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

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). 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). 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. 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.