Clinical paperValidation of a universal prehospital termination of resuscitation clinical prediction rule for advanced and basic life support providers☆
Introduction
Sudden cardiac arrest is a leading cause of death in North America,1, 2, 3with approximately 30,000 to 45,000 cases reported in Canada per year and the majority of these occur in the prehospital environment.4 Despite recent improvements in advanced cardiac life support, the survival rates for out of hospital cardiac arrest remain quite low ranging from 4% to 9%.2, 5 Traditionally, these patients have been transported with ongoing resuscitative efforts to the closest emergency department.6 However, there is a growing body of evidence to suggest that termination of resuscitation clinical prediction rules can be safely and logistically applied to a subset of prehospital cardiac arrest patients that are considered futile based on response to treatment provided by either paramedics6, 7, 8, 9, 10, 11, 12 or defibrillation-only emergency medical technicians.13, 14, 15
In addition to the accumulating scientific evidence, national and international bodies such as the American Heart Association and the National Association of Emergency Medical Services Physicians have weighed in on this contentious topic by issuing their own guidelines for termination of resuscitation by paramedics in the prehospital environment.
In 2000, the National Association of Emergency Medical Services Physicians published a position statement on termination of resuscitation in adults with nontraumatic out of hospital cardiac arrest, stating that resuscitative efforts could be terminated in patients who do not respond to at least 20 min of advanced life support treatments such as cardiopulmonary resuscitation, definitive airway management, medication and defibrillation as needed.6
According to the 2005 American Heart Association guidelines, termination of resuscitation in the prehospital setting following system-specific criteria and under direct medical control should be standard practice in all Emergency Medical Services systems, as evidence confirms that ongoing advanced life support care in the Emergency Department offers no advantage over similar care in the field.16 Variability in termination of resuscitation rates has been recorded when termination is left to the discretion of individual physicians providing medical control.17 To address this variability, investigators from the University of Toronto derived an advanced life support clinical prediction rule through a secondary analysis of a study where adult cardiac arrest patients were treated by paramedics.18 The rule predicted that prehospital cardiac arrest patients could be considered for termination of resuscitation by advanced life support paramedics if there was no return of spontaneous circulation at any point during resuscitation, no shock was given, the arrest was not witnessed by Emergency Medical Services personnel or bystanders and no bystander cardiopulmonary resuscitation was delivered (Fig. 1).
Investigators from the University of Toronto also derived and validated a basic life support termination of resuscitation clinical prediction rule addressing the lack of prospective data and treatment guidelines on this subject in the current literature.15, 19 Patients treated solely by defibrillation-only emergency medical technicians could be considered for termination of resuscitation if there was no return of spontaneous circulation prior to transport, no shock was given and the arrest was not witnessed by Emergency Medical Services personnel (Fig. 2).
Ideally, a single universal termination of resuscitation rule that could be employed by all levels of Emergency Medical Services providers should be developed to optimize consistency in practice across EMS services. Therefore, we sought to conduct an external validation of each rule on an identical prehospital patient cohort attended by both levels of providers. Diagnostic test characteristics and the transport rate for both the advanced life support termination of resuscitation and the basic life support termination of resuscitation clinical prediction rules were measured and compared with the aim of determining which rule, if either, could be recommended as a universal termination of resuscitation rule.
Section snippets
Study design
This investigation is an external validation of each rule retrospectively applied to data originally collected by the University of Toronto for the Resuscitation Outcomes Consortium Epistry – Cardiac Arrest trial; a population based registry of all out of hospital cardiac arrests.20 The University of Toronto center is comprised of the Emergency Medical Services Systems within the city of Toronto and 5 adjacent municipalities (Peel, Durham, Hamilton, Muskoka and Simcoe) and the province-wide air
Results
From 1 April 2006 to 1 April 2007, a total of 4854 cases of out of hospital cardiac arrest occurred in our catchment area. Of this total, 2439 were excluded where 472 cases were deaths due to obvious cause; 259 cases recorded ‘Do Not Resuscitate’ advance directives, 1553 cases were obviously dead as defined by legislation and 155 cases were less than 18 years of age. The remaining 2415 cardiac arrest patients attended to by paramedics (n = 1992; 82.5%) or defibrillation-only emergency medical
Discussion
Both rules achieved high specificity and high positive predictive value when applied to a patient cohort attended by either paramedics or defibrillation-only emergency medical technicians or both. Our findings support using the basic life support termination of resuscitation rule as a universal clinical prediction rule in emergency medical services systems employing providers with either or both levels of certification. We suggest that implementation of this rule would result in a lower overall
Conclusion
We have conducted an external validation of two termination of resuscitation clinical prediction rules on a patient cohort attended by advanced life support paramedics and defibrillation-only emergency medical technicians, and found both rules to have high specificity and high positive predictive value for patients unlikely to benefit from further resuscitation. Transport rates and sensitivities varied greatly between the two rules. Implementing the basic life support rule as a universal
Funding
The Resuscitation Outcome Consortium (ROC) is supported by a series of cooperative agreements to 10 regional clinical centers and one data Coordinating Center (5U01 HL077863, HL077881, HL077871, HL077872, HL077866, HL077908, HL077867, HL077885, HL077885, HL077863) from the National Heart, Lung and Blood Institute in partnership with the National Institute of Newurological Disorders and Stroke, The Canadian Institutes of Health Research (CIHR) – Institute of Circulatory and Respiratory Health,
Conflict of interest statement
None to declare.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2008.11.014.