Atelectasis

Atelectasis means loss of air. There are 4 types of atelectasis namely

1. Absorptive
2. Relaxation
3. Adhesive
4. Cicatricial

In absorptive atelectasis there is an obstructive lesion in the bronchus. There is no ventilation to the lobe beyond the obstruction. Gradually the air gets absorbed by pulmonary circulation. The involved lobe eventually is devoid of air and becomes atelectatic.

Radiologic criteria for absorptive atelectasis is:

1. A density corresponding to a segment or lobe
2. Significant signs of loss of volume
3. Compensatory hyperinflation of normal lungs

We have to develop similar understanding of cardiac, pleural, mediastinal and airway pathological processes.