Factors That Affect Recovery of Spontaneous Circulation by Patients With Cardiac Arrest Before Arrival at a Hospital in Daegu Metropolitan City, South Korea


 BackgroundThis study was conducted to investigate the factors that influence Return of Spontaneous Circulation (ROSC) in patients who suffered cardiac arrest before arriving at the emergency room in DMC, Korea. MethodsThis study considered data for cardiac arrest patients by 119 paramedics from January 1, 2019 to December 31, 2019 in Daegu. Chi-squared analysis was conducted to analyze whether the subjects showed ROSC before arriving at the emergency room. Binary logic regression analysis was conducted to identify the factors that affect ROSC. ResultsROSC when a mechanical compression device was used was reduced to 0.82 of that when it was not used (95% CI = 0.60 ~ 0.92). ROSC was 3.13 times higher when a first-aid defibrillator was used than when it was not used (95% CI = 1.40 ~ 6.99). ROSC was 657 times higher when epinephrine was injected than when it was not injected. Lastly, ROSC was 1.82 (95% CI = 1.04 ~ 3.19) times higher when intubation was used than when it was not used. ConclusionThis study suggests that continuous CPR education, securing financial support, and expansion of emergency rooms for local residents are necessary.


Background
The death rate by Cardiovascular system disease in South Korea was 117.4 per 100,000 people in 2019. [1]. Sudden cardiac arrest (SCA) results in death with hemodynamic failure if the heart is not restarted within minutes [2]. In the United States, more than 550,000 patients suffer SCA each year before and during hospitalization, and SCA accounts for more than half of cardiovascular mortality, and is therefore a major concern for national interest and prevention [3]. The recovery rate of patients with cardiac arrest before arrival at the hospital in Korea increased by about 7 times from 1.1% in 2007 to 7.6% in 2017, but compared to advanced countries such as the US 11.4%, Sweden 14.0%, and Norway 13.0%, the rate is still very low [4,5]. To solve the practical problems of emergency medical treatment, the Korean government has been actively studying the prevention and management of diseases by establishing cardiovascular and cerebrovascular prevention centers to consider the characteristics of each disease in Korea.
Daegu Metropolitan City (DMC) in southeastern Korea has the fourth-largest population (2.4 million) in the country. The number of emergency room deaths among emergency-room users in DMC was 0.418%, which was the highest in the country, but the death rate before arrival in the emergency room was 0.05%, which was the lowest in the country [7].
Considering the these opposing characteristics in the emergency medical situations in DMC, the factors that in uence Return of Spontaneous Circulation (ROSC) in patients with cardiac arrest in pre-hospital, where and rapid response is required, may contribute to improvement of community participation and emergency care. Previous studies have shown that pre-emergency factors that are closely related to patient survival rate include whether the cardiac arrest patient was witnessed, whether witnesses performed CPR, whether electrocardiogram rhythm was de brillable, and whether the ROSC occurred spontaneously [8,9]. However, the factors that affect ROSC have not been studied in depth by country or region. This lack occurs because the environment and resources of emergency medical care in each country are different, so the rapid treatment and methods of coping with patients who have pre-hospital cardiac arrest may also differ.
Rather than identifying the theoretically known factors that affect the ROSC, this study focuses on patient data applied by actual paramedic, and identi es factors that in uence ROSC in the region in a practical and multifaceted manner, and thereby contributes to development of emergency medical services. Therefore, the goal of this study was to identify factors that can improve ROSC rate of prehospital cardiac arrest patients, and thereby provide basic data that can be exchanged between countries and contribute to development of emergency medical systems beyond the local community The purpose of this study is to determine whether patients with cardiac arrest recovered their circulation spontaneously before arriving at an emergency room in DMC in 2019, and to determine the factors that affected this recovery. The speci c purposes were: To identify whether or not spontaneous circulation is restored before a patient arrives at the emergency room, and to identify factors that affect ROSC before a patient's arrival in the emergency room.

Study Setting
This study considered data from patients with cardiac arrest treated by 119 paramedics from January 1, 2019 to December 31, 2019 in DMC. For data collection, the purpose and suitability of the study was explained to the head of the DMC Fire Department, and the use of the data was approved.
The emergency activity log and the details of the cardiopulmonary arrest detailed situation table were anonymized. The total number of cardiac arrest procedures during the target period was 2750. Among them, 1307 cases were selected for the ROSC; cases for which CPR was withheld or suspended by medical guidance of paramedics due to apparent death or other causes, were not considered.

Data Collection
This study selected and investigated items that are estimated to have an effect on ROSC, as suggested by the emergency-activity log and the detailed cardiopulmonary arrest schedule prepared by 119 paramedics.
The dependent variables were the ROSC of cardiac arrest patients; independent variables were the Type of occurrence, Place of occurrence, Whether the cardiac arrest was witnessed, Whether CPR was performed, Whether a mechanical compression device was used, Whether a rst-aid de brillator was used, Whether epinephrine had been administered intravenously, and Whether intubation was performed.

Statistical Analysis
In this study, IBM SPSS/WIN 23.0 Program was used for data analysis. Frequency analysis was used to quantify the general characteristics of the subjects, and Chi-squared analysis was conducted to analyze whether the subjects showed ROSC before arriving at the emergency room. Binary Logistic Regression Analysis was conducted to identify factors that affected ROSC.

Ethical consideration
The data in this study were approved and obtained from the emergency activity log and cardiopulmonary arrest detailed situation chart prepared by 119 paramedics at the DMC Fire Department, and obtained approval from K University Institutional Review Board (IRB) for the exemption of deliberation (IRB-1041459-202103-HR-003-01).

General characteristics of out-of-hospital cardiac arrest patients
Of the patients, 90.3% had a disease. Home (86.9%) has the most frequent place of occurrence. Most of the cardiac arrests were not witnessed (69.9%), and CPR was usually not performed (63.2%).

Discussion
This study con rmed that the use of a mechanical compression device affects the probability of ROSC before the patient arrives at the emergency room. These ndings show that use of a mechanical compression device was less effective than manual CPR in achieving ROSC. This result contradicts a prior study [11], which showed that mechanical compression devices were more effective than CPR in achieving ROSC, and with a review of 1,187 systems [12], which showed no signi cant difference between mechanical compression devices and hand CPR in achieving ROSC. This con icting nding may be a result of the situational environment of the country, because paramedics in Korea they tend to prefer hand CPR over mechanical compression unless the ambulance ride is long. In addition, mechanical compression devices are not always available in ambulances nationwide in Korea. These observations indicate that active research and preparation for the use of mechanical compression devices is necessary in Korea. To increase the e ciency of the use of mechanical compression devices, appropriate training on teamwork and the use of these machines should be provided, but the difference in education level and scope of work for each paramedic raises another practical problem.
This study determined that use of a rst aid de brillator increased the ROSC by 3.13 times. A previous study [13] suggested that improvement of the quality of CPR and the availability of AEDs can improve the probability that a patient will survive heart failure. The latest ALS guidelines suggest that about 20% of patients with out-of-hospital cardiac arrests experience ventricular tachycardia or ventricular brillation [14]. In pre-hospital patients, especially during ventricular tachycardia or ventricular brillation, a reduction in the time before AED is applied increases the probability of obtaining ROSC [15]. This nding is consistent with the results of a study conducted only with cardiac arrest patients who had been treated using an AED, and that showed that de brillation was possible 63.6 ~ 70.8% of the time, and that a high rate ROSC [16,17]. Therefore, early application of an AED to restore appropriate rhythms can achieve ROSC and contribute strongly to the survival rate of pre-hospital cardiac arrest patients.
This study also con rmed that intravenous administration of epinephrine increased the likelihood of ROSC before arrival at the emergency room. These ndings were found in previous studies [18] that epinephrine injection during out-of-hospital cardiac arrest increases the probability of both ROSC and short-term survival. In general, epinephrine should be injected as soon as possible when arrhythmia does not respond to AED [19]. In another previous study [20], the average time before intravenous injection during cardiac arrest outside the hospital was 19.4 minutes. People who receive injected epinephrine as soon as possible (within 10 min) are approximately 4.52 times more likely to show ROSC than those who receive it late (within 30 min). Therefore, this study suggests that fast acquisition of intravenous access is an important factor that in uences ROSC. These ndings suggest that rapid treatment by paramedics is needed when pre-hospital cardiac arrest occurs, and that fast and skilled application of intravenous epinephrine is needed. However, paramedics have different pro ciencies, so the probability of success applying intravenous epinephrine can vary. Korea is investing time and training for paramedics to secure skillful intravenous access, but the difference in skill levels of paramedics must be corrected. Finally, in this study, intubation increased the probability of ROSC before arrival in the emergency room. The latest ALS guidelines described several approaches to intubation during CPR; they should be applied step-by-step by considering patient factors and rescuer skills [14]. This conclusion implies that a suitable intubation method must be chosen for the patient by considering the skilled teamwork and communication of paramedics. The results of this study con rmed that intubation increased the probability of ROSC, but a previous study [14] suggested that attempting intubation at a pre-hospital site may cause interruption of CPR and may cause harmful hyperventilation. Therefore, the appropriateness of intubation should be discussed in the future.

Limitations
This study identi ed the factors affecting the ROSC before arrival in the emergency room by considering data of 2,750 people in one metropolitan area, so the results may not be full applicable to all of Korea.

Future Research
The results of this study suggest that factors that affect the ROSC before arriving at the emergency room for samples from all over Korea. The various independent variables that were identi ed to affect ROSC should be veri ed.
The effects of time on spontaneous circulation should be evaluated. For example, the relationship between the time to arrival at the emergency room and the probability of ROSC, and the relationship between the time to achieve intravenous access and the probability of ROSC.

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The results of this study identi ed that the factors that affect ROSC before arriving at the emergency room include the use of mechanical compression devices, the use of rst-aid de brillators, application of epinephrine, and use of intubation. To increase the probability of ROSC before the patient arrives at the emergency room, the following suggestions shall be made. First, continuous CPR education should be provided for local residents. CPR education is being provided by region in Korea, but has not been implemented for the entire community. Therefore, expansion of the population and national support may improve the CPR capabilities of local residents. Increase in the number of emergency rooms is also necessary; this number tends to be proportional to the population, so their availability may be limited for residents who live in the outskirts of cities.