title: Emergency medical system response time does not affect incidence of return of spontaneous circulation after prehospital resuscitation in one million central European agglomeration residents.
abstract: BACKGROUND
  The survival of out-of-hospital sudden cardiac arrest (OHSCA) in Europe still remains low. The State Medical Rescue System is composed of several elements. The efficacy of each of these elements may have an influence on the victim's survival. Until now, the incidence of return of spontaneous circulation (ROSC) and its correlation with rescue services time in the city of Poznan has not been determined.
  
  
  OBJECTIVE
  The main purpose of this study was to assess incidents of OHSCA and prehospital frequency of ROSC after OHSCA in Poznan city and district. We also wanted to analyse whether ROSC depends on Emergency Medical System (EMS) reaction time.
  
  
  METHODS
  Retrospective analysis based on medical documentation conducted in 2015 in Poznan EMS.
  
  
  RESULTS
  Return of spontaneous circulation was achieved in 68.88% of cases. It was most frequent when OHSCA occurred in public places (p = 0.000, contingency factor = 0.233) and victims were younger (p = 0.042, contingency factor = 0.129). 63.17% of patients were male, but sex did not affect the incidence of ROSC. The median time of system response was 8.53 min, while time from ambulance departure to arrival was 5.42 min. We did not find any statistically significant difference between the number of deaths and those parameters (p = 0.723, p = 0.891). However, longer team response time correlated with the highest mortality (p = 0.042, contingency factor = 0.126). In the group where ROSC was achieved the median time of EMS response was 8.18 min, while among the group of deceased the median was 8.63 min.
  
  
  CONCLUSIONS
  The incidence of OHSCA in our region is similar to other Polish and European cities. EMS response time does not affect the frequency of ROSC. ROSC was achieved more often if OHSCA occurred in public and the victim was younger.
authors.affiliation: Department of Rescue and Disaster Medicine, Poznan University of Medical Sciences, Poznan, Poland. klosiewicz.tomek@gmail.com.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kłosiewicz
authors.forename: Ilona
authors.initials: I
authors.lastname: Skitek-Adamczak
authors.forename: Marcin
authors.initials: M
authors.lastname: Zieliński
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation; D002648:Child; D002675:Child, Preschool; D004632:Emergency Medical Services; D005060:Europe; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000453:epidemiology / Q000628:therapy*; D011930:Reaction Time; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: emergency medical services; resuscitation; treatment efficacy