Patients with suspected diaphragm paralysis (e.g., elevated hemidiaphragm on chest x-ray, a surgery that is high risk for compromising the phrenic nerve, etc.) can be evaluated using motion mode (“M-mode”) ultrasonography at the bedside. M-mode tracks the motion of tissue along a linear path over time. In this video, I’ve acquired a view of the right hemidiaphragm with my Butterfly iQ+ using the liver as my acoustic window.
When the diaphragm contracts during inspiration, it moves caudally (downward) toward the liver and ultrasound probe. The diaphragm’s motion is accentuated using a series of “sniff” tests, clearly showing that the diaphragm is moving in the expected direction with each forced inspiration. This rules out diaphragm paralysis at that point using a fast, non-invasive, and reproducible point-of-care ultrasound (POCUS) technique.
Drop me a comment below with your experiences and questions regarding this technique!