diaphragmatic paradox on ultrasound

The video is an ultrasound clip taken from the right midaxillary line in the ninth intercostal space. What are shown are a right pleural effusion, diaphragm, liver, and ascites between diaphragm and liver. There is obvious respiratory motion and, from the timing, it is possible to determine that the diaphragm, liver, and ascites move cephalad (to the left) during inspiration. Normally the diaphragm contracts and moves caudally during inspiration. In this case, the diaphragm moves paradoxically. As other inspiratory muscles lower the pleural pressure, the diaphragm, unable to contract, is pulled passively upward, along with the liver (or spleen). In this case, the presence of ascites makes it especially easy to appreciate the forces at work.

Diaphragm dysfunction is relatively common during critical illness and appreciated more often when ultrasound is used regularly. Underlying problems include neurological diseases; phrenic nerve lesions; and intrinsic muscular problems of the diaphragm, such as ventilator-induced diaphragm dysfunction. The lower limit of normal for diaphragm excursion in a supine, critically ill patient is 11 mm. Values less than this should raise consideration of diaphragm dysfunction.123

Footnotes

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  2. Dass C, Dako F, Simpson S, et al. Sonographic evaluation of diaphragmatic dysfunction: technique, interpretation, and clinical applications. J Thorac Imaging. 2019;34(6):W131-W140. PubMed ↩

  3. Tuinman PR, Jonkman AH, Dres M, et al. Respiratory muscle ultrasonography: methodology, basic and advanced principles and clinical applications in ICU and ED patients-a narrative review [published online ahead of print January 14, 2020]. Intensive Care Med. doi: 10.1007/s00134-019-05892-8. PubMed ↩