The most capital-intensive consideration in emergency service planning is that of station location. EMS stations are difficult to site, expensive to build and costly to maintain. And, poor station location can significantly impact overall system performance. So, designing and justifying a new location or station scheme can be a challenging endeavor.
Fortunately, commercial software tools can aid in this process. The most useful of these allow planners to evaluate different scenarios by simulating or modeling performance under varying conditions. The results permit planners to estimate the effect of different station locations and justify their plans to political stakeholders. Software tools (and the resulting plans), however, may be limited by the assumptions of the underlying model and the data used, which means the accuracy is sensitive to these components. Three components are of utmost importance: potential station location, response-time goals and future call volume. By carefully considering these assumptions, planners can create a system that better meets the needs of their patients.
Potential Station Locations
Another important consideration is the identification of appropriate station locations. Municipal services stations may be limited to publicly-owned properties and facilities, and for economic reasons, this often results in co-location with police or fire services. In fact, many major cities employ some degree of co-location between fire and EMS. For health system services, stations are typically located at hospitals and other health-care facilities.
We’ve recently seen some innovation around location selection for emergency response stations. Some services use temporary or “satellite” stations based in residential areas. Usually, this entails purchasing and retrofitting a house in a high-traffic location for use as a station. This approach provides a number of benefits. One is the variety of locations to choose from, which allows a closer proximity to the estimated optimum. Also, the cost of purchasing and retrofitting a house is only a fraction of the cost of building a new station. Finally, as a community grows and a station location becomes suboptimal, it can easily be closed and sold as a residence, thereby recouping a portion of the capital invested.
Drawbacks to satellite stations are mainly related to community oppositions, or the “not-in-my-backyard” (NIMBY) characteristics, which plague many public location efforts. These can be reduced by selecting noisy, high-traffic locations to begin with and by delaying the use of lights and sirens until the vehicle has left the residential neighborhood.
Response-time goals are the primary means of evaluating EMS system performance; therefore, expected performance is a major consideration when locating stations.(1) Most services have a goal of responding to 90% of calls in eight or nine minutes. The origin of this standard is a 1979 study in Seattle that measured the survival rate of witnessed cardiac arrests with respect to the response time of an ALS unit.(2) The study found higher survival rates for patients that were reached in eight minutes or less. Recent research suggests the true cut-off may be closer to four minutes or five minutes, and the survival rate improves progressively as the response time approaches zero.(3,4)
Future Call Volume
Most station-location planning strategies use some form of historical call volume to predict future call volume. This is generally pretty accurate because the geographical concentration of calls changes little from year to year. Exceptions may include the opening or closing of retirement centers or other high call-volume locations. Also keep in mind the type of call data used in estimation. For example, the planner may choose to include all calls, only high priority calls, only calls that resulted in a patient transport, or all calls with the exception of inter-facility transfers.
The inclusion or exclusion of different call types can influence station location. Each call cluster acts as a magnet that pulls potential station locations toward it. If transfer calls are included, potential station locations will be pulled toward hospitals or other health-care facilities. If only transport calls are included, potential station locations will be pulled toward areas in which calls result in a transport. In either case, certain types of calls—and segments of the population—will receive longer response times.
EMS system performance is often based on compliance with a response-time goal, and the station’s location can affect the achievement of this goal. In the prediction of future call volume and subsequent location assessment, use call data consisting of those calls that will benefit the most from timely EMS response. For instance, some high-priority cardiac calls will have drastically different outcomes depending on the response time, whereas patients awaiting a transfer between hospitals are already accessing advanced care. In almost all these cases, the patients or other care facilities will be unaffected by a slightly longer response. Similarly, patients with low-priority calls can afford to wait a couple minutes longer.
So, how do you identify these calls? Although Medical Priority Dispatch System (MPDS) card types may be a good first-cut approximation, in some services it can be inaccurate and may not be suitable for your decision. Given that we’re examining complete historic data, it may not be necessary to rely on the call evaluator’s judgment in assigning card types. Instead, we can analyze the call data to identify the subset of patients we feel will benefit the most from an improved response time. Ideally, this patient data would come from hospital records. However, reviewing a few of the most appropriate MPDS card types could identify a reasonably accurate subset.
A Patient-Centric Approach
Rather than ignore the recent clinical research on response times and continue to judge performance on arbitrary response standards of eight or nine minutes, let’s take a different perspective. Reaching high-priority calls in four or five minutes is, in fact, achievable when response is measured from the patient’s point of view. To do so, planners need to also include data on other responders who arrive prior to EMS.
My firm’s research shows that in some major cities, nearly half of the high-priority calls can be reached in less than five minutes by units that respond solely from fire stations. Many fire services run BLS-AED or ALS engine first response systems and are able to stabilize cardiac patients. We’ve seen examples where as much as 8% of high priority calls originated within a single hospital. Surely these patients would be stabilized by hospital personnel. We suggest that co-locating EMS stations in hospitals or fire stations may be redundant; most patients will receive the first responder care they need, and the EMS system may be allocating resources inefficiently.
In many major cities, call volumes follow a general “80:20” rule: Eighty percent of calls originate from 20% of the locations. But it’s typically much more concentrated. For example, in one city we studied, the top percentile of locations accounted for nearly 30% of calls. In another, two large seniors’ complexes accounted for nearly one quarter of all calls.
Many of the locations, particularly retirement centers, have on-site medical staff that could be trained to stabilize patients while awaiting EMS. At the very least, these centers could be required to have AEDs—and many of them already do. Additionally, urgent-care centers, police stations, large industrial sites, and even some shopping malls, have or could have first-response capabilities. When examining the cost to serve these centers, a municipality could build a case for requiring on-site training for staff at these locations.
If calls to locations or areas covered by other services (e.g., police, fire or other dedicated response teams) were removed from the station-location consideration, a five-minute response—from the patient’s point of view—may actually be achievable. This method would place EMS stations in coverage gaps within the city, therefore bumping up the overall first-responder performance. This isn’t to say EMS units wouldn’t respond to calls that have already received first response. Transport units would back up these first responders in almost all instances. However, the system would no longer be designed to focus solely on EMS response, but rather the response of numerous agencies and trained lay persons.
Although a patient-centric approach requires a change of mindset, it wouldn’t require a complete reform of public services. In some cases, police, fire and other services would need to augment their training. A quality assurance program would also need to be created to ensure safe and effective care, but it wouldn’t necessarily require a huge effort in coordinating dispatches or communicating across different services. Often, fire, police and EMS dispatch is handled by the same team of dispatchers.
Municipal policies and regulations may also need to be changed to facilitate a community approach to patient response. Municipal regulations could require automated defibrillators and trained staff for locations with significant high-priority call volumes. And planners may find that paying for a portion of this cost is far less expensive than additional stations or paramedic units. The result should be better patient outcomes for equal or lower cost.
1. Shah MN. The formation of the emergency medical services system. Am J Public Health. 2006;96:414–423.
2. Eisenberg MS, Bergner L, Hallstrom A. Cardiac resuscitation in the community. Importance of rapid provision and implications for program planning. JAMA. 1979;241:1905–1907.
3. Pons PT, Haukoos JS, Bludworth W, et al. Paramedic response time: does it affect patient survival? Acad Emerg Med. 2005;12:594–600.
4. Blackwell TH, Kaufman JS. Response time effectiveness: comparison of response time and survival in an urban emergency medical services system. Acad Emerg Med. 2002;9:288–295.