Chest Abdominal-Focused Assessment Sonography for Trauma during the primary survey in the Emergency Department: the CA-FAST protocol

Purpose To evaluate the feasibility of a new protocol, Chest Abdominal-Focused Assessment Sonography for Trauma (CA-FAST), during the primary survey and to estimate its diagnostic accuracy when compared with thoracoabdominal computed tomography (CT) scan.MethodsA prospective accuracy study was performed from November 2012 to November 2013 at the Emergency Department. Only adult trauma patients who underwent a CA-FAST examination prior to a thoracoabdominal CT scan were enrolled. In addition to standard patterns detected by Extended-FAST (E-FAST) such as pneumothorax (PTX), hemothorax (HTX), pericardial and intraabdominal effusion, CA-FAST protocol also included the research of lung contusions (LCs).ResultsSix hundred and one patients were enrolled. The mean time for protocol execution was 73min. Chest ultrasonography showed the following results (all p<0.001): LCs sensitivity 59%, specificity 98%, positive predictive value (PPV) 92%, negative predictive value (NPV) 86%, accuracy 87%; PTX sensitivity 84%, specificity 98%, PPV 93%, NPV 95%, accuracy 95%; HTX sensitivity 82%, specificity 97%, PPV 87%, NPV 95%, accuracy 94%. The standard 4-views FAST examination showed a diagnostic accuracy of 91% with a sensitivity of 75%, specificity of 96%, PPV of 81% and NPV of 94%.Conclusion According to our results CA-FAST protocol proved to be a rapid bedside method, with good accuracy and high NPV in detection of ultrasonographic patterns suggestive of serious injury in trauma patients; moreover, the additional research of LCs did not cause a delay in the diagnosis. Ultrasonography should be used as initial investigation during the primary survey, sending to further diagnostic studies (CT scan) only those patients not clearly classified.