The Construction Of Out-of-Hospital Cardiac Arrest Database And The Research On Optimal Allocation And Strategy Of Emergency Resources Based On MCLP

ObjectivesAs the leading cause of death worldwide,out-of-hospital cardiac arrest(OHCA)is a frequent medical condition with a low survival rate.Early cardiopulmonary resuscitation(CPR)and rapid defibrillation are the key measures in the "chain of survival".First responder can initiate CPR and deliver defibrillation with the use of automated external defibrillator(AED)prior to the arrival of emergency medical personnel,so as to shorten the emergency response time of OHCA victims.In China,as a result of the limited resources of first responder and AED and the lack of rational utilization,the situation of pre-hospital emergency care is so severe.Therefore,our study takes Pudong New Area of Shanghai as an example,to construct the OHCA database based on Utstein style;to optimize the AED deployment and first responder allocation on the basis of Maximal Covering Location Problem(MCLP);to establish pre-hospital emergency care process of OHCA event based on first responder and AED,then to form the OHCA event pre-hospital emergency care mode in order to make full use of first responder and AED to effectively participate in OHCA pre-hospital emergency care and improve the survival rate of OHCA.Methods1.Construct OHCA database based on Utstein style and analyze the OHCA situationBased on the Utstein-style report,AHA guidelines,European Resuscitation Council guidelines and OHCA databases abroad,and the collection of OHCA emergency medical records from January 2012 to July 2017 in Pudong New Area,the OHCA database was constructed with the use of MySQL software and under the guidance of E-R model as well as the third paradigm.Besides,the structure of OHCA was determined by expert group meeting.Then,we analyzed the current stuation of OHCA cases in Pudong New Area by means of OHCA database.2.Construct and verify the optimization of AED placementThe status of AED configuration in Pudong New Area was analyzed through information collection and field investigation.The geographic data for OHCA incidents from 2012～2016 and AEDs were converted by geocoding and plotted in ArcGIS.The distance from OHCA to AED was calculated by Euclidean metric and the current AED coverage level for OHCA was analyzed.The optimization of AED placement was constructed by setting two parameters that the AED effective coverage radius and numbers of AED based on MCLP model and running the model.The optimization of AED placement was then verified on the basis of OHCA cases of 2017 in Pudong New Area.3.Construct the first responder spatial configuration based on requirementBased on the OHCA geographic data from 2012 to 2016 in ArcGIS and MCLP model,dividing Pudong New Area into several grid units according to the community grid management as the moving area of first responder,setting two parameters that the effective coverage radius of first responder and OHCA coverage,the spatial demand configuration of first responder was constructed.4.Form the pre-hospital emergency care mode of OHCA event based on first responder and AEDCombined with the optimization of AED placement and first responder spatial configuration,the pre-hospital emergency care process of OHCA event based on first responder and AED was constructed through literature analysis and expert group meeting.Based on the process and the actual situation,the the pre-hospital emergency care mode of OHCA event based on first responder and AED was formed.Results1.The establishment of OHCA database based on Utstein styleThe OHCA database we established was based on the characteristics of pre-hospital emergency care in Pudong New Area,international guidelines’ and expert group meeting.It standardized the input standard and expression of OHCA content.It is the database with clear structure,detailed content,convenient operation,and has the functions of input,export,inquiry and management,which can provide a template for the routine OHCA registration in Emergency Medical Service.A number of 16122 OHCA cases were analyzed based on database;the OHCA incidence was increasing;the incidence of OHCA was high in 71～80 years old;the rate of ROSC and survival to hospital discharge were lower;80.22%of OHCA occurred at home and OHCA events occurred most frequently at public locations categorized as "Roads";65.9%of OHCA were presumed to be of cardiac origin;the majority of victims exhibited asystole as the initial rhythm and most of initial rhythm was non-shockable;less OHCA cases were witnessed and received bystander CPR;More than half of OHCA chose "do not resuscitation";the 6～12 o’clock was the peak time of OHCA and the incidents was higher in winter;the duration of OHCA and response time exceeded 4 min.2.The construction of OHCA-based AED rational configuration schemeThe results showed that there was a weak correlation of AED placement and OHCA incidents.The AED coverage level was only 4.60%when the effective range was 100 m.The mean distance between OHCA and closest AED was 1124.99 m.After optimization,the coverage level was improved significantly and the distance of OHCA-AED was reduced.Comparing the two optimization strategies,the second strategy that assumed the location of deployed AED can be adjusted was better than the other one,which was more cost-effective.Besides,the validation of AED optimization showed that the time to obtain AED exceeded 4 min just by walking,but it could reduce the time within 4 min through riding and electric-riding.The conclusion from validation experiments is consistent with the previous results,proving the AED rational configuration scheme was reasonable and feasible.3.The construction of spatial demand configuration of first responderThe results showed that when the effective range was 100 m,which means that the first responder could walk quickly to OHCA patients,there were required 4626 first responder in order to realize 95%the coverage level for OHCA.If the first responder ridded or ridded electrically to the victim,the corresponding effective range were 300 m and 500 m.On these conditions,1626 and 1262 first responders were required to increase coverage level of OHCA to 95%.4.The formation of the pre-hospital emergency care mode of OHCA event based on first responder and AEDBased on previously comprehensive consideration,the AED optimization scheme were selected as follows:① assuming the deployed AED could not be removed,the effective range was 100 m and the number of added AEDs was 400;②assuming the deployed AED could be removed,the effective range was 100 m and the number of AEDs was 1000.The spatial configuration scheme of first responder were selected as follows:①the effective range was 500 m and the coverage level for OHCA was 90%;②the effective range was 500 m and the coverage level for OHCA was 95%.Combining selected AED optimization scheme and first responder spatial configuration scheme,according to pre-hospital emergency care process based on first responder and AED,the OHCA event pre-hospital emergency care mode based on first responder and AED was formed.In the mode,the first responder and AED under different effective range were dispatched according to the traffic conditions of first responder and the available vehicles of OHCA locations,to make the first responder and AED can reach the OHCA victim before the arrival of emergency medical personnel and the time was within 4 minutes.ConclusionsThe OHCA database based on Utstein style not only had the characteristics of cardiac arrest in China,but also took into account the Utstein-style report and foreign mature database,which can standardize the input of OHCA pre-hospital medical records and efficiently manage and analyze OHCA data.Besides,the OHCA database could provide the support of clinical and scientific research decision,and had a good practical value and application prospects.The analysis of large-sample OHCA cases showed that the incidence of OHCA events increased by year,but the ROSC rate and survival rate were low,which indicate the situation of pre-hospital emergency care was severe.The low rate of OHCA event witness,bystander CPR and defibrillation rates highlights the importance of effective participation of first responders and AEDs in pre-hospital care.In addition,the current AED configuration was unreasonable.The OHCA-based AED optimization scheme could effectively make up for the defect and give full play to the AED value in pre-hospital emergency care.Besides,the first responder spatial configuration provided a reference for the establishment of the first responder program.It suggested that when it comes to the configuration of first responder,the vehicle could be reasonably allocated according to the recruited number of first responder and if possible the first responder could carry AED so as to shorten the emergency response time.The pre-hospital emergency care mode of OHCA event based on first responder and AED provided a new model for the first responder and AED to participate in OHCA pre-hospital emergency care,and a reference for pre-hospital emergency care in the future,in order to effectively shorten the emergency response time of OHCA patients,improve the current situation of pre-hospital emergency care,and increase the survival rate and the quality of life of OHCA patients.