The occult pneumothorax: An increasing diagnostic entity in trauma

The increasing use of CT for the evaluation of blunt abdominal trauma has d iagnosed undetected pneumothoraces in many patients. We performed a retrosp ective study at a major trauma center to determine the incidence of occult pneumothorax in the trauma patient. All trauma patients (3121) admitted to a Level I trauma center over a 51-month period were reviewed to determine t he incidence of pneumothorax and occult pneumothorax, the method of diagnos is, and treatment. All major trauma patients received a chest X-ray (CXR), whereas 842 patients (27%) underwent an abdominal CT scan. In the 172 patie nts diagnosed with pneumothorax,157 abdominal CT scans were performed and 1 43 were positive for pneumothorax. CXR revealed 49 right-sided pneumothorac es and 58 left-sided pneumothoraces in 95 patients. Abdominal CT scans diag nosed 73 right pneumothoraces and 90 left pneumothoraces in 143 patients. T here were 67 patients (71 thoraces) who were seen to have a pneumothorax on abdominal CT scan not seen on admission CXR. This represents 2.2 per cent of all trauma patients and 7.9 per cent of patients with abdominal CT scans . In looking at just trauma patients with pneumothorax, the CT scan was res ponsible for diagnosing 39 per cent of the patients with a pneumothorax. Th e occult pneumothorax is being diagnosed more frequently as methods of eval uating and diagnosing trauma patients become more sensitive.