Evidence-Based Medicine
The Setup:
A young woman finds her 59-year-old father in his bedroom, absent of vital signs. Upon EMS arrival, CPR is initiated. In the midst of your busy evening shift, you receive a radio patch from EMS personnel.

The Choice
Considering both the age of the patient and the dismal outcome of out-of-hospital cardiac arrest (OHCA), do you:
1. Order the transport of the patient with lights and sirens and continue resuscitative efforts?
2. Order a termination of resuscitation and pronounce the patient?
3. Ask for additional specific criteria to determine the probability that this patient will not survive before terminating resuscitation?

The Evidence

Morrison LJ, Visentin LM, Kiss A, Theriault R, Eby D, Vermeulen M, Sherbino J, Verbeek PR; TOR Investigators. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med. 2006;355(5):478-87.

This article examines OHCA involving exclusive prehospital basic life support, including automatic external defibrillation (AED) as required. This study is a prospective, multi-site validation of a clinical decision rule that enrolled 1,240 patients in Ontario, Canada. The BLS-TOR rule recommends termination of resuscitation when:
No AED shocks are administered prior to transport, no return of spontaneous circulation (ROSC) occurs, and the arrest is not witnessed by EMS personnel.

The BLS-TOR rule recommended termination of resuscitation in 776 patients. Of these patients four survived, three with good cerebral performance. The positive predictive value (PPV) for death was 99.5% (95% Confidence Interval [CI], 98.9 to 99.8%). The BLS-TOR rule would decrease the transportation of all patients by 62.6%.


Sasson C, Hegg AJ, Macy M, Park A, Kellermann A, McNally B; CARES Surveillance Group. Prehospital termination of resuscitation in cases of refractory out-of-hospital cardiac arrest. JAMA. 2008;300(12):1432-8.

This second article examines OHCA involving prehospital advanced life support. This study is a retrospective validation of the previous BLS-TOR rule and a newly derived ALS-TOR rule, using a cardiac arrest registry database of 5,556 patients from eight American cities. The ALS-TOR rule recommends termination of resuscitation when:
-No AED shocks are administered prior to transport,
-No return of spontaneous circulation (ROSC) occurs,
-The arrest is not witnessed by either EMS personnel or bystanders, and
-No bystander CPR is administered.

In this population, the BLS-TOR rule recommended termination of resuscitation in 2, 592 patients. Of these patients five survived, four with good cerebral performance. The PPV for death was 99.8% (95% CI 99.6 to 99.9%). The transportation rate of all patients would decrease by 47.1%. The ALS-TOR rule recommended termination of resuscitation in 1,192 patients. Of these patients none survived. The PPV for death was 100.0% (95% CI 99.7 to 100.0%). The transportation rate would decrease by 21.7%.
The Bottom Line:
Only the BLS-TOR rule, in the setting of OHCA receiving exclusive basic life support care with AED use as required, is rigorously validated to warrant widespread adoption. Currently, in an EMS system where OHCA is treated with advanced life support care; neither the BLS-TOR nor the ALS-TOR rules have been appropriately validated, in a large, prospective trial, to provide reliable data upon which to make determinations to terminate resuscitation.

The Caveats:
A TOR rule that misses even a single survivor will invite debate. However, a survival rate of less than one percent achieves published rates of medical futility. The novelty of this field of research is that it is one of the few areas that document unexpected survival when aggressive resuscitation ceases. Regardless of whether one does not accept this argument, ignores the potential harm of high-speed prehospital transport and discounts the system impact of inappropriate utilization of limited EMS resources, it should be noted that the term “rule” does not imply required standard. Rather, TOR rules should be viewed as evidence that may advise local EMS systems to make appropriate decisions that reflect the needs of their community.

The Outcome:
You quickly establish that your patient has only received basic life support care. No shocks have been delivered by the AED and no ROSC has occurred. Since the patient was found vital signs absent by his daughter, all of the elements of the BLS-TOR rule have been established. As per your EMS protocol, you document these findings and order termination of resuscitation and a field pronouncement of death.

Jonathan Sherbino MD MEd FRCPC
BEEM (Best Evidence in Emergency Medicine) Faculty
Assistant Professor, Division of Emergency Medicine, McMaster University



# BLS and ALS TOR Rules -- Useful for U.S. Physicians?Chris Carpenter 2009-11-20 12:48
EPM Readers:

Would you use the BLS or ALS TOR within your pre-hospital systems? If not, why? If so, do you foresee any barriers to uptake and appropriate utilization among your pre-hospital providers, community, and/or professional peers?

Christopher Carpenter, MD, MSc.
Chief Clinical Editor, Emergency Physicians Monthly

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