Timing of ultra-portable ultrasound (UPUS) Examinations in detecting clinically concerning recurrent pneumothorax.

Background: Recurrent pneumothorax (rPTX) is a common complication following thoracostomy tube (TT) removal in chest trauma patients. While chest X-ray (CXR) is most commonly used to detect a rPTX, bedside ultraportable ultrasound (UPUS) is a feasible, low cost, and radiation free alternative. No consensus exists with regards to the optimal timing of diagnostic imaging to assess for rPTX post-TT removal. Accordingly, we sought to identify an ideal UPUS timing to detect a rPTX METHODS: We conducted a single center prospective study of adult (≥18years) patients admitted with a chest trauma. UPUS examinations were performed using the Butterfly iQ⁺™ ultrasound. Three intercostal spaces (ICS) were evaluated (2nd through 4th). Post-TT UPUS examinations were performed at different timepoints following tube removal (1-6 h). A rPTX on UPUS was defined as the absence of lung-sliding in one or more intercostal spaces, and was considered a clinically concerning rPTX if lung-sliding was absent in ≥2 ICS. UPUS findings were compared to CXR.

Results: Ninety-two patients (97 hemi-thoraces) were included in the analysis. A total of 58 patients had a post-TT removal rPTX of which 11 were either clinically concerning or expanding. Comparing UPUS findings to CXR, the 3-hour post-TT removal ultrasound examinations were associated with the highest sensitivity. By hour 4, no rPTX showed expansion in size. Three patients required an intervention for a clinically concerning rPTX, all of whom were detected on UPUS 3-hour post-TT removal.

Conclusion: Bedside UPUS performed at 3-hour post-TT removal has the highest sensitivity in detecting clinically concerning rPTX. Size of rPTX appears to stabilize by hour 4. In the absence of clinical symptoms, repeat imaging or observation of non-significant rPTX beyond 4 h may not provide added clinical benefit.

Level of evidence: Level II, Diagnostic Tests or Criteria.