Abstract 10508: Variation in Community and Emergency Medical Systems Processes for Out-of-Hospital Cardiac Arrest During the COVID-19 Pandemic: A Systematic Review and Meta-Analysis

Introduction: Bystander cardiopulmonary resuscitation (B-CPR) with early defibrillation and immediate emergency medical services (EMS) care significantly increases a victim's chance of survival from out-of-hospital sudden cardiac arrest (OHCA). Few studies have assessed the overall effect of the COVID-19 pandemic on the prehospital chain of survival. Objectives: We sought to quantify the effect of the COVID-19 pandemic on prehospital processes including B-CPR, bystander defibrillation, community characteristics, and EMS process measures. We hypothesized that B-CPR rates would decrease and OHCA occurring in the home would increase during the pandemic. Methods: We conducted a systematic review and meta-analysis of studies identified through 05/03/2021. We examined 5 bibliographic databases and searched terms including cardiac arrest, OHCA, and COVID-19. Data were abstracted and independently coded. Subgroup analysis and meta-regression analysis were performed. Our primary outcome was B-CPR; our secondary outcomes were community processes and EMS characteristics. Results: The original search yielded 966 articles; 20 articles were included in our analysis. Studies originated from 10 different countries and were retrospective in study design. There was no difference in B-CPR rates during COVID-19 compared to Pre-COVID-19 (OR: 0.94 (0.80-1.11), p=0.46). Patients had a 1.38 (1.11-1.71) higher likelihood of having an OHCA at home during COVID-19 compared to Pre-COVID-19 (p=0.01). Receipt of bystander defibrillation was significantly lower during COVID-19 compared to Pre-COVID-19 (OR: 0.65 (0.48-0.88), p=0.01). There was a significant increase in EMS call to arrival time during COVID-19 compared to Pre-COVID-19 (Mean difference in minutes= 0.27 (0.13-0.40), p<0.01). Statistical heterogeneity was moderate-to-high; findings were robust to sensitivity analyses with no publication bias detected. Conclusion: B-CPR rates remained unchanged during the pandemic, while OHCA in the home increased. Bystander defibrillation decreased, while EMS response time increased during the pandemic. These findings may inform future public programing, particularly to consider interventions to improve the prehospital chain of survival.

Effects of rewarming with extracorporeal membrane oxygenation to restore oxygen transport and organ blood flow after hypothermic cardiac arrest in a porcine model

We recently documented that cardiopulmonary resuscitation (CPR) generates the same level of cardiac output (CO) and mean arterial pressure (MAP) during both normothermia (38 °C) and hypothermia (27 °C). Furthermore, continuous CPR at 27 °C provides O2 delivery (ḊO2) to support aerobic metabolism throughout a 3-h period. The aim of the present study was to investigate the effects of extracorporeal membrane oxygenation (ECMO) rewarming to restore ḊO2 and organ blood flow after prolonged hypothermic cardiac arrest. Eight male pigs were anesthetized and immersion cooled to 27 °C. After induction of hypothermic cardiac arrest, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed with ECMO. Organ blood flow was measured using microspheres. After cooling with spontaneous circulation to 27 °C, MAP and CO were initially reduced to 66 and 44% of baseline, respectively. By 15 min after the onset of CPR, there was a further reduction in MAP and CO to 42 and 25% of baseline, respectively, which remained unchanged throughout the rest of 3-h CPR. During CPR, ḊO2 and O2 uptake (V̇O2) fell to critical low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. Rewarming with ECMO restored MAP, CO, ḊO2, and blood flow to the heart and to parts of the brain, whereas flow to kidneys, stomach, liver and spleen remained significantly reduced. CPR for 3-h at 27 °C with sustained lower levels of CO and MAP maintained aerobic metabolism sufficient to support ḊO2. Rewarming with ECMO restores blood flow to the heart and brain, and creates a “shockable” cardiac rhythm. Thus, like continuous CPR, ECMO rewarming plays a crucial role in “the chain of survival” when resuscitating victims of hypothermic cardiac arrest.

Beyond return of spontaneous circulation: update on post-cardiac arrest management in the intensive care unit

A well-functioning chain of survival is critical for good outcomes following out-of-hospital cardiac arrest, a major public health concern in Singapore. While the percentage of survivors to hospital admission has increased over the years, the percentage of survivors to hospital discharge and the number of patients with good neurological recovery can be greatly improved. This underscores the urgent need to focus on ‘post-cardiac arrest care’, the fifth link in the chain of survival, to improve the outcomes of patients who are admitted to the intensive care unit (ICU) after return of spontaneous circulation. This review builds on earlier recommendations of the Singapore National Targeted Temperature Management Workgroup in 2017 to provide a focused update on post-cardiac arrest management and a practical guide for physicians managing resuscitated patients with cardiac arrest in the ICU.

Variation in Community and Ambulance Care Processes for Out-of-Hospital Cardiac Arrest During the COVID-19 Pandemic: A Systematic Review and Meta-Analysis

Bystander cardiopulmonary resuscitation (BCPR) and early defibrillation can double the chance of survival from out-of-hospital sudden cardiac arrest (OHCA). We investigated the effect of COVID-19 on the pre-hospital chain of survival. We searched five bibliographical databases for articles that compared prehospital OHCA care processes during and before the COVID-19 pandemic. Random effects meta-analyses were conducted, and meta-regression with mixed-effect models and subgroup analyses were conducted where appropriate. The search yielded 966 articles; 20 articles were included in our analysis. OHCA at home was more common during the pandemic (OR=1.38, 95%CI 1.11-1.71, p=0.0069). BCPR did not differ between COVID-19 and Pre-COVID-19 populations (OR=0.94, 95%CI 0.80-1.11, p=0.4631), although bystander defibrillation was significantly lower during the COVID-19 period (OR=0.65, 95%CI 0.48-0.88, p=0.0107). EMS call-to-arrival time was significantly higher in COVID-19 populations (SMD=0.27, 95%CI 0.13-0.40, p=0.0006). Resuscitation duration did not differ significantly between pandemic and pre-pandemic timeframes. The COVID-19 pandemic significantly affected prehospital processes for OHCA. These findings may inform future interventions, particularly to consider interventions to increase BCPR and improve the pre-hospital chain of survival.

Towards individualised treatment of out-of-hospital cardiac arrest patients: an update on technical innovations in the prehospital chain of survival

Out-of-hospital cardiac arrest (OHCA) is a major healthcare problem, with approximately 200 weekly cases in the Netherlands. Its critical, time-dependent nature makes it a unique medical situation, of which outcomes strongly rely on infrastructural factors and on-scene care by emergency medical services (EMS). Survival to hospital discharge is poor, although it has substantially improved, to roughly 25% over the last years. Recognised key factors, such as bystander resuscitation and automated external defibrillator use at the scene, have been markedly optimised with the introduction of technological innovations. In an era with ubiquitous smartphone use, the Dutch digital text message alert platform HartslagNu (www.hartslagnu.nl) increasingly contributes to timely care for OHCA victims. Guidelines emphasise the role of cardiac arrest recognition and early high-quality bystander resuscitation, which calls for education and improved registration at HartslagNu. As for EMS care, new technological developments with future potential are the selective use of mechanical chest compression devices and extracorporeal life support. As a future innovation, ‘smart’ defibrillators are under investigation, guiding resuscitative interventions based on ventricular fibrillation waveform characteristics. Taken together, optimisation of available prehospital technologies is crucial to further improve OHCA outcomes, with particular focus on more available trained volunteers in the first phase and additional research on advanced EMS care in the second phase.