Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 3 4 2019 06 22 e39 e39 Farhad Heydari Department of Emergency Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Babak Masoumi Department of Emergency Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Majid Zamani Department of Emergency Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran Mohammad Nasr-Esfahani Department of Emergency Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran 2019 05 04 2019 06 01 Introduction: The observation period was recently challenged by some studies; and it has been suggested that a 1-hour observation period may be sufficient to allow safe discharge in asymptomatic patients with penetrating thoracic injury (PTI) and normal initial Chest X-Ray (CXR). Objective: The current study was performed to investigate if in asymptomatic and hemodynamically stable patients with PTIs who has an initial normal evaluation, 1-hour observation interval is safe to detect clinically significant injuries and is it possible to discharge these patients safely after a negative Extended – Focused Assessment with Sonography in Trauma (E-FAST) at hour1 instead of hour 3. Method: This cross-sectional study was performed on asymptomatic patients with penetrating thoracic injury, referred to emergency department (ED) and normal initial CXR and the Extended Focused Assessment with Sonography in Trauma (E-FAST). The second E-FAST was done 1 hour after the first one and the third repeat E-FAST and control CXR then performed 3 hours post-injury. 24 hours follow up by phone call was done for each patient after discharge. Results: Finally, 117 patients with the average ages of 25.9 ± 7.8 years were enrolled of whom 92.5% were male. Eight patients developed PTX or HTX during first hour of observation that were diagnosed by E-FAST or CT scan requested by the in-charge physician. One hundred-nine patient completed E-FAST and radiograph studies at times zero, 1 h, and 3 h. One patient had a normal initial evaluation but demonstrated a PTX on the 3-h managed without intervention. The rate of delayed abnormality after an initially normal study was 7.7 % (9/117). No discharged patients returned to our ED with delayed manifestations of either PTX or HTX. Conclusion: The results of our study have shown that asymptomatic patients with PTI with negative initial evaluation and no deterioration at intervals, about 1 hour may be sufficient for detection of clinically significant pathology, considered for safe and early discharge. https://fem.tums.ac.ir/index.php/fem/article/view/148 https://fem.tums.ac.ir/index.php/fem/article/download/148/190