In January 2018, the U.S. Food and Drug Administration (FDA) issued a safety communication to alert health care providers and patients about a potential problem in the charging circuitry of the Zoll LifeVest 4000, which had the potential to prevent it from delivering a life-saving shock to patients. If the message “Call for Service – Message Code 102” is displayed on the screen, users have been advised to contact Zoll immediately for a replacement. A software update has been replaced that includes a more prominent warning to immediately contact Zoll should that message code appear. The full safety communication can be viewed at