Prospective Evaluation of Thoracic Ultrasound in the Detection of Pneumothorax

Introduction: Pneumothorax (PTX) occurs commonly in trauma patients and is confirmed by examination and radiography. Thoracic ultrasound (VIS) has been suggested as an alternative method for rapidly diagnosing PTX when X-ray is unavailable as in rural, military, or space flight settings; however, its accuracy and specificity are not known. Methods: We evaluated the accuracy of thoracic U/S detection of PTX compared to radiography in stable, emergency patients with a high suspicion of PTX at a Level-l trauma center over a 6-month period. Following University and NASA Institutional Review Board approval, informed consent was obtained from patients with penetrating or blunt chest trauma, or with a history consistent with PTX. Whenever possible, the presence or absence of the " lung sliding" sign or the "comet tail" artifact were determined by U/S in both hemithoraces by residents instructed in thoracic U/S before standard radiologic verification of PTX. Results were recorded on data sheets for comparison to standard radiography. Results: Thoracic VIS had a 94% sensitivity; two PTX could not be reliably diagnosed due to subcutaneous air; the true negative rate was 100%. In one patient, the VIS exam was positive while X ray did not confirm PTX; a follow-up film 1 hour later demonstrated a small PTX. The average time for bilateral thoracic VIS examination was 2 to 3 minutes. Conclusions: Thoracic ultrasound reliably diagnoses pneumothorax. Presence of the "lung sliding" sign conclusively excludes pneumothorax. Expansion of the FAST examination to include the thorax should be investigated.