Archives of Academic Emergency Medicine. 2021; 9(1): e70 OR I G I N A L RE S E A RC H Cardiopulmonary Resuscitation Outcomes of Patients with COVID-19; a One-Year Survey Afshin Goodarzi1, Masoud Khodaveisi2, Alireza Abdi3, Rasoul Salimi4, Khodayar Oshvandi5∗ 1. Department of Nursing, Hamadan University of Medical Sciences, Hamadan, Iran. 2. Chronic Diseases (Home Care) Research Center, Department of Community Health Nursing, Hamadan University of Medical Sciences, Hamadan, Iran. 3. Department of Nursing, School of Nursing & Midwifery, Kermanshah University of Medical Sciences, Kermanshah, Iran. 4. Department of Emergency Medicine, School of Medicine, Besat Hospital, Hamadan University of Medical Sciences, Hamadan, Iran. 5. Mother and Child Care Research Center, Nursing and Midwifery School, Hamadan University of Medical Sciences, Hamadan, Iran. Received: August 2021; Accepted: September 2021; Published online: 4 November 2021 Abstract: Introduction: Assessing cardiopulmonary resuscitation (CPR) outcomes of patients with COVID-19 and em- ploying effective strategies for their improvement are essential. This study is designed in this regard. Methods: This cross-sectional study was conducted between January 20, 2020 and January 20, 2021 in the emergency de- partments of two hospitals in Hamadan and Kermanshah, Iran. Participants were 487 patients with confirmed COVID-19 and cardiac arrest (CA) who had undergone CPR during the study period. Data were collected us- ing the available CPR documentation forms developed based on the Utstein Style and analyses were performed using Chi-square, Fisher’s exact, and Mann-Whitney U tests and the logistic regression analysis. Results: Par- ticipants’ mean age was 69.31±14.73 years and most of them were male (61.8%) and suffered from at least one underlying disease (58.1%). The rate of total and in-hospital CA was 9.67% and 9.39%, respectively. The most prevalent first documented rhythm was asystole (67.9%) and the highest responsivity to CPR was for shockable rhythms. The rate of the return of spontaneous circulation (ROSC) was 9% and the rate of survival to hospital discharge was 2%. The significant predictors of CPR success were age (p = 0.035), epinephrine administration time interval (p = 0.00), CPR duration (p = 0.00), and First documented rhythm (p = 0.009). Conclusion: The rate of in-hospital CA among studied COVID-19 cases was 9.39% with 9% ROSC and 2% survival to hospital discharge rates after CPR. Primary CPR success among patients with COVID-19 was poor, particularly among those with asystole and bradycardia. It seems that old age and improper doses of epinephrine can reduce CPR success. Keywords: Cardiopulmonary resuscitation; Heart Arrest; COVID-19; Epinephrine Cite this article as: Goodarzi A, Khodaveisi M, Abdi A, Salimi R, Oshvandi K. Cardiopulmonary Resuscitation Outcomes of Patients with COVID-19; a One-Year Survey. Arch Acad Emerg Med. 2021; 9(1): e70. https://doi.org/10.22037/aaem.v9i1.1381. 1. Introduction Involvement of the cardiovascular system, particularly among patients with a history of cardiovascular disease, is one of the most serious complications of COVID-19 (1). Al- though COVID-19 is primarily manifested as a severe res- piratory infection, different studies reported that it can cause stroke due to cerebrovascular ischemia, pulmonary ∗Corresponding Author: Khodayar Oshvandi; Mother and Child Care Re- search Center, Nursing and Midwifery School, Hamadan University of Medical Sciences, Hamadan, Iran. Email: oshvandi2005@gmail.com, Mobile number: +989188117729, ORCID: http://orcid.org/0000-0002-2224-8870. artery thrombosis, spontaneous pneumothorax, cardiovas- cular disease, and type II diabetes mellitus due to the dys- function of the pancreatic beta cells (2-6). Respiratory dys- function and subsequent alteration of tissue oxygenation in patients with COVID-19 can directly affect the cardiovascular system and cause serious problems such as myocarditis, my- ocardial injuries, acute myocardial infarction, heart failure, cardiac dysrhythmia, and thromboembolism. These prob- lems can lead to cardiac arrest (CA) (7). Studies on patients with COVID-19 show the increasing prevalence of in-hospital and out-of-hospital CA. For exam- ple, a study reported two times increase in the rate of out-of- hospital CA and reduced survival during the COVID-19 pan- demic (8). A meta-analysis on four studies also indicated two 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 A. Goodarzi et al. 2 times increase in the rate of in-hospital CA among patients with COVID-19 (9). Before the COVID-19 pandemic, in the U.S., an average of 292,000 cardiac arrests occurred annually (10, 11). There are no reliable statistics on CA rate in Iran; however, the average rates of CA in the United Arab Emirates and Saudi Arabia were respectively 11.7 and 7.76 cases per 1000 hospitalizations before the pandemic (12, 13). The American Heart Association noted that CPR for patients with COVID-19 is the same as CPR for patients without COVID-19 but recommended the use of personal protective equipment throughout CPR in order to reduce the risk of in- fection transmission (14). For instance, a study in China re- ported that the primary CPR outcomes among patients with COVID-19 are poor success rate and thirty-day survival rate were 13.2% and 2.9%, respectively(15). Two other studies on out-of-hospital and in-hospital CA among patients with COVID-19 reported a survival to hospital discharge rate of zero percent (16, 17). CPR outcomes depend on a wide range of factors such as cause of CA, underlying disease, the first documented rhythm, age, CA type (witnessed or unwitnessed), CPR du- ration, response time, call-to-arrival time, and adherence to CPR protocols (18-21). The lower CPR success rate among patients with COVID-19 has been attributed to factors such as the first documented rhythm (15, 16, 22). Despite the wide prevalence and the high mortality rate of COVID-19 throughout the world, there are limited reliable data about CPR and its outcomes among afflicted patients. This study aimed to assess the epidemiology and one-year outcomes of CPR among patients with COVID-19. ‡ ‡ 2. Methods 2.1. Study design and setting This cross-sectional study was conducted on CPRs per- formed for patients with confirmed COVID-19 during the one-year period between January 20, 2020 and January 20, 2021 in emergency departments of Besat Hospital, Hamadan, Iran, and Imam Reza hospital complex, Kermanshah, Iran. The Institutional Review Board and the Ethics Commit- tee of Hamadan University of Medical Sciences, Hamadan, Iran, approved the study protocol (codes: 9909186284 and IR.UMSHA.REC.1399.689). Necessary permissions for enter- ing the study setting and performing data collection were ob- tained from the Research Administration of Hamadan and Kermanshah Universities of Medical Sciences, Hamadan and Kermanshah, Iran, and provided to the authorities of the study setting. Patients’ data were managed confidentially. It is noteworthy that in the study setting, consents for us- ing patient data for research purposes were routinely ob- tained from patients and their family members at the time of hospital admission and were available via in-patient medical records. 2.2. Participants Study population consisted of all patients with confirmed COVID-19, who had been hospitalized in the two mentioned hospitals and had undergone out-of-hospital or in-hospital CPR. Inclusion criteria were age over eighteen years, defi- nite diagnosis of COVID-19 (based on PCR or PCR and high resolution computed tomography (HRCT), depending on the hemodynamic status), and out-of-hospital or in-hospital CA based on the Utstein Style criteria (23, 24). Patients with CA and no indication of CPR (i.e., those with rigor mortis or livor mortis) were not included. Patients with out-of-hospital CA and return of spontaneous circulation (ROSC) before hospi- tal arrival who experienced another CA in emergency depart- ment were considered as out-of-hospital CA. 2.3. Data collection The data collection instrument was the standard national CPR forms, which had been developed based on the Utstein Style and were routinely used for CPR documentation by CPR nurses in the study setting. The items on these forms in- clude demographic characteristics, underlying disease, ini- tial and final diagnoses, consciousness on arrival, CA type (in-hospital or out-of-hospital), out-of or in-hospital CPR, the first documented cardiac rhythms, use of defibrillation, necessary time for intravenous (IV ) cannulation, adminis- tered medications during CPR, CPR duration, and CPR suc- cess. Data were collected from patients’ medical records. Hospital discharge status (dead or alive) was also assessed using the electronic medical record system of the study set- ting. Based on the Utstein Style, the core CPR success out- comes are ROSC, post-CPR survival up to hospital discharge or for thirty days, and optimum neurological function up to hospital discharge or for thirty days. Complementary out- come based on this style is one-year survival after successful CPR (23). In this study, ROSC was considered as the primary outcome of CPR and post-CPR survival to hospital discharge was considered as the final outcome of CPR. We defined adrenaline average dosing interval as the time between the first adrenaline dose and the resuscitation end- point, divided by the total number of adrenaline doses re- ceived after the first dose. 2.4. Data analysis Data were analyzed using SPSS software (v. 20.0). The nor- mality of age and CPR duration variables was tested using Kolmogorov-Smirnov test. Chi-square, Fisher’s exact, and Mann-Whitney U tests were used to assess the relationship of CPR outcomes with demographic characteristics, CPR time, CPR duration, epinephrine administration intervals, and IV 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. 2021; 9(1): e70 Table 1: Baseline characteristics and outcomes of cardiopulmonary resuscitation in studied cases Variable N (%) ROSC Survival* Gender Male 301 (61.8) 31(10.30) 7 (2.32) Female 186 (38.2) 13 (6.99) 3 (1.61) Type of CA In-hospital 471 (96.7) 43 (9.13) 10 (2.12) Out-of-hospital 16 (3.3) 1 (6.25) 0 (0) On-arrival status Alert 242 (51.2) 25(10.33) 6 (2.48) Verbal 131 (27.6) 16(12.21) 4 (3.05) Painful 51 (10.8) 2 (3.92) 0 (0) Unresponsive 50 (10.5) 1 (2.0) 0 (0) CPR time 08:00–14:00 131 (26.9) 15(11.45) 2 (1.53) 14:01–20:00 126 (25.9) 12 (9.52) 5 (3.97) 20:01–24:00 80 (16.4) 6 (7.5) 0 (0) 00:01–07:59 150 (30.8) 11 (7.33) 3 (2) Underlying disease Hypertension 95(26.4) 11(11.58) 2(2.10) Diabetes mellitus 95(26.4) 10(10.53) 1(1.05) Cancer 34(9.4) 3(8.82) 0(0) IHD 70(19.4) 7(10) 3(4.29) CKD 15(4.2) 1(6.66) 1(6.66) COPD 10(2.8) 0(0) 0(0) Transplantation 2(0.5) 0(0) 0(0) CVA 6(1.7) 0(0) 0(0) Other 33(9.2) 1(3.03) 0(0) First documented rhythm Ventricular tachycardia 3 (0.6) 2 (66.66) 1 (33.33) Ventricular fibrillation 3 (0.6) 1 (33.33) 0 (0) Asystole 330 (67.9) 31 (9.39) 4 (1.21) PEA 3 (0.6) 0 (0) 0 (0) Bradycardia 147 (30.2) 10 (7.30) 5 (3.40) Epinephrine administration Intervals < 3 minutes 2 (0.4) 0 (0) 0 (0) 3–5 minutes 66 (13.7) 23(34.85) 6 (9.09) > 5 minutes 414 (85.9) 21 (5.07) 4 (0.97) Intravenous cannulation time < 1 minutes 464 (95.3) 43 (9.27) 10 (2.15) >1 minute 23 (4.7) 1 (4.35) 0 (0) Epinephrine delay Yes 38(7.9) 2(5.26) 0(0) No 446(92.1) 42(9.42) 10(2.24) Atropine Yes 128(87.7) 9(7.03) 4(3.12) No 19(12.93) 1(5.26) 1(5.26) Amiodarone Yes 5(83.33) 3(60) 1(20) No 1(16.67) 0(0) 0(0) Defibrillation Yes 6(100) 3(50) 1(33.33) No 0(0) (0) 0(0) Airway management Intubation 479(98.56) 43(8.98) 10(2.09) Mask 7(1.44) 1(14.28) 0(0) Data are presented as number (%). CA: cardiac arrest; CPR: cardiopulmonary resuscitation; COPD: chronic obstructive pulmonary disease; CVA: Cerebrovascular accident; CKD: chronic kidney disease; IHD: Ischemic heart disease; PEA: pulseless electrical activity. * Survival to discharge. cannulation time. Moreover, logistic regression analysis was performed to predict CPR outcomes. Variables with a signifi- cant relationship with CPR outcomes in univariable analysis were entered into the logistic regression model. 3. Results 3.1. Baseline characteristics of studied cases During the one-year assessment period of the study, 5034 pa- tients with COVID-19 had been hospitalized in the studied hospitals and 487 of them had experienced out-of-hospital or in-hospital CA. The mean age of patients with CA was 69.31±14.73 years and most of them were male (61.8%) and suffered from at least one underlying disease (58.1%). Base- 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 A. Goodarzi et al. 4 Table 2: The relationships of participants’ characteristics with return of spontaneous circulation (ROSC) Variable ROSC P-value Gender Male 31 (10.30) 0.216 Female 13 (6.99) Type of CA In-hospital 43 (9.13) 0.693 Out-of-hospital 1 (6.25) On-arrival status Alert 25 (10.33) 0.088 Verbal 16 (12.21) Painful 2 (3.92) Unresponsive 1 (2.0) CPR time 08:00–14:00 15 (11.45) 0.632 14:01–20:00 12 (9.52) 20:01–24:00 6 (7.5) 00:01–07:59 11 (7.33) Underlying disease Yes 21 (7.72) 0.142 No 23 (11.73) First documented rhythm Ventricular tachycardia 2 (66.66) 0.023* Ventricular fibrillation 1 (33.33) Asystole 31 (9.39 PEA 0 (0) Bradycardia 10 (7.30) Epinephrine administration Intervals < 3 minutes 0 (0) < 0.001* 3–5 minutes 23 (34.85) > 5 minutes 21 (5.07) Intravenous cannulation time < 1 minutes 43 (9.27) 0.422 >1 minutes 1 (4.35) Epinephrine delay Yes 2(5.26) 0.393 No 42(9.42) Atropine Yes 9(7.03) 0.775 No 1(5.26) Amiodarone Yes 3(60) 1.00 No 0(0) Defibrillation Yes 3(50) N/A‡ No (0) Airway management Intubation 43(8.98) 0.488 Mask 1(14.28) Data are presented as number (%).CA: cardiac arrest; CPR: cardiopulmonary resuscitation; PEA: pulseless electrical activity. ‡ not available. * Significant at level 0.05. line characteristics and CPR outcomes of the studied cases are presented in table 1. The total rate of CA among patients with COVID-19 was 9.67% and the total rate of in-hospital CA was 9.39%. Among patients with out-of-hospital CA, only 12.5% had been taken to hospital by the emergency medical services and had re- ceived CPR before hospital arrival. The most prevalent car- diac dysrhythmia was asystole (67.9%) and the mean CPR du- ration was 41.98 ± 8.98 minutes. The time interval between each two epinephrine administrations was 9.02 ± 4.31 min- utes and in most cases (95.3 %) IV cannulation had been per- formed in less than one minute. The mean age of patients who experienced ROSC was 64.82±14.00 years, which was significantly less than the mean age in patients who had not experienced ROSC (69.76±14.74 years; Z=-2.464; p = 0.014). The mean age of patients who experienced survival to dis- charge was 64.50±9.11 years, and less than the mean age in patients who did not survive until discharge (64.91±15.26; Z=-0.533; p = 0.594). Also, the mean CPR duration of patients who experienced ROSC was 24.09±12.58 minutes, which was significantly shorter than the mean CPR duration in patients who had not experienced ROSC (43.77±6.17 minutes; Z=- 9.716; p = 0.00), and the mean CPR duration of patients who experienced survival to discharge was 18.80±5.83 minutes, this time was 25.65±13.64 minutes in patients who did not survive to discharge (Z=-1.101; p = 0.271). The total rates of ROSC and survival to hospital discharge were 9.03% and 2.05%, respectively (Table 1). 3.2. Outcomes The ROSC outcome significantly correlated with partici- pants’ age (p = 0.014), the first documented rhythm (p = 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. 2021; 9(1): e70 Table 3: The relationships of participants’ characteristics with survival to discharge Variable Survival† P-value Gender Male 7 (2.32) 0.971 Female 3 (1.61) Type of CA In-hospital 10 (2.12) 1.00 Out-of-hospital 0 (0) On-arrival status Alert 6 (2.48) 1.00 Verbal 4 (3.05) Painful 0 (0) Unresponsive 0 (0) CPR time 08:00–14:00 2 (1.53) 0.194 14:01–20:00 5 (3.97) 20:01–24:00 0 (0) 00:01–07:59 3 (2) Underlying disease Yes 5 (1.84) 0.870 No 5 (2.55) First documented rhythm Ventricular tachycardia 1 (33.33) 0.042* Ventricular fibrillation 0 (0) Asystole 4 (1.21) PEA 0 (0) Bradycardia 5 (3.40) Epinephrine administration Intervals < 3 minutes 0 (0) 0.578 3–5 minutes 6 (9.09) > 5 minutes 4 (0.97) Intravenous cannulation time < 1 minutes 10 (2.15) 1.00 >1 minutes 0 (0) Epinephrine delay yes 0 (0) 1.00 no 10(2.24) Atropine yes 4(3.12) 1.00 no 1(5.26) Amiodarone yes 1(20) N/A‡ no 0(0) Defibrillation yes 1(33.33) N/A‡ no 0(0) Air way management Intubation 10(2.09) 1.00 Mask 0(0) Data are presented as number (%). CA: cardiac arrest; CPR: cardiopulmonary resuscitation. † Survival to discharge. ‡ not available. * Significant at level 0.05. Table 4: The predictors of cardiopulmonary resuscitation (CPR) outcomes Dependent Independent B SE Wald df p-value OR 95% CI Lower Upper ROSC First documented rhythm (VT) 3.311 1.268 6.819 1 0.009* 27.40† 2.284 328.774 Epinephrine interval (q/3–5min) 2.304 0.342 45.394 1 < 0.001* 10.010‡ 5.122 19.564 CPR duration -0.198 0.022 82.010 1 < 0.001* 0.820 0.785 0.856 Age -0.021 0.010 4.442 1 0.035* 0.979 0.960 0.999 Survival to discharge First documented rhythm (Asystole) -1.910 1.512 1.594 1 0.207 0.148¶ 0.008 2.871 †. Reference level: Bradycardia;‡. Reference level: Epinephrine administration Intervals> 5 minutes; ¶. Reference level: VT; * Significant at level 0.05. SE: standard error; OR: odds ratio. ROSC: return of spontaneous circulation; CI: confidence interval; VT: Ventricular tachycardia. 0.023), epinephrine administration time interval (p= 0.001), and CPR duration (p = 0.001) but survival to hospital dis- 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 A. Goodarzi et al. 6 charge only had a significant relationship with the first docu- mented rhythm (p = 0.042; Tables 2 and 3, respectively). The results of the regression analysis showed age (p = 0.035), epinephrine administration time interval (p = 0.001), the first documented rhythm (p = 0.009), and CPR duration (p = 0.001) as the significant predictors of ROSC (Table 4). 4. Discussion The rate of in-hospital CA among studied COVID-19 cases was 9.39% with 9% ROSC and 2% survival to hospital dis- charge rates after CPR. Primary CPR success among patients with COVID-19 was poor, particularly among those with asystole and bradycardia. It seems that old age and high or low doses of epinephrine can reduce CPR success. In line with this finding, a previous study reported that the rate of in-hospital CA among patients with COVID-19 was 10% (9). Most participants suffered from at least one underlying dis- ease, particularly diabetes mellitus, hypertension, cardiovas- cular disease, and cancer. A meta-analysis also reported the prevalence of different underlying diseases among patients with COVID-19 (25). Affliction by underlying diseases in- creases mortality rate among patients with COVID-19 (25, 26). Compromised immunity due to diabetes mellitus, de- creased inflammatory cytokines among patients with car- diovascular disease, or chemotherapy among patients with cancer is considered as a major risk factor for affliction by COVID-19 (27, 28). On the other hand, findings showed that 41.9% of participants had no underlying disease, denoting the high prevalence of COVID-19 among people with no un- derlying disease. These findings question the widespread belief that COVID-19 affects people with no underlying dis- ease less frequently. The high transmissibility of the virus is a significant factor contributing to the high prevalence of COVID-19 even among people with no underlying disease. Primary CPR success, i.e., ROSC, was observed among only 9% of the patients with COVID-19 who had experienced CA. CPR success rate among patients with in-hospital CPR was also higher than patients with out-of-hospital CPR. A previ- ous study in this area reported that the rate of ROSC after CPR was 25.9% for out-of-hospital CA and 30.6% for in-hospital CA (16). Moreover, a meta-analysis on four studies on 621 patients with COVID-19 showed that the pooled prevalence of primary CPR success was 39% (95% CI: 21.0%–59.0%) (9). The rate of primary CPR success in the two mentioned stud- ies are much better than the rate in our study. Compari- son of the findings of the present study with the findings of two previous studies in Iran before the COVID-19 pandemic also reveals a lower CPR success rate among patients with COVID-19 (21, 29). This lower CPR success rate can be at- tributed to the higher prevalence of asystole in the present study compared with previous studies on patients with and without COVID-19 (16, 17, 29, 30). Asystole is less respon- sive to CPR than other shockable dysrhythmias. Another reason for the lower CPR success rate in the present study may be non-adherence to epinephrine administration pro- tocols. Some studies also reported that poor CPR outcomes among patients with COVID-19 may be due to the employ- ment of novice staff for CPR during the COVID-19 pandemic, delayed CPR onset due to the need for using personal pro- tective equipment, and CPR staff’s concern over affliction by COVID-19 during CPR (31, 32). Delayed or slow CPR onset and subsequent CPR prolongation have significant negative relationships with CPR outcomes (33-35). The lower rate of CPR success among patients with out-of-hospital CA in the present study may also be due to the fact that only 12.5% of them had been taken to hospital by emergency medical ser- vices and the others had been transported using private vehi- cles or taxi and hence, had not received out-of-hospital CPR. A previous study had also reported the same finding (36). Study findings showed that only 2% of patients had survival to hospital discharge. All these patients had experienced in- hospital CA. A meta-analysis on patients with COVID-19 and in-hospital CA also reported that the cumulative prevalence of survival to discharge rate was 3% (9), while in two other studies none of the patients with COVID-19 and in-hospital CA had survived to hospital discharge (16, 30). COVID-19 sig- nificantly affects different body organs and hence, CA among afflicted patients is mostly fatal. Therefore, preventive mea- sures, timely treatments, and careful monitoring of critically- ill patients with COVID-19 are necessary to prevent the oc- currence of CA. Findings revealed that primary CPR success a had signif- icant relationship with age, the first documented rhythm, epinephrine administration interval, and CPR duration, while final CPR success had a significant relationship only with the first documented rhythm. The logistic regression analysis revealed age, epinephrine administration interval, the first documented rhythm, and CPR duration as the signif- icant predictors of primary CPR success. The mean CPR du- ration was 24 minutes (with an interquartile range of 15–30) for patients with successful primary CPR and 43 minutes for unsuccessful CPR. The mean CPR duration was six min- utes (with an interquartile range of 4–14) among patients with successful primary CPR and in-hospital CA in a previ- ous study (22) and eight minutes (with an interquartile range of 4–10) in another study (17). The longer CPR duration in the present study compared with previous studies may be due to the fact that the study included patients with out-of-hospital CA. A study reported that there is no maximum time for CPR efforts, while longer CPRs were associated with greater sur- vival to discharge rate (37). Although the mean CPR duration among survived patients in the present study was shorter, 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 7 Archives of Academic Emergency Medicine. 2021; 9(1): e70 6.8% of successful CPRs had lasted more than 45 minutes, de- noting that CPR prolongation can be a determining factor in CPR success. The mean of participants’ age in the present study was 69 years and the mean age among participants with success- ful CPR was significantly less than those with unsuccess- ful CPR. The results of a meta-analysis on more than half a million patients with COVID-19 from different countries also reported age as a significant predictor of mortality (38). These findings highlight the importance of timely preven- tive measures for older patients to improve treatment out- comes among them because they are less responsive to treat- ments in critical conditions such as CA. Epinephrine admin- istration interval was one of the significant predictors of pri- mary CPR success in the present study. This interval was 5.41±1.74 minutes for patients with successful primary CPR. The rates of primary CPR success and survival to hospital discharge were 34.85% and 9.09%, respectively, for patients who had received epinephrine every 3–5 minutes, and 5.07% and 0.97% for patients who had received it in intervals longer than five minutes. Moreover, none of the patients who had received extra high doses of epinephrine (i.e., with intervals less than three minutes) had experienced successful primary CPR and survived to hospital discharge. The standard dose of epinephrine for adults is 1 milligram every 3–5 minutes throughout CPR (39). Our findings showed that CPR success among patients who had received high doses of epinephrine was less than those who had received it in doses less than the recommended standard dose. Although poor CPR outcomes among patients with COVID-19 can be attributed to COVID- 19 severity, the role of high doses of epinephrine in causing cytokine storms should be taken into account. Further stud- ies are needed to assess this role and the necessity to use safer medications instead of epinephrine for the CPR of patients with COVID-19. The most prevalent first documented cardiac rhythms among study participants were asystole and bradycardia, re- spectively, and the prevalence of shockable dysrhythmias was 1.24%. The prevalence of shockable dysrhythmias in five earlier studies on patients with COVID-19 was 3.7%–13%, which is less than the rate among patients without COVID- 19 (15-17, 22, 30). Pulmonary involvement and its associated hypoxia may be a reason for the lower rate of shockable dys- rhythmias among patients with COVID-19. The highest rate of successful primary CPR and survival to discharge rate were among patients with pulseless ventric- ular tachycardia. The first documented rhythm was a sig- nificant predictor of primary CPR success in the present study. Studies on patients without COVID-19 (40, 41) and a meta-analysis on patients with COVID-19 found poorer CPR outcomes for patients with non-shockable dysrhyth- mias (9). Despite the lower prevalence of shockable dys- rhythmias among patients with COVID-19, these dysrhyth- mias have better prognosis than non-shockable dysrhyth- mias. Although the Primary CPR success rate in our study was lower than the results reported by other studies in this area, the survival to hospital discharge rate in this study was at an acceptable level compared to other studies. The prevalence of shockable dysrhythmias among patients with COVID-19 is also much lower than patients without COVID-19, resulting in lower responsiveness to CPR among patients with COVID- 19. Old age and high doses of epinephrine are factors that can negatively affect CPR outcomes, particularly primary CPR success, among patients with COVID-19. Further studies are needed to assess the effects of epinephrine administration on CPR outcomes among these patients. Although the mean CPR duration among survived patients in the present study was shorter, the increase in resuscitation time was associ- ated with an increase in the number of survivors. On the other hand, by comparing the results of the present study with studies conducted in Iran before the epidemic, and in non-COVID patients, it can be claimed that the outcomes of resuscitation are weaker in patients with COVID-19. Poor CPR outcomes among patients with COVID-19 highlight the importance of exploring CPR staff’s experiences and the ef- fects of their concerns over affliction by COVID-19 on CPR quality and outcomes. 5. Limitations Our study had limitations; in some cases, some information related to the resuscitation process was not available in re- suscitation registration forms and patient records. It is pos- sible for some information to be incorrectly recorded by CPR staff, and these limitations were beyond the control of the re- searchers. 6. Conclusion The rate of in-hospital CA among studied COVID-19 cases was 9.39% with 9% ROSC and 2% survival to hospital dis- charge rates after CPR. Primary CPR success among patients with COVID-19 was poor, particularly among those with asystole and bradycardia. It seems that old age and high or low doses of epinephrine can reduce CPR success. 7. List of abbreviations CPR: Cardio Pulmonary Resuscitation, CA: Cardiopulmonary Arrest, IV: Intravenous, ROSC: Return of Spontaneous Circu- lation 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 A. Goodarzi et al. 8 8. Declarations 8.1. Availability of data The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. 8.2. Acknowledgments We would like to thank the Research Administration of Hamadan University of Medical Sciences, Hamadan, Iran, as well as the authorities, nurses, and medical records staff of the study setting who helped us conduct this study. 8.3. Funding Financial resources for the design of the present study and collection, analysis, and interpretation of data and writing the manuscript are provided by Hamadan University of Med- ical Sciences. 8.4. Competing interests The authors declare that they have no competing interests. 8.5. Conflict of interest statement The authors declare that they have no competing interests 8.6. Author contribution Study design: AG, KO; Data gathering: AG, RS; Analysis: AG, ARA; Interpreting: AG, , MK, ARA; Drafting: AG, KO; Critically revised the paper: All authors. 8.7. Data Presentation The information of this manuscript has not been presented in any meeting(s). References 1. Ranard LS, Fried JA, Abdalla M, Anstey DE, Givens RC, Kumaraiah D, et al. Approach to acute cardiovascular complications in COVID-19 infection. Circulation: Heart Failure. 2020;13(7):e007220. 2. y Galán JTG. Stroke as a complication and prognos- tic factor of COVID-19. Neurología (English Edition). 2020;35(5):318-22. 3. Ekanem E, Podder S, Donthi N, Bakhshi H, Stodghill J, Khandhar S, et al. Spontaneous pneumothorax: An emerging complication of COVID-19 pneumonia. Heart & Lung. 2021;50(3):437-40. 4. 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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 Introduction Methods Results Discussion Limitations Conclusion List of abbreviations Declarations References