Detection of occult pneumothoraces in the significantly injured adult with blunt trauma.

Background: Identification of pneumothoraces is essential during the initial assessment of major injury. Prompt intervention is crucial for effective resuscitation and for subsequent safe management. Historically, emergency departments have relied on chest X-ray for detection of pneumothoraces. More recently, the increasing availability of computed tomography (CT) has provided a more sensitive means of detection. Occult pneumothoraces are those that are missed on clinical examination and chest X-ray, but are detected on subsequent CT.

Objective: To determine the incidence of occult pneumothoraces and their impact on subsequent management.

Patients: All blunt trauma patients with CT scans from a single, large, adult emergency department in 1 year.

Methods: Patient records were analysed to determine the proportion of pneumothoraces detected on CT that had not been previously detected on chest X-ray. Records were further examined to determine how many occult pneumothoraces required additional management after detection.

Results: In all, 134 blunt trauma patients required a CT scan. Thirty-five pneumothoraces were detected in 27 patients; 15 were occult. Six of these 15 were managed with intercostal drain insertion, all proceeding to mechanical ventilation. Of the eight patients (one bilateral) managed observantly, all had uncomplicated recoveries. CT was significantly more sensitive in the detection of pneumothoraces (P=0.03). Retrospective review by a radiology specialist identified three chest X-rays that had findings (deep sulcus sign and prominent cardiac outline) that were suggestive of pneumothorax.

Conclusions: A sufficiently high proportion of pneumothoraces is missed on chest X-ray to advocate a low threshold for use of CT in the early assessment of blunt trauma patients, especially if mechanical ventilation is required for ongoing management.