Svensson 2010.
| Methods | Randomized controlled trial | |
| Participants | Inclusion criteria: The collapse had been witnessed (seen or heard), and the participant was unconscious and was not breathing or not breathing normally Exclusion criteria: Cardiac arrest caused by trauma, airway obstruction, drowning, or intoxication; participants's age under 8 years; and difficulty of the dispatcher in communicating with the caller. Some at the scene had started CPR already before the caller, or the caller already knew how to perform CPR 1276 participants were included |
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| Interventions | Intervention group: the caller was instructed to perform compression‐only CPR Contral group: the caller was instructed to perform standard CPR (mouth‐to‐mouth ventilation plus chest compression, consisting of 2 ventilations alternating with 15 compressions) |
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| Outcomes | 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 | |
| Notes | The study started before the guidelines for CPR changed the recommendation from 2 ventilations alternating with 15 compressions to 30 compressions alternating with 2 ventilations. The instructions in this study of 2 ventilations alternating with 15 compressions were maintained, since the new guidelines did not address dispatcher‐assisted CPR | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | The random sequence generation was based on the random number generator in SPSS software |
| Allocation concealment (selection bias) | Low risk | If the inclusion criteria had been met, the type of CPR on which the caller was instructed was determined on the data collection sheet. 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 |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Bystanders did not know that they were recruited in this study, so this would not have affected survival outcomes. EMS personnel and other physicians who gave advance therapy for the participants were not blinded and so care received following the arrival of EMS and other medical teams could have been affected by knowledge prior to treatment received |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | The data were collected from EMS records, and information about survival status was collected from national registers. Although there was no description about blinding in this study, 50% of the data collection forms were double‐checked and no relevant deviations were observed. In addition, the researchers evaluated 100 recorded calls and reviewed the corresponding data‐collection forms, finding no deviation of the information in each |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Information on follow‐up was unavailable for 132 of 1952 participants (6.8%) in this study. The main reason being loss of the corresponding EMS field reports, occurring primarily in a small number of EMS districts. The authors, therefore, performed a subgroup analysis excluding districts where more than 18% of participants were lost to follow‐up. No difference from the main results was found |
| Selective reporting (reporting bias) | Low risk | Main outcomes of out‐of‐hospital cardiac arrest were reported in full |
| Other bias | Low risk | We did not identify other sources of bias |
CPR: cardiopulmonary resuscitation; EMS: emergency medical service; ROC: resuscitation outcomes consortium; ROSC: return of spontaneous circulation.