Defibrillators should be applied to heart attack (cardiac arrest) patients within two minutes. A delay above this amount of time has been shown to cause a higher probability of death.
The researchers studied the records of 6,789 patients from 369 hospitals (taking part in the National Registry of Cardiopulmonary Resuscitation) between 2000 and 2005 with respect to their episodes of heart attacks in hospital settings and public areas, and the application of electrical shock through defibrillators.
Since 1991, based on information provided by the American Medical Association, the medical community has known that defibrillators should be used within two minutes to be most effective in saving the patient’s life. However, this study found that defibrillator treatment took longer than two minutes in thirty percent of the cases when in the hospital.
The study found that only 70% of hospital patients received an electrical shock within the recommended two minutes. For those lucky patients that received defib-treatment within the first two minutes, the chances of leaving the hospital alive were 39%.
About 17% of the patients were shocked in the third through the fifth minute—their survival rate was 28%. And when hospital personnel took longer than five minutes to shock a patient, the survival rate fell to 15%. These two groups of patients, on average survived about 22% of the time—17% less than those who got treatment during the first two minutes.
Surprisingly, the researchers found that over 50% of heart-attack patients survive heart attacks while in crowded areas, such as airports, casinos, and other public places where defibrillators are frequently used.
The results of the study ("Delayed Time to Defibrillation after In-Hospital Cardiac Arrest") were published Wednesday, January 3, 2008, in The New England Journal of Medicine (volume 358, pages 9-17, number 1). The researchers, which included Paul S. Chan, Harlan M. Krumholz, Graham, Nichol, and Brahmajee K. Nallamothu, estimate that 370,000 to 750,000 people have a heart attack each year in the United States. Delays in the treatment of patients with defibrillators increase by thousands the number of deaths each year in the United States.
Lead author in the study, Dr. Chan, of Saint Luke’s Mid America Heart Institute (Kansas City, Missouri) and the University of Michigan, said that delays occur often times in hospitals because of the time of day (most delays occur at night or on the weekends), the type of hospitals (smaller ones had more delays), the quality of hospital, the unavailability of doctors at the time of the heart attack, and the lack of heart monitors in hospitals.
Chan stated, "We found that delayed defibrillation was common, and that rapid defibrillation was associated with sizable survival gains in these high-risk patients.However, the real work has yet to be done in this field. We now have to develop systems of care within the hospital to improve defibrillation times nationally." [Medical News Today]
For more information, read the University of Michigan article: "Study confirms delayed defibrillation for hospitalized patients linked to decreased survival".