.5L

Question 13

Vocal cord paralysis / extrathoracic variable obstruction : NOT a cause post operatively ?
- Thyroidectomy for goitre
- Thoracic aortic aneurysm repair
- Anterior cervical spine decompression
- Nasal Septoplasty for septal deviation

Answer 13

Nasal Septoplasty for septal deviation

Question 14

Spirometry : proportional decline in FEV1 and FVC suggestive of ?

Answer 14

Underlying restriction (or gas trapping)
= pregnancy, obesity if DLCO N

Question 15

Myasthenia gravis on spirometry ?

Answer 15

Extraparenchymal lung disease so restriction with normal diffusion capacity

Question 16

Isolated reduction in functional residual capacity : dx ?

Answer 16

obesity

Question 17

DDX of fixed airway obstruction ?

Answer 17

Postintubation stenosis, large goiter, endotracheal malignancy and bronchial stenosis