Responding to Cardiac Arrest in the Community in the Digital Age

Recurrence of ventricular fibrillation in out-of-hospital cardiac arrest: Clinical evidence and underlying ionic mechanisms

Defibrillation remains the optimal therapy for terminating ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) patients, with reported shock success rates of ∼90%. A key persistent challenge, however, is the high rate of VF recurrence (∼50-80%) seen during post-shock cardiopulmonary resuscitation (CPR). Studies have shown that the incidence and time spent in recurrent VF are negatively associated with neurologically-intact survival. Recurrent VF also results in the administration of extra shocks at escalating energy levels, which can cause cardiac dysfunction. Unfortunately, the mechanisms underlying recurrent VF remain poorly understood. In particular, the role of chest-compressions (CC) administered during CPR in mediating recurrent VF remains controversial. In this review, we first summarize the available clinical evidence for refibrillation occurring during CPR in OHCA patients, including the postulated contribution of CC and non-CC related pathways. Next, we examine experimental studies highlighting how CC can re-induce VF via direct mechano-electric feedback. We postulate the ionic mechanisms involved by comparison with similar phenomena seen in commotio cordis. Subsequently, the hypothesized contribution of partial cardiac reperfusion (either as a result of CC or CC independent organized rhythm) in re-initiating VF in a globally ischaemic heart is examined. An overview of the proposed ionic mechanisms contributing to VF recurrence in OHCA during CPR from a cellular level to the whole heart is outlined. Possible therapeutic implications of the proposed mechanistic theories for VF recurrence in OHCA are briefly discussed.

Canadian Cardiovascular Society/Canadian Cardiovascular Critical Care Society/Canadian Association of Interventional Cardiology Clinical Practice Update on Optimal Post Cardiac Arrest and Refractory Cardiac Arrest Patient Care

Survival to hospital discharge among patients with out-of-hospital cardiac arrest (OHCA) is low and important regional differences in treatment practices and survival have been described. Since the 2017 publication of the Canadian Cardiovascular Society's position statement on OHCA care, multiple randomized controlled trials have helped to better define optimal post cardiac arrest care. This working group provides updated guidance on the timing of cardiac catheterization in patients with ST-elevation and without ST-segment elevation, on a revised temperature control strategy targeting normothermia instead of hypothermia, blood pressure, oxygenation, and ventilation parameters, and on the treatment of rhythmic and periodic electroencephalography patterns in patients with a resuscitated OHCA. In addition, prehospital trials have helped craft new expert opinions on antiarrhythmic strategies (amiodarone or lidocaine) and outline the potential role for double sequential defibrillation in patients with refractory cardiac arrest when equipment and training is available. Finally, we advocate for regionalized OHCA care systems with admissions to a hospital capable of integrating their post OHCA care with comprehensive on-site cardiovascular services and provide guidance on the potential role of extracorporeal cardiopulmonary resuscitation in patients with refractory cardiac arrest. We believe that knowledge translation through national harmonization and adoption of contemporary best practices has the potential to improve survival and functional outcomes in the OHCA population.

What do consumer and providers view as important for integrated care? A qualitative study

BACKGROUND

Integrated care is a model recognised internationally, however, there is limited evidence about its usability in the community. This study aimed to elicit community and provider views about integrated care and how implementation could meet their healthcare needs in a new hospital.

METHODS

Using a qualitative approach, consumer and provider views on the strengths, barriers and enablers for integrated care were collected via a series of online workshops and supplementary interviews.

RESULTS

A total of 22 consumers and 49 providers participated in 11 focus groups; all perceived integrated care to be an accessible and efficient model that offers a high level of care which enhanced staff and patient well-being. Providers expressed concerns about longer waiting times and safety risks associated with communication gaps and insufficient staff. Enablers include supporting consumers in navigating the integrated care process, co-ordinating and integrating primary care into the model as well as centralising patient electronic medical records.

DISCUSSION

Primary, tertiary and community linkages are key for integrated care. Successful interoperability of services and networks requires an investment in resources and infrastructure to build the capability for providers to seamlessly access information at all points along the patient pathway.

CONCLUSION

Integrated care is perceived by consumers and providers to be a flexible and patient-focused model of healthcare that offers benefits for a hospital of the future.

Understanding Etiologies of Cardiac Arrest: Seeking Definitional Clarity

Cardiac arrest leading to death and sudden cardiac death (SCD) may refer implicitly to situations in which death is unexpected and primarily of cardiac cause. National and international societies have published differing definitions for the various terms relating to cardiac arrest and SCD. We highlight the controversies in defining SCD, including the lack of a universal definition, the heterogeneity in the operationalization of the term "sudden," and limitations of time-based systems of SCD classification. We discuss the importance of a standardized methodology for classifying cardiac arrest as recommended by the World Health Organization (WHO) that should include use of multisource evidence (eg, coroner, autopsy, and toxicology reports) for confirming or refuting a cardiac cause of arrest. We reveal how a universal definition of SCD has been incorrectly attributed to the WHO and how this has been perpetuated in the literature. We make the case that definitional clarity is essential to understanding epidemiology, evaluating novel treatments, forming international collaboration, and innovating public health prevention strategies. We propose a practical schema to categorize cardiac arrest events to describe and study this population more accurately.

Long-term Mortality, Readmission, and Resource Utilization Among Hospital Survivors of Out-of-Hospital Cardiac Arrest

BACKGROUND

Among patients with out-of-hospital cardiac arrest (OHCA), the influence of pre- and in-hospital factors on long-term survival, readmission, and resource utilization is ill-defined, mainly related to challenges combining disparate data sources.

METHODS

Adult nontraumatic OHCA from the British Columbia Cardiac Arrest Registry (January 2009 to December 2016) were linked to provincial datasets comprising comorbidities, medications, cardiac procedures, mortality, and hospital admission and discharge. Among hospital-discharge survivors, the 3-year end point of mortality or mortality and all-cause readmission was examined with the use of the Kaplan-Meier method and multivariable Cox regression model for predictors. The use of publicly funded home care and community services within 1 year after discharge also was evaluated.

RESULTS

Of the 10,674 linked, emergency medical services-treated adult OHCAs, 3230 were admitted to hospital and 1325 survived to hospital discharge. At 3 years after discharge, the estimated Kaplan-Meier survival rate was 84.1% (95% CI 81.7%-86.1%) and freedom from death or all-cause readmission was 31.8% (29.0%-34.7%). After exclusions, 26.6% (n = 315/1186) accessed residential or home care services within 1 year. Independent predictors of long-term outcomes included age and comorbidities, but also favourable arrest characteristics and in-hospital factors such as revascularization or receipt of an intracardiac defibrillator before discharge.

CONCLUSIONS

Among OHCA hospital survivors, the long-term death or readmission risk persists and is modulated by both pre- and in-hospital factors. However, only 1 in 4 survivors required residential or home care after discharge. These results support efforts to improve care processes to increase survival to hospital discharge.