Residual apical space (RAS) correlation with recurrence in primary spontaneous pneumothorax after surgery:...

This study aims to evaluate residual apical space (RAS) as a predictor of pneumothorax recurrence in patients undergoing video-assisted thoracoscopic surgery (VATS) for primary spontaneous pneumothorax (PSP) and to assess its impact by surgical treatment type.

Data of 463 patients undergoing VATS for PSP at three Italian high-volume thoracic surgery centers (January 2012-March 2023) were retrospectively reviewed. Exclusions included secondary pneumothorax, patients < 18 years, and those undergoing thoracotomy. Four surgical approaches were analyzed, with RAS measured using the Collins method (4.2% equivalent to 0 cm RAS) on chest X-ray before discharge. The primary outcome of interest was the recurrence rate stratified by surgical procedure. Statistical analyses were performed to correlate RAS, clinical and surgical variables with pneumothorax recurrence.

The overall recurrence rate was 6.9% (32 patients). The mean hospitalization was 6.5 ± 3.5 days, with an average RAS before discharge of 9.7 ± 5.4%=1.15 cm. Mechanical pleurodesis alone had an higher recurrence risk (*p* = 0.0027), while apicectomy with chemical pleurodesis significantly reduced recurrence risk (*p* < 0.0001). Increased RAS (> 9.7%) was associated with a higher recurrence rate (*p* = 0.063). Multivariate analysis confirmed that increased RAS significantly predicts recurrence (*p* = 0.002), particularly in patients aged > 34 years. Stratifying by type of surgery, an increased RAS value was associated to higher rate of recurrence (*p* = 0.001) in patients who underwent apicectomy combined to mechanical pleurodesis.

Apicectomy combined with chemical pleurodesis is still the most protective approach for recurrence. However, despite its proven efficacy, this strategy is being progressively used less. Residual apical space may represent a procedure-dependent radiological marker associated with recurrence, particularly in patients undergoing apicectomy and mechanical pleurodesis and may be considered to reduce recurrence rates.