Chest Pain and Validity of an Emergency Medical Dispatch Algorithm

Abstract

Chest pain is a unique symptom in medical narration because the underlying cause can vary from mild acidity to massive Acute Myocardial Infarction also known as heart attack. Medical dispatching today is geared towards patient safety however too many Advanced Life Support (ALS) responses are made due to protocol of following every chest pain call. These ALS responses lead to inefficient use of community resources. Computerized dispatch protocol integrated with the dispatch station can achieve same level of patient safety with better utilization of Emergency Medical System (EMS) resources.

Objective

The objective of our study was to test the ability of our advanced chest pain medical dispatch algorithm. This algorithm outlines a system aimed at maintaining patient safety with better utilization of resources.

Methodology

A Literature search was performed and we developed a criteria based dispatching system which is a modification of dispatch protocol system developed by King County Seattle. This four level response algorithm was developed at UAB and incorporated into the Intergraph Computer Assisted Dispatch (I/CAD) system deployed at research test bed of NLM funded Advanced Networking Infrastructure for Health and Disaster Management project. Medical necessity criteria were developed based on current medical facts to support the sequence of caller questioning. Dispatch decisions and records of new algorithm were reviewed to determine safety and efficiency of four level response system. Twenty simulated emergency cases and their presentation to Emergency Department were prepared and reviewed by emergency medicine experts at UAB. Experts provided differential diagnosis and indicated preferred mode of transport to the hospital for each simulated case. This served as Gold Standard (GS) for our study. Based on ED records, loose scripts were prepared and randomly distributed to actors who presented as 911 callers. The medical dispatcher questioned the caller using structured format of protocol while callers used the script provided to them. All the calls and dispatch decisions were recorded in I/QA module of I/CAD system.

These record sets were compared to GS of emergency medicine experts to measure safety and validity of chest pain algorithm.

Results

1. ALS sensitivity of the system; 88.23%

2. ALS specificity of the system; 66%

3. Positive Predictive value (PPV); 93.75%

4. 16 out of 20 cases (80%) were dispatched an ALS response by new algorithm compared to 85% ALS response by the GS.

5. 15 out of 20 responses were dispatched with a paramedic on board by ED physicians and out of these 9 responses were same with new dispatch algorithm. Concurrency rate for ambulance with paramedic determined to be 60%.

6. Three cases were correctly identified by our dispatch algorithm requiring ‘just transport’ when compared with GS.

7. The new dispatch algorithm needs improvement in the area of managing non-MI urgent chest pain conditions. Spontaneous pneumothorax was one condition that was inappropriately managed by our system.

Conclusion

Computerized, multilevel dispatch system can be used to balance safety of an individual with cost effective deployment of resources of the community. The chest pain dispatch protocol had high sensitivity and high PPV. For some scenarios it appears to be safe alternative for traditional resource intensive dispatch system. Further controlled studies and clinical trials are needed to establish safety in a live environment.