Survival outcomes for individuals experiencing out-of-hospital cardiac arrest (OHCA) improve when bystanders deliver uninterrupted, effective cardiopulmonary resuscitation (CPR) until professional help arrives. This review sought to map existing evidence on the factors—both hindering and enabling—that arise during interactions between emergency callers and call-takers and influence whether bystander CPR (B-CPR) is started, sustained, and performed with adequate quality during OHCA calls. Included studies examined emergency callers and call-takers, explored psychological, physical, or communication-related influences on the initiation or delivery of B-CPR, and analysed recordings or transcripts of OHCA emergency calls. Comprehensive searches of Medline, CINAHL, Cochrane CENTRAL, Embase, Scopus and ProQuest were undertaken from database inception through 9 March 2022. Relevant study details were collected and synthesised descriptively, supported by summary tables. Across the 30 included studies, numerous elements were reported to influence whether B-CPR was initiated or carried out during the call. Twenty-eight studies highlighted obstacles to giving CPR instructions and to beginning CPR, with frequently cited issues including caller hesitation, limitations in physical ability, and callers disconnecting before receiving guidance. Only a small number of studies examined factors affecting the continuation (n = 2) or quality (n = 2) of CPR once started. By analysing emergency call interactions, this review outlines key challenges to delivering CPR instructions and achieving timely initiation of B-CPR. There remains a significant gap in understanding what promotes or impedes maintaining CPR and ensuring high-quality performance during the call. Further work is needed to evaluate call-taker techniques aimed at supporting callers in providing effective B-CPR.
