Blunt Traumatic Aortic Injury in the Pan-scan Era.

BACKGROUND: In the era of frequent head-to-pelvis computed tomography (CT) for adult blunt trauma evaluation, we sought to update teachings regarding aortic injury by determining 1) the incidence of aortic injury; 2) the proportion of patients with isolated aortic injury (without other concomitant thoracic injury); 3) the clinical implications of aortic injury (hospital mortality, length of stay [LOS], and rate of surgical interventions); and 4) the screening value of traditional risk factors/markers (such as high-energy mechanism and widened mediastinum on chest x-ray [CXR]) for aortic injury, compared to newer criteria from the recently developed NEXUS Chest CT decision instrument (DI). METHODS: We conducted a preplanned analysis of patients prospectively enrolled in the NEXUS Chest studies at 10 Level I trauma centers with the following inclusion criteria: age > 14 years, blunt trauma within 6 hours of ED presentation, and receiving chest imaging during ED trauma evaluation. RESULTS: Of 24,010 enrolled subjects, 42 (0.17%, 95% confidence interval [CI] = 0.13% to 0.24%) had aortic injury. Most patients (79%, 95% CI = 64% to 88%) had an associated thoracic injury, with rib fractures, pneumothorax/hemothorax, and pulmonary contusion occurring most frequently. Compared to patients without aortic injury this cohort had similar mortality (9.5%, 95% CI = 3.8% to 22.1% vs. 5.8%, 95% CI = 5.4% to 6.3%), longer median hospital LOS (11 days vs. 3 days, p < 0.01), and higher median Injury Severity Score (29 vs. 5, p < 0.001). High-energy mechanism and widened mediastinum on CXR had low sensitivity for aortic injury (76% [95% CI = 62% to 87%] and 33% [95% CI = 21% to 49%], respectively), compared to the NEXUS Chest CT DI (sensitivity 100% [95% CI = 92% to 100%]). CONCLUSIONS: Aortic injury is rare in adult ED blunt trauma patients who survive to receive imaging. Most ED aortic injury patients have associated thoracic injuries and survive to hospital discharge. Widened mediastinum on CXR and high-energy mechanism have relatively low screening sensitivity for aortic injury, but the NEXUS Chest DI detected all cases.

Pneumothorax and Hemothorax in the Era of Frequent Chest Computed Tomography for the Evaluation of Adult Patients With Blunt Trauma.

STUDY OBJECTIVE: Although traditional teachings in regard to pneumothorax and hemothorax generally recommend chest tube placement and hospital admission, the increasing use of chest computed tomography (CT) in blunt trauma evaluation may detect more minor pneumothorax and hemothorax that might indicate a need to modify these traditional practices. We determine the incidence of pneumothorax and hemothorax observed on CT only and the incidence of isolated pneumothorax and hemothorax (pneumothorax and hemothorax occurring without other thoracic injuries), and describe the clinical implications of these injuries. METHODS: This was a planned secondary analysis of 2 prospective, observational studies of adult patients with blunt trauma, NEXUS Chest (January 2009 to December 2012) and NEXUS Chest CT (August 2011 to May 2014), set in 10 Level I US trauma centers. Participants' inclusion criteria were older than 14 years, presentation to the emergency department (ED) within 6 hours of blunt trauma, and receipt of chest imaging (chest radiograph, chest CT, or both) during their ED evaluation. Exposure(s) (for observational studies) were that patients had trauma and chest imaging. Primary measures and outcomes included the incidence of pneumothorax and hemothorax observed on CT only versus on both chest radiograph and chest CT, the incidence of isolated pneumothorax and hemothorax (pneumothorax and hemothorax occurring without other thoracic injuries), and admission rates, hospital length of stay, mortality, and frequency of chest tube placement for these injuries. RESULTS: Of 21,382 enrolled subjects, 1,064 (5%) had a pneumothorax and 384 (1.8%) had a hemothorax. Of the 8,661 patients who received both a chest radiograph and a chest CT, 910 (10.5%) had a pneumothorax, with 609 (67%) observed on CT only; 319 (3.7%) had a hemothorax, with 254 (80%) observed on CT only. Of 1,117 patients with pneumothorax, hemothorax, or both, 108 (10%) had isolated pneumothorax or hemothorax. Patients with pneumothorax observed on CT only had a lower chest tube placement rate (30% versus 65%; difference in proportions [Δ] -35%; 95% confidence interval [CI] -28% to 42%), admission rate (94% versus 99%; Δ 5%; 95% CI 3% to 8%), and median length of stay (5 versus 6 days; difference 1 day; 95% CI 0 to 2 days) but similar mortality compared with patients with pneumothorax observed on chest radiograph and CT. Patients with hemothorax observed on CT had only a lower chest tube placement rate (49% versus 68%; Δ -19%; 95% CI -31% to -5%) but similar admission rate, mortality, and median length of stay compared with patients with hemothorax observed on chest radiograph and CT. Compared with patients with other thoracic injury, those with isolated pneumothorax or hemothorax had a lower chest tube placement rate (20% versus 43%; Δ -22%; 95% CI -30% to -13%), median length of stay (4 versus 5 days; difference -1 day; 95% CI -3 to 1 days), and admission rate (44% versus 97%; Δ -53%; 95% CI -62% to -43%), with an admission rate comparable to that of patients without pneumothorax or hemothorax (49%). CONCLUSION: Under current imaging protocols for adult blunt trauma evaluation, most pneumothoraces and hemothoraces are observed on CT only and few occur as isolated thoracic injury. The clinical implications (admission rates and frequency of chest tube placement) of pneumothorax and hemothorax observed on CT only and isolated pneumothorax or hemothorax are lower than those of patients with pneumothorax and hemothorax observed on chest radiograph and CT and of those who have other thoracic injury, respectively.

Prevalence and Clinical Import of Thoracic Injury Identified by Chest Computed Tomography but Not Chest Radiography in Blunt Trauma: Multicenter Prospective Cohort Study.

STUDY OBJECTIVE: Chest computed tomography (CT) diagnoses more injuries than chest radiography, so-called occult injuries. Wide availability of chest CT has driven substantial increase in emergency department use, although the incidence and clinical significance of chest CT findings have not been fully described. We determine the frequency, severity, and clinical import of occult injury, as determined by changes in management. These data will better inform clinical decisions, need for chest CT, and odds of intervention. METHODS: Our sample included prospective data (2009 to 2013) on 5,912 patients at 10 Level I trauma center EDs with both chest radiography and chest CT at physician discretion. These patients were 40.6% of 14,553 enrolled in the parent study who had either chest radiography or chest CT. Occult injuries were pneumothorax, hemothorax, sternal or greater than 2 rib fractures, pulmonary contusion, thoracic spine or scapula fracture, and diaphragm or great vessel injury found on chest CT but not on preceding chest radiography. A priori, we categorized thoracic injuries as major (having invasive procedures), minor (observation or inpatient pain control >24 hours), or of no clinical significance. Primary outcome was prevalence and proportion of occult injury with major interventions of chest tube, mechanical ventilation, or surgery. Secondary outcome was minor interventions of admission rate or observation hours because of occult injury. RESULTS: Two thousand forty-eight patients (34.6%) had chest injury on chest radiography or chest CT, whereas 1,454 of these patients (71.0%, 24.6% of all patients) had occult injury. Of these, in 954 patients (46.6% of injured, 16.1% of total), chest CT found injuries not observed on immediately preceding chest radiography. In 500 more patients (24.4% of injured patients, 8.5% of all patients), chest radiography found some injury, but chest CT found occult injury. Chest radiography found all injuries in only 29.0% of injured patients. Two hundred and two patients with occult injury (of 1,454, 13.9%) had major interventions, 343 of 1,454 (23.6%) had minor interventions, and 909 (62.5%) had no intervention. Patients with occult injury included 514 with pulmonary contusions (of 682 total, 75.4% occult), 405 with pneumothorax (of 597 total, 67.8% occult), 184 with hemothorax (of 230 total, 80.0% occult), those with greater than 2 rib fractures (n=672/1,120, 60.0% occult) or sternal fracture (n=269/281, 95.7% occult), 12 with great vessel injury (of 18 total, 66.7% occult), 5 with diaphragm injury (of 6, 83.3% occult), and 537 with multiple occult injuries. Interventions for patients with occult injury included mechanical ventilation for 31 of 514 patients with pulmonary contusion (6.0%), chest tube for 118 of 405 patients with pneumothorax (29.1%), and 75 of 184 patients with hemothorax (40.8%). Inpatient pain control or observation greater than 24 hours was conducted for 183 of 672 patients with rib fractures (27.2%) and 79 of 269 with sternal fractures (29.4%). Three of 12 (25%) patients with occult great vessel injuries had surgery. Repeated imaging was conducted for 50.6% of patients with occult injury (88.1% chest radiography, 11.9% chest CT, 7.5% both). For patients with occult injury, 90.9% (1,321/1,454) were admitted, with 9.1% observed in the ED for median 6.9 hours. Forty-four percent of observed patients were then admitted (4.0% of patients with occult injury). CONCLUSION: In a more seriously injured subset of patients with blunt trauma who had both chest radiography and chest CT, occult injuries were found by chest CT in 71% of those with thoracic injuries and one fourth of all those with blunt chest trauma. More than one third of occult injury had intervention (37.5%). Chest tubes composed 76.2% of occult injury major interventions, with observation or inpatient pain control greater than 24 hours in 32.4% of occult fractures. Only 1 in 20 patients with occult injury was discharged home from the ED. For these patients with blunt trauma, chest CT is useful to identify otherwise occult injuries.