[1] Hosp Univ Penn, Dept Med, 3400 Spruce St, Philadelphia, PA 19104 USA
[2] Hosp Univ Penn, Vasc Lab, 3400 Spruce St, Philadelphia, PA 19104 USA
[3] Hosp Univ Penn, Dept Med, Div Pulm & Crit Care, 3400 Spruce St, Philadelphia, PA 19104 USA
[4] Penn Presbyterian Med Ctr, Dept Emergency Med, Div Emergency Ultrasound, Philadelphia, PA USA