SGEM#143: Call Me Maybe for Bystander CPR
Podcast Link: SGEM143
Date: January 14th, 2016
Guest Skeptics: Dave Harrison, Carl Berdahl and Todd Schneberk are Emergency Medicine residents in the Department of Emergency Medicine at the Keck School of Medicine of the University of Southern California.
Case: A 78-year-old man with a history of hypertension and coronary artery disease suddenly collapses at home in front of his wife. She calls 911 but is unable to get on her knees and provide CPR due to her comorbidities.
Background: Sudden cardiac arrest is common with approximately 500,000 cardiac arrests each year in the USA. More than half of these cardiac arrests are out of hospital cardiac arrests (OHCA) and the survival rate is pretty poor.
The American Heart Association came out with updated CPR & ECC Guidelines in 2015 that included its “Chain-of-Survival”. There are five steps in the Chain-of-Survival for OHCA.
- Step One – Recognition and activation of the emergency response system
- Step Two – Immediate high-quality CPR
- Step Three – Rapid defibrillation
- Step Four – Basic and advanced emergency medical services
- Step Five – Advanced life support and post arrest care
The fourth step in the chain was covered with the EM Swami on SGEM#64. This was the classic OPALS trial done by Ian Stiell and his group in Ottawa, Canada. It demonstrated ACLS did not increase survival to hospital discharge over BLS for patients with OHCA.
In contrast, step two has been associated with a significant increase in survival. Bystander-initiated CPR improves chances of survival compared to those people who did not receive such help. A major barrier to improved survival of OHCA remains the low rates of bystander-initiated CPR.
There has been a dramatic increase in mobile phones over the last few years. These devices are becoming tools used in health care. One fascinating application has been automated text messaging to remind discharged emergency department patients of their follow-up appointments. This was a study published in AEM by Sanja Arora showed the NNT (number needed to text) was 10 (SGEM#102).
Clinical Question: Can using a mobile-phone positioning system to dispatch lay volunteers who were trained in CPR increase the rate of bystander-initiated CPR for patients with OHCA?
Reference: Ringh et al. Mobile-Phone dispatch of Laypersons for CPR in Out-of-Hospital Cardiac Arrest. NEJM June 2015
- Population: Cases suspected by 911 dispatcher to be out-of-hospital cardiac arrest that occurred during daytime hours (6am-11pm) in Stockholm, Sweden and ended up getting treated by EMS.
- Excluded: Patients less than 8 years of age, hazardous environment, and cases of OHCA caused by drowning, trauma, intoxication, or suicide.
- Intervention: Volunteer within 500m radius called to scene of possible cardiac arrest, with the assumption that CPR should likely be performed.
- Comparison: Usual care. No volunteer called to the scene. EMS called as usual.
- Primary: Bystander-initiated CPR before the arrival of EMS (ambulance, fire, and police services).
- Secondary: Bystander-initiated CPR, including CPR that was given only with the help of instructions given over the telephone, findings of ventricular fibrillation or ventricular tachycardia at the first electrocardiographic assessment, return of spontaneous circulation, and 30-day survival.
Author’s Conclusions: “A mobile-phone positioning system to dispatch lay volunteers who were trained in CPR was associated with significantly increased rates of bystander-initiated CPR among persons with out-of-hospital cardiac arrest.”
Quality Checklist for Randomized Clinical Trials:
- The study population included or focused on those in the emergency department. No. These were OHCA.
- The patients were adequately randomized. Yes
- The randomization process was concealed. Yes
- The patients were analyzed in the groups to which they were randomized. Yes
- The study patients were recruited consecutively (i.e. no selection bias). No
- The patients in both groups were similar with respect to prognostic factors. Yes
- All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No. Bystanders and EMS likely knew if a responder arrived on scene first and started CPR but the investigators were unaware of group assignment until after the study was analyzed.
- All groups were treated equally except for the intervention. Yes
- Follow-up was complete (i.e. at least 80% for both groups). Yes. Only one patient in each group had missing data for the primary outcome.
- All patient-important outcomes were considered. No
- The treatment effect was large enough and precise enough to be clinically significant. Unsure
Key Results: They recruited close to 10,000 lay volunteers and trained them in CPR for the study. For perspective, Stockholm County has a population of 2 million covering an area of 6,500 square kilometres.
The mobile-phone positioning system was activated in 667 out-of-hospital cardiac arrests: 46% (306 patients) in the intervention group and 54% (361 patients) in the control group.
First responders (police or fire vehicle) arrived on scene before an ambulance in close to 40% of all the OHCA. The median time to arrival of EMS or first responders was 7.5 minutes. Bystander CPR was performed for at least two minutes in almost 50% of the cases and up to five minutes in over 80% of the cases.
- Primary Outcome: The rate of bystander-initiated CPR was 62% (188/305 patients) in the intervention group and 48% (172/360 patients) in the control group (absolute difference for intervention vs. control, 14 percentage points; (95% CI 6 to 21; P<0.001).
Number Needed to Text = 7
If you included the cases in which instructions for how to perform CPR were provided over the telephone were counted as bystander-initiated CPR the rate increased to 64.3% in the intervention group and 54.7% in the control group. So about a 10% improvement in CPR rates if they got instructions over the phone giving a NNT of 10.
- Secondary Outcome: None of the secondary outcomes were statistically significant (return of spontaneous circulation, initial cardiac rhythm, and 30-day survival).
This was a very interesting study using technology in a way that was probably never conceived when it was being designed. The merging of mobile phones, texting, and global positioning can be a powerful force. How we use our tools is a statement of what kind of society we live in. This idea of crowd sourcing layperson CPR is fascinating way to use this modern tool.
There were a few issues with this study to discuss in more detail:
- Consecutive: Not all patients with OHCA were randomized. There were 237 patients where the dispatcher suspected OHCA but did not activate the system for one reason or another, which we don’t really know. These patients represent a significant proportion (¼) of all eligible patients, but in the authors’ defense they were similar to the group who were randomized (mostly older men at home), so unlikely to change much. About 40% of these non-randomized daytime OHCA patients received bystander CPR.
- Blinding: Bystanders and EMS would know if a responder arrived on scene first and started CPR. However, the investigators were unaware of group assignment until after the study was analyzed. Bias may have been introduced by this lack of blinding but its effect is unknown.
- Patient Oriented Outcomes: The primary outcome was the rate of bystander-initiated CPR, which is a surrogate marker and not patient oriented. One of their secondary outcomes was 30-day survival rate but their study was underpowered to detect a statistical difference. This is also not really patient oriented. What we really care about in these OHCA studies is survival with good neurologic function. Nobody calls it a “win” if you have improved 30 day survival but the survivors were all completely brain dead. A larger study will need to be performed to determine if mobile-phone dispatching of lay volunteers trained in CPR will be superior to usual care for survival with good neurologic outcome.
- Exclusions: There were a number of exclusions with the biggest one being nighttime. The system did not operate from 11pm until 7am. Over 200 patients had OHCA at night. They excluded children under eight years of age, hazardous environment, and cases of OHCA caused by drowning, trauma, intoxication, or suicide. Would the same improvement in layperson-initiated CPR occur at night and in these other circumstances?
- External Validity: This is one of the very big concerns about this study. It represented one dispatch system in one health care system with a dense population. Whether or not these results would be replicable in other settings is unclear. Stockholm is a very developed, well-educated, progressive city with only ~10% foreign-born residents. Does this reflect the community you work in currently?
- Rural vs. Urban: EMS response times tend to be longer in rural areas but the population is less dense. So the professional would take longer to arrive but so probably would the layperson. There is also a lack of cell phone signal in some rural areas. So would this work better or worse in rural communities?
- Los Angeles: LA is a very large, ethnically, socioeconomically diverse city with varying degrees of health literacy and language. LA has ~40% foreign born as opposed to 10%, with a diaspora of languages spoken, compared to Stockholm which has near total Swedish fluency and even over 90% English proficiency. Not to mention in LA the amount of cultural and other barriers to communication separating people. It makes you wonder, would people allow strangers into their homes? Stockholm’s crime rate pales in comparison to LA. What would be the reaction of the neighbours in these cases? Would responders have some badge or identification displayed on their mobile phone? What about safety of the provider and of the individual? Would trained volunteers in CPR also carry protection or guns? What would be the legal implications if the volunteer is injured or the patient is harmed?
Comment on author’s conclusion compared to SGEM Conclusion: We agree that this system can improve layperson CPR in Stockholm, Sweden without improving 30-day survival for patients with OHCA.
SGEM Bottom Line: Using mobile phones to increase bystander CPR for OHCA is a cool use of technology but we would want to see it externally validated and demonstrate survival with good neurologic outcome.
Case Resolution: EMS arrives and defibrillates her husband successfully.
Clinically Application: None, as we do not have a mobile phone dispatch system of laypersons trained in CPR at this time. However, high-quality bystanders CPR should be initiated immediately for people with an OHCA.
What do I tell my patient? After they have survived their OHCA, I would encourage them to get trained in CPR because someday they may save a life. In addition, their life may be saved in the future by a layperson trained in CPR sent to their location by a text message if they have another OHCA.
Keener Kontest: Last weeks winner was Christopher Scheumann from Parkview Trauma Services in Fort Wayne, Indiana. Chris knew the first metered dose inhaler was produced by Riker Laboratories that was later bought out by 3M.
Listen to the SGEM to hear this weeks’ keener question. If you know the answer send it to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.
Essentials of Emergency Medicine (EEM) is one of the largest live emergency medicine educational conferences in the world. Inspired by the contest operated by EMCrit and ALiEM, the Skeptics’ Guide to Emergency Medicine is partnering with CanadiEM to offer a Canadian emergency medicine resident the opportunity to attend EEM for free as an Essentials of Emergency Medicine Education Fellow.
- What can they win?
- Full live conference registration at Essentials of Emergency Medicine
- A four (4) night stay at The Cosmopolitan Hotel
- A $500 US travel stipend
- The opportunity of a lifetime to network with amazing EM Educators
- What do they have to do to win?
- Submit either a blog post or video covering a topic that is clinically or educationally relevant to EM providers.
- When do they have to submit by?
- Deadline is Feb 8th and winner announced in March
Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.