Nearly one third of patients who go into cardiac arrest in the hospital do not receive defibrillation within the recommended two minutes, increasing the risk of brain damage and death.
The startling finding comes from a new study of 6,789 patients at 369 U.S. hospitals who experienced cardiac arrest because of ventricular fibrillation or ventricular tachycardia over a 5.5-year period (N Engl J Med. 2008; 358:9-17). A multicenter research team found that the overall median time to defibrillation was one minute, but 30.1% experienced delays of longer than two minutes. The probability of survival to discharge was 22.2% in the delayed group compared with 39.3% in those who underwent defibrillation within two minutes. Survival rates fell for each minute of delay.
Only 37.4% of the delayed-defibrillation patients survived for 24 hours after the cardiac arrest, compared with 55% of those who underwent timely shock. Spontaneous circulation was also less likely to return in the delayed-defibrillation patients. In addition, 51.7% of the delayed group escaped major neurologic disabilities compared with 60.1% of the non-delayed subjects. Major functional disabilities were avoided by 26.2% of the delayed group and by 34.6% of those receiving prompt defibrillation therapy.
Patient characteristics associated with delayed defibrillation include black race, noncardiac admitting diagnosis, admission to a smaller hospital (<250 beds), and occurrence of cardiac arrest nocturnally or on weekends.
In hospitals as a whole, delays may be even more frequent. All the hospitals in the study had joined a national registry on cardiac arrest and were therefore making special efforts to meet the two-minute resuscitation guideline.