Define Atelectasis
collapse or incomplete expansion of lung tissue → ↓ gas exchange
what are the types of atelectasis
Resorption (Obstructive)
Compression
Contraction
Adhesive
Passive
what is the mechanism of Resorption (Obstructive)
Air distal to obstruction is absorbed → collapse
what are the causes of Resorption (Obstructive) atelectasis
Mucus plug, foreign body, tumour
what is the mechanism of Compression Atelectasis
External pressure on lung
What are the causes of Compression Atelectasis
Pleural effusion, pneumothorax, tumour
What is the mechanism of Contraction atelectasis
Fibrosis pulls the lung in
What are the causes of Contraction atelectasis
TB, radiation fibrosis, chronic inflammation
What is the mechanism of Adhesive atelectasis
Surfactant deficiency → alveoli collapse
What are the causes of Adhesive atelectasis
Neonatal RDS, ARDS
What is the mechanism of Passive Atelectasis
Shallow breathing, pain inhibition of inspiration
What are the causes of Passive Atelectasis
Post op
Pathophysiology of Atelectasis
↓ Alveolar ventilation
↓ Functional residual capacity (FRC)
V/Q mismatch → hypoxemia
Shunting (perfusion without ventilation)
↑ Risk of infection (stagnant secretions)
what is the difference between resorptive (obstructive) and compressive atelectasis
Resoprtive - Collapse due to airway obstruction
Trapped air is absorbed into blood → alveoli collapse
Compressive - Collapse due to external pressure on
Lung compressed by fluid, gas, or mass outside lung
Resorptive = Reabsorption of gas behind a blocked bronchus
Compressive = Compression from outside the lung
All of the following cause compressive atelectasis, with the exception of?
A Asthma
B Pleural effusion
C Ascites
D Pneumothorax
A Asthma
In obstructive (resorptive) atelectasis, which of the following statements is correct?
A The mediastinum moves away from the lesion
B It involves the reabsorption of air
C It is caused by pleural fluid
D Due to a partial obstruction of an airway
B It involves the reabsorption of air
Which of the following is not a cause of compressive atelectasis?
A Pneumothorax
B Asthma
C Congestive cardiac failure (CCF)
D Pleural effusion
B Asthma
A young non-smoking woman presents with a 3 month history of cough with occasional blood-stained sputum. Her older brothers are married but without children. What is the most likely diagnosis?
A Primary ciliary dyskinesia
B Lung cancer
C Pulmonary TB
D Cystic fibrosis
A Primary ciliary dyskinesia
