Atelectasis – Left Lobar Collapse

Table of Contents

Table of Contents

Published February 2020

Brandon Fainstad, MD

Assistant Professor, Internal Medicine University of Colorado


  1. Identify characteristic findings of a pneumothorax and response to decompression by a chest tube.

Teaching Instructions

Plan to spend 5-10 minutes familiarizing yourself with the animations of the powerpoint and the key findings of this chest X-ray.

Present the image either by expanding the window (bottom right) in a browser or downloading the PowerPoint file.  Have the image pulled up in presenter mode before learners look at the screen to avoid revealing the diagnosis. Advance through the animations to prompt learners with key questions and reveal the findings, diagnosis, and teaching points.  Read the following beforehand in preparation: 

Diagnosis: Underlying obstructive lung disease with bi-apical hyperinflation and lucency suggestive of apical emphysema. New opacification in the left lower lung field that abuts the mediastinum losing the left lower cardiac margin. The mediastinum is shifted significantly to the left

Teaching: The large opacification along the left lower heart border with a mediastinal shift toward that side indicates a left-sided volume loss due to left lower lobe collapse. If this dense opacity were due to a consolidation or pleural effusion the mediastinum would remain in the central chest or event slightly shifted to the patient’s right. The CT series demonstrates and occlusion of the proximal left lower airway with distal collapse. The LLL vessels remain opacified with contrast confirming her severe hypoxemia refractory to supplementary O2 is due to shunt physiology. Her condition rapidly improved after the successful aspiration of a mucus plug by bronchoscopy.

Presentation Board

Take Home Point

  1. Use shifting of the mediastinum to determine if a large lung opacity is due to a space-occupying lesion due to volume loss from atelectasis.
  2. Severe hypoxemia that does not respond to increased supplemental O2 is often due to shunt physiology.


McLoud, Boiselle, & Boiselle, Phillip M. (2010). Thoracic radiology : The requisites (2nd ed., Requisites in radiology). Philadelphia: Mosby/Elsevier.

Brandon Fainstad


Comment on this article