Reply: Is the Finding of an Absent "Sinusoid Sign" on Lung Ultrasound Meaningful?

From the Authors:

We would like thank Herman and colleagues for their constructive review of our case discussion, “The Absent Sinusoid Sign,” published in the April 2019 issue of the AnnalATS. We agree that the significance of ultrasound findings such as sinusoid sign or absence thereof require a continued discussion. Ultrasound Reflections allows for brief, illustrated case vignettes for the purpose of teaching application and interpretation of point-of-care ultrasound imaging. One cannot derive direct significance of this ultrasound finding just yet, based on this case or prior abstracts alone. In our case discussion, we convey that our diagnosis of trapped lung was based on pleural manometry and not the ultrasound findings alone (1), as pleural manometry patterns may be used during pleural drainage procedures to indicate expansion (or nonexpansion) of the lung parenchyma. Furthermore, we allude to the fact that prospective research is ongoing. This work is expected to provide useful definitions of bedside ultrasound for the prediction of underlying pulmonary physiology, including trapped lung and lung entrapment. This research in fact stems from another set of cases described years before by our same group (2), as well as the case described here in this Ultrasound Reflections publication.

The takeaway from our article should have been that the bedside usability and potentials of bedside ultrasound for pleural disease are more expansive than what is currently depicted in the literature, one feasible application being the prediction of a nonexpandable lung. Responsible readers should approach any case-based publication with caution, avoiding inference into broader meaningfulness. We are grateful to be allowed to share our expertise with the medical community through an outlet such as Ultrasound Reflections, we appreciate the attention from zealous readers looking to expand their own applications of bedside ultrasound, and we look forward to identifying the precise significance the ultrasound finding of Absent Sinusoid Sign carries in the diagnostics and management of pleural disease, as “absent sinusoid sign is a phenomenon we continue to investigate” (1).