Macklin effect

Last revised by Hillel S. Maresky on 3 Feb 2023

The Macklin effect describes one of the pathophysiological processes of pneumothorax and pneumomediastinum in blunt chest trauma. This effect accounts for the formation of ~40% of severe blunt traumatic pneumomediastinum. Exclusion of tracheobronchial and esophageal causes of pneumomediastinum is mandatory to exclude concomitant injury.

The mechanism proposed by Macklin was alveolar rupture with air dissecting along peribronchovascular interstitial sheaths, interlobular septa, and the visceral pleura into the mediastinum 1.

Pulmonary interstitial emphysema with air tracking along the peribronchovascular sheaths towards the hilum and associated pneumomediastinum. 

The pathophysiologic process was first proposed by C C Macklin in 1939 2.

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Cases and figures

  • Fig 1: illustration
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  •  Case 1
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  • Case 2
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  • Case 3: subcutaneous emphysema ("end result")
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  • Case 4: pneumomediastinum
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