Archives of Academic Emergency Medicine. 2022; 10(1): e72 OR I G I N A L RE S E A RC H Factors Associated with Return of Spontaneous Circu- lation following Pre-Hospital Cardiac Arrest in Daegu Metropolitan City, South Korea; a Cross-Sectional Study Hyun-Ok Jung1, Seung-Woo Han2∗ 1. College of Nursing, The Research Institute of Nursing Science, Dageu Catholic University, Daegu, Korea 2. Department of Emergency Medical Technology, Kyungil University, Korea. Received: June 2022; Accepted: July 2022; Published online: 1 September 2022 Abstract: Introduction: The probability of Return of Spontaneous Circulation (ROSC) in cardiac arrest cases in pre- hospital setting is still low. This study aimed to identify the factors that may improve the rate of ROSC in patients with pre-hospital cardiac arrest. Methods: This retrospective cross-sectional study is a secondary data analysis of cardiac arrest patients, who were managed by paramedics in the pre-hospital setting, from January 1, 2019, to December 31, 2019, in Daegu, South Korea. The association of ROSC with place of arrest occurrence, car- diac arrest being witnessed, performing cardiopulmonary resuscitation (CPR), using compression device and defibrillator, administration of epinephrine, and intubation was analyzed and independent predictive factors of ROSC were reported. Results: 2750 out-of-hospital cardiac arrest cases, which were managed by paramedics in the pre-hospital setting were studied. 2034 (86.9%) cases of arrest had occurred at home, 2028 (73.7%) were not witnessed, and CPR was not performed for 1721 (64.1%) cases. ROSC before arriving to emergency depart- ment (ED) was more probable if the cardiac arrest was witnessed (p < 0.001), if CPR was performed (p = 0.044), if a mechanical compression device was used (p < 0.001), if a first-aid defibrillator was used (p < 0.001), and if intravenous access was secured (p < 0.001). Multivariate regression analysis revealed that using mechanical compression device (OR: 0.18; 95% CI = 0.08 - 0.40; p = 0.001), using first-aid defibrillator (OR: 3.13; 95% CI = 1.40 - 6.99; p = 0.005), administration of epinephrine (OR: 6.57; 95% CI = 2.16 - 19.53; p = 0.001), and intubation (OR: 1.82; 95% CI = 1.04-3.19; p = 0.001) were independent predictive factors of ROSC before arrival to ED. Con- clusion: It seems that chest compression by hand instead of using chest compression device, using defibrillator, epinephrine administration, and intubation my increase the probability of ROSC in pre-hospital arrest cases. Keywords: Out-of-Hospital Cardiac Arrest; Return of Spontaneous Circulation; Patients; Korea Cite this article as: Jung H-O, Han S-W. Factors Associated with Return of Spontaneous Circulation following Pre-Hospital Car- diac Arrest in Daegu Metropolitan City, South Korea; a Cross-Sectional Study. Arch Acad Emerg Med. 2022; 10(1): e72. https://doi.org/10.22037/aaem.v10i1.1589. 1. Introduction The rate of death due to cardiovascular system disease in South Korea was 117.4 per 100,000 people in 2019 (1). Sud- den cardiac arrest (SCA) results in death due to hemody- namic failure if the heart is not restarted in minutes (2). In the United States, more than 550,000 patients suffer SCA, be- fore and during hospitalization, each year. SCA accounts for more than half of cardiovascular mortalities and is a major ∗Corresponding Author: Seung-Woo Han; Gamasilgil Hayangeup, Gyeong- buk 38428 Korea. Email: swhan@kiu.ac.kr, Tel: 82-53-600-5691, Fax: 82-53- 600-5699, ORCID: http://orcid.org/0000-0001-9144-3285. national concern (3). The probability of patients recovering from cardiac arrest that occurred before hospital arrival in Korea increased from 1.1% in 2007 to 7.6% in 2017, but this recovery rate is still very low compared to developed countries, such as the U.S. 11.4%, Sweden 14.0%, and Norway 13.0% (4, 5). To solve the practical problems associated with emergency medical treat- ment, the Korean government has been actively studying the prevention and management of diseases by establishing car- diovascular and cerebrovascular prevention centers in Korea (6). Daegu Metropolitan City (DMC) in southeastern Korea has the fourth largest population (2.4 million) in the country. The rate of emergency department (ED) deaths among ED users This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem H-O. Jung et al. 2 in DMC was 0.418%, which was the highest in the country (7). Identifying the factors that influence the Return of Spon- taneous Circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA), where a rapid response is required, may improve community participation and emergency care. Previous studies have shown that pre-hospital factors that are closely related to the patient survival rate include: whether the patient was witnessed, if witnesses performed cardiopulmonary resuscitation (CPR), and whether the ROSC occurred spontaneously (8, 9). However, the factors that af- fect ROSC have not been studied in depth by country or re- gion. Because the environment and emergency medical care resources in each country are different, rapid treatment and methods of coping with patients who have pre-hospital car- diac arrest may also differ. This study aimed to identify the factors that may improve rate of ROSC in patients with pre- hospital cardiac arrest. 2. Methods 2.1. Study design and setting This retrospective cross-sectional study is a secondary data analysis of cardiac arrest patients, who were managed in the pre-hospital setting by paramedics, from January 1, 2019, to December 31, 2019, in Daegu, South Korea. The association of arrest characteristics with ROSC were analyzed and inde- pendent predictive factors of ROSC were reported. The data in this study were approved and obtained from the emer- gency activity log and cardiopulmonary arrest detailed sit- uation chart prepared by paramedics at the DMC Fire De- partment. We obtained approval from the K University In- stitutional Review Board (IRB) for the exemption of delib- eration (IRB- 1041459-202103-HR-003-01). We anonymized the emergency activity log and the details of the cardiopul- monary arrest detailed situation table. 2.2. Participants Cases for which CPR was withheld or suspended by paramedics due to apparent death or other causes were not considered. Specifically, the subjects included in this study were cases of cardiac arrest provided by the Daegu Metropolitan City Fire Department. 2.3. Data gathering For data collection, the purpose and suitability of the study were explained to the head of the DMC Fire Department, and data use was approved. This study selected and investigated items that may affect ROSC, as suggested by the emergency activity log and the detailed cardiopulmonary arrest sched- ule prepared by paramedics. In addition, vaguely written items, for example, subjects with blanks on whether or not to recover spontaneous circulation or subjects whose occur- Table 1: Baseline characteristics of studied out-of-hospital cardiac arrest cases Characteristics Number (%) Underlying disease Yes 1879 (90.3) No 202 (9.7) Occurrence place House (parking lot, yard) 2034 (86.9) Ambulance 99 (4.2) Nursing institution (medical facility) 101 (4.3) Other 106 (4.6) Witnessed Yes 722 (26.3) No 2028 (73.7) CPR performed Yes 963 (35.9) No 1721(64.1) Using mechanical chest compression device Yes 856 (39.6) No 1307 (60.4) Using first-aid defibrillator Yes 223 (8.1) No 2527 (91.9) Epinephrine administered Yes 380 (31.7) No 819 (68.3) Intubation performed Yes 504 (42.0) No 695 (58.0) Recovery of spontaneous circulation Yes 187 (14.3) No 1120 (85.7) * The sum of the case numbers may not match the total number due to the missing data. CPR: cardiopulmonary resuscitation. rence location is not clear, were reassessed until the two re- searchers agreed. The dependent variables were the ROSC and independent variables were the type and place of occurrence, whether there were witnesses to the cardiac arrest, if CPR was per- formed, if a mechanical compression device or first-aid de- fibrillator was used, whether epinephrine had been adminis- tered intravenously, and if intubation was performed. The raw data were provided by the DMC Fire Department, and to ensure the anonymity of patients, data such as name, gender, age, and occupation of the patients were deleted. In this study, two experts in the relevant field gathered and se- lected variables suitable for this study. And the selected vari- ables were used after final review by one emergency medical expert. 2.4. Statistical analysis In this study, the IBM SPSS/WIN 23.0 Program was used for data analysis. To confirm the difference in ROSC based on This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2022; 10(1): e72 Table 2: Association between different pre-hospital arrest characteristics and return of spontaneous circulation (ROSC) before arriving to emergency department Characteristics ROSC* P Yes (n = 187) No (n = 1120) Underlying disease Yes 159 (15.7) 852 (84.3) 0.850 No 9 (16.4) 46 (83.6) Place of occurrence House (parking lot, yard) 101 (12.0) 742 (88.0) In an ambulance 13 (13.8) 81 (86.2) 0.872 Nursing institution (medical facility) 6 (9.5) 57 (90.5) Other 7 (13.0) 47 (87.0) Witnessed Yes 122 (19.9) 490 (80.1) 0.001 No 65 (9.4) 630 (90.6) CPR performed Yes 117 (16.0) 616 (84.0) 0.044 No 58 (11.1) 464 (88.9) Using mechanical chest compression device Yes 61 (7.1) 795 (92.9) 0.001 No 107 (27.6) 281 (72.4) Using first-aid defibrillator Yes 89 (40.3) 132 (59.7) 0.001 No 98 (9.0) 988 (91.0) Epinephrine administered Yes 87 (23.0) 291 (77.0) 0.001 No 13 (6.4) 189 (93.6) Intubation performed Yes 80 (15.9) 422 (84.1) 0.052 No 20 (25.6) 58 (74.4) * The sum of the case numbers may not match the total number due to the missing data. Data are presented as number (%). CPR: cardiopulmonary resuscitation. the subjects’ general characteristics, we calculated the fre- quency and percentage and performed a cross-analysis us- ing a χ2-test. We conducted a complex sample logistic re- gression analysis to identify the factors that affected ROSC. In this study, statistics were applied to the raw data without manipulation or alteration. 3. Results 3.1. Baseline characteristics of participants 2750 out-of-hospital cardiac arrest cases, which were man- aged by paramedics in pre-hospital setting were studied. Ta- ble 1 summarizes the baseline characteristics of studied ar- rest cases. 2034 (86.9%) cases of arrest had occurred at home, 2028 (73.7%) were not witnessed, and CPR was not performed for 1721 (64.1%) cases. 3.2. Associated factors of ROSC before arriving to ED The recovery of spontaneous circulation was experienced by 187 (14.3%) cases. Table 2 evaluates the association of ROSC with different pre-hospital arrest characteristics. Based on univariate analysis, ROSC before arriving to ED was more probable if the cardiac arrest was witnessed (χ2 = 29.727, p < 0.001), if CPR was performed (χ2 = 6.232, p = 0.044), if a mechanical compression device was used (χ2 = 95.596, p < 0.001), if a first-aid defibrillator was used (χ2 = 146.241, p < 0.001), and if intravenous access was secured (χ2 = 25.364, p < 0.001). Multivariate regression analysis introduced us- ing mechanical compression device (OR: 0.18; 95% CI = 0.08 - 0.40; p = 0.001), using first-aid defibrillator (OR: 3.13; 95% CI = 1.40 - 6.99; p = 0.005), administration of epinephrine (OR: 6.57; 95% CI = 2.16 - 19.53; p = 0.001), and intubation (OR: 1.82; 95% CI = 1.04-3.19; p = 0.001) as independent predictive factors of ROSC before arrival to ED (table 3). 4. Discussion It seems that chest compression by hand instead of using chest compression device, using defibrillator, epinephrine administration, and intubation may increase the probability of ROSC in pre-hospital arrest cases. This study showed that mechanical compression devices This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem H-O. Jung et al. 4 Table 3: Association between different pre-hospital arrest characteristics and return of spontaneous circulation (ROSC) before arriving to emergency department Characteristics B OR 95% CI P Using mechanical chest compression device Yes -1.70 0.18 0.08-0.40 0.001 No 1.00 1.00 Using first-aid defibrillator Yes 1.14 3.13 1.40-6.99 0.005 No 1.00 1.00 Epinephrine administration Yes 1.88 6.57 2.16-19.53 0.001 No 1.00 1.00 Intubation performed Yes 0.60 1.82 1.04-3.19 0.001 No 1.00 1.00 OR: odds ration; CI: confidence interval. are less effective than manual CPR in achieving ROSC. This result contradicts prior studies (10, 11) that showed that mechanical compression devices were more effective than CPR in achieving ROSC and a review of 1,187 systems that showed no significant difference between mechanical com- pression devices and hand CPR in achieving ROSC (12). This conflict may be a result of the situational environment, as paramedics in Korea tend to prefer hand CPR over mechani- cal compression unless the ambulance ride is long. In addi- tion, mechanical compression devices are not always avail- able in ambulances across Korea. This study determined that a first aid defibrillator increased the probability of ROSC by 3.13 times. A previous study (13) suggested that improvements in CPR quality and automated external defibrillator (AED) availability can improve the like- lihood that a patient will survive heart failure. The latest ad- vanced life support (ALS) guidelines suggest that about 20% of patients with out-of-hospital cardiac arrests experience ventricular tachycardia or ventricular fibrillation (14). In pre- hospital patients, especially during ventricular tachycardia or ventricular fibrillation, a reduction in the time before AED is applied increases the probability of obtaining ROSC (15). This finding is consistent with the results of a study con- ducted only on cardiac arrest patients who had been treated using an AED, which showed that defibrillation was possible 63.6 ∼ 70.8% of the time, resulting in a high rate of ROSC (16, 17). Therefore, early application of an AED to restore appro- priate rhythms can achieve ROSC and contributes to the sur- vival of pre-hospital cardiac arrest patients. This study also showed that intravenous administration of epinephrine increased the likelihood of ROSC before arrival at the emergency room. Previous studies found (18) that epinephrine injection during an out-of-hospital cardiac ar- rest 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 study (20), the average time before intravenous injection during cardiac arrest outside the hospital was 19.4 minutes. People who receive injected epinephrine within 10 minutes are approximately 4.52 times more likely to show ROSC than those who receive it within 30 minutes. Al- though this study only investigated the administration of epinephrine, based on previous studies, it is believed that the rapid injection of epinephrine, will have a positive effect on ROSC. These findings suggest that when pre-hospital car- diac arrest occurs, rapid treatment by paramedics and fast and skilled application of intravenous epinephrine is needed. However, paramedics have different proficiencies, so the suc- cess of intravenous epinephrine application can vary. Korea is training paramedics on securing intravenous access, but the difference in paramedic skill levels must be corrected. Finally, in this study, intubation increased the probability of ROSC before arrival in the emergency room. In cardiopul- monary resuscitation, cardiac output and coronary perfu- sion pressure are related to ROSC in cardiac arrest patients, and provision of sufficient respiratory volume through ap- propriate intubation during CPR is an important factor in ROSC (21). Therefore, it is considered that intubation can contribute to improving the survival rate of out-of-hospital cardiac arrest patients. The various independent variables that were identified should be verified. The effects of time on spontaneous cir- culation should be evaluated. For example, the relationship between the time of emergency room arrival or the time to achieve intravenous access and the probability of ROSC must be examined. In addition, the samples provided in this study are raw data, in which personal characteristics, such as gender, age, and occupation, which may affect ROSC, have been deleted to ensure anonymity. So, if these factors are presented more This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 5 Archives of Academic Emergency Medicine. 2022; 10(1): e72 clearly, it can help to identify their probable effect on ROSC. we suggest that continuous CPR education should be pro- vided for residents. CPR education is being provided on a re- gional basis in Korea, but has not been implemented across the country. Therefore, national support may improve the CPR capabilities of local people. Increasing the number of emergency rooms is also necessary, as this tends to be pro- portional to the population, making them unavailable to res- idents who live outside of cities. 5. Limitations This study used raw data of acute cardiac arrest patients in Daegu Metropolitan City during 1 year in 2019. However, it should be noted that there is a limit to confirming the fac- tors influencing ROSC in patients with acute cardiac arrest with one year of data from one region. Because, a capital city with a population close to 10 million like Seoul or the current COVID-19 situation could affect ROSC. Therefore, a study us- ing multi-year data will be helpful in more accurately identi- fying the influencing factors. 6. Conclusion It seems that chest compression by hand instead of using chest compression device, using defibrillator, epinephrine administration, and intubation may increase the probability of ROSC in pre-hospital arrest cases. 7. Declarations 7.1. Acknowledgments We would like to thank the Daegu Metropolitan City Fire De- partment and its staff for their cooperation in the research. It is expected that this study will contribute to the improve- ment of ROSC. 7.2. 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