Cardiac arrests strike without warning often causing a complete loss of responsiveness. If someone loses consciousness in front of you and does not respond to being tapped on the shoulders or answer if they are OK, you should call 9-1-1 immediately and get an AED if one is available. If the person has stopped breathing, you should administer CPR. In this article we explore CPR survival rates and the science surrounding early response variations in assisting someone experiencing sudden cardiac arrest.
CPR and AEDs are both recommended for the treatment of sudden cardiac arrest. There are multiple methods for administering CPR and the combination of these variants along with the shock from AEDs may affect the long-term survival rate of an individual. We’ll examine the differences between the survival rates of cardiac arrest victims who receive compression-only CPR versus those that receive traditional CPR, which includes both mouth-to-mouth and compressions. These CPR methods will also be studied with the additional administration of an AED shock or without an AED shock to help determine the best option for increasing cardiac arrest survival rates.
Compression Only CPR vs. Conventional CPR with AED Shock
A national observational study of consecutive out-of-hospital cardiac arrest patients with resuscitation attempts was conducted in Japan from 2005 to 2009. The study’s sample consisted of all out-of-hospital cardiac arrests of presumed cardiac origin that received shocks from public-access automated external defibrillation (AEDs) operated by bystanders. Of these individuals, a comparison was made of the outcomes by the type of bystander-initiated CPR, either chest compression-only CPR or conventional CPR with compressions and rescue breathing.
During the 5-year period studied, 1,376 out-of-hospital cardiac arrests of cardiac origin received bystander CPR and shocks with AEDs administered by bystanders. Out of this group, 506 individuals, which is equivalent to 36.8%, received chest compression-only CPR. Another 870 individuals, or 63.2%, received conventional CPR. The results found that the chest compression-only CPR group had a significantly higher survival rate at 1-month and a favorable neurological outcome. The study suggests that compression only CPR may be better for out-of-hospital cardiac arrest survival rates when the incident is witnessed and the victim also receives defibrillation.
Table 1: 1-Month Survival Rate of Chest Compression-Only CPR vs. Conventional CPR with AED Shocks
|Type of CPR (+ AED shock)||Rate of 1-Month Survival|
|Chest Compression-Only CPR||206 of 506||40.7%|
|Conventional CPR||286 of 870||32.9%|
Compression-Only CPR vs. Conventional CPR without AED Shock
In another study conducted in Sweden between 2005 and 2009, dispatchers at Emergency Medical Dispatch Call Centers gave instructions for either chest compression-only CPR or standard (mouth-to-mouth and compression) CPR to calls about out-of-hospital witnessed, either seen or heard, cardiac arrests not caused by trauma. The dispatcher determined which instructions to give based on data-collection sheets created through a random-number generator.
The analysis showed a 24.0% survival rate at one day for those who received compression-only CPR, and a 8.7% survival rate at 30 days for those who received compression-only CPR. Additionally, the analysis also revealed a 20.9% survival rate at one day for those who received standard CPR, and a 7.0% survival rate at 30 days for those that received standard CPR. While compression-only CPR had a slightly higher survival rate at both intervals, neither difference was statistically significant. No statistical differences were found in any of the compared subgroups either. The authors also reported that these findings are in line with the findings of previous studies.
Table 2: Survival Rates of Compression-Only CPR vs. Standard CPR at 1 Day & 30 Days
|Type of CPR||Survival Rate (%)*|
|1 Day||30 Days|
* Results are not statistically significant.
Overall Comparison of Both Methods of CPR with & without AED Shocks
So what is the best case scenario for the survival of a sudden cardiac arrest event? One study found that although compression-only CPR had a slightly higher survival rate at both one day and thirty days, there were no statistically significant differences between compression-only CPR and standard CPR. But, another study conducted with both methods of CPR and the addition of AED shock did find a difference between the two CPRs with compression-only CPR having the statistically higher survival rate. While compression-only CPR is not better than standard CPR on its own, it does appear that compression-only CPR is better than standard CPR when paired with an AED.
The major difference found between the survival rates of sudden cardiac arrest victims can be seen when a comparison between the two studies is made. When either type of CPR is combined with AED shock, the rate of survival drastically increases at the one month mark. Standard CPR alone has just a 7% survival rate at one month, but standard CPR combined with the utilization of an AED has an amazing 32.9% survival rate at one month, which is over three times higher. An even bigger increase is witnessed in the comparison of compression-only CPR. Compression-only CPR by itself yields an 8.7% survival rate at one month, but when combined with AED shock, the survival rate drastically increases to 40.7%. While the direct comparison of these two studies may be limited by their varying populations and methods, the pronounced difference between the studies’ outcomes shows that the best chance of survival from a cardiac arrest event is to treat the patient immediately with both compression-only CPR and an AED.
Table 3: Survival Rates of All Four Treatment Options
|Type of Treatment||Survival Rate (%)|
|1 Day||30 Days|
|Compression-Only CPR without AED*||24.0||8.7|
|Standard CPR without AED*||20.9||7.0|
|Compression-Only CPR with AED||–||40.7|
|Standard CPR with AED||–||32.9|
* The differences between these two categories are not statistically significant.
American Heart Association. (2011, July 12). Warning signs and emergency treatment of cardiac arrest. Retrieved from http://www.heart.org/HEARTORG/Conditions/More/CardiacArrest/Warning-Signs-and-Emergency-Treatment-of-Cardiac-Arrest_UCM_307911_Article.jsp#.VsJR__krLIU.
Iwami, T., Kitamura, T., Kawamura, T., Mitamura, H., Nagao, K., Takayama, M, … Kimura, T. (2012). Chest compression-only cardiopulmonary resuscitation for out-of-hospital cardiac arrest with public-access defibrillation. Circulation, 126. Retrieved from http://circ.ahajournals.org/content/126/24/2844.full.
Svensson, L., Bohm, K., Castren, M., Pettersson, H., Engerstrom, L, Herlitz, J., & Rosenqvist, M. (2010). Compression-only CPR or standard CPR in out-of-hospital cardiac arrest. The New England Journal of Medicine, 363. Retrieved from http://www.nejm.org/doi/full/10.1056/NEJMoa0908991#t=articleBackground.
. American Heart Association. (2011, July 12). Warning signs and emergency treatment of cardiac arrest. Retrieved from http://www.heart.org/HEARTORG/Conditions/More/CardiacArrest/Warning-Signs-and-Emergency-Treatment-of-Cardiac-Arrest_UCM_307911_Article.jsp#.VsJR__krLIU.
. Iwami, T., Kitamura, T., Kawamura, T., Mitamura, H., Nagao, K., Takayama, M, … Kimura, T. (2012). Chest compression-only cardiopulmonary resuscitation for out-of-hospital cardiac arrest with public-access defibrillation. Circulation, 126. Retrieved from http://circ.ahajournals.org/content/126/24/2844.full.
. Svensson, L., Bohm, K., Castren, M., Pettersson, H., Engerstrom, L, Herlitz, J., & Rosenqvist, M. (2010). Compression-only CPR or standard CPR in out-of-hospital cardiac arrest. The New England Journal of Medicine, 363. Retrieved from http://www.nejm.org/doi/full/10.1056/NEJMoa0908991#t=articleBackground.