Materials and methods
The analysis covered dispatch orders forms and emergency medical procedure forms of the VRS in Katowice collected in 2016 (N = 249 872). The retrospective analysis involved exclusively cases of OHCA in patients over the age of 18 years. The above criteria were fulfilled in 1603 cases.  The VRS in Katowice is the greatest public operator in Poland, taking care of 2.7 mln inhabitants of the Silesian province. 

Results
There were 1037 male patients (64.7%), 566 female patients (35.3%). Women were generally older (p = 0.000). The average age of the group was 65.7 years. The attack rate amounted to 59.37/100 000. OHCA most often occurred in domestic conditions (71.1 %; p = 0.000), usually in the presence of a witness (about 70.0%; p= 0.000). Most of the OHCA cases were reported in the first quarter of the year SCA most frequently occurred during the day (between 07.01 a.m. and 07.00 p.m.) (n = 1013; 63.2%, p=0,000). The most frequently elements of providing patients with airway patency were intubation (51.4%) and laryngeal mask airway (n = 235, 14.7%). Respirators were used less often (20.2%). VF was reported in only 22.0% of the cases. ROSC rate was higher in the group of patients with diagnosed ventricular fibrillation than in the group of non-shockable rhythms  (VF -55.43% vs. asystole- 24.05%, p = 0.000).  In 1603 cases of diagnosed OHCA with cardiopulmonary resuscitation, ROSC was reported in 536 cases (33.4%).

Conclusions 
However, OHCA cases are often unsuccessful. Performing actions in accordance with current knowledge leads to a higher rate of effective resuscitation in patients. Both the witness of the incident and the emergency medical dispatcher play a crucial role in OHCA cases. Performing actions in accordance with current knowledge leads to a significantly higher ROSC rate.

2 - An analysis of activities and medical rescue actions in patients with OHCA in the system of emergency medical services in Silesia region (Poland)