Author: Aaron Lessen M.D. Educational Pearls Ultrasound  is helpful in the setting of cardiac arrest for finding a cause like cardiac tamponade or PE, but also for predicting outcomes for non-shockable rhythms. One study showed that in those that presented with asystole or PEA and cardiac activity on US had a 4% survival rate, while those without cardiac activity had almost no chance. References:  Philip Salen, Larry Melniker, Carolyn Chooljian, John S. Rose, Janet Alteveer, James Reed, Michael Heller, Does the presence or absence of sonographically identified cardiac activity predict resuscitation outcomes of cardiac arrest patients?, The American Journal of Emergency Medicine, Volume 23, Issue 4, 2005, Pages 459-462, ISSN 0735-6757, http://dx.doi.org/10.1016/j.ajem.2004.11.007.