PROJECT SUMMARY Children with severe respiratory and cardiopulmonary illness who need out-of-hospital (prehospital) emergency care are vulnerable to error and preventable harm. Improving prehospital patient safety for children is a national research priority. Video-consultation with pediatric experts on telemedicine platforms (expert teleconsultation) is a promising intervention that has produced safer care for children in hospitals and narrowed gaps in access for underserved communities. However, the potential safety benefits of expert teleconsultation remain largely untapped by Emergency Medical Service (EMS) systems. Studies demonstrating efficacy of pediatric applications are urgently needed to improve EMS technology adoption. This R03 application builds on skills, experience, and pilot data from Dr. Boyle’s K23 award to compete for a future R01 award to support her transition to research independence as a clinician scientist conducting prehospital trials. To prepare for a future efficacy trial, Dr. Boyle worked with EMS providers to design a low-cost mobile platform for use in ambulances and adapt a simulation model to assess the technical performance of prehospital teams in high-risk pediatric transports and measure the effects of interventions on patient safety outcomes. She conducted a pilot simulation-based randomized controlled trial (RCT) to test intervention acceptability, feasibility and estimate statistical parameters for the future R01 efficacy trial. This work identified two gaps that must be addressed before progressing to the larger trial. First, the primary assessment tool lacked accuracy as it measured harm indirectly via performance, so needed further adaptation. Second, teleconsultants had relevant expertise but used unstructured communication which lessened intervention fidelity. This R03 application leverages existing K23 pilot RCT video- recordings and qualitative data to (1) adapt and validate the simulation performance checklist to measure serious safety events, a clinically important patient centered outcome, and (2) refine intervention training to standardize communication processes in prehospital teleconsultation encounters. In Aim 1, the study team will use a modified Delphi process with expert consensus to develop a safety event checklist and apply it to K23 video-recordings to gather validity evidence to support its use in the future trial. In Aim 2, the team will test the feasibility of using a tool to measure intervention fidelity and combine this with qualitative K23 stakeholder feedback to refine the intervention training protocol to standardize communication processes. This R03 will produce the necessary measurement tools and standardized intervention training to compete for a future R01 award that tests the efficacy of teleconsultation to reduce harm in children who require prehospital emergency care, a national research priority.