Emergency Medical Dispatch: The True First Responder

Each year, an estimated 240 million calls are made to 911 by patients or bystanders for the full range of emergencies.1 For the majority of callers, it is their first interaction with the emergency medical services (EMS) system.

At the other end of the call is often a specially trained call-taker who is referred to as an Emergency Medical Dispatcher (EMD).2 Without ever seeing the patient or the scene, these individuals are tasked with identifying the complaint, triaging the patient’s severity, and providing pre-arrival instructions to callers.2,3 Historically, these providers were overlooked as key links in the EMS and emergency health care system, leading to low standards, poor funding, and inadequate training.2 However, the expertise of EMDs, together with their calm demeanor and guiding nature, has led to improvements in patient outcomes.

Emergency medical dispatching, similar to other aspects of EMS, is a relatively new concept. In the 1970s it was recognized that calls for emergency medical help were on the rise and systems needed to be developed to deploy resources appropriately. In 1978 Salt Lake Fire/EMS identified the dispatcher as the "weak link" in the chain of survival.4 It wasn't until the 1980s that the first structured EMD protocols and training started to be adopted. Service providers wanted to send the right resource, to the right person, for the right complaint, and provide direction prior to that resource’s arrival. Even today, the availability of EMD is not standardized and different answering points may deploy different avenues for emergency response.

The Call
Generally, in the United States, once a prehospital emergency becomes apparent, most patients gain access to the emergency medical system by dialing or having a bystander call 911. These calls are routed to a designated Public Safety Answering Point (PSAP). The first priority of the call-taker is to determine the nature of the emergency; in other words, are police, fire, or EMS assistance needed? The first immediate challenge can be determining the location of the emergency. This can be difficult as callers may not know their location, cell phones may ping a tower that is outside the jurisdiction of the local PSAP, or automatic location technology (E911) may be inaccurate.5 However, call-takers are trained in dealing with this challenge and can promptly help callers identify their location and then direct the appropriate first responders to the closest location.2

Once the nature and location of the emergency has been confirmed, the call-taker's responsibility turns to identifying the chief complaint, age, level of consciousness and breathing status of the patient.2 Challenges quickly arise as callers may not fully understand or may not be able to describe effectively a patient's condition. For example, a patient with altered mental status may be having a stroke, toxic exposure, metabolic emergency, or hypoxia. Therefore, many agencies choose to employ a standardized interrogation of the caller designed to elicit key information that allows the chief complaint to be categorized as one of 33 standard chief complaints.2 An example of this approach is known as the Medical Priority Dispatch System (MPDS).

MPDS is a set of protocolized decision tools designed to allow the identification of the complaint, determine the appropriate resource response, and provide pre-arrival instructions.3 The system involves use of a computer-based script that helps the call-taker guide the caller through a series of yes/no questions. Depending on the answers, the call-taker is prompted to ask different follow-up questions.

The process begins by asking the patient’s age and chief complaint followed by "Are they conscious?" and then "Are they breathing?"2 If the answer is "no" to both of these questions, the call-taker determines that the patient is likely in cardiac arrest and will require the highest level response ("ECHO") as well as pre-arrival instructions for the caller to perform bystander cardiopulmonary resuscitation (CPR). This results in the simple concept of "no-no-go," resulting in earlier CPR, which has been proven to be one of the main mitigating factors that can positively influence the outcome of an out-of-hospital cardiac arrest6. Otherwise, if the answers are "yes," the call-taker continues to ask questions per the algorithm, ultimately sending the appropriate response, giving pre-arrival instructions to the caller on basic medical care, making the scene easy for responders to find, and mitigating on-scene safety concerns.

There are several other obstacles that call-takers must overcome when gathering information about an emergency. In addition to the caller not knowing the exact location of the patient, panic or refusal by the caller to provide pre-arrival care are common challenges.2,3 EMDs are trained to overcome these obstacles using techniques such as repeatedly asking the same question and reassuring callers that help is on the way even as they speak.3 This particular type of dispatch is known as horizontal dispatch, which refers to the call-taker continuing to gather information from the caller while a second EMD simultaneously dispatches response units.2

Pre-arrival Instructions
From the time the call is dispatched to the time the first unit arrives on scene, the EMD plays an important role in providing pre-arrival instructions (PAI). These are a set of medically approved, standardized, and protocolized instructions given to a layperson by EMDs.2 A study by Billittier et al found that callers expect instructions to be given while waiting for responders to help mitigate the situation.7 PAI incorporate components of Dispatch Life Support (DLS) and have been shown to effectively prevent further mortality and morbidity during the response phase of EMS.2 Examples include opening the airway, cooling burns, removing dangerous objects from around the victim, and administering certain medications. One of the first instances of PAI took place in Phoenix, Arizona, in 1975. In that case, a paramedic in the dispatch center gave instructions to the mother of an apneic child while EMS was en route.4 That child survived.

DLS focuses on the most time-sensitive medical emergencies such as acute myocardial infarctions, stroke, trauma, and cardiac arrest. Cardiac arrest victims are the most time-sensitive of all prehospital patients. Without bystander CPR, their chance of survival quickly diminishes.8,9,10 Laypersons are often ineffective in locating a pulse, and they may not be able to identify agonal breathing. The risks associated with performing CPR on a patient not in arrest are significantly less than the risks associated with withholding CPR, and therefore the assumption is that the patient is in cardiac arrest.2 Dispatch Assisted-CPR or Telephone-CPR (DA-CPR or T-CPR) instructs the caller on how to perform CPR and has been associated with increased rates of bystander CPR.10 Some systems employ specific instructions on how to perform CPR along with counters or metronomes to identify inadequate breathing and ensure CPR is done at an appropriate rate.11 EMDs may also be able to identify the location of automatic external defibrillators (AEDs) and help callers properly place and use AEDs: another proven life-saving intervention.12,13

Calls to 911 for chest pain are common. One study suggests those that call 911 with chest pain may self-select and be sicker than those that transport themselves to the hospital.16 Aspirin has been shown to be the drug of choice for reducing mortality in acute myocardial infarction.17 Some call centers will identify the patient experiencing chest pain and have the patient self-administer aspirin if the caller has access to the drug.18

Stroke is difficult to identify over the phone as callers often use vague terms to describe symptoms.14 For example, a caller may dial 911 for “fall” but not recognize focal weakness. Despite these challenges, EMDs are able to correctly identify strokes with surprising accuracy.14,15 The EMD will interrogate callers for time of symptom onset, rule out common stroke mimics (eg, hypoglycemia), gather important previous medical history (eg, prior strokes), and discover pertinent medications (eg, antiplatelet agents or anticoagulants), thereby helping responders make improved triage and transport decisions.

Trauma patients are clearly also in need of prompt emergency medical care. Bleeding control and expedited transport to surgical services are mainstays in prehospital treatment of trauma. The EMD will attempt to identify the mechanism of injury (eg, gunshot wound versus fall), the severity of the injury (eg, fall from standing versus fall from height), and the timing of the injury (eg, occurring today or occurring > 9 hours ago).2 Additionally, the EMD plays an important role in recognizing life-threatening bleeding. Language that differentiates the type of bleeding (venous versus arterial) is employed by asking if the blood is “spurting or shooting” from the wound. The EMD may instruct the caller to simply apply direct pressure or even guide tourniquet placement.2 In the San Antonio Fire Department, in Texas, the first metropolitan EMS service to carry whole blood, dispatchers are responsible for determining what calls may warrant the dispatch of whole blood, which is carried by a select number of units in the city.19

Medical Oversight
Physician oversight of EMD protocols are an integral part of ensuring the quality of out-of-hospital emergency medical care. EMS Medical Directors should be directly involved in the development, review, and implementation of EMD protocols. Some protocols require input depending on local medical resources. For example, a community with limited percutaneous coronary intervention might adjust their dispatch protocols to include the placement of helicopter EMS resources on standby when chest pain is the chief complaint. Protocols will occasionally need updating as new evidence-based practices change the prehospital care plan. Quality review of protocol compliance has been shown to improve the accuracy of resource allocation and DLS implementation, which is an important part of medical direction.2

Future Developments
Improvements in cell phone technology continue to be game-changing in the initial care and triage of patients. Ideas being developed include the use of crowdsourcing responses from non-traditional responders. Programs such as PulsePoint push cardiac arrest locations to registered laypersons notifying them of a nearby cardiac arrest, thereby allowing for bystander CPR to be initiated faster.20

 A large percentage of 911 calls are made from smartphones with built-in cameras. Further developments in technology could allow EMDs and first responders to see the patient prior to EMS arrival, resulting in better triage and pre-arrival instructions to the caller. In one feasibility study, dispatchers were able to view a livestream from the caller's phone in order to decide on whether to dispatch a helicopter to the scene.21

Other ideas include incorporating augmented reality to demonstrate proper CPR, identify patient medications, and provide instructions to stop life-threatening bleeding.

Dispatcher Health and Wellness
It is important to remember that EMDs are critical members of the emergency response system. They often have to listen to extremely dynamic, heart-wrenching, and violent incidents, all while maintaining their composure and professionalism. They provide emergency medical care without being able to directly see or interact with patients. Often they are not able to find out the outcome of the patients they interact with as they have to immediately move on to the next caller.22 These factors can lead to burnout, depression, and posttraumatic stress disorder. Timely resources should be provided to EMDs, as would be provided to other first responders, including counseling, incident debriefing, and praise for jobs well done.

Emergency medical dispatching is a relatively new component of emergency medical care but is critical in order to provide effective and timely care. Dispatchers play significant roles in patient outcomes and efforts should be made to ensure all systems that provide emergency medical care have properly trained and equipped EMDs. Medical directors should regularly interact with EMDs and continue to review areas for improvement. Advances in technology will likely change the way EMDs interact with patients, leading to more efficient resource allocation, improved triage, and better pre-arrival instructions. EMDs need to be recognized as part of the emergency medical team and be supported doing their difficult and important job.


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  2. Clawson JJ, Dernocoeur KB. Principles of Emergency Medical Dispatch. Priority Press. 2003.
  3. Cone D, Brice JH, Delbridge TR, Myers JB. Eds. Emergency medical services: Clinical practice and systems oversight, 2 Volume Set. John Wiley & Sons. 2014.
  4. Zachariah BS, Pepe PE. The development of emergency medical dispatch in the USA: a historical perspective. European J Emerg Med. 1995;2(3):109-112.
  5. Lecher C. This is what happens when 911 fails: our most important lifeline isn’t always there when you need it. The Verge. Retrieved from https://www.theverge.com/2014/10/3/6414949/911-call-failures-fcc
  6. Rea TD, Eisenberg MS, Culley LL, Becker L. Dispatcher-assisted cardiopulmonary resuscitation and survival in cardiac arrest. Circulation. 2001;104(21):2513-2516.
  7. Billittier IV AJ, Lerner EB, Tucker W, Lee J. The lay public's expectations of prearrival instructions when dialing 9-1-1. Prehospital Emergency Care. 2000;4(3):234-237.
  8. Chan PS, McNally B, Tang F, Kellermann A. Recent trends in survival from out-of-hospital cardiac arrest in the United States. Circulation. 2014;130(21):1876-1882.
  9. Shah M, Bartram C, Irwin K, et al. Evaluating dispatch-assisted CPR using the CARES registry. Prehospital Emergency Care. 2018;22(2):222-228.
  10. Shimamoto T, Iwami T, Kitamura T, et al. Dispatcher instruction of chest compression-only CPR increases actual provision of bystander CPR. Resuscitation. 2015;96(1):9-15.
  11. (n.d.) Retrieved from https://youtu.be/TXN1qF367Yc
  12. Riyapan S, Lubin J. Emergency dispatcher assistance decreases time to defibrillation in a public venue: a randomized controlled trial. Am J Emerg Med. 2016;34(3):590-593.
  13. Fredman D, Svensson L, Ban Y, et al. Expanding the first link in the chain of survival–experiences from dispatcher referral of callers to AED locations. Resuscitation. 2016;107:129-134.
  14. Richards CT, Wang B, Markul E, et al. Identifying key words in 9-1-1 calls for stroke: a mixed methods approach. Prehospital Emergency Care. 2017;21(6):761-766.
  15. Viereck S, Møller TP, Iversen HK, Christensen H, Lippert F. Medical dispatchers recognise substantial amount of acute stroke during emergency calls. Scandinavian J Trauma, Resus, Emerg Med. 2016;24(1):89.
  16. Becker L, Larsen MP, Eisenberg MS. Incidence of cardiac arrest during self-transport for chest pain. Ann Emerg Med. 1996;28(6):612-616.
  17. Brener SJ, Mehran R, Lansky AJ, Ayele GM, Stone GW. Pretreatment with aspirin in acute coronary syndromes: lessons from the ACUITY and HORIZONS-AMI trials. European Heart Journal: Acute Cardiovascular Care. 2016;5(5):449-454.
  18. Barron T, Clawson J, Scott G, et al. Aspirin administration by emergency medical dispatchers using a protocol-driven aspirin diagnostic and instruction tool. Emerg Med J. 2013;30(7):572-578.
  19. Winckler CJ. (2019, October 1). Fire-Based EMS: Whole Blood Deployment. Retrieved February 27, 2020, from https://www.firehouse.com/operations-training/ems/article/21094923/whole-blood-deployment-process-blood-transfusion-san-antonio-fire
  20. Create a culture of action in your community. PulsePoint. https://www.pulsepoint.org/pulsepoint-respond/. Published September 22, 2019. Accessed March 5, 2020.
  21. Avest E, Lambert E, De Coverly R, et al. Live video footage from scene to aid helicopter emergency medical service dispatch: a feasibility study. Scandinavian J Trauma, Resus, Emerg Med. 2019;27(1):55.
  22. Soria JR. Emergency Dispatcher Vulnerabilities. OFFICE OF SUICIDE & VIOLENCE PREVENTION, 14.

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