A research study of emergency medical incidents in San Francisco found that dispatchers using emergency medical dispatching (EMD) instructions devised by Priority Dispatch Corp. sent out emergency units to seven reports of cardiac arrests for every one incident that turned out to be a true cardiac event. The study covered over 100,000 patients during an 18-month period starting in 2008, and was intended to determine how finely-tuned the EMD protocols were for identifying cardiac incidents. If a questioning protocol is too narrow, it might miss real cardiac events, while a broad protocol would waste valuable EMS resources by sending units to non-cardiac events. According to lead researcher Nicholas J. Johnson, previous studies have found that medical priority dispatch systems (MPDS), “identify most but not all urgent calls with a considerable degree of overtriage.” Johnson cited previous studies of MPDS accuracy, one reporting 36 percent accuracy in identifying a cardiac incident during dispatch, and another reporting 99 percent accuracy.
Hoping to more accurately study the issue, Johnson surmised that comparing the number of dispatches for each cardiac arrest to actual events might be a useful way to quantify the degree of mistriage and to help optimize the EMD protocols.
Besides the 7:1 average ratio for the overall “cardiac/respiratory arrest” protocol determinant, Johnson found varying results for sub-groups: ineffective breathing was 120:1, working arrest/not breathing was 4:1, and obvious death was 11:1.
After analyzing the results, he said the research results support the notion that, “dispatchers using EMD struggle to diagnose cardiac arrest.” The results also raise questions about the usefulness of multiple cardiac arrest determinants and subgroups in the MPDS, Johnson wrote in the study.
The study was just published in the latest issue of Resuscitation magazine, and is available on-line for a fee from Elsevier.
2 comments… add one
While the study likely does accurately reflect true life, our dispatchers can only make decisions based on what is being told to them by the callers. We do not ask them to diagnose, we ask them to assess the symptoms as reported by the caller and make a response decision based on that information. The study needs to take into consideration that our dispatchers are not on the scene, they are remote to the incident.
You could take the same study for emergency rooms and see that in most cases when a person calls an emergency room to see what they should do, they are advised to just go to said emergency room for help. No other assistance is provided over the phone.
MPDS systems are in place to provide a standard for all to follow, it will give a caller assurance that no matter where they may call 911 from. If anyone is expecting a more accurate diagnosis based on information gathered from a very short phone call, they we need to change our system and have Doctors answering the calls, and even then they would not be able to make an accurate diagnosis more than 30% of the time.
This is very interesting. The agency I work with is doing a similar study, performing increased QA/QI audits on incidents that come in NOT as a cardiac arrest, but are in fact, a cardiac arrest upon the arrival of a medical responder. These include reports of persons unconscious or having seizures. As per the protocols, a person unconscious with unverifiable breathing (2nd party) as well as those having seizures where breathing cannot be verified when the seizure is over, are to be considered to be in cardiac arrest until proven otherwise. Some EMDs, erring on the side of doubt, send them out… the 2nd part is not to be in doubt so much. Even when a caller states they are calling about someone who “can’t breathe,” in case entry after confirming the patient is unconscious, there is an opportunity to use diagnostic tools to confirm the effectiveness of breathing. If nothing else, stay on the line with the caller, follow the correct links in the protocols and ensure the airway is maintained through pre-arrival instructions. EMDs should not be hanging up on callers when the patient they are dealing with is unconscious. As well, throughout the call process, there are opportunities to reconfigure responses as appropriate (and per local protocol). EMDs also should not be diagnosing anything; so it would add to the struggle to add more determinants to decipher. What is needed, after such a study, is continuing dispatch education of EMD matters and a reiteration of standards.
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