Abstract
Objective: Chest tube insertion is not always necessary for patients with mild pneumothorax. The ‘air-width,’ which is defined as a maximal width of free air space in the pleural cavity measured by computed tomography (CT) imaging, may be a good marker for the indication of chest tube insertion.
Methods: We retrospectively analyzed patients who were brought to our hospital's emergency department (ED) and diagnosed with a traumatic pneumothorax by thoracic CT imaging on arrival. Pneumothoraces which did not require initial chest tube placement were evaluated. CT images were then reassessed to measure air-widths and pneumothoraces were divided into 2 groups: the large air-width group (≥10mm) and the small air-width group (<10mm). Pneumothoraces in each group which did not have chest tube insertion at the time of the ED evaluation were then assessed for insertion later in the hospital course by a search through their medical records. The receiver-operating characteristic (ROC) curve was used to assess if an air-width of 10 mm is the optimal cut-off point.
Results: Out of 78 pneumothoraces, 51 cases did not receive chest tube insertion while in the ED. When assessed by air-width, the large air-width group contained 8 cases which did not receive a chest tube and the small air-width group had 43 cases not treated by chest tube. Comparatively, 4 of the 8 cases (50%) without initial chest tube insertion eventually needed chest tube placement later in their hospital course in the large air-width group while the small air-width group had 4 out of 43 cases (9.3%) which needed chest tube placement later on. Multiple logistic regression analysis revealed that an air-width ≥10mm was the only independent risk factor for chest tube insertion (odds ratio = 9.75; confidential interval 1.74-54.78). The area under the ROC curve for the necessity of chest tube insertion in pneumothorax was 0.850 and Youden index showed that the optimal air-width cut-off point was 10.9 mm.
Conclusions: Traumatic pneumothoraces whose air-widths are smaller than 10mm based on CT imaging obtained during their ED assessment can be managed safely without chest tube insertion. Thus an air-width greater than 10mm may be an optimal cut-off point. This value may also be easy to remember while managing patients in a busy environment.
