Topic 18: Obstructive + restrictive respiratory diseases

Question 1

Give the 2 categories of dysfunction that yield abnormal results during spirometry

Answer 1

1) Obstructive lung disease
2) Restrictive lung disease

Question 2

Give additional conditions affecting respiratory function

Answer 2

• Diseases affecting diffusion of O2/CO2 across pulmonary membranes
• Reduced ventilation due to mechanical failure
• Failure of adequate pulmonary blood flow
• Ventilation/perfusion abnormalities involving poor matching of air + blood = efficient gas exchange doesn’t occur

Question 3

Describe flow volume loops

Answer 3

• Used to diagnose + follow up lung disease
• Follow flow rate + volume changes throughout respiratory cycle

Question 4

Define Forced Vital Capacity (FVC)

Answer 4

• The maximum volume of air that can be forcibly exhaled after taking the deepest possible breath = full inspiration
• Measured in liters

Question 5

Define Forced Expiratory Volume in 1 second (FEV1)

Answer 5

• The maximum volume of air that can be forcibly exhaled in the first second of the FVC maneuver
• Measured in liters

Question 6

What is the FEV1/FVC ratio (FEV1%) and what is its normal value?

Answer 6

• The ratio of FEV1 to FVC expressed as a percentage
• Normal is 75–80%

Question 7

Describe FEV1 + FVC + FEV1/FVC ratio in obstructive lung diseases

Answer 7

• FEV1: Decreased = due to increased airway resistance
• FVC: May be normal or increased = due to air trapping
• FEV1/FVC: Decreased = <80% often ~45%

Question 8

Describe FEV1 + FVC + FEV1/FVC ratio in restrictive lung diseases

Answer 8

• FEV1: Decreased
• FVC: Decreased = more so than FEV1
• FEV1/FVC: Normal or Increased = >80% due to preserved airflow relative to reduced lung volume

Question 9

Describe obstructive lung disease

Answer 9

• Airway obstruction
• Restricted expiration
• ↓ FEV1,
• ↓ FEV1/FVC
• ↓ compliance + elastic recoil

Question 10

Give types of obstructive lung diseases

Answer 10

• Chronic bronchitis
• Bronchiolotis
• Asthma
• Emphysema
• Bronchiectasis
• Cystic fibrosis

Question 11

Describe restrictive lung diseases

Answer 11

• Restricted lung expansion
• Restricted inspiration + expiration
• ↓ FEV1 + ↓ FVC,
• FEV1/FVC normal or increased
• ↓ compliance
• ↓ elastic recoil

Question 12

Give 3 signs of restrictive lung disease

Answer 12

1) Dyspnoea = shortness of breath
2) Hypoxemia = low O2 levels
3) Cor pulmonale = right heart failure due to pulmonary hypertension

Question 13

Give types of restrictive lung diseases

Answer 13

• Interstitial diseases = pneumonia
• Fibrosis of lungs = asbestosis silicosis
• Restriction to breath = pneumothorax + rib fracture + large pleural effusion + malformaties e.g. kyphosis