Pulmonary emboli after blunt trauma: timing, clinical characteristics and natural history.

BACKGROUND: Venous thromboembolism (VTE) frequently complicates the recovery of trauma patients, and contributes to morbidity and mortality. Recent studies showed an increase in diagnosis of pulmonary embolism (PE) mainly in the early or immediate period after trauma. The clinical significance of those incidental PEs is unclear.
METHODS: The study cohort included all blunt trauma patients who had a contrast-enhanced CT of the chest performed as part of their initial trauma assessment from January 1, 2005 to January 31, 2007 in a large academic Canadian trauma centre. Patients diagnosed with PE at any point during admission were identified using our institutional trauma registry. All chest CT scans and electronic charts were reviewed. Patients were classified according to time of PE detection (immediate, early or late) and symptoms (asymptomatic or symptomatic). The clinical characteristics and hospital course of the patients who were diagnosed with immediate PE were described.
RESULTS: 1259 blunt trauma patients were reviewed. Six patients presented with immediate PE (0.5%); nine patients were found to have early PE (0.7%) and 13 had late PE (1.0%). All six of the patients with immediate PE were classified as asymptomatic. Five of the nine patients with early PE were symptomatic and all 13 patients who developed late PE were symptomatic. Amongst the six patients with immediate PE, five survived 24h hospitalisation. Four of them were managed with prophylactic low molecular weight heparin and no other thromboembolic events were observed during admission or after discharge.
CONCLUSIONS: The increased use of advanced CT technology in trauma patients has resulted in an increased diagnosis of incidental PEs that are asymptomatic. The clinical significance and management of these small, incidental PE are uncertain and further studies are needed to clarify the natural history of this controversial finding.