This study assessed the one-year epidemiology and outcomes of CPR among patients with COVID-19. Findings showed that the total rate of in-hospital CA was 9.39%. In line with this finding, a former 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 disease, particularly diabetes mellitus, hypertension, cardiovascular disease, and cancer. A meta-analysis also reported the prevalence of different underlying diseases among patients with COVID-19 (34). Affliction by underlying diseases increases mortality rate among patients with COVID-19 (34, 35). Compromised immunity due to diabetes mellitus, decreased inflammatory cytokines among patients with cardiovascular disease, or chemotherapy among patients with cancer is considered as a major risk factor for affliction by COVID-19 (36, 37). 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 underlying disease. These finding questions the widespread belief that COVID-19 less frequently affects people with no underlying disease. 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 former 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 (25). 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 these two studies are much better than the rate in our study. Comparison of the findings of the present study with the findings of two former studies in Iran before the COVID-19 pandemic also reveals the lower CPR success rate among patients with COVID-19 (21, 29). This lower CPR success rate can be attributed to the higher prevalence of asystole in the present study compared with former studies on patients with and without COVID-19 (21, 25, 27, 38). Asystole is less responsive 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 protocols. Some studies also reported that poor CPR outcomes among patients with COVID-19 may be due to the employment of novice staff for CPR during the COVID-19 pandemic, delayed CPR onset due to the need for using personal protective equipment, and CPR staff’s concern over affliction by COVID-19 during CPR (39, 40). Delayed or slow CPR onset and subsequent CPR prolongation have significant negative relationships with CPR outcomes (41–43). The lower rate of CPR success rate 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 services and the others had been taken by private vehicles or taxi and hence, had not received out-of-hospital CPR. A former study also reported the same finding (44).
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 none of the patients with COVID-19 and in-hospital CA in two other studies had survived to hospital discharge (25, 38). COVID-19 significantly affects different body organs and hence, CA among afflicted patients is mostly fatal. Therefore, preventive measures, timely treatments, and careful monitoring of critically-ill patients with COVID-19 are necessary to prevent the occurrence of CA.
Findings revealed that primary CPR success had significant relationship with age, the first documented rhythm, epinephrine administration interval, and CPR duration, while final CPR success had significant relationship only with the first documented rhythm. The logistic regression analysis revealed age, epinephrine administration interval, and CPR duration as the significant predictors of primary CPR success. The mean of CPR duration was 24 minutes (with an interquartile range of 15–30) for patients with successful primary CPR and 43 minutes for unsuccessful CPR. The mean of CPR duration was six minutes (with an interquartile range of 4–14) among patients with successful primary CPR and in-hospital CA in a former study (30) and eight minutes (with an interquartile range of 4–10) in another study (27). The longer CPR duration in the present study compared with former 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 survival to discharge rate (45). Although the mean of CPR duration among survived patients in the present study was shorter, 6.8% of successful CPRs had lasted more than 45 minutes, denoting 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 successful CPR was significantly less than those with unsuccessful 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 (46). These findings highlight the importance of timely preventive measures for older patients to improve treatment outcomes among them because they are less responsive to treatments in critical conditions such as CA.
Epinephrine administration interval was one of the significant predictors of primary 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 respectively 34.85% and 9.09% 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 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 (15). Our findings showed that CPR success among patients who had received high doses of epinephrine was less than those who had received it with 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 studies 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 respectively asystole and bradycardia 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 (25–27, 30, 38). Pulmonary involvement and its associated hypoxia may be a reason for the lower rate of shockable dysrhythmias among patients with COVID-19.
The highest successful primary CPR rate and survival to discharge rate were among patients with pulseless ventricular tachycardia. Although the first documented rhythm was not a significant predictor of CPR outcome in the present study, it had significant relationship with primary CPR success and survival to discharge rate. Studies on patients without COVID-19 (20, 47) and a meta-analysis on patients with COVID-19 found poorer CPR outcomes for patients with non-shockable dysrhythmias (9). Despite the lower prevalence of shockable dysrhythmias among patients with COVID-19, these dysrhythmias have better prognosis than non-shockable dysrhythmias.