CPR was first developed in 1960, at which time the American Heart Association started a program to train physicians in closed-chest cardiac resuscitation., Today, it is recommended that every health-care provider be certified in basic cardiac life support or ACLS and that every patient consider its use in an advanced directive. Cardiac arrests are not uncommon, with an estimated 359,400 events occurring outside the hospital and 209,900 occurring in the hospital each year.,, Bedside ultrasonography has been used increasingly in emergency and critical care medicine as a rapid diagnostic technique, and can now be performed using pocket-sized devices. However, once a patient has deteriorated into cardiac arrest, no formal guidelines exist for the incorporation of bedside ultrasonographic techniques into ACLS protocols. During a code, multiple considerations such as cardiac standstill, intervening hypoxemia, metabolic acidosis, and central blood shifting, as well as resuscitative efforts, including chest compressions, positive pressure ventilation, and administered epinephrine, may confound the accuracy of a causal diagnosis. Furthermore, because of the extreme urgency and space limitations imposed by a code situation, the practical use of bedside ultrasonography may be to rapidly provide intermittent information to assess the resuscitation process itself (Video 2, Discussion video).