Ambulance and helicopter response times in emergency medical services. The AHRTEMIS project.

RESUME

Response time for emergency medical service vehicles such as ambulances and helicopters is one of the usually proposed key performance indicators in emergency medical services systems. It is beyond doubt that short response time is pivotal in critical conditions such as out-of-hospital cardiac arrest and trauma. However, using light and sirens and moving fast in ambulances is dangerous for patients and personnel and may be detrimental to public safety. Each year, several serious and fatal accidents related to ambulances occur worldwide. In Scandinavia, the decision to apply lights and sirens in response to an emergency is carried out using a criteria-based dispatch tool used by the Emergency Medical Dispatch Center.

PERSPECTIVE AND PURPOSE

This AHRTEMIS project aims to enhance the knowledge and the understanding in the field of criteria-based dispatch and provide decision-makers with the option of performing further differentiated response urgency for optimal resource utilization. Therefore, a Ph.D. thesis consisting of three studies and one protocol article is planned to combine a systematic review and meta-analysis with two observational studies on criteria-based dispatch types, prehospital interventions, and prehospital time stamps and their association with mortality and other effect parameters such as for instance, days spent in the intensive care unit, days on ventilator support, and illness severity. We aim to propose a differntiated response model, based on the findings of the AHRTEMIS project.

PROJECT GROUP

Peter Martin Hansen, MD, M.Sc., Ph.d. student, Consultant. The Prehospital Research Unit, Region of Southern Denmark, Odense University Hospital, Denmark, Danish Air Ambulance, Aarhus, Denmark, Department of Regional Health Research, University of Southern Denmark, Odense, Denmark. Ph.D. student.

Søren Mikkelsen, MD, Ph.D., Consultant, Professor, The Prehospital Research Unit, Region of Southern Denmark, Odense University Hospital, Denmark, Department of Regional Health Research, University of Southern Denmark, Odense, Denmark. Main supervisor.

Marius Rehn, MD, Ph.D., Consultant, Professor, Oslo University Hospital, The Norwegian Air Ambulance Foundation, Oslo, Norway, Department of Regional Health Research, University of Southern Denmark, Odense, Denmark. Co-supervisor.

Anders Perner, MD, Ph.D., Consultant, Professor, Rigshospitalet, Copenhagen, Denmark. Co-supervisor.

Annmarie Touborg Lassen, MD, Ph.D., DMA, Consultant, Professor, Head of Research, Emergency Medicine Research Unit, Odense University Hospital, .Department of Clinical Medicine, University of Southern Denmark, Odense, Denmark.  Co-supervisor.

Anne Craveiro Brøchner, MD, Ph.D., Consultant, Associate Professor, The Prehospital research Unit, Region of South Denmark, Kolding University Hospital, Denmark, Department of Regional Health Research, University of Southern Denmark, Odense, Denmark. Co-worker.

Helle Collatz Christensen, MD, Ph.D., Consultant, Associate Professor, Emergency Medical Services, Prehospital Center, Region Zealand, Næstved, University of Copenhagen. Co-worker

BACKGROUND

Response time for emergency medical service (EMS) units such as ambulances, rapid response cars and helicopters is a key performance indicator and is frequently used in the political debate on EMS coverage and performance. Short response time is considered pivotal in critical conditions such as out-of-hospital cardiac arrest and major trauma. Studies have shown reduced response time association with improved outcome, and the opposite has been described as well. Using lights and sirens for rapid EMS response may put conveyed patients, prehospital personnel, and public at potential risk and each year, several serious and fatal accidents occur.

In Scandinavia, the use of criteria-based dispatch is the standard procedure and widely used. The type of EMS response and urgency is decided within the Emergency Medical Dispatch Center by a specialist call-taker, usually a nurse or emergency medical technician. To achieve short response time, EMS vehicles utilize lights and sirens, and crews are allowed to be non-compliant with traffic rules, posing a risk for accidents. Less severe conditions may be managed according to national and international guidelines despite longer response time, suggesting the consideration of additional levels of response beyond the current practice guidelines.

Apart from specific conditions such as out-of-hospital cardiac arrest and trauma, there is lack of scientific evidence, other than best practice, to justify the shortest possible response time is related to improved patient outcomes. Several confounders may affect patient outcomes, including crowding in the receiving hospital and a shortage of personnel. Similarly, prolonged on-scene times as the result of time-consuming complex medical procedures, may affect the time to final treatment in the hospital. Thus, the intention to describe several factors influencing time to an event such as mortality remains paramount.

With the access to a complete database of all ambulance and helicopter missions in Denmark and the unique Danish Civilian Registration Register, we have the ability to merge response time data, on-scene time, transport time to a hospital; interventions, length of hospital stay; days spent in the intensive care unit including ventilator days, dialysis, vasopressor use, and mortality, with several, high-quality national registries on patient demographics and other characteristics, relevant to the research question.