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: None

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: Theresa Olasveengen

CoSTR Citation

Bray J, Cash R, Nehme Z, de Caen A, Perkins G, Dewan M, Dicker B, Dassanayake V, Raffay V, Vaillancourt C, Olasveengen T, Tjelmeland I, Kleinman M, Olasveengen T, on behalf of the International Liaison Committee on Resuscitation (ILCOR) Basic Life Support Task Force. Bystander (without DA-CPR) Compression-only CPR compared with Conventional CPR in Adults Consensus on Science with Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force, 2^nd November 2024. Available from: http://ilcor.org

Methodological Preamble and Link to Published Systematic Review

The continuous evidence evaluation process for the production of Consensus on Science with Treatment Recommendations (CoSTR) started with a systematic review of basic life support (Ashoor, 2017, 50300 – PROSPERO citation) conducted by the Knowledge Synthesis Unit at St Michael’s Hospital, Toronto, Canada with involvement of clinical content experts. Following a review of the Ashoor et al. publication and changes to the PICOST, changes were made to the review protocol. Some of these changes have impacted the search and included studies:

• changes were made to the search strategy, as many articles were found in the reference lists of included studies and not via the search strategy in the 2017 review. Our review of the search criteria found problematic search terms, which, when removed, the missing papers appeared in the search. To check no other studies were missing, we re-ran the search for the period of the last review (database inception to January 15, 2016) without these terms, and found no new studies from that period. We ran the revised search strategy in MEDLINE and Cochrane Central Register of Controlled Trials on June 18 and October 21,2024.
• The meta-analysis of bystander CPR papers in the 2017 review included unadjusted and adjusted data and different study populations. All studies that provided data comparing the CPR groups reported imbalances between groups in factors known to influence survival (Bohm 2007 2908, Ong 2008 119, Bobrow 2010 1447). Thus, the review group decided to exclude observational studies not reporting adjusted outcomes (Van Hoeyweghen 1993 47, Waalewijn 2001 273, Panchal 2013 435), and to report the included evidence narratively. A further study(Holmberg 2001 511) was also excluded as it reported data for a period of time included in another larger study(Bohm 2007 2908) covering the same region.
• To inform the provision of immediate bystander CPR, it was decided to examine this question without cases where dispatcher-assisted CPR instructions were provided. Four studies previously included in this COSTR (Iwami 2007 2900, SOS-Kanto Study Group 2007 920, Olasveengen 2008 914, Iwami 2015 415) included cases with dispatcher-assisted CPR (DA-CPR) and have been moved to the relevant CoSTR.

Evidence for adult and pediatric literature was sought and considered by the Basic Life Support Adult Task Force and the Pediatric Task Force groups, respectively.

Systematic Review

Cash R, Nehme Z, de Caen A, Perkins G, Dewan M, Dicker B, Dassanayake V, Raffay V, Vaillancourt C, Olasveengen T, Tjelmeland I, Kleinman M, Bray J. Impact of different cardiopulmonary strategies on patient outcomes strategies: A systematic review. In draft.

PICOST

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

Population: Adults in out-of-hospital cardiac arrest.

Intervention: Chest compression-only CPR (CCO-CPR)

Comparators: Conventional CPR (C-CPR) with compressions and ventilations

Outcomes: Critical: Favourable neurological survival (as measured by cerebral performance category or modified Rankin Score) at discharge or 30-days and at any time interval after 30-days. Important: Survival to discharge or 30 days, Survival to hospital admission, Survival to any time interval after discharge or 30 days survival, Return of spontaneous circulation (ROSC), Quality of life as measured by any indicator or score.

Study Designs: Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies) are eligible for inclusion. Unpublished studies (e.g., conference abstracts, trial protocols) are excluded. All relevant publications in any language are included as long as there is an English abstract.

Timeframe: Literature search updated to October 21, 2024.

PROSPERO Registration CRD42024559318

Consensus on Science

After excluding the abovementioned studies, three observational studies compared bystander compression-only CPR (CCO-CPR) with conventional CPR (C-CPR) at a ratio of 15:2 (Bohm 2007 2908, Ong 2008 119) and 30:2 (Bobrow 2010 1447) in adults without dispatcher-assisted CPR (DA-CPR) instructions (DA-CPR). As 15:2 CPR is no longer recommended, all outcomes, including these studies, were downgraded for indirectness. Where no data for any outcome was reported, indirect evidence from combined bystander-only and DA-CPR studies is provided if the studies indicate the sample included high rates of bystander-only CPR.

For the critical outcome of favorable neurological function, we identified no studies without dispatcher assistance. Indirect evidence of very-low certainty (downgraded for risk of bias and indirectness) from one cohort study of combined bystander (76% of cases) and DA-CPR (24% of cases) suggests favorable neurological function (adjusted OR 2.22, 95%CI: 1.17 to 4.21) with CO-CPR compared to 15:2 CPR in 4,068 adult bystander-witnessed OHCAs.(SOS-Kanto Study Group 2007 920)

For the critical outcome of survival to hospital discharge or 30 days, we identified very-low certainty of evidence (downgraded for risk of bias, imprecision and indirectness) from three cohort studies.(Bohm 2007 2908, Ong 2008 119, Bobrow 2010 1447) One study in 5,272 adult presumed cardiac OHCAs reported significantly higher survival to hospital discharge with CCO-CPR compared to 30:2 CPR (adjusted OR 1.60, 95%CI: 1.08 to 2.35).(Bobrow 2010 1447) The remaining two studies, which examined all age OHCAs, reported no difference between the two CPR strategies for survival to 30 days and 15:2 CPR (adjusted OR 1.18, 95%CI: 0.89 to 1.56)(Bohm 2007 2908) or hospital discharge (adjusted OR 1.32, 95%CI: 0.35 to 4.94).(Ong 2008 119)

For the important outcome of survival to hospital admission, we identified very-low certainty of evidence (downgraded for risk of bias, imprecision and indirectness) from one cohort study.(Bohm 2007 2908) This all-age cohort study (n=11,275) reported no difference in ROSC with CCO-CPR compared to 15:2 CPR (adjusted OR 1.02, 95%CI: 0.60 to 1.73).(Ong 2008 119)

For the important outcome of ROSC, we identified very-low certainty of evidence (downgraded for risk of bias, imprecision and indirectness) from one cohort study.(Ong 2008 119) This all-age cohort study (n=441) reported no difference in ROSC with CCO-CPR compared to 15:2 CPR (adjusted OR 1.02, 95%CI: 0.60 to 1.73).(Ong 2008 119)

Treatment Recommendations

We continue to recommend that chest compressions be performed for all adults in cardiac arrest (good practice statement).

We suggest that bystanders who are trained, able and willing give chest compressions with rescue breaths for adults in cardiac arrest (weak recommendation, very-low-certainty evidence).

Justification and Evidence to Decision Framework Highlights

In making these recommendations, the task force acknowledged the very-low-quality evidence and comparison to 15:2 CPR, but placed higher emphasis on the need to give chest compressions in adult CPR and the potential to increase rates of bystander CPR with the introduction of CCO- or compression-focused CPR in adults.(Bray 2011 1393, Kitamura 2012 2834, Iwami 2015 415, Malta Hansen 2015 255) The task force also considered:

• Bystander CPR more than doubles OHCA survival.(Sasson 2010 63) We placed a higher emphasis on providing any bystander CPR over rescue breaths in adults with non-asphyxial or drowning causes.
• Three additional studies reported no difference in unadjusted patient outcomes between CCO-CPR and C-CPR.(Van Hoeyweghen 1993 47, Waalewijn 2001 273, Panchal 2013 435)
• One of these studies conducted in the 1980’s, reported higher unadjusted survival when 15:2 was correctly performed compared to incorrectly (31%vs 8%) or when compared to CCO-CPR (31% vs 20%).(Van Hoeyweghen 1993 47) Rates of correctly applied 15:2 were higher in bystanders who were healthcare professionals than lay bystanders (58% vs 42%).(Van Hoeyweghen 1993 47)
• Given the included studies were conducted without dispatcher assistance, it could be assumed that the CPR was performed by CPR trained individuals or off-duty health care professionals.
• In systems with EMS, dispatchers can provide DA-CPR instructions if it is determined in the emergency call that ventilations are required (e.g. long EMS response time).
• Indirect evidence from three RCTs comparing CCO-CPR with C-CPR in dispatcher CPR instructions reported no difference in patient outcomes.(Hallstrom 2000 1546, Rea 2010 423, Svensson 2010 434)
• Increases in rates of bystander CPR and patient outcomes have been reported following the introduction of CCO- or compression-focused CPR in adults.(Bray 2011 1393, Kitamura 2012 2834, Iwami 2015 415, Malta Hansen 2015 255) Public surveys show chest-compression only CPR for strangers is preferable.(Cheskes 2016 253, Bray 2017 158)
• Most bystander CPR for adults is given DA-CPR instructions, even in the presence of CPR-trained lay bystanders.(Riva 2024 e010027)
• Two included studies suggest no difference in patient outcomes for bystander-only CCO-CPR and C-CPR at 15:2 by duration of EMS response.(Bohm 2007 2908, Ong 2008 119)
• Effective chest compressions generate cumulative coronary perfusion pressure, which falls to near zero when compressions stop. Therefore, early effective chest compressions are vital to establishing and maintaining coronary perfusion pressure.(Nassar 2017 1061)
• Two adult studies, which included DA-CPR, found no difference in good neurological outcomes between bystander CCO-CPR and C-CPR in respiratory/asphyxial OHCAs.(Fukuda 2017 493, Javaudin 2021 812)
• A pilot RCT, including DA-CPR, showed no difference in survival at 1-day between CCO-CPR and C-CPR when delivered by trained laypersons.(Riva 2024 e010027)
• A review found compression-only CPR resulted in a higher total number of chest compressions. However, as it continues, rescuers may experience fatigue, which can reduce the depth of compressions compared to those delivered in conventional CPR with pauses for breaths.(Min Ko 2016 882)
• Opening the airway and delivery of ventilations is technical, and bystanders, especially if untrained or minimally trained, are typically unable to deliver effective ventilations during simulated CPR.(Beard 2015 138)

Knowledge Gaps

• There is a lack of research comparing compression-only CPR to 30:2 CPR without dispatcher assistance.
• There is a lack of data in pediatric populations.

ETD summary table: BLS 2220 Bystander compression only CPR compared with conventional CPR in adults Et D

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