CPR and rapid shock increase cardiac arrest survival - ALS does not
World's largest pre-hospital study suggests refocusing on the basics

OTTAWA, August 11, 2004 - Contrary to popular belief, new research suggests that pre-hospital advanced life support (ALS) training does not increase the survival rate for people who experience a cardiac arrest outside of a hospital. On the other hand, bystander CPR and rapid defibrillation programs are crucial interventions that have a significant impact on survival. So concludes the largest multi-centre controlled trial ever conducted in a pre-hospital setting. The study is published in the August 12, 2004 edition of the New England Journal of Medicine. The lead author, Dr. Ian Stiell, is an emergency room physician, researcher and teacher affiliated with The Ottawa Hospital, the Ottawa Hospital Research Institute and the University of Ottawa.

Sudden death due to cardiac arrest remains an important public health concern. Every year, approximately half a million American lives are lost due to cardiac arrest, with almost one in two occurring outside of a hospital. The issue is equally as serious in Canada. In May of this year, a study in the journal Health Affairs showed that Canada has the worst record for cardiac arrest survival compared to four other major industrialized countries.

In the hopes of increasing survival chances and quality of life, Ontario introduced ALS training for paramedics several years ago. This additional training gives paramedics the ability to perform advance procedures at the scene of a cardiac arrest, including airway management (intubation) and the administration of intravenous drug therapy. ALS is one part of a comprehensive approach to strengthening community response to cardiac arrest and improving survival rates. Other parts of the approach include CPR training for police officers, firefighters, and the general public, as well as the installation of automatic defibrillators (computer-assisted devices that give electric shock to the heart) in public places so that they can be close at hand when a cardiac arrest occurs.

Before committing funds to expand ALS training, however, the Ministry of Health and Long-Term Care required further research to demonstrate the effectiveness of the program. The Ontario Pre-hospital Advanced Life Support (OPALS) study was created to determine the impact of ALS training in comparison with other interventions on survival rates for cardiac arrests that take place in non-hospital settings. An Ottawa-based research team led by Dr. Stiell studied over 10,000 patients over ten years across 17 urban centres in Ontario to determine the added benefit of ALS programs.

Researchers concluded that the best chance of surviving a cardiac arrest is if someone actually witnesses the event and intervenes immediately. The study also showed that cardiac arrest survival improved significantly if a citizen or first responder (a police officer or firefighter, for example) performs CPR, and if rapid defibrillation is applied within 8 minutes. Researchers could not, however, demonstrate a change in survival rates associated with having ALS trained personnel attend to the cardiac arrest victim, mainly because immediate intervention is key. According to the researchers, "cardiac arrest witnessed by a bystander, CPR by a bystander and use of a defibrillator in eight minutes or less were strongly associated with improved survival."

Given these findings, the researchers raise concerns about the low rates of citizen-initiated CPR and suggest that investing more in training and awareness programs for the general public may have a greater impact on cardiac arrest survival rates than expanding the number of ALS-trained personnel at this time. "In order to save lives, health officials and planners must go back to the basics, and make citizen CPR training and the rapid availability of defibrillation priorities," said Dr. Stiell.

"This study does not suggest that the ALS training we've provided for our paramedics is without value," Dr. Stiell continued. "To the contrary, we've demonstrated that some outcomes for cardiac arrest victims are improved and that paramedics save busy Emergency Departments and hospital considerable resource use," he said. "As well, early indications from our follow-up study on respiratory chest pain patients suggest ALS plays an important role in saving hundreds of lives each year, " he added.

Dr. Stiell also suggests that the community and the media have a role to play in the awareness of the benefits of CPR. "High tech automated defibrillator machines are the object of a great deal of public attention," he said. "While these machines are a great advancement, they will only help about 15 % of people. That's because the majority of people don't have cardiac arrests in malls, arenas or public pools; they have them at home or in private residences. This is why citizen CPR training is so important and it needs to be promoted. The low-tech combination of your hands and mouth is as essential to saving lives as any high tech machine."

Future studies will examine the benefits of various interventions, including ALS, on patients with breathing difficulties and trauma patients. A recently awarded $ 4 million (CDN) grant from the U.S. National Institutes of Health will ensure that Dr. Stiell's Ottawa-based research group can continue to shape the future planning of pre-hospital emergency medical services.

Dr. Stiell is an emergency physician at The Ottawa Hospital, a Chair of Emergency Medicine Research at the Ottawa Hospital Research Institute, and Head of Department of Emergency Medicine at University of Ottawa. The author of the world-renowned Ottawa ankle and knee rules, a clinical decision aid, Dr. Stiell holds the titles of Distinguished Investigator with the Canadian Institutes of Health Research, and is a rare Canadian member of Institute of Medicine with the U.S. National Academy of Sciences.

The OPALS study was funded by the Emergency Health Services Branch of the Ministry of Health and Long-Term Care of Ontario, and Canadian Health Services Research Foundation.

Media Contact:

Ron Vezina,
Manager, Public Affairs and Media Relations
The Ottawa Hospital
(613) 737-8460


  • Over 500,000 Americans die every year from sudden cardiac arrest. Extrapolated, those numbers translate into approximately 50,000 Canadian deaths each year.

  • Most communities have overall out-of-hospital cardiac arrest survival rates of less than 5%.

  • In Ontario, only 15% of cardiac arrest victims benefit from citizen/bystander CPR.

  • The OPALS study by the numbers:
    • 10 year study (1994)
    • 10,000 patients
    • 17 urban centres participated (began with 20, but 3 centres could not meet criteria)
    • Aggregate population of centres: 2.5 million
    • Cost of study: $2 million for research; $15 million for training, equipment, and ALS program implementation
  • The American Heart Association's Chain of Survival is a model for optimizing community response. Research has demonstrated that the three first links - early access, early CPR, and rapid defibrillation (within 8 minutes) - are all associated with improved survival. However, the fourth link, ALS, is believed by many to improve survival and outcomes because it provides advanced airway management and intravenous drug therapy. However, the incremental value of this link has never been scientifically proven.

  • Previous research had studied Rapid Defibrillation and ALS together, never determining the individual relevance of each intervention.

  • Quality assurance was vigorously monitored and communities that failed to meet the following system criteria were excluded. The criteria were:
    1. Maintaining the 8 minute Rapid Defibrillation response in 90 % of cases
    2. ALS paramedic response to 95% of cases
    3. Paramedic response on scene in 11 minutes for 80% of cases
    4. Successful intubation for 90% of cases
  • Although the study was limited to centres in Ontario, researchers believe their findings can be generalized to any urban centres with a population of up to one million, who have rapid defibrillation programs.

  • Study results revealed that chances of surviving a cardiac arrest
    • Increased 4.4 times if it was witnessed
    • Increased 3.7 times if a first responder or bystander performed CPR
    • Increased 3.4 times if the region had a rapid defibrillation program
    • Showed no significant increase as a result of being treated by ALS trained responders
  • Although ALS programs did not increase survival of cardiac arrest, the researchers did note that secondary outcomes improved, such as the return of spontaneous circulation and admission to hospital.

  • Early indications from a follow-up study that this research team is conducting on respiratory and chest pain patients suggest that ALS plays an important role in reducing morbidity and mortality.

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