Survival from on-street cardiac arrest is dependent on three factors: early recognition, CPR, and defibrillation. These three elements rely on a successful and complex interaction between a remote dispatcher and a bystander non-expert in on-site care. Digital applications have been developed to assist the bystander in performing the rescue procedures. This study focuses on the impact of introducing such an application on the already complex interactions between a bystander and a dispatcher. We performed cardiac arrests simulations and analyzed the results under the prism of distributed cognition. The results show that although the application helps the bystanders perform CPR, it disrupts an already complex interaction due to its characteristics; the distance and number of speakers can hinder the activity of the dispatcher while causing a feeling of loss of meaning and insecurity.