Each year, there are between 50-80 cases of cardiac arrest for every 100,000 people. The chance of survival is tripled if bystanders perform the simplest reanimation measure (cardiac massage). The emergency assistant “LiSa (LifeSaver) is worn on the wrist like a watch. With its integrated acceleration sensor it supports the first aider by displaying the strength of the cardiac massage and the required frequency. Additionally, it will signal for rescue breathing. The intuitive bar graph shows whether the cardiac massage is carried out to the right depth. It thus helps in particular non-specialist first aiders to carry out reanimation measures in the difficult situation of a cardiac arrest and increases the patient’s chances of survival. With its clear and reduced form and easy to read display LiSa is intuitive to use. Thanks to the elastic band the emergency assistant can quickly be attached to the arm. The angled, user-aimed display gives easily understandable feedback to the first aider that helps saving live. LiSa`s cost-effective design and realisation allows wide dispersal among the population, e.g. in the glove box of every motor vehicle.