The aim of the study is to analyse if live video as a supplement to emergency calls can improve medical dispatchers' situation awareness and enhance the assistance they provide including provision of pre-hospital resources. Focus will also be on evaluating the unconscious patient and improve CPR quality.

The general experience from the medical dispatcher and the person calling the emergency number regarding the feasibility of adding live video will also be analysed.

Setting; The study will be conducted in Copenhagen Emergency Medical Services (EMS), which covers a population of approximately 1.84 million people and an area of 2559 km2. In case of an emergency, there is a single emergency phone number (1-1-2) to a call center that identifies the need for police, fire or medical assistance. If the problem is medical, the caller is re-directed to the EMS where medical dispatchers answer, process and respond to the call by activating the appropriate EMS response and delivering medical advice.

In every emergency call, the medical dispatcher starts by asking the caller about the nature of the problem and whether the patient is awake and breathing normally. In case of suspected cardiac arrest, the dispatcher follows a guideline for dispatcher assisted cardiopulmonary resuscitation based on the European Resuscitation Council Guidelines for Resuscitation. The medical dispatchers are specially trained registered nurses or paramedics with experience within emergency care. They all have a basic life support course and advanced course in DA-CPR. Their decision-making process is supported by a criteria-based, nationwide Emergency Medical Dispatch System (Danish Index), which is a validated tool for managing emergency calls for the most urgent cases of emergencies. The instructions in DA-CPR is divided into two depending on whether the bystander have received a basic CPR course (BLS course). If the bystanders have a BLS course they are also instructed in ventilation. Instructions to lay people consist of short commands. E.g., "place the victim in the supine position". All medical dispatcher has a metronome available to support they guidance. The medical dispatcher guide bystander until ambulance arrival.

Methods; When the medical dispatcher receives an emergency call they decide emergency priority level, dispatch vehicle type and competence allocation and guide in CPR as before the study. Afterwards then can add livestreaming to the emergency call. Each medical dispatcher can choose in which emergency call they want to add live video, but they are recommended to do it with all unconscious patients including cardiac arrest after bystander CPR is started.

Technical solution; For livestreaming of video footage the dispatcher sends a text message, asking the caller to give their consent to share stream video from their camera on their smartphone. When the caller confirms consent, the smartphone automatically starts securely transmitting a video live stream from the scene back to the medical dispatcher. When the emergency call is finished the link will be inactivated.

Data collection and outcome; All medical dispatchers will participate. After each emergency call with stream of live video the medical dispatcher fills out a questionnaire about their evaluations of the patient before and after live video, if the live video resulted in changed treatment of the patient, or different response. Emergency priority level, emergency response, date and time for the call and symptom-based criteria from Danish Index (1-39 items) will be collected from the dispatch system Logis CAD and compared with emergency calls without use of live video.

The person calling the emergency number 1-1-2 and accepted transmission of live video to the emergency medical dispatcher will afterwards receive a text message with a questionnaire about their experience. We will collect data for aprox. 500 emergency calls where live video is added to the call including around 200 cases with unconscious patients and 53 cases with cardiac arrest patients. We will analyse the change in CPR quality before the medical dispatcher assist in CPR using live video and after the medical dispatcher has assisted. The first evaluation of CPR quality will be as soon as possible from the streamed video and the after score will be registered when the CPR is optimized as much as possible.

Inclusion Criteria:

- Inclusion criteria (stream live video footage) These are assessed by the medical dispatcher before stream of live video footage.

• Emergency call about an unconscious patient. (The patient is defined as unconscious, if the patient is unresponsive to verbal or pain stimulus according to the Danish Index. (Inclusion criterion in relation to the Danish Index is "unconscious patient with normal breathing. A.01.03", as well as all sub-criteria that meet the above criteria e.g. "A.06.01, Unresolved problem;" Does not respond to call or pain stimulus, but no breathing problems ").
• Emergency call about suspected cardiac arrest where CPR is provided
• Emergency call about a patient with trauma/illness where the medical dispatcher thinks it will be a benefit with live video footage
• Video-capable smartphone present
• Caller by the patient's side
• Caller expected age≥ 18 years
• More than two bystanders present

Exclusion Criteria:

• If caller, patient or other bystanders do not want livestreaming to be added to the emergency call.
• No video-capable smartphone present
• Caller not by the patient's side
• Caller a child
• Less than two bystanders present

Emergency medical dispatchers in Copenhagen who added live video footage to the emergency call