Validation of the 35-mm rule in traumatic pneumothorax in an Asian population.

Objectives: Thoracic injury crucially threatens human health. Recent studies have suggested using computed tomography (CT) to observe traumatic pneumothorax (PTX). However, cross-ethnic validation is required to overcome potential barriers for the global application of this method. This study aimed to validate the 35-mm rule in traumatic PTX in a Korean population.

Methods: Data from the institutional registry were analyzed, and chest CT images were reviewed. Factors for observation failure were evaluated via logistic regression analysis, and a receiver-operating curve was created to calculate the optimal cutoff value.

Results: In total, 286 participants were included in this study. The average PTX size was 8.2 (3.2-26.5) mm, and 210 of 213 (95.3%) initially observed patients with a PTX size of ≤35 mm successfully completed the safety observation. Multivariate regression analysis revealed that a PTX size of >35 mm is associated with observation failure and suggested a cutoff of 24.5 mm.

Conclusion: Most patients with traumatic PTX of ≤35 mm on CT had undergone successful 4-h observation without thoracostomy. Additionally, PTX of >35 mm was an independent risk factor for observation failure. Considering the lower optimal cutoff value and high failure rates observed in this study, the current guidelines need modifications.