Compression Only CPR is Appropriate for Bystander-Witnessed Adult Cardiac Arrest

July 2011

Compression Only CPR is Appropriate for Bystander-Witnessed Adult Cardiac Arrest

Search Strategy: Since this is a “therapy” question, you quickly peruse the Cochrane Database of Systematic Reviews using the search term “cardiopulmonary resuscitation” noting five reviews but none pertinent to this PICO question. You next conduct a therapy Pubmed Clinical Query “compression only CPR” broad/sensitive search revealing 258 articles (see including all four of the manuscripts below.

You are having dinner with your buddy from college at a local restaurant. While you are sitting at the bar waiting for a table, you notice a commotion in the back of the restaurant. A waiter who is rushing out of the room tells you that an elderly man is sick. He had been clutching his chest and then cried out before slumping into his cannelloni and falling to the floor. A large crowd has gathered so you figure you should see if they need help. By the time you make your way over you notice a young women kneeling beside the elderly customer who is starting to do CPR. She is asking for someone to help by doing mouth to mouth on this stricken gentleman. Her boyfriend shuffles forward, but seems hesitant to get involved. The girl doing chest compressions yells at him “go ahead and breath for him – if you don’t he is going to die!” Just then the medics arrive and take over.

Thirty minutes later the heroine and her boyfriend are standing at the bar where she is berating him for not getting involved. You wonder, what would I have done in this situation? You vaguely remember something that was mentioned at your most recent ACLS recertification class about the limited utility of rescue ventilations during CPR. Before your next shift in the emergency department, you begin to review the literature on bystander CPR.

PICO Question

Population: Presumed cardiac arrest patients who receive immediate out-of-hospital bystander CPR

Intervention: Compression-only CPR

Comparison: Compressions-altering with rescue breathing

Outcome: Mortality, neurological recovery


First years: CPR with chest compression alone or with rescue breathing, N Engl J Med 2010; 363: 423-433. (

Second years: Compression-only CPR or standard CPR in out-of-hospital cardiac arrest, N Engl J Med 2010; 363: 434-442. (

Third years: Chest compression only CPR by lay rescuers and survival from out-of-hospital cardiac arrest, JAMA 2010; 304: 1447-1454. (

Fourth years: Chest-compression-only versus standard cardiopulmonary resuscitation: a meta-analysis, Lancet 2010; 376: 1552-1557 (

*1st, 2nd & 3rd years use the Therapy Critical Review Form 4th years use the Meta-analysis Critical Review Form


Article 1: Early Goal-Directed Therapy in the Treatment of Severe Sepsis and Septic Shock, NEJM 2001; 345: 1368-1377

Article 2: Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008, Crit Care Med 2008; 36: 296-327

Article 3: Translating research to clinical practice: a 1-year experience with implementing early goal-directed therapy for septic shock in the emergency department, Chest 2006; 129: 225-232

Article 4: The costs and cost-effectiveness of an integrated sepsis treatment protocol, Crit Care Med 2008; 36: 1168-1174

Bottom Line

In the United States about 300,000 individuals suffer an out-of-hospital cardiac arrest each year, but less than 30% have bystander CPR performed. Bystanders are usually not medically trained and myriad obstacles likely impede their willingness or ability to perform traditional ventilation-compression CPR including: reluctance to make mouth-to-mouth contact including fear of contracting infectious diseases, complexity of psychomotor requirements alternating between compressions and ventilations with incomplete understanding of anatomy and physiology, fear of causing harm, and panic. Data also suggests that interruptions in CPR can be detrimental. Therefore, any alterations that remove or reduce some or all of these obstacles and reduce the time-to-CPR by bystanders who have the quickest access to cardiac arrest patients could theoretically improve outcomes which vary considerably, but generally reside around 10% survival rates.

Theoretically, compression only CPR (COCPR) may have distinct advantages over conventional CPR by reducing the rapid deterioration of forward blood flow that occurs during chest compression disruptions and the significant time required to perform breaths.  Animal models have previously demonstrated that COCPR is at least as effective as conventional CPR. In addition, three randomized controlled trials have demonstrated that dispatcher-assisted CPR instructions comparing conventional CPR with COCPR showed consistent, non-statistically significant trends favoring COCPR. Specifically, Hallstrom et al. noted a survival to hospital discharge advantage (COCPR 14.6% vs. CPR 10.4%, p=0.18), while Rea et al. (15.5% vs. 12.3%, p =0.09) and Svensson et al. (19.1% vs. 14.8%, p=0.16) noted similar non-statistically significant trends. Since each of these trials assessed dispatcher-assisted CPR, bystanders did not immediately initiate resuscitation.

SHARE – The Arizona Experience

In 2005, healthcare leaders in Arizona recognized extremely poor outcomes for out-of-hospital cardiac arrest victims. Consequently, they implemented change at multiple levels including EMS protocols to minimize interruptions in chest compressions during CPR as well as a statewide media campaign educating bystanders to use COCPR rather than conventional CPR. In addition, they formed the Save Hearts in Arizona Registry and Education (SHARE) program that consisted of 30 EMS agencies in 2005 and grew to 90 agencies (serving 80% of the state’s population) by 2009. Arizona did not have dispatcher-assisted CPR programs during this interval.

The SHARE research program was a prospective, observational cohort including all adult cardiac arrest victims between Jan 2005 and Dec 2009 (4493 patients). Multivariable logistic regression analysis was used to assess whether type of bystander CPR performed was independently associated with outcomes when adjusted for such confounding variables as age, gender, location of arrest, EMS dispatch time, initial rhythm, and therapeutic hypothermia. The annual rate of bystander CPR increased significantly from 2005 to 2009 from 28.2% to 39.9%, corresponding with an increase in COCPR from 19.6% to 75.9%. During this time overall survival also increased from 3.7% to 9.8%. COCPR was independently associated with an improved odds of survival compared with either no CPR or conventional CPR (NNT = 27). The investigators also recognized potential concerns about the unintended and untested use of COCPR in children under age 12-years where respiratory arrests predominate, but their analysis demonstrated that only 10/127 children (7.9%) received COCPR during this interval and that all types of bystander CPR had low overall survival rates in pediatric populations.

The SHARE research was an observational trial subject to multiple biases that randomized controlled trials reduce via allocation of unrecognized/unmeasured confounding variables across treatment groups. It is an unfortunate (but real-world) limitation that the SHARE trial could not be randomized since the intervention decision rests with the bystander at an unpredictable point in time when they are present to witness a cardiac arrest. Therefore, although unmeasured confounding variables such as underlying co morbid disease burden, local bystander CPR competence, or EMS resuscitation proficiency could bias these findings and cannot be completely eradicated via statistical adjustments with regression analysis, the current trial is probably the best design that emergency providers can hope for with this clinical question.

One limitation that the SHARE investigators failed to address is the potential impact of a Hawthorne effect. While some experts debate whether this bias even exists, theoretically subjects or research assistants who are knowingly under investigation as part of a research protocol may adjust their actions in a way that they would not outside the research milieu. For example, bystanders who were aware that Arizona was leading the nation in incorporating minimally interrupted cardiac resuscitation might have been more likely to respond to a witnessed arrest or worked harder to perform skillful COCPR than would others who have not been exposed to a media blitz. In addition, EMS providers responsible for determining whether bystanders performed COCPR who are collecting data for SHARE might also be more aggressive about collecting data (ascertainment bias) or alter their ALS-protocols or institution of therapeutic hypothermia knowing that the results of their actions are being observed and systematically analyzed.

In summary, the benefit of COCPR by bystanders is largest in adult patients with sudden cardiac arrest. Recent minimally interrupted CPR recommendations by the American Heart Association are appropriate and EMS dispatchers should instruct bystanders unfamiliar with CPR to perform COCPR. The evidence suggests that doing so will simultaneously increase bystander acceptability/compliance and improve cardiac arrest victim survival.