Clinical consequences of the introduction of mechanical chest compression in the EMS system for treatment of out-of-hospital cardiac arrest-a pilot study

AIM: To evaluate the outcome among patients suffering from out-of-hospital cardiac arrest (OHCA) after the introduction of mechanical chest compression (MCC) compared with standard cardiopulmonary resuscitation (SCPR) in two emergency medical service (EMS) systems. METHODS: The inclusion criterion was witnessed OHCA. The exclusion criteria were age < 18 years, the following judged etiologies behind OHCA: trauma, pregnancy, hypothermia, intoxication, hanging and drowning or return of spontaneous circulation (ROSC) prior to the arrival of the advanced life support (ALS) unit. Two MCC devices were allocated during six-month periods between four ALS units for a period of two years (cluster randomisation). RESULTS: In all, 328 patients fulfilled the criteria for participation and 159 were allocated to the MCC tier (the device was used in 66% of cases) and 169 to the SCPR tier. In the MCC tier, 51% had ROSC (primary end-point) versus 51% in the SCPR tier. The corresponding values for hospital admission alive (secondary end-point) were 38% and 37% (NS). In the subset of patients in whom the device was used, the percentage who had ROSC was 49% versus 50% in a control group matched for age, initial rhythm, aetiology, bystander-/crew-witnessed status and delay to CPR. The percentage of patients discharged alive from hospital after OHCA was 8% versus 10% (NS) for all patients and 2% versus 4%, respectively (NS) for the patients in the subset (where the device was used and the matched control population). CONCLUSION: In this pilot study, the results did not support the hypothesis that the introduction of mechanical chest compression in OHCA improves outcome. However, there is room for further improvement in the use of the device. The hypothesis that this will improve outcome needs to be tested in further prospective trials.