Frequency and relevance of acute peritraumatic pulmonary thrombus diagnosed by computed tomographic imaging in combat casualties

BACKGROUND: Posttraumatic pulmonary embolism is historically diagnosed after clinical deterioration within the first week after injury. An increasing prevalence of immediate and asymptomatic pulmonary embolism have been reported in civilian and military trauma, termed hereafter as acute peritraumatic pulmonary thrombus (APPT). The objective of this study was to define the frequency of APPT diagnosed by computed tomographic (CT) imaging in wartime casualties. An additional objective was to identify factors, which may be associated with this radiographic finding METHODS: A 1-year retrospective cohort analysis conducted using the US and UK Joint Theater Trauma Registries performed to determine the prevalence of and risk factors for the diagnosis of APPT in casualties admitted to Bastion Hospital, Afghanistan. APPT imaging characteristics were collected, and demographics, injury severity and mechanism, and risk factors were included in the analysis. Logistic regression was used to identify factors independently associated with APPT. RESULTS: APPT was found in 66 (9.3%) of 708 consecutive trauma admissions, which received a CT chest with intravenous contrast as part of their initial evaluation. Diagnosis of APPT at the time of injury was made in 23 patients (3.2%), while thrombus was detected in 43 additional patients (6.1%) at the time of reexamination of CT images. Of the APPTs, 47% (n = 31) were central, 38% (n = 25) were segmental, and 15% (n = 10) were subsegmental. Forty-seven percent (n = 31) had bilateral APPT. Logistic regression found presence of deep venous thrombosis on admission (odds ratio, 5.75; 95% confidence interval, 2.44-13.58; p < 0.0001) and traumatic amputation (odds ratio, 2.53; 95% confidence interval, 1.10-5.85; p = 0.030) to be independently associated with APPT. All APPTs were felt to be incidental and likely would not have required interventions such as anticoagulation or vena caval interruption. CONCLUSION: This report is the first to characterize acute, peritraumatic pulmonary thrombus in combat injured. Nearly 1 in 10 patients with severe wartime injury has findings of pulmonary thrombus on CT imaging, although many instances require repeat examination of initial images to identify the clot. APPT is a phenomenon of severe injury and associated with deep venous thrombosis and lower-extremity traumatic amputation. Additional study is needed to characterize the natural history of peritraumatic pulmonary thrombus and the indications for anticoagulation or vena cava filter devices. LEVEL OF EVIDENCE: Epidemiologic and prognostic study, level III.