Occult Pneumothorax in Patients Presenting with Blunt Chest Trauma: An Observational Analysis.

Background: We aimed to assess the management and outcome of occult pneumothorax and to determine the factors associated with failure of observational management in patients with blunt chest trauma (BCT). Methods: Patients with BCT were retrospectively identified from the trauma database over 4 years. Data were analyzed and compared on the basis of initial management (conservative vs. tube thoracostomy). Results: Across the study period, 1928 patients were admitted with BCT, of which 150 (7.8%) patients were found to have occult pneumothorax. The mean patient age was 32.8 ± 13.7 years, and the majority were male (86.7%). Positive-pressure ventilation (PPV) was required in 32 patients, and bilateral occult pneumothorax was seen in 25 patients. In 85.3% (n = 128) of cases, occult pneumothorax was managed conservatively, whereas 14.7% (n = 22) underwent tube thoracostomy. Five patients had failed observational treatment requiring delayed tube thoracostomy. Pneumonia was reported in 12.8% of cases. Compared with those who were treated conservatively, patients who underwent tube thoracostomy had thicker pneumothoraxes and a higher rate of lung contusion, rib fracture, pneumonia, prolonged ventilatory days, and prolonged hospital length of stay. Overall mortality was 4.0%. The deceased had more polytrauma and were treated conservatively without a chest tube. Patients who failed conservative management had a higher frequency of lung contusion, greater pneumothorax thickness, higher Injury Severity Scores (ISS), and required more PPV. Conclusions: Occult pneumothorax is not uncommon in BCT and can be successfully managed conservatively with a close clinical follow-up. Intervention should be limited to patients who have an increase in size of the pneumothorax on follow-up or become symptomatic under observation. Patients who fail conservative management may have a greater pneumothorax thickness and higher ISS. However, large prospective studies are warranted to support these findings and to establish the institutional guidelines for the management of occult pneumothorax.