The activation interval in out-of-hospital cardiac arrest response: We should be looking for time savings

Secondary Public Safety Answering Points Delay the Response to out of Hospital Cardiac Arrest

Background: National guidelines recommend that high-performing systems process 9-1-1 calls within 60 s and deliver the first telecommunicator cardiopulmonary resuscitation compression within 90 s. The inability of systems employing secondary public safety answering points (PSAPs) to capture the call arrival timestamp at the primary PSAP is a challenge in out-of-hospital cardiac arrest response time research.Objective: We sought to measure the interval from call receipt at primary PSAPs to call answer at secondary PSAPs in metropolitan areas.Methods: This was a retrospective observational study evaluating 9-1-1 call transfers between PSAPs serving large urban populations. Call transfer records were extracted from the 9-1-1 telephony systems at the primary and secondary PSAPs covering seven metropolitan EMS systems. For each transferred call, we obtained the call arrival timestamp at both the primary and secondary PSAPs. The primary outcome was the interval between these two times. Results were compared to a national standard of 90% of calls forwarded within 30 s of receipt.Results: Data collected at seven metropolitan EMS agencies from January 1, 2021, through June 30, 2021, yielded 299,679 records for evaluation. The median interval required to transfer a 9-1-1 caller from primary to secondary PSAPs was 41 s (IQR 31, 59), and 86 s at the 90th percentile. The 90th percentile performance level at individual agencies ranged from 63 s to 117 s.Conclusions: The primary to secondary PSAP transfer interval lengths observed in this study preclude these EMS agencies from meeting out-of-hospital cardiac arrest performance recommendations at the 90% percentile performance level.

Relationship Between Emergency Medical Services Response Time and Bystander Intervention in Patients With Out-of-Hospital Cardiac Arrest

Background

The response time of emergency medical services (EMS) is an important determinant of survival after out‐of‐hospital cardiac arrest. We sought to identify upper limits of EMS response times and bystander interventions associated with neurologically intact survival.

Methods and Results

We analyzed the records of 553 426 patients with out‐of‐hospital cardiac arrest in a Japanese registry between 2010 and 2014. The primary study end point was 1‐month neurologically intact survival (Cerebral Performance Category scale 1 or 2). Increased EMS response time was associated with significantly decreased adjusted odds of 1‐month neurologically intact survival (adjusted odds ratio [aOR] for each 1‐minute increase, 0.89; 95% confidence interval [CI], 0.89–0.90), although this relationship was modified by bystander interventions. The bystander interventions and the ranges of EMS response times that were associated with increased adjusted 1‐month neurologically intact survival were as follows: bystander defibrillation, from ≤2 minutes (aOR, 3.10 [95% CI, 1.25–7.31]) to 13 minutes (aOR, 5.55 [95% CI, 2.66–11.2]); bystander conventional cardiopulmonary resuscitation, from 3 minutes (aOR 1.48 [95% CI, 1.02–2.12]) to 11 minutes (aOR 2.41 [95% CI, 1.61–3.56]); and bystander chest‐compression‐only cardiopulmonary resuscitation, from ≤2 minutes (aOR 1.57 [95% CI, 1.01–2.25]) to 11 minutes (aOR 1.92 [95% CI, 1.45–2.56]). However, the increase in neurologically intact survival of those receiving bystander interventions became statistically insignificant compared with no bystander interventions when the EMS response time was outside these ranges.

Conclusions

The upper limits of the EMS response times associated with improved 1‐month neurologically intact survival were 13 minutes when bystanders provided defibrillation (typically with cardiopulmonary resuscitation) and 11 minutes when bystanders provided cardiopulmonary resuscitation without defibrillation.