Three Hours of Follow-Up Is Sufficient for Asymptomatic Penetrating Thoracic Trauma
Plain films at 6 hours did not detect any pneumothoraces or hemothoraces that were not seen at presentation or at 3 hours.
Penetrating thoracic trauma is termed "asymptomatic" if the patient has no symptoms, signs, or radiographic findings of intrathoracic injury, but delayed pneumothorax or hemothorax occurs in about 3% of such patients and usually necessitates tube thoracostomy. Patients with asymptomatic thoracic penetrating trauma usually are observed and undergo repeat chest radiography after 6 hours. However, findings from two studies suggest that 3 hours is sufficient for follow-up (JW Emerg Med May 16 2001 and Surg Gynecol Obstet 1992; 175:249).
In a prospective study, researchers compared chest radiography findings at 3 and 6 hours after presentation in patients who presented to a single emergency department within 2 hours after asymptomatic penetrating thoracic trauma (anatomic boundaries of injury: clavicles and base of the neck, superiorly; inferior costal margin and iliac crests, inferiorly). Supine anteroposterior chest radiographs were obtained at presentation, and upright posterioanterior and lateral chest radiographs were obtained at 3 and 6 hours. Patients with worrisome clinical or laboratory findings or findings of pneumothorax or hemothorax on the initial radiograph were excluded.
Of 100 patients who met inclusion criteria, 75% were men, 75% had stab wounds, and 25% had gunshot wounds. The average ED stay was 8.8 hours. Two patients had findings of pneumothorax on the 3-hour film; both patients underwent tube thoracostomy. No new cases of pneumothorax or hemothorax were detected on the 6-hour films. Patient charges, including the cost of radiographs and continuous pulse oximetry monitoring, were US$2802 for the 3-hour observation period and $4521 for the 6-hour period.
Comment: In the three studies published to date (including this study) that compared chest radiography findings at 3 and 6 hours, 8 of the combined total of 304 patients (2.6%) developed pneumothoraces within 3 hours, and no patients developed pneumothoraces or hemothoraces within the next 3 hours. The inherent value of a 3-hour follow-up chest radiography policy is that the stay is shortened, thereby relieving ED overcrowding, and associated healthcare costs are reduced considerably. Moreover, this approach limits radiation exposure, a matter of increasing concern. Some authors have advocated for the use of chest computed tomography (CT) at presentation, with immediate discharge if the scan is negative. However, that approach is a poor alternative because thoracic CT transmits 8 mSv of ionizing radiation — an amount that is 400 times the radiation dose of a two-view chest radiograph and is equivalent to 3 years of background radiation in the U.S. Finally, the evolving role of ED ultrasound, such as the extended FAST examination, and its ability to identify pneumothorax remain to be determined.
Published in Journal Watch Emergency Medicine October 10, 2008
Seamon MJ et al. Follow-up after asymptomatic penetrating thoracic injury: 3 hours is enough. J Trauma 2008 Sep; 65:549.