You’ve Got Questions? Research Has the Answers

Emergency medical dispatch (EMD) practice has evolved exponentially in the last few decades. It wasn’t long ago that emergency dispatchers were answering seven-digit phone lines, recording information manually and tracking calls with punch cards. Prearrival instructions for medical callers in need were nearly nonexistent and most dispatchers were strictly clerical; they simply obtained a location and dispatched a resource. Today, sophisticated computers track, record and manage everything from the time the call is received to the time the responder(s) has cleared the call and, in some cases, patient records are added to the dispatch database. Prearrival instructions are now in widespread use and are considered a current standard of care. However, while advances in technology can explain the use of computer-aided dispatch systems, the advancement of the clinical aspect of EMD (prearrival instructions and priority dispatch practice) is less clear. This is because clinical research in this field is far less evolved as compared with traditional medicine. Even given the popularity of EMD today, with both modern communication centers and the general public, EMD is relatively unproven in the eyes of research-oriented clinicians. The lack of EMD research is likely the result of several unique factors.

Traditionally, clinicians and scholars, primarily physicians, have conducted clinical research and in a profession that has only recently been viewed as clinical, there has been little physician involvement. However, this fact is changing rapidly as medical directors today are overseeing EMS systems full-time. Emergency physician groups are advocating EMD research as the public has grown to expect prearrival instructions that are delivered safely and responsibly.

Another factor that has thwarted EMD research is the fact that established dispatch protocols have different goals than the typical on-scene clinician. Protocols attempt to provide for prearrival safety, designate an efficient and effective response allocation and mode, provide prearrival instructions and inform responders rather than provide a specific diagnosis. The misconception that EMD protocols are diagnostic has prompted attempts to compare paramedic impressions or hospital diagnosis to EMD protocol codes; because these outcomes are so vastly different, this sort of research is akin to comparing apples to oranges.

Some studies have attempted to compare patient acuity, as evaluated by clinicians or a focus group using a standardized acuity scale, to dispatch protocol codes in an attempt to validate the dispatch protocols. While the acuity scales used in these studies generally relate to patient acuity, their relationship to dispatch protocols is subjective. In other words, people, generally a focus group, must assign a range of dispatch protocol codes to the established acuity scale. This subjective assignment introduces variance that, while perhaps acceptable depending on application, restricts the validity of the study.

Variance is an important consideration. Good research is dependent upon controls that ensure the studies’ conclusions are accurate and not falsely based on an uncontrolled variable. With patients and callers out of sight, and with considerable time delays between caller interrogation and responder arrival, there are enough variables to discourage even the most determined researcher.

Perhaps the most easily controlled but often neglected variable in dispatch research is protocol compliance. Unfortunately, the vast majority of studies involving dispatch protocol have not reported compliance rates. Specifically, if compliance to the dispatch protocol is not absolute, unacceptable variance is introduced that will certainly affect the outcome of the study. If the protocol is not followed exactly, then the outcomes may be nothing more than the product of an individual’s decisions, rather than the protocol itself.

Studies that attempt to compare patient outcomes with dispatch decisions are perhaps the most useful. In other words, did the decisions made in the dispatch center affect the patient(s)? To do this, one must first consider the protocol’s purpose and then attempt to determine if the goal has been accomplished as a direct result of the protocol. For example, a primary dispatch protocol goal is to prioritize a response. That is, the protocol attempts to recommend a response that best fits the needs of the patient while conservatively considering the needs of the EMS system. The problem is, no one can seem to agree on just exactly what the patient needed before arriving at the hospital.

One commonly used control is a paramedic’s decision to transport with lights and siren. The theory is that if the paramedic chose to transport emergently, then the patient needed an emergent, typically ALS response. However, studies that use lights and siren use as a high-acuity definition are flawed, as this determination has great variability among individual paramedics. Paramedic experience, the age of the patient, traffic conditions, paramedic impression and other factors typically influence transport decisions. Because patient acuity is not the only factor, such decisions cannot accurately and consistently reflect patient acuity.

In addition to response mode, dispatch protocols also attempt to predict response allocation or resource need. A typical research question may be: Did the patient receive the right resource for the situation at hand? In an attempt to answer this, some studies have used the need for ALS vs. BLS as a litmus test. However, there is a great deal of controversy surrounding the benefits of ALS over BLS. ALS interventions, except in specific clinical situations, are not well proven as beneficial. Perhaps most important, the decision to provide ALS intervention varies from one paramedic to another.

In spite of all the drawbacks, research into EMD has produced some valid results. This is because even with the variables previously mentioned, trends have developed among multiple studies that support several hypotheses.

It seems clear that emergency medical dispatchers, using a standardized protocol in a compliant manner, can consistently identify high-acuity patients, specifically those in cardiac arrest.1,2 This should be of particular interest to any EMS agency that is interested in identifying critical patients that may benefit from an urgent response. A study in London, England, documented a 200% increase in the detection of cardiac arrest after implementation of an EMD protocol, which allowed “fast response” resources to be dispatched and arrive on scene an average of 1.3 minutes faster than if an ambulance alone had been sent.1 In areas where the demand for EMS resources is high, the early identification of high-acuity patients allows for the efficient use of scarce resources and gets prompt and appropriate help to time-critical patients.

The identification of low-acuity patients is equally as important to EMS agencies as the discovery of critical patients. Doing so allows for the safe, nonemergent response of an appropriate resource, perhaps even a referral to a more-specific resource.3 Sending only what is needed to stable patients also frees up resources that may be needed for time-critical patients. Recent research has shown that the identification of low-acuity patients is possible by identifying dispatch codes associated with low acuity.4–6 The implications of such research are enormous when one considers the volume of EMS calls in the nonemergency category. Many prehospital experts believe that less than 5% of emergency calls are actually life-threatening. If protocols can be developed that can safely triage even 25% of the nonemergent volume, the potential resource savings are staggering.

While a great deal of EMD research has been done in recent years, a tremendous void still exists. We know that certain dispatch codes can predict high- or low-acuity patients, but we know very little about the patients in between. Although prearrival instructions are the current standard of care, much work needs to be done to validate their specific influence on patients, thereby opening the door for quality improvement. The key to accomplishing this research is involvement, specifically by the nonphysicians, in the emergency dispatch profession. If EMD is to be considered a vital link in the chain of survival, then research is a responsibility to be shouldered by the EMD players who are responsible for the validation and improvement of their profession. Research is the answer, one question at a time.

References

1. Heward A, Damiani M, Hartley-Sharpe C. Does the use of the advanced medical priority dispatch system affect cardiac arrest detection? Emerg Med J 21(1):115–8, 2004.

2. Feldman MJ, Lyons D, Verbeek PR, et al. Which dispatch protocols accurately triage high acuity calls? A comparison of the medical priority dispatch system to a validated prehospital acuity score. Abstract. Prehosp Emerg Care 9(1):118, Jan–Mar, 2005.

3. Schmidt T, Neely KW, Adams AL, et al. Is it possible to safely triage callers to EMS dispatch centers to alternative resources? Prehosp Emerg Care 7(3):368–74, Jul–Sep, 2003.

4. Shah MN, Bishop P, Lerner EB, et al. Derivation of emergency medical services dispatch codes associated with low-acuity patients. Prehosp Emerg Care 7(4):434–9, Oct–Dec, 2003.

5. Shah MN, Bishop P, Lerner EB, et al. Validation of using EMS dispatch codes to identify low acuity patients. Prehosp Emerg Care 9(1):24–31, Jan–Mar, 2005.

6. Myers JB, Hinchey P, Zalkin J, et al. EMS dispatch criterias can accurately identify patients without high acuity illness or injury. Abstract. Prehosp Emerg Care 9(1):119, Jan–Mar, 2005.