Occult Pneumothorax in Patients With Blunt or Penetrating Trauma: A Descriptive, Cross-sectional Study

Thoracic injuries are the third most common cause of trauma-related morbidity/mortality and hospitalization after heart disease and malignancies. At least 25% of blunt traumatic deaths are a direct consequence of chest trauma. Additionally, rib fracture and pneumothorax are the first two most frequent blunt thoracic traumas, respectively.

Pneumothorax (PTX) is a common life-threatening complication and frequently seen in patients who have been admitted to the Emergency Department (ED) and Intense Care Units (ICU). Some traumatic PTXs are clinically and radiologically silent, not identified during the initial assessment and cannot be visible on supine chest x-ray (CXR), but later diagnosed by computed tomography (CT). This type of PTX is called occult pneumothorax (OPTX) and has been found in 30-55% of chest trauma cases. The clinical diagnosis of PTX is incorrect in approximately 30% of all traumatic cases. Besides, it has been stated that PTX has the potential to elevate the mortality rate in patients with trauma if it is not quickly managed.

On the other hand, small or medium undetected PTX usually is not life-threatening. However, delays in the diagnosis and management may result in a rapid progression of OPTX to tension PTX and lead to severe dyspnea and even death. Therefore, early detection is crucial and may influence the evaluation and management of PTX and probably be a lifesaving action.

The initial diagnostic screening test of PTX is usually CXR. However, studies reported that CXR is an insensitive and unreliable test. When the chest x-ray of the patient is acquired in a supine position, even if all of the symptoms related to pneumothorax are present (since the air is not located at the apical pulmonary region), there may not be an image consistent with PTX. For this reason, although CXR is usually used for many thoracic injuries as a screening test, it may miss the diagnosis of some thoracic injuries, including rib fractures, pulmonary contusions, and OPTX.

On the other hand, the role of CT in the assessment of chest injuries has expanded considerably in the management of both blunt and penetrating traumas. The increasing use of CT in the evaluation and management of patients with chest trauma has led to correct and sensitive identification of undetected injuries, including OPTX.