Clinical paperOut-of-hospital cardiac arrest outcomes stratified by rhythm analysis☆,☆☆
Introduction
Cardiopulmonary arrest is defined by one of four rhythms on surface electrocardiogram: pulseless ventricular tachycardia (pVT), ventricular fibrillation (VF), pulseless electrical activity (PEA), or asystole. Two of these, pVT and VF, are classified as shockable rhythms while PEA and asystole are non-shockable rhythms. Among out-of-hospital cardiac arrest (OHCA) patients with a first recorded rhythm (FRR) of PEA or asystole, conversion to a shockable rhythm can occur during attempted resuscitation.
Currently, when a non-shockable rhythm converts to a shockable rhythm during resuscitation efforts, immediate defibrillation (aka rescue shock [RS]) is recommended, regardless of arrest duration or underlying myocardial physiology. There are no treatments specifically directed at pVT/VF under these circumstances.
Controversy exists regarding the appropriateness of this approach because alternatives have never been studied. The authors of a recent study have suggested that such patients derive no benefit from defibrillation attempts and that new treatment strategies may be necessary.1 Results from three subsequent studies contradict this assertion,2, 3, 4 and conclude that current treatment recommendations are adequate.5
This study was done to compare resuscitation outcomes in OHCA among a large cohort of adults in the Cardiac Arrest Registry to Enhance Survival (CARES [https://mycares.net]) dataset stratified by three rhythm categories: initial shockable (IS), converted to shockable (CS), and never shockable (NS) to help clarify this issue. We hypothesized that outcomes in OHCA would vary based upon the first recorded ECG rhythm as follows: the most favorable outcomes would occur after a FRR of pVT/VF, intermediate outcomes would occur in patients with FRR of PEA or asystole who subsequently receive a defibrillation attempt during resuscitation efforts, and the worst outcomes would occur after persistent PEA or aystole.2, 3, 4
Section snippets
Methods and statistical analysis
The study was reviewed and approved by the Baystate Health Institutional Review Board (BH-10-223) through expedited review.
Results
There were 40,274 OHCA records submitted to the CARES registry during the study period. After non-cardiac etiology arrests (1867 trauma, 1175 respiratory, 206 drowning, 26 electrocution, and 3306 other) and cases of missing hospital outcomes (n = 8380) were screened out, 31,894 OHCA records were provided for evaluation. Further excluding patients under the age of 18 and those with missing or unknown mortality outcome (n = 885), missing or unspecified FRR (n = 47), and missing or “no resuscitation
Discussion
This is the first large-scale study done to compare resuscitation outcomes in OHCA among adults stratified by all 3 of the rhythm groups (IS, CS, and NS). We found that outcomes in OHCA vary based upon the first recorded ECG rhythm. The most favorable outcomes occur after a FRR of pVt/VF, and less favorable outcomes occur in patients with FRR of PEA or asystole whether or not a defibrillation attempt occurs during resuscitation efforts.
Currently, the treatment of CS and IS rhythms do not
Conclusion
We conclude that for OHCA, the survival rate for converted shockable cardiac arrest victims is significantly lower than for initial shockable patients based on a rigorous multivariable analysis on a large, validated database of recent OHCA cases. Further, stratification by non-shockable first recorded rhythm types suggests differences between subgroups as well. These findings support the contention that converted shockable and initial shockable rhythms may not be the same. The major implication
Conflict of interest statement
None of the authors have a conflict of interest to report.
Acknowledgements
The Cardiac Arrest Registry to Enhance Survival (CARES) is funded by grant support from the Center for Disease Control and Prevention (CDC) MM-0917-05. The American Association of Medical Colleges is the grant administer of CARES. This analysis was funded by a project grant from the Laerdal Foundation for Acute Care Medicine.
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Demystifying non-shockable rhythms in Out-of-Hospital Cardiac Arrest
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2022, ResuscitationCitation Excerpt :Forty years ago almost 70% of the initial rhythms detected in OHCA cases were shockable43 but during the past 3–4 decades, there has been a significant shift, with a reversal of proportions. The proportion of shockable rhythms continues to progressively decrease and non-shockable rhythms comprise 70% or greater of presenting rhythms.44–48 Reasons for this paradigm shift are not fully clear but could reflect a combination of factors including progressively increasing age of the population, decrease in the incidence of OHCA associated with coronary disease, and effects of prescription medications as well as other substances.
Impact of the modified SESAME ultrasound protocol implementation on patients with cardiac arrest in the emergency department
2021, American Journal of Emergency MedicineCitation Excerpt :Based on these guidelines, we used the following interpretations: less than 0 (poor), 0–0.20 (slight), 0.21–0.40 (fair), 0.41–0.60 (moderate), 0.61–0.80 (substantial), and 0.81–1.00 (almost perfect) [21]. For the study variables, we followed the recommendations of previous CA studies [4,22-25]. Data were collected by a well-trained single investigator and extracted from medical records during the pre-intervention period and medical records and study sheets during the post-intervention period.
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.03.033.
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Prior presentation: The American Heart Association Resuscitation Science Symposium. November 2010. Chicago, IL. The National Association of EMS Physicians. January 2011. Bonita Springs, FL.
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For the CARES Surveillance Group.