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Abstract
Emergency medical service (EMS) providers respond to and treat patients with a variety of conditions and levels of urgency. During the EMS response process, a patient is assessed multiple times to inform travel, treatment, and transport decisions. As a result, the urgency with which an EMS unit responds dynamically changes throughout the response process. We use data provided by the National EMS Information System (NEMSIS) to analyze 665,050 ambulance responses and explore how EMS response changes at each step of the EMS response process. We perform multiple logistic regressions to explore how various factors are associated with these changes and demonstrate that response mode decisions are correlated with differences in service time. This research demonstrates that capturing uncertainty in the urgency of EMS response is necessary to accurately model an EMS system and needs greater attention in EMS planning research. We conclude with some insights for future research in EMS planning.
Keywords
Emergency medical services, Patient assessment, Dynamic response, Logistic regression, Linear regression.
1. Introduction
Emergency medical service (EMS) support following a request for emergency care is a dynamic process. At the time of an initial request, a patient's condition is often uncertain, and an EMS system must decide how to respond using the limited information provided during the phone screening. An EMS dispatcher must assign a station to respond to the patient, determine if lights and sirens should be used, and whether an advanced life support (ALS) vehicle staffed by paramedics is needed or if a basic life support (BLS) vehicle will suffice. Then, at the scene of the incident and throughout the remainder of the response process, the patient's condition is assessed multiple times to inform other treatment and transport decisions. Often EMS personnel act conservatively and assume a higher level of urgency (over-triage) until they are confident that an emergent response mode is unnecessary. As a result, more than 75% of EMS responses that start as emergent are believed to be over-triaged [1]. Given this prevalence, understanding how EMS response evolves and its impact on EMS performance are critical to designing an efficient EMS system.
In this analysis, we define EMS response mode as the urgency of EMS service at a particular decision point. We consider four decision points: the...