Cardiac Arrest Management: Part 2

Understanding the role of advanced life support in the latest American Heart Association guidelines.


     Last month's issue discussed the most recent AHA guidelines' emphasis on improving basic life support in managing cardiac arrest. It is known that high-quality CPR and defibrillation within minutes after collapse improve the chances of survival.1 What is less well known is the effectiveness of advanced therapies to treat cardiac arrests. In fact, traditional advanced procedures, such as advanced airway placement and medication delivery, have not been shown to increase survival to hospital discharge.1 Recent literature has also questioned the efficacy of advanced life support (ALS) for out-of-hospital cardiac arrests.2 It appears that certain advanced procedures may decrease the likelihood of survival if done incorrectly, at the wrong time, or in a manner that compromises CPR and defibrillation.

THE OPALS STUDY
     Many difficult questions about the value of ALS in cardiac arrest came to light after publication of articles from the Ontario Prehospital Advanced Life Support (OPALS) study. The study took place in Ontario, Canada, where EMS was delivered by only BLS services in many areas. When faced with requests for money to upgrade the EMS system, the government funded a large clinical trial in several cities to determine the effectiveness of adding paramedics trained in advanced life support.2

     One aspect of the study was a three- phase evaluation on the effectiveness of each link of the AHA's Chain of Survival for cardiac arrests: early recognition and calling 9-1-1, early CPR, early defibrillation and early advanced care.

     The first two phases evaluated bystander CPR, first responder CPR and an expanded AED program. These programs showed a significant increase in long-term survival, and it was presumed that adding ALS would make the survival rate even higher.2

     In phase three, paramedics were implemented in some cities to establish IV access, administer medications and perform endotracheal intubation in cardiac arrests. Survival rates from the earlier phases of the study were then compared to those patients who received ALS care.

     The results showed no benefit of advanced life support for long-term survival from out-of-hospital cardiac arrests, and only a slightly higher rate of survival to hospital admission (patients who survived long enough to be placed on life support but later died).2

     It should be noted that other aspects of the study showed ALS treatment to be beneficial for certain medical problems. A significantly lower mortality rate was found in the group of patients with respiratory distress who received ALS rather than BLS only.3 While the study showed a questionable benefit for ALSO in cardiac arrests, it may prevent cardiac arrest from ever occurring in some medical patients.

     One theory as to why there appeared to be little benefit in cardiac arrest patients who received ALS is that in a system that worked on improving BLS care by responders, good CPR took a backseat to advanced procedures once paramedics were introduced. Based on cardiac arrest data, the OPALS study group recommended that communities allocate more resources to the first links in the chain of survival (early CPR and AED programs) than to early advanced life support.2

THE EFFICACY OF ALS IN CARDIAC ARREST MANAGEMENT
     The literature now clearly defines which interventions are most valuable in managing cardiac arrests, as well as which have questionable value. The OPALS trial showed little benefit to advanced life support when it was added to optimized BLS care. Last month, we explored how CPR is already done poorly much of the time, with frequent pauses, inadequate depth and relaxation of compressions, and too frequent and forceful ventilation.1 When CPR is already inadequate, pauses for advanced procedures are even less likely to help.

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