Discussion
OHCA, cardiac arrest
CARDIAC ARREST
In this randomized controlled simulation study, we measured chest compression effectiveness (rate, depth and hand position) and time-related factors (time of check the breathing, time to call the ambulance, and time to the first chest compression) in a cardiac arrest scenario comparing V-CPR, T-CPR and U-CPR groups. In addition, we collected data about CPR self-assessment and attitudes toward V-CPR technology. Since the effectiveness of V-CPR is affected by several factors, we tried to give a wide picture of the topic (CPR effectiveness, time-related factors, attitude and self-assessment). Our results showed that V-CPR method performed by lay responders could lead to higher-quality chest compressions compared to T-CPR and U-CPR. However, V-CPR instructions were not enough to achieve high-quality chest compression depth related to the ERC guidelines in the majority of the casesEarly recognition of OHCA, activation of the EMS, and performing high-quality CPR can improve survival rate which can be supported by dispatcher-assisted CPRIn our study, participants performed chest compression-only CPR because it is the recommended protocol during dispatcher-assisted resuscitation in HungaryAnalyzing data from another perspective, we measured time-related parameters. The time of check the breathing was the longest in the V-CPR group. The reason for this result could be that the dispatcher fixed some problems in many cases and gave real-time feedback based on the video picture (e.g. participants did not tilt the head back during the procedure of check the breathing). Participants in the V-CPR group called the ambulance earlier than in the T-CPR and U-CPR groups. It can be explained with the prior information that they will be able to communicate with the dispatcher via a video call if they need some support. Time to the first chest compression was shorter in the V-CPR group than in the T-CPR group, however, was longer than in the U-CPR group. The difference between V-CPR and T-CPR can be explained with the more clear instructions by the dispatchers: in the V-CPR group, dispatchers could see the situation and were able to give adequate prompts, and it was not necessary to ask the lay rescuer for any feedback which could decrease the delays during the process. In addition, the difference between the V-CPR and U-CPR groups can be explained by the fact, that the process is faster (though not necessarily more efficient) when lay rescuers can do the process without any external instructions. Based on a systematic review, dispatcher-assisted CPR demonstrated inferior outcomes compared to unassisted (bystander-initiated) CPRIn dispatcher-assisted CPR, human factors are essential, as well (e.g. trained dispatchers, physical abilities and attitudes of the lay responders)Based on our results, V-CPR is feasible to improve the quality of CPR compared to T-CPR and U-CPR. However, analyzing the data from the view of real-life requirements (e.g. international guidelines), only a minority of the V-CPR participants were able to achieve high-quality chest compressions in all aspects together which conformed to the ERC guidelinesOur study has several limitations. First, since V-CPR is not been implemented in real emergency situations in Hungary yet, we could not set up a „real dispatcher room” fitting the requirements of V-CPR, and we did not have a standardized V-CPR protocol (dispatchers used the usual T-CPR protocol with some modifications expanded by the live video picture). Second, our study was made under optimal circumstances (sufficient light, stable WiFi connection, no negative environmental and weather factors, etc.), and we used a CPR manikin as the victim during a 2 min long scenario. In addition, participants were informed about the opportunities of the different groups which limited the realism. Regarding these facts, we do not know, how our participants would react in a possible real-life OHCA situation, or what would be the results during a longer scenario. Third, we used a study operator who handled the smartphone and managed the emergency call. In a real emergency situation, a second person may not always be present and/or is not prepared with the usage of the V-CPR technology. Furthermore, the participants in our study were university students (young adults). Examining different age groups of lay responders would lead to other results.