Thoracic ultrasound.

Dyspnea and hypotension often present a diagnostic challenge to the emergency physician. With limitations on traditional methods of evaluating these patients, lung ultrasound has become an essential assessment tool. With the sensitivity of lung ultrasound approaching that of CT scan for many indications, it is quickly becoming a fundamental technique in assessing patients with thoracic emergencies. This article reviews the principles of thoracic ultrasound; describes the important evidence-based sonographic features found in pneumothorax, pleural effusion, pneumonia, and pulmonary edema; and provides a framework of how to use thoracic ultrasound to aid in assessing a patient with severe dyspnea.