Optimal management of the critically ill patient in shock requires rapid identification of its etiology. We describe a successful application of an emergency physician performed bedside ultrasound in a patient presenting with shock and subsequent cardiac arrest. Pulmonary embolus was diagnosed using bedside echocardiogram and confirmed with CTA of the thorax. Further validation and real-time implementation of this low-cost modality could facilitate the decision to implement thrombolytics for unstable patients with massive pulmonary embolism who cannot undergo formal radiographic evaluation.