National characteristics of emergency medical services responses in the United States.

OBJECTIVE: Despite its long history and current prominence in U.S. communities, only limited data describe the national characteristics of emergency medical services (EMS) care in the United States. We sought to characterize out-of-hospital EMS care in the United States. METHODS: We conducted an analysis of the 2010 National Emergency Medical Services Information System (NEMSIS) research data set, encompassing EMS emergency response data from 29 states. From these data, we estimated the national number and incidence of EMS responses. We also characterized EMS responses and the patients receiving care. RESULTS: There were 7,563,843 submitted EMS responses, corresponding to an estimated national incidence of 17.4 million EMS emergency responses per year (56 per 1,000 person-years). The EMS response incidence varied by U.S. Census region (South 137.4 per 1,000 population per year, Northeast 85.2, West 39.7, and Midwest 33.3). The use of lights and sirens varied across Census regions (Northeast 90.3%, South 76.7%, West 68.8%, and Midwest 67.5%). The percentage of responses resulting in patient contact varied across Census regions (range 78.4% to 95.7%). The EMS time intervals were similar between Census regions; response median 5 minutes (interquartile range [IQR] 3-9), scene 14 minutes (10-20), and transport 11 minutes (7-19). Underserved populations (the elderly, minorities, rural residents, and the uninsured) were large users of EMS resources. CONCLUSION: These data highlight the breadth and diversity of EMS demand and care in the United States.

Comparison of methods for the determination of cardiopulmonary resuscitation chest compression fraction.

OBJECTIVE: While cardiopulmonary resuscitation (CPR) chest compression fraction (CCF) is associated with out-of-hospital cardiac arrest (OHCA) outcomes, there is no standard method for the determination of CCF. We compared nine methods for calculating CCF. METHODS: We studied consecutive adult OHCA patients treated by Alabama Emergency Medical Services (EMS) agencies of the Resuscitation Outcomes Consortium (ROC) during January 1, 2010 to October 28, 2010. Paramedics used portable cardiac monitors with real-time chest compression detection technology (LifePak 12, Physio-Control, Redmond, WA). We performed both automated CCF calculation for the entire care episode as well as manual review of CPR data in 1-min epochs, defining CCF as the proportion of each treatment interval with active chest compressions. We compared the CCF values resulting from 9 calculation methods: (1) mean CCF for the entire patient care episode (automated calculation by manufacturer software), (2) mean CCF for first 3 min of patient care, (3) mean CCF for first 5 min, (4) mean CCF for first 10 min, (5) mean CCF for the entire episode except first 5 min, (6) mean CCF for last 5 min, (7) mean CCF from start to first shock, (8) mean CCF for the first half of resuscitation, and (9) mean CCF for the second half of resuscitation. We compared CCF for Methods 2-9 with Method 1 using paired t-tests with a Bonferroni-adjusted p-value of 0.006 (99.5% confidence intervals). RESULTS: Among 102 adult OHCA, patient demographics were: mean age 60.3 years (SD 20.8 years), African American 56.9%, male 63.7%, and shockable ECG rhythm 23.5%. Mean CPR duration was 728 s (95% CI: 647-809 s). Mean CCF for the 9 CCF calculation methods were: (1) 0.587%; (2) 0.526%; (3) 0.541%; (4) 0.566%; (5) 0.562%; (6) 0.597%; (7) 0.530%; (8) 0.550%; and (9) 0.590%. Compared with Method 1, Method 7 CCF (start to first shock) was slightly lower (-0.057; 99.5% CI: -0.100 to -0.014). There were no other statistically significant CCF differences (range: -0.054 to 0.013). Correlation between CCF 2-9 and CCF varied (ρ=0.48-0.85). CONCLUSION: CCF varies minimally with different calculation methods. Automated CCF determination may prove sufficient for evaluating CPR quality.