Assessment of Emergency Medical Service (EMS) response times and operational factors in out-of-hospital cardiac arrests (OHCA): a retrospective analysis

Introduction:
Out-of-hospital cardiac arrests (OHCAs) require rapid emergency medical service (EMS) responses to improve patient outcomes. This study examines non-patient factors affecting EMS response times and OHCA outcomes, particularly return of spontaneous circulation (ROSC), with a focus on factors such as location, time of day, and season.

Aim:
To evaluate the influence of operational and situational factors on EMS response times and their association with ROSC rates.

Material and methods:
A retrospective analysis was performed using EMS records from the Lublin Voivodeship, Poland, covering 2014 to 2017. A total of 4,361 OHCA χcases were selected from an initial 5,111 identified cases through ICD-10 and ICD-9 codes, utilizing call-out cards and medical rescue activity cards. Statistical analyses, including χ² tests and correlation coefficients, assessed the impact of socio-demographic and operational factors on ROSC outcomes.

Results:
Shorter EMS response times were significantly associated with higher ROSC rates, with a mean response time of 7.92 min for ROSC cases (SD = 4.86) versus 8.29 min for non-ROSC cases (SD = 4.19; p = 0.0430). High-priority cases (K-1) had better ROSC outcomes (16.97%) compared to lower-priority cases (K-2: 12.30%; p < 0.05). Time of day and season did not significantly impact response effectiveness.

Conclusions:
Rapid EMS response and effective prioritization improve ROSC rates in OHCA incidents. The findings highlight the need to optimize EMS protocols and training, with targeted strategies that consider operational factors to enhance survival rates across varied populations.