CPR prior to defibrillation (BLS): Systematic Review

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This Review is a draft version prepared by ILCOR, with the purpose to allow the public to comment and is labeled “Draft for Public Comment". The comments will be considered by ILCOR. The next version will be labelled “draft" to comply with copyright rules of journals. The final Review will be published on this website once a summary article has been published in a scientific Journal and labeled as “final”.

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 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: (none applicable)

CoSTR Citation

Graesner JT, Mancini, MB, Avis S, Considine J, Perkins GD, Kudenchuck P, Semeraro F, Smith C, Morley PT, Olasveengen TM -on behalf of the International Liaison Committee on Resuscitation Basic Life Support Task Force.

CPR prior to defibrillation Consensus on Science with Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force, 2020 Jan 1. Available from: http://ilcor.org

Methodological Preamble

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 conducted by Jan-Thorsten Graesner and Suzanne Avis with involvement of clinical content experts. Evidence for adult literature was sought and considered by the Basic Life Support Adult Task Force. These data were taken into account when formulating the Treatment Recommendations.

PICOST

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

Population: Adults and children in any setting (in-hospital or out-of-hospital) with cardiac arrest and a shockable rhythm at initiation of cardiopulmonary resuscitation (CPR)

Intervention: A prolonged period of chest compressions before defibrillation

Comparators: A short period of chest compressions before defibrillation

Outcomes: Survival to hospital discharge with good neurological outcome and survival to hospital discharge were ranked as critical outcomes. Return of spontaneous circulation (ROSC) was ranked as an important outcome.

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.

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 Oct 27th, 2019.

Consensus on Science

For the critical outcome survival to 1 year with favorable neurological outcome we have identified low-certainty evidence (downgraded for risk of bias and imprecision) from 1 randomized controlled trial (Wik 2003 1389) enrolling 200 adult out-of-hospital cardiac arrests which showed no benefit from a prolonged period of chest compressions before defibrillation when compared with a short period of chest compressions before defibrillation (RR, 1.15; 95%CI, -0.57–2.34; absolute risk reduction [ARR],

−1.92%; 95% CI, −11.48% to 7.85%, or 19 more patients/1000 survived with the intervention [95% CI, 54 fewer patients/1000 to 167 more patients/1000 survived with the intervention])

For the critical outcome survival to hospital discharge with favorable neurological outcome we have identified low-certainty evidence (downgraded for inconsistency and imprecision) from 4 randomized controlled trials (Wik 2003 1389; Baker 2008 424; Stiell 2011 787; Ma 2012 806) enrolling 10,424 adult out-of-hospital cardiac arrests which showed no benefit from a prolonged period of chest compressions before defibrillation when compared with a short period of chest compressions before defibrillation (RR, 1.02; 95% CI,- 0.01–0.01; absolute risk reduction [ARR], −1.02%; 95% CI, −1.04% to 0.78%, or 1 more patient/1000 survived with the intervention [95% CI, 7 fewer patients/1000 to 11 more patients/1000 survived with the intervention])

For the critical outcome survival to 1 year we have identified low-certainty evidence (downgraded for risk of bias and imprecision) from 2 randomized controlled trials (Wik 2003 1389; Jacobs 2005 39) enrolling 456 adult out-of-hospital cardiac arrests which showed no benefit from a prolonged period of chest compressions before defibrillation when compared with a short period of chest compressions before defibrillation (RR, 1.19; 95%CI, 0.69–2.04; absolute risk reduction [ARR], −1.77%; 95% CI, −7.51% to 3.89%, or 18 more patients/1000 survived with the intervention [95% CI, 29 fewer patients/1000 to 98 more patients/1000 survived with the intervention])

For the critical outcome survival to hospital discharge we have identified low-certainty evidence (downgraded for risk of bias and imprecision) from 5 randomized controlled trials (Wik 2003 1389; Jacobs 2005 39; Baker 2008 424; Ma 2012 806; Stiell 2011 787) enrolling 10,680 adult out-of-hospital cardiac arrests which showed no benefit from a prolonged period of chest compressions before defibrillation when compared with a short period of chest compressions before defibrillation (RR, 1.01; 95%CI, 0.90–1.15; absolute risk reduction [ARR], −0.12%; 95% CI, −1.19% to 0.93%, or 1 more patient/1000 survived with the intervention [95% CI, 8 fewer patients/1000 to 13 more patients/1000 survived with the intervention])

For the important outcome ROSC we have identified low-certainty evidence (downgraded for risk of bias and imprecision) from 5 randomized controlled trials (Wik 2003 1389; Jacobs 2005 39; Baker 2008 424; Ma 2012 806; Stiell 2011 787) enrolling 10,680 adult out-of-hospital cardiac arrests which showed no benefit from a prolonged period of chest compressions before defibrillation when compared with a short period of chest compressions before defibrillation (RR, 1.03; 95%CI, 0.97–1.10; absolute risk reduction [ARR], −0.84%; 95% CI, −2.53% to 0.85%, or 8 more patients/1000 survived with the intervention [95% CI, 9 fewer patients/1000 to 27 more patients/1000 survived with the intervention])

Treatment Recommendations

We suggest a short period of CPR until the defibrillator is ready for analysis and/or defibrillation in unmonitored cardiac arrest. (weak recommendation, low-certainty evidence)

Justification and Evidence to Decision Framework Highlights

This topic was prioritized by the BLS Task Force as it had not been reviewed since the 2015 ILCOR Consensus on Science and Treatment Recommendations. Given the availability of comparative data from several RCTs, we did not include non-RCTs. No new RCTs were identified since the 2015 review process, but as the outcome templates have been altered for the 2020 ILCOR review process, the review has been updated.

In making the recommendation to provide CPR until the defibrillator is ready for analysis and/or defibrillation in unmonitored cardiac arrest, we placed a high value on being consistent with previous recommendations. The BLS Task Force acknowledges that every change in guidelines comes with a significant risk and cost as CPR educators and providers are asked to change current practice and implement new treatment strategies for complex and high stress medical emergencies.

Important issues remained in the evaluation of the 5 included RCTs, and lead to the BLS Task Force downgrading the certainty of the treatment recommendation. The trial by Jacobs et al. (Jacobs 2006 39) did not use a random sequence generation and did not conceal randomization prior to rhythm analysis leading to potential bias. In all RCTs, the treating EMS personnel could not be blinded to the interventional strategy post randomization. There was also significant heterogeneity in these trials with regards to the duration of CPR provided before defibrillation with a range of 90 to 180 seconds. For the purposes of this review the 90 to 180 seconds of CPR was considered as a combined group. It is also important to note that the trials were conducted in different countries (Australia, Canada, Norway, Taiwan, United States) with varying EMS system structural configurations (BLS, ALS, physician on scene) as well as response times and treatment protocols. Only one of the included trials attempted to document and adjust for the quality of the intervention (or chest compressions) prior to defibrillation, (Stiell 2011 787) leaving the possibility that the intervention in the other trials were of various quality. The studies also only included adult (age ≥ 18) OHCA patients and cannot be generalized to the IHCA or pediatric populations.

Two subgroup analyses were considered in the 2015 review. One subgroup analysis looked at enrolments based on EMS response interval, comparing those with intervals of less than 4 to 5 minutes versus those with intervals of 4 to 5 minutes or more. Within this subgroup, 1 study (Wik 2003 1389) found a favourable relationship with CPR for 180 seconds before defibrillation when the response interval was 5 minutes or more, but this relationship was not confirmed in 3 other RCTs.(Jacobs 2005 39; Baker 2008 424; Stiell 2011 787) The second subgroup analysis (Rea 2014 1) examined outcomes from early versus late analysis based on baseline EMS agency VF/pVT survival rates. Among EMS agencies with low baseline survival to hospital discharge (defined as less than 20% for an initial rhythm of VF/pVT); higher neurologically favourable survival was associated with early analysis and shock delivery, as opposed to CPR and delayed analysis and shock delivery. Yet for EMS agencies with higher baseline survival to hospital discharge (greater than 20%), 3 minutes of CPR followed by analysis and defibrillation resulted in higher neurologically favourable survival. These subgroup analyses underscore the difficulty in making “one size fits all” recommendations for resuscitation systems which may vary considerably in both population served and treatments offered.

Knowledge Gaps

Current knowledge gaps include but are not limited to:

  • What effect does the quality of bystander CPR have?
  • Can electrocardiographic waveform characteristics be used to determine optimal strategy?
  • If CPR first strategy is adopted, what is the optimal duration of CPR (90 seconds, 120 seconds, or 180 seconds)?
  • What system level characteristics might influence adopted strategy?

Attachments

Evidence-to-Decision Table: BLS-363 CPR prior to defibrillation

References

Baker PW, Conway J, Cotton C, Ashby DT, Smyth J, Woodman RJ, Grantham H; Clinical Investigators. Defibrillation or cardiopulmonary resuscitation first for patients with out-of-hospital cardiac arrests found by paramedics to be in ventricular fibrillation? A randomised control trial. Resuscitation. 2008;79(3):424-31

Jacobs IG, Finn JC, Oxer HF, Jelinek GA. CPR before defibrillation in out-of-hospital cardiac arrest: a randomized trial. Emerg Med Australas. 2005;17(1):39-45

Ma MH, Chiang WC, Ko PC, Yang CW, Wang HC, Chen SY, Chang WT, Huang CH, Chou HC, Lai MS, Chien KL, Lee BC, Hwang CH, Wang YC, Hsiung GH, Hsiao YW, Chang AM, Chen WJ, Chen SC. A randomized trial of compression first or analyze first strategies in patients with out-of-hospital cardiac arrest: results from an Asian community. Resuscitation. 2012;83(7):806-12

Stiell IG, Nichol G, Leroux BG, Rea TD, Ornato JP, Powell J, Christenson J, Callaway CW, Kudenchuk PJ, Aufderheide TP, Idris AH, Daya MR, Wang HE, Morrison LJ, Davis D, Andrusiek D, Stephens S, Cheskes S, Schmicker RH, Fowler R, Vaillancourt C, Hostler D, Zive D, Pirrallo RG, Vilke GM, Sopko G, Weisfeldt M; ROC Investigators. Early versus later rhythm analysis in patients with out-of-hospital cardiac arrest.

N Engl J Med. 2011;365(9):787-97.

Wik L, Hansen TB, Fylling F, Steen T, Vaagenes P, Auestad BH, Steen PA. Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial. JAMA. 2003;289(11):1389-95.


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