Best Evidence Topics

Randomised control trial

Svenson, Leif, et al.
Compression-Only CPR or Standard CPR in Out-of-Hospital Cardiac Arrest
The New England Journal of Medicine
July 29, 2010; 434442
  • Submitted by:Brady Wilkinson - ER Resident
  • Institution:Grand Rapids Medical Education Partners/Michigan State University
  • Date submitted:24th April 2011
Before CA, i rated this paper: 6/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  Yes. The aim of this prospective, randomized study was to evaluate the possible superiority of compression-only CPR over standard CPR with respect to survival.
2 Design
2.1 Is the study design suitable for the objectives
  Yes. Randomized control trial.
2.2 Who / what was studied?
  Patients with suspected, witnessed, out-of-hospital cardiac arrest.
2.3 Was this the right sample to answer the objectives?
2.4 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  We estimated that a sample of 2213 patients in each treatment group would be needed to provide a statistical power of 80% to detect an absolute difference of 2 percentage points in the 30-day survival rate between the two groups, assuming a rate of 5% with standard CPR and 7% with compression-only CPR, with a two-sided alpha value of 0.05. Because CPR guidelines were altered during the study, giving compression-only CPR a more prominent role,7 and because of the practical difficulties of running a study for more than 4 years, we decided that 1000 patients in each group was the largest number that would be realistic to include in our study.
2.5 Were all subjects accounted for?
2.6 Were all appropriate outcomes considered?
  The primary end point was 30-day survival. The secondary end points were 1-day survival, defined
as survival until midnight of the day of admission to the hospital, as well as the first detected cardiac rhythm and survival to discharge from the hospital.
2.7 Has ethical approval been obtained if appropriate?
  The study protocol was approved by the Regional Ethics Committee at Karolinska Institutet, Stockholm.
2.8 Were the patients randomised between treatments?
2.9 How was randomisation carried out?
  Data-collection sheets were distributed in blocks of 100 sheets, 50 for each treatment assignment. The order of sheets within each block was unique and was based on the random-number generator in SPSS software (version 18).
2.10 Are the outcomes clinically relevant?
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
  Yes. The primary end point was 30-day survival. The secondary end points were 1-day survival, defined as survival until midnight of the day of admission to the hospital, as well as the first detected cardiac rhythm and survival to discharge from the hospital.
3.2 Are the measurements valid?
  Yes. The measurement is 30-day survival.
3.3 Are the measurements reliable?
  Yes. The measurement is 30-day survival.
3.4 Are the measurements reproducible?
3.5 Were the patients and the investigators blinded?
  No. This would not be possible.
4 Presentation of results
4.1 Are the basic data adequately described?
4.2 Were groups comparable at baseline?
4.3 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
  Yes. The primary analysis showed a 30-day survival rate of 8.7% in the group receiving compression only CPR and 7.0% in the group receiving standard CPR (absolute difference for compression-only vs. standard CPR, 1.7 percentage points; 95% confidence interval, −1.2 to 4.6; P = 0.29) (Table 3).
4.4 Are the results internally consistent, i.e. do the numbers add up properly?
4.5 Were side effects reported?
5 Analysis
5.1 Are the data suitable for analysis?
  Yes. Fairly narrow confidence intervals.
5.2 Are the methods appropriate to the data?
5.3 Are any statistics correctly performed and interpreted?
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
  Yes. Previous studies in animals have shown no differences in survival or neurologic outcomes with standard CPR and compression-only CPR.3,9 One investigation even showed adverse outcomes related to the interruption of chest compression in order to perform mouth-to-mouth ventilation.
6.2 Is the discussion biased?
  No. It discusses several limitations of the study.
7 Interpretation
7.1 Are the authors' conclusions justified by the data?
  Yes. Overall, this study lends further support to the hypothesis that compression-only CPR, which is easier to learn and to perform, should be considered the preferred method for CPR performed by bystanders in patients with cardiac arrest.
7.2 What level of evidence has this paper presented? (using CEBM levels)
  1b. Individual RCT (with narrow Confidence Interval") and individual inception cohort study with > 80% follow-up; CDR" validated in a single population
7.3 Does this paper help me answer my problem?
After CA, i rated this paper: 5/10
8 Implementation
8.1 Can any necessary change be implemented in practice?
  Yes. This can be taught in the BLS and ACLS courses.
8.2 What aids to implementation exist?
  Does not require more than one maneuver. People will not have to do mouth-to-mouth.
8.3 What barriers to implementation exist?
  Compression-only CPR is not significantly better than standard CPR does not apply to cardiac arrest caused by trauma, respiratory failure, or intoxication or to children under the age of 8 years or patients in whom bystanders perform CPR without instructions from dispatchers.