Advanced emphysema tied to high false positivity rate for pneumothorax in point of care ultrasound, finds study
Advanced emphysema linked to high false positivity rate for pneumothorax in point of care ultrasound suggests a new study published in the Respiratory Medicine.
Point of Care Ultrasound (POCUS) is widely used to evaluate pleural apposition in acute disease; however, the prevalence of abnormal findings among emphysematous patients is unknown. The aim of the study was to characterize POCUS findings in advanced emphysema and correlate parenchymal and spirometric changes with abnormal POCUS results. They retrospectively evaluated POCUS images obtained in hyperinflated COPD patients. Images were obtained in the 2nd intercostal space (upper lobes) and above diaphragm insertion (lower lobes).
Pleural sliding was graded as “present” or “absent,” and M-mode images graded as “seashore,” “barcode,” or “hybrid” patterns; patients were then assigned to four groups based on the combination of findings. Differences between pulmonary function testing and high-resolution CT were made by Chi Square or ANOVA testing, and association by Spearman's correlation. Agreement among three scorers (two pulmonologists and one radiologist) was assessed using Kappa statistics.
Results: The study included 48 patients with 159 lobes imaged. We found a substantial percentage of lobes had either barcode M-mode appearance (13.8 %) or indeterminate/absent lung sliding (20.3 %). We identified 87 lobes (54.7 %) that did not fit any typical definition for M-mode ultrasound findings. There was no strong association of abnormal ultrasound patterns with airflow obstruction or emphysema percentage.
There was wide interrater variability among B-mode (0.20–0.611) and M-mode (0.24-0.049) among the three graders. Hyperinflated patients often show abnormal pleural sliding appearance on POCUS, with a high false positive rate of barcode pattern. This should be considered when interpretation of POCUS drives therapeutic decisions.
Reference:
Gangemi AJ, Dass CA, Zhao H, Patel M, Marchetti N, Criner GJ, Desai P. Advanced emphysema leads to high false positivity rate for pneumothorax in point of care ultrasound. Respir Med. 2024 Dec;235:107860. doi: 10.1016/j.rmed.2024.107860. Epub 2024 Nov 16. PMID: 39557207.
