Purpose: To evaluate die accuracy of die Emergency Medical Priority Dispatch System (EMPDS) with respect to response level for cardiac arrest cases, and to compare response times for delta versus other response levels. The study setting was an urban ALS system that adopted a priority dispatch system 2.5 years ago. The sensitivity of the EMPDS has not been evaluated with regard to cardiac arrest cases since its implementation. We hypothesized that 99% of cardiac arrest cases would receive the highest level of response.
Methods: We retrospectively reviewed 1994 emergency medical services (EMS) atraumatic cardiac arrest incident reports. We compared response time to response level using a subsample of 230 cases for which complete data were available. We used ANOVA and chi-square tests in our analyses.
Results: Of 284 cardiac arrest cases, 258 (90.8%) were classified as delta, 17 (6.0%) as charlie, eight (2.8%) as bravo, and one (0.4%) as alpha. More cases were misclassified as charlie or lower than expected (p <0.0001). Response time was slightly faster for delta (mean = 6.9 minutes; 95% CI = 6.5, 7.3) than other (mean = 7.6; 95% CI = 6.8, 8.5) response levels (p = 0.25).
Conclusion: The EMPDS has high sensitivity in identifying and responding to cardiac arrest calls. The highest priority calls had, on average, approximately one minute faster response times than the lower priority calls. This reflects the importance of accuracy in this system, particularly with regard to conditions, such as cardiac arrest where response time is highly correlated with survival. The results of this study support the use of the EMPDS, and indicate the need for more specific analyses of the causes and consequences of misclassification of cardiac arrest cases.