CPR Prior to Call for Help (BLS): Systematic Review

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Conflict of Interest Declaration

The ILCOR Continuous Evidence Evaluation process is guided by a rigorous ILCOR Conflict of Interest policy. The following Task Force members and other authors were recused from the discussion as they declared a conflict of interest: (insert names or declare none applicable)

The following Task Force members and other authors declared an intellectual conflict of interest and this was acknowledged and managed by the Task Force Chairs and Conflict of Interest committees: (insert names or declare none applicable)

CoSTR Citation

Smith CM, Hatanaka T, Mancini MB, Avis S, Brooks S, Castren M, Chung S, Escalante R, Kudenchuk P, Nishiyama C, Perkins G, Ristagno G, Semeraro F, Smyth M, Morley P, Olasveengen TM - on behalf of the BLS Task Force. CPR Prior to Call for Help Consensus on Science and Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) BLS Task Forces, 2020 Jan 1. Available from:

<... Preamble

The continuous evidence evaluation process for the production of Consensus on Science with Treatment Recommendations (CoSTR) started with a systematic review of performing CPR prior to an emergency call for help in adults suffering out-of-hospital cardiac arrest. It was conducted by ILCOR evidence reviewers (Smith CM and Hatanaka T). Evidence was sought and considered by the Basic Life Support (BLS) Task Force group.


The PICOST (Population, Intervention, Comparator, Outcome, Study Designs and Timeframe)

Population: Adults who are in cardiac arrest (out-of-hospital cardiac arrest)

Intervention: A call for help to the EMS dispatch centre by a lone bystander with a mobile phone after one minute of CPR.

Comparators: An immediate call for help to the EMS dispatch centre by a lone bystander with a mobile phone

Outcomes: Survival with favourable neurological outcome until and beyond hospital discharge or 30 days; survival until and beyond hospital discharge or 30 days; Return of Spontaneous Circulation (ROSC)

Study Designs: We included RCTs, non-randomised studies, case-series with at least five cases. We considered papers in all languages provided there was an English language abstract available for review. We excluded unpublished studies, conference abstracts, manikin or simulation studies, narrative reviews, editorials or opinions with no primary data, animal studies and experimental / lab models.

Timeframe: All years and all languages were included as long as there was an English abstract; unpublished studies (e.g., conference abstracts, trial protocols) were excluded. Literature search updated to October 2019.

Consensus on Science

For the critical outcomes of survival with favorable neurological outcome (N=1, Kamikura 2015 37), we only identified a single observational study. The overall certainty of evidence was rated as very low due to a very serious risk of bias. With the identification of only one study, no meta-analyses were performed.

For the critical outcome survival to hospital discharge we identified very-low-certainty evidence (downgraded for very serious risk of bias) from one cohort study including 17,461 out-of-hospital cardiac arrest cases (OHCA) from Japan (2005-2012), which showed no benefit from a “CPR first” strategy (cohort of 5446 OHCA) compared with a “call first” strategy (cohort of 1820 OHCA) (RR, 1.08; 95%CI, 0.94–1.24; P=0.30; absolute risk reduction [ARR], -0.90%; 95% CI, −2.69% to 0.77%, or 9 more patients/1000 survived with the intervention [95% CI, 7 fewer patients/1000 to 28 more patients/1000 survived with the intervention]).The third, and presumably optimal group receiving both “call and CPR first” strategy (cohort of 10,195 OHCA) had similar outcomes to the two other groups (survival with favorable outcome 11.5%, 12.4% and 11.5% for the “call and CPR first”, “call first” and “CPR first“ strategy, respectively.) (Kamikura 2015 37)

Adjusted analysis were performed on various subgroups suggesting significant improvements in survival with a favorable neurological outcome with a “CPR first” strategy compared to “call first” for: non-cardiac etiology OHCA (adjusted Odds [adjOR] 2.01 [95% CI 1.39-2.98]); under 65 years of age (adjOR 1.38 [95% CI 1.09-1.76]); under 20 years of age (adjOR 3.74 [95% CI 1.46-9.61]) and; under 65 years of age and non-cardiac etiology (adjOR 4.31 (95% CI 2.38-8.48]).(Kamikura 2015 37)

Treatment Recommendations

We recommend that a lone bystander with a mobile phone should dial EMS, activate the speaker or other hands-free option on the mobile phone and immediately begin CPR, with EMS dispatcher assistance if required (strong recommendation, very-low-certainty of evidence).

Justification and Evidence to Decision Framework Highlights

The included paper only analyzed 17,461 OHCA from 925,288 cases recorded in the national registry in the time period 2005-2012. Analysis was limited to cases where lay rescuers witnessed the OHCA and spontaneously performed CPR (without the need for dispatcher assistance), and the groups compared were different with respect to age, gender, initial rhythm, bystander CPR characteristics and EMS intervals. Although some factors were adjusted for in subgroup analysis, there is significant risk of confounding. Despite very-low-certainty evidence, there was consensus among the BLS Task Force to make a strong recommendation. In doing so, we placed a high value on consistently communicating the importance of early bystander CPR.

There were a large number of exclusion criteria: unwitnessed, prehospital involvement of physician or unknown, EMT-witnessed OHCA, bystander witnessed cases with missing data on time to intervention, no B-CPR, DA CPR, no intervention in 0-1 minutes, No CPR at all within 4 minutes, etiology (cardiac or non-cardiac) not known.

There were some benefits noted in subgroup analyses, but these groups were not specified a priori. We cannot expect a bystander to reliably determine whether a cardiac arrest is of cardiac or non-cardiac etiology. The results are not generalizable to all OHCA as they refer specifically to bystander-witnessed cases in which the bystander spontaneously initiates CPR after only a short delay.

The timings of interventions were determined after the event by EMS personnel who interviewed the bystanders. These timings may be imprecise or inaccurate in an undetermined number of cases.

The ubiquitous presence of mobile phones may reduce the likelihood that a lone bystander would have to leave a victim to phone EMS. Pragmatically, it is now often possible to perform both actions simultaneously, and the focus should be on empowering people to recognize OHCA and initiate both an EMS call and CPR as soon as possible. In the absence of any evidence to the contrary, this would apply to both witnessed and non-witnessed OHCA, excepting circumstances where there are appropriate reasons not to start CPR.

In the situation where a lone rescuer would have to leave a victim themselves to dial EMS, the priority should be on the prompt activation of EMS, before subsequently returning to the victim to initiate CPR as soon as possible.

Knowledge Gaps

There is no evidence comparing an immediate call to EMS for help with a call after one minute of CPR in the specific circumstance of a lone bystander with a mobile phone.



Kamikura T, Iwasaki H, Myojo Y, Sakagami S, Takei Y, Inaba H. Advantage of CPR-first over call-first actions for out-of-hospital cardiac arrests in nonelderly patients and of noncardiac aetiology. Resuscitation. 2015;96:37-45.



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