Rapid Defibrillation for Cardiac Arrest
Benefits in NNT
1 in 2.5 were helped (prevented death)
62% saw no benefit
38% were saved from death
Harms in NNT
None were identifiably harmed (side effects from cardioversion/electricity)
0% were harmed (side effects from cardioversion/electricity)
SourceValenzuela TD Roe DJ, Nichol G, Clark LL, et al. Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. NEJM. 2000; 343(17): 1206-9.
NarrativeHundreds of thousands of individuals suffer sudden cardiac arrest (SCA) each year in the United States and abroad. Rapid defibrillation has been thought highly effective for SCA, but data have been sparse. This review examined the utility of rapid defibrillation under the best of possible circumstances: in a public location, with otherwise relatively healthy patients who suffer witnessed, sudden cardiac arrest, and in whom defibrillation is typically available within 3-4 minutes.
Under these unusual circumstances 90 of 148 (61%) arrests were associated with an initial cardiac rhythm of ventricular fibrillation when the defibrillator was placed on the patient. Survival to hospital discharge was 38% overall and 59% among those patients found to be in ventricular fibrillation.
CaveatsWe are including this study in our NNT review database because it represents a remarkable biologic description of SCA and is likely to remain the highest form of research available on this topic. There will never be a randomized trial of rapid defibrillation versus standard care without rapid defibrillation, nor should there be. However, this type of data makes bold presumptions. It presumes that all of those untreated would die. While this is likely true, it is less clear whether or not CPR without electrical countershock would provide some degree of life saving benefit. It seems probable that it would, though it is not possible to quantify this. Furthermore, the maximized conditions (witnessed arrests, healthy subjects, immediate response) do not represent a typical circumstance for the current use of defibrillation or general resuscitation in virtually any setting.
Finally, there may be harms associated with attempts to perform resuscitation. Intensive care unit admissions, comatose or vegetative state survivors, and substantial resource utilization (both during resuscitation and in post-resuscitation care) are all important potential harms that should be considered both for society at large and for those individuals who survive bur do not regain neurologic function, and for their families.