EBQ:Trial of Continuous or Interrupted Chest Compressions during CPR

Complete Journal Club Article
Nichol G et al. "Trial of Continuous or Interrupted Chest Compressions during CPR". New England Journal of Medicine. 2015. :epub.
PubMed Full text PDF

Clinical Question

Does continuous chest compressions improve outcomes vs the traditional 30:2 CPR format in patients with OHCA?

Conclusion

In patients with OHCA receiving CPR via EMS providers, continuous chest compressions did not result in improved survival to hospital discharge rates.

Major Points

Standard CPR protocol consists of chest compressions and positive pressure ventilations to maintain blood flow and oxygenation. Prior to an advanced airway, a two person rescuer scenario involves compressions interrupted by ventilations at a 30:2 ratio. The interruptions for rescue breaths reduce blood flow and theoretically reduce the effectiveness of CPR and survival rates. One strategy suggested to minimize these interruptions is to provide asynchronous ventilations while giving continuous chest compressions.

The '"CCC Trial" tested whether this strategy of continuous compressions compared to the 30:2 ratio would improve outcomes. The trial was conducted by the Resuscitation Outcomes Consotrium (ROC) and involved 8 ROC sites with 114 associated EMS agencies. 23,711 patients were included in the cluster randomized trial with crossover. The intervention (CCC) was administered to patients with OHCA via EMS providers, and continued for the first 3 cycles of CPR lasting two minute each; after which standard protocols were assumed (e.g. 30:2, advanced airway placement etc.).

Ultimately the study did not show a difference in survival or favorable neurologic status whether patients received continuous or interrupted compressions during OCHA treated by EMS providers.

Study Design

Cluster randomized trial with crossover, including 114 EMS agencies. Clusters of agencies were randomly assigned in a 1:1 ratio to perform continuous or interrupted chest compressions. Twice per year each cluster was crossed over to the other strategy. Trial ran from June 2011 to May 2015.

Population

Trial was run by the Resuscitation Outcomes Consortium (ROC), which includes 10 clinical sites in North America and their associated regional EMS agencies. 8 ROC sites and 114 EMS agencies participated in this study.

Patient Demographics

No major differences in pretreatment characteristics of patients.

Characteristic CCC 30:2
Age 66.4 66.2
Male sex 63.5% 64.4%
Obvious cause of arrest 3.1% 3.2%
Arrest in public location 14.2% 14.8%
Bystander witnessed arrest 42.0% 43.5%
Bystander CPR 46.90% 47.1%
Time from dispatch to EMS arrival 5.9 min 5.9 min

Inclusion Criteria

  • Adults with non-trauma related OHCA

Exclusion Criteria

  • EMS witnessed arrest
  • Written advanced directive DNR
  • Traumatic injury, asphyxial cause of arrest, or uncontrolled bleeding/exsanguination
  • Pregnancy
  • Preexisting tracheostomy
  • Prisoners
  • Initial CPR performed by a nonparticipating EMS provider, use of mechanical CPR device, or advanced airway management prior to EMS arrival

Interventions

CCC Group (n=12,613)

  • Continuous chest compressions at a rate of 100 per minute
  • Asynchronous positive pressure ventilations delivered at a rate of 10 ventilations per minute

30:2 Group (n=11,035)

  • Chest compressions that were interrupted for ventilations at a ratio of 30 compressions to 2 ventilations
  • Ventilations were to be given with positive pressure during a pause in compressions of less than 5 seconds in duration

Common to both groups

  • Ventilation strategy maintained via oral airway for initial 3 CPR cycles (2 minutes each). If not ROSC or termination of CPR, an advanced airway was inserted after this third cycle ASAP.
  • Once an advanced airway was obtained, continuous chest compressions with asynchronous ventilations was the standard.

Outcomes

Primary Outcome

  • Survival to Hospital Discharge: no significant difference demonstrated between groups.
Outcome CCC 30:2 P Value
Survival to Discharge 9% 9.7% 0.07

Secondary Outcomes

  • No statistical difference in percent of survivors with a favorable neurologic outcome (Modified Rankin >3)
  • Statistical difference (of questionable clinical significance, however) in number of hospital free survival days at 30 days after arrest favoring the 30:2 Group (1.5 days) vs. CCC (1.3 days)
Outcome CCC 30:2 P Value
Hospital Free Days at 30 Days 1.3 1.5 0.004
Favorable Neurologic Outcome 7.00% 7.70% 0.09

Additional Data Analysis & Outcomes

Outcome CCC 30:2 P Value
ROSC at ED Arrival 24.20% 25.30% 0.07
Compression Fraction 0.83% 0.77% <0.001
# pauses > 2 seconds 3.8% 7.0% <0.001
Bystander CPR 46.9% 47.1%

Criticisms & Further Discussion

  • Both groups received extremely high quality CPR with little difference in compression fractions: 83% (CCC) and 77% (30:2). Because the CPR was highly monitored and performed with such high standards, this may not reflect actual CPR performance and compression fractions in usual situations, missing potential differences in outcomes.
  • The differences in CPR techniques were only maintained for the first 6 minutes total of the resuscitation; after which standard ACLS protocols were followed. It is possible that 6 minutes is not enough time to affect differences in outcomes. [1]

External Links

See Also

Funding

Sponsored by the National Heart, Lung, and Blood Institute, the Canadian Institutes of of Health Research, and others.

References