What is the role of ultrasonography in the workup of diaphragmatic paralysis?

Updated: Oct 10, 2018
  • Author: Justina Gamache, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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M-mode ultrasonography is a relatively simple and accurate test for diagnosing paralysis of the diaphragm in the adult population and it can be performed at the bedside.

The paralyzed side shows no active caudal movement of the diaphragm with inspiration and abnormal paradoxical movement (ie, cranial movement on inspiration), particularly with the sniff test.

Patients can be scanned in the anterior axillary line with a curved linear transducer probe angled cranially at a 90° angle to the diaphragm. In this view, the liver is used as a window on the right, while the spleen is used on the left. [15]

B-mode ultrasonography of diaphragm thickness in the zone of apposition of the diaphragm to the rib cage can also provide a sensitive and specific noninvasive assessment of diaphragmatic paralysis. Less than 20% thickening of the diaphragm muscle during inspiration is diagnostic of diaphragmatic paralysis. [3, 16]

Ultrasonography can also be used to serially monitor patients with diaphragmatic paralysis for recovery. [3]

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