Out of hospital cardiac arrest (OHCA) is a leading cause of death among adults in the United States. Approximately 300,000 OHCA events happen each year in the U.S. and about 92% of the victims die. An OHCA is defined as cessation of cardiac mechanical activity that is confirmed by the absence of signs of circulation that occurs outside the hospital setting. The majority of those who experience an OHCA event do not receive bystander CPR or defibrillation by AED which have both proven to increase survival rates. Because over half of OHCA events are witnessed, efforts to increase survival rates should focus on timely and effective delivery of interventions by bystanders and EMS personnel. In 2004, the Center of Disease Control (CDC) established the Cardiac Arrest Registry to Enhance Survival (CARES) that seeks to evaluate OHCA events of a presumed cardiac etiology (not including CA caused by trauma, asphyxiation, drowning etc) that involve persons who received resuscitative efforts, including CPR and defibrillation in a voluntary study from sources that define the continuum of emergency cardiac care: 1. 911 centers, 2. EMS providers and 3. receiving hospitals.
In the period between 10/1/2005 and 12/31/2010, 31,689 OHCA events of presumed cardiac etiology (i.e. myocardial infarction or arrhythmia) that received pre-hospital resuscitation were recorded and analyzed. The mean age was 64.0 years and 61.1% were male. The survival rate to hospital discharge was 9.6%. Approximately 36.7% of OHCA were witnessed, of which only 33.3% received bystander CPR and only 3.7% were treated with early defibrillation before arrival of EMS. The group most likely to survive was those whose OHCA event was witnessed by a bystander and found in a “shockable rhythm” (ventricular fibrillation or pulseless ventricular tachycardia). Among this group, survival to discharge was 30.1% as opposed to 9.6% of those who did not receive early intervention.
This study helped CARES identify room for improvement in out of hospital cardiac arrest care. The data from this study confirms that patients who receive CPR/AED care from bystanders have a greater chance of surviving OHCA than those who do not. Public health professionals have used this study to spark a wide action for education of public officials and community members on the importance of bystander CPR as well as promoting the use of early defibrillation by lay and professional rescuers.
(B McNally et al., CDC's Morbidity and Mortality Weekly Report. 29 July 2011. Vol. 60 No. 8: 1-19)
It’s surprising that less than 40% of OHCA victims witnessed received by stander help by either CPR or defibrillation. Only 3.7% were treated with early defibrillation which makes sense because in most cases there’s probably not a defibrillation device around. Do you happen to know the survival rate of those treated with defibrillation compared to CPR? From doing some quick reading on PubMed.gov it seems that the two "shockable rhythms" relate to uncoordinated contractions of the ventricles or no ventricle contractions, and the two “non-shockable” rhythms is when there is no electrical activity or there is electrical activity but no pulse. It seems that if there were no electrical activity the defibrillation would be effective but maybe the cardiac cells die quickly, so if no defibrillator is used immediately then it’s too late.
ReplyDeleteIt really is shocking that such a small amount of the thousands of OHCA receive attention by a bystander. You make a good point in saying that most events might not happen in a public place or where a defibrillator was accessible. Per the data section of this paper, approximately 66.4% of arrests occurred in a home or private residence (13.5% of which were in a nursing home) and the rest occurred in a public place. Most public locations are mandated to have an AED available, just like every building is mandated to have a certain number of fire extinguishers. The percentage of persons who had a publicly witnessed event who received bystander CPR was 48.3%. Overall survival to hospital discharged of patients whose event was not witnessed by EMS was 8.5% and patients who received bystander CPR had a higher rate of survival at 11.2%, but there was no specification between survival rates of those who received CPR and AED or just one of the two.
ReplyDeleteThis article and its statistics are important to bring to the attention of the public. Bystander CPR or defibrillations by AED are ways to improve the survival of OHCA events—as confirmed in the previously discussed study. I agree that the availability of AEDs correspsonds to the low percentage of response to OHCA victims by defibrillations. Only 33.3% of OHCA victims witnessed received bystander help by CPR (McNally et al, 1-19). This value is surprisingly low. Is it the lack of education—not being able to recognize cardiac arrest? Do CPR trained individuals forget the appropriate numbers of chest pumps per breaths? Survival rates could be optimized by increasing the frequency of bystander cardiopulmonary resuscitation (CPR). This can be accomplished by recognizing cardiac arrest, simplifying CPR, and training the community (Nolan, 520). Importantly, bystanders should be able to recognize when an individual is unresponsive and not breathing normally. By recognizing this event, chest compressions should be started and rescue breathing if the rescuer is trained or confident in this technique (Nolan, 521). Chest-only compressions remain controversial because studies show that conventional CPR (rescue breaths and compressions) have better outcomes than chest compression-only CPR (Nolan, 521). In conclusion, to increase the survival of OHCA it is important to recognize the event of cardiac arrest and be able to apply simplistic CPR. Even if the technique is not perfectly performed, any response to cardiac arrest is better than nothing for OHCA victims.
ReplyDeleteB. McNalley et al., CDC’s Morbidity and Mortality Weekly Report. 29 July 2011. Vol. 60 No. 8: 1-19.
Nolan, Jerry P. Optimizing outcome after cardiac arrest. Current Opinion in Critical Care. Vol 17(5), October 2011, pages 520-526.
The low percentage of bystanders who perform CPR with or without the assistance of an AED is suprising because, yes, recognizing whether or not a person has a pulse and whether or not they are breathing is relatively simple. However, people are particularly fearful of direct mouth-to-mouth contact with a stranger, especially with so many communicable diseases. Other than friends who are paramedics, I don't know any average person who carries around a CPR mask with them. This is why the implementation of hands-only CPR by the American Red Cross is so important. It eliminates the fear people may have of putting their mouth to the mouth of a stranger. And because providing breaths is not required during the first few minutes of cardiac arrest due to residual oxygen in the lungs, hands-only CPR has been shown to be as effective as conventional CPR. Hopefully, people will be more inclined to help a stranger in need with hands-only CPR until an AED and/or medical personnel can arrive.
ReplyDeleteHands-Only CPR. American Heart Association. January 12, 2011. www.handsonlycpr.org/faqs