Observational Management of Penetrating Occult Pneumothoraces: Outcomes and Risk Factors for Interval Thoracostomy Tube Placement.

BACKGROUND Guidelines for penetrating occult pneumothoraces (OPTXs) are based on blunt injury. Further understanding of penetrating OPTX pathophysiology is needed. In observational management of penetrating OPTX we hypothesized that specific clinical and radiographic features may be associated with interval thoracostomy tube (TT) placement. Our aims were to 1) describe OPTX occurrence in penetrating chest injury, 2) determine the rate of interval TT placement in observational management and clinical outcomes compared to immediate TT placement, and 3) describe risk factors associated with failure of observational management. METHODS Penetrating OPTX patients presenting to our Level 1 trauma center from 2004-2019 were reviewed. OPTX was defined as a pneumothorax (PTX) on chest computed tomography but not on chest radiograph. Patient groups included immediate TT placement versus observation. Clinical outcomes compared were TT duration and complications, need for additional thoracic procedures, length of stay (LOS) and disposition. Clinical and radiographic factors associated with interval TT placement were determined by multivariable regression. RESULTS Of 629 penetrating PTX patients 103 presented with OPTX (16%). Thirty-eight patients underwent immediate TT placement and 65 were observed. Twelve observed patients (18%) needed interval TT placement. Regardless of initial management strategy, TT placement was associated with longer LOS and more chest radiographs. Chest injury complications and outcomes were similar. Factors associated with increased odds of interval TT placement included Chest Abbreviated Injury Scale ≥4 (aOR = 7.38 [95% CI 1.43-37.95]), positive pressure ventilation (aOR = 7.74 [1.07-56.06]), concurrent hemothorax (aOR = 6.17 [1.08-35.24]), and retained bullet fragment (aOR = 11.62 [1.40-96.62]) (all p < 0.05). CONCLUSION The majority of patients with penetrating OPTX can be successfully observed with improved clinical outcomes (LOS, avoidance of TT complications, reduced radiation). Interval TT intervention was not associated with risk for adverse outcomes. In patients undergoing observation, specific clinical factors (chest injury severity, ventilation) and imaging features (hemothorax, retained bullet) are associated with increased odds for interval TT placement, suggesting need for heightened awareness in these patients. LEVEL OF EVIDENCE Prognostic, level IV.