Emergency system in Seoul
Seoul is a large city with a population of approximately 10 million people within a total of 605 km2. The number of 119 reports, the code indicating an emergency, per year is approximately 2 million, of which approximately 600,000 were disaster reports.5 To establish an effective disaster prevention system, the Seoul Emergency Operations Center (SEOC) was established in 2002. The SEOC is in charge of disasters such as typhoons, floods, heavy rain, strong wind, heavy snow, and earthquakes as well as emergency medical consultation and medical guidance in situations that threaten the safety and property of Seoul citizens. Currently, the system has been established with 24 fire departments and 151 emergency medical services. After the standard DA-CPR protocol is applied,5 a more systematic and immediate consultation is performed by professional medical staff. The emergency command system is operated by following a written protocol. First, when a call comes in, the primary situation call-taker receives the report and roughly ascertains the main contents of the report. Then, the call-taker confirms the chief complaint and delivers the dispatch order to each EMS. In particular, if emergency treatment is needed, including instruction after a pre-hospital cardiac arrest, a phone call to an emergency medical dispatcher is made immediately. The dispatcher ascertains the patient's condition and provides first aid guidance as necessary. In an out-of-hospital cardiac arrest, the secondary dispatcher immediately executes a dispatcher CPR order and shares information about the patient's condition with the emergency unit until they arrive at the scene. When the paramedics arrive, they contact to the first aid doctor in the center by phone, providing information on the patient’s condition to the doctor and performing procedures according to the medical guidance provided (Supplemental Figure S3).
This is a real-time support system of “Smart Video First Aid Instruction” where a 119 consultant provides first aid instructions through a video call with a caller until ambulance arrives. The system consists of three steps as follows: 1) after providing CPR instruction to the caller, the 119 consultant identifies the patient’s condition through a video call; 2) the 119 consultant provides proper CPR techniques including the rescuer’s position, hand position, and the adequate chest compression rate and depth until the emergency medical service (EMS) arrives; and 3) an emergency medicine doctor affiliated with the 119 situation room in SEOC constantly interacts with the EMS from the scene to the hospital. Video-instructed DA-CPR was attempted if the following conditions were met: 1) the presence of two or more bystanders and 2) the availability of a video call when CPR guidance based on the telephone consultation protocol was initiated by the secondary dispatcher.5 In such case, thee callers were reconnected by a video call. The system was conducted on a trial basis from January 16 to March 31, 2017. During the trial period, the system did not significantly increase the rates of favorable neurologic outcome and survival to discharge (Supplemental Figure S1). However, there were positive effects between the dispatcher and caller via video-instructed DA-CPR, such as real-time feedback, better identification of the patient’s condition, and better guidance when the caller was hesitant or panicked in the emergency situation. Therefore, an official decision was made to implement the system by extending the period.
Data collection, variables, and study outcomes
We collected data from the EMS-assessed out-of-hospital cardiac arrest database in the SEOC between January 2018 and October 2019 (Figure 2). Records regarding demographical factors, underlying diseases, CPR location, and time from collapse to CPR were reviewed. The demographics included gender and age. Age over 65 years was used to define elderly patients.11 The underlying diseases were hypertension, diabetes mellitus, coronary artery disease, cerebrovascular disease, and cancer. The CPR location was divided into three groups of home, medical or nursing institutions, and other places. The time from collapse to CPR was categorized into four groups of time < 4 min, ≥ 4 and < 8 min, ≥8 and < 15 min, and >15 min.12
The primary outcome was the difference in favorable neurologic outcome in the video-instructed DA-CPR and audio-instructed DA-CPR. The favorable neurologic outcome was defined as cerebral performance category (CPC) scores of 1 and 2 measured at hospital discharge, indicating independent activities of daily life after CPR.12 The secondary outcome was the survival to discharge rates between the two instruction methods. We also compared the differences in the first rhythm recorded by the paramedics and the return of spontaneous circulation (ROSC) before arriving at the hospital. Study design was performed according to the principles of the Declaration of Helsinki and were approved by the Institutional Review Board (IRB) of the Chuncheon Sacred Heart Hospital (IRB No. 2020-09-016). All methods in this retrospective study were performed in accordance with the relevant guidelines and regulations in manuscript. The requirement for informed consent was waived by the IRB of the hospital.
Continuous variables are described as the mean and standard deviation (SD). A Chi-square or Student’s t-test was performed to find differences according to the type of CPR instruction. Binary logistic regression analysis was performed to identify outcome predictors such as favorable neurologic outcome and survival to discharge in adult OHCA patients. Independent variables with a p value of < 0.05 in univariable analyses were entered into multivariable models and expressed as adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Statistics were performed with R (version 3.6.1) and MedCalc (www.Medcalc.org) with a statistical significance indicated at p<0.05.