Article updated November 13, 2017
The long history of providing EMS to communities began with programs that provided safe, rapid and high-quality care for victims of major injury and cardiac illnesses. In about 50 years of addressing emergency medical needs, there has been a wide variety of tools developed to improve identification of these patients.
The 12-lead EKG monitor has proven to be a landmark addition to the EMS toolkit as the critical diagnostic aid to provide care in the field, guide transport to the most appropriate hospital for acute heart conditions and allow notification of the hospital so that emergency staff can be prepared.
The 12-lead EKG monitor can also identify a variety of other heart problems, rhythm abnormalities and cardiac injuries. Its addition serves as the basis for updating EMS protocols to improve the care of patients suffering many types of acute cardiac events.
Most importantly, the 12-lead EKG is the only tool to identify a patient with an ST elevation myocardial infarction (STEMI). Not all hospitals provide acute treatment interventions for this condition, so the crucial EMS role is to identify patients with that disease and then, if possible, transport the patient for an immediate intervention. There are many outstanding cases of EMS personnel identifying the patient having an MI, communicating that condition to the emergency department and helping move the patient to the cardiac lab.
percutaneous coronary intervention (PCI) is the procedure to restore flow to occluded coronary arteries for patients with STEMI, and it is well-established as the preferred treatment strategy. Shortening the time interval between onset of the MI and restoration of infarct artery flow (reperfusion) reduces mortality and preserves heart muscle. EMS systems across the United States are organized to facilitate rapid transport of STEMI patients directly to PCI-capable hospitals.
The EMS portion of the STEMI care system
It is getting harder and harder to recognize the patients who are having an acute MI.
The patient with an acute MI presenting with classic symptoms is rare. Many patients with an MI may NOT report having chest pain. Instead, their chief complaints include:
- “Discomfort” between the jaw and the inguinal area
- Shortness of breath
- “Indigestion”
- Syncope
- Unexplained diaphoresis
- Palpitations or unexplained cardiac rhythm abnormality
- Profound weakness
- Dizziness
- An altered level of consciousness
The 12-lead EKG monitor, therefore, serves a crucial role in the EMS evaluation.
A history must be obtained for any history of cardiac diseases, diabetes, hypertension, prior abnormalities known to the patient and whether he or she has had an EKG performed in the past. The physical exam should include vital signs and evidence of any trauma or other obvious cause for the discomfort the patient is having.
EMS protocols in systems with 12-lead EKG capability will include the use of that tool in patients with the above complaints. It is critical to understand that the three-lead cardiac rhythm monitor is NOT the tool to use to look for cardiac ischemia; it is for rhythm interpretation only.
As with any procedure that involves potential exposure of the patient and physical contact, take care to explain the procedure to the patient and obtain permission to remove or displace clothing as necessary to apply the electrodes.
When possible, perform the procedure with the assistance of a second provider so that a witness is present to verify the appropriateness of physical contact.
Ask the patient if he or she knows of abnormalities on any EKGs done in the past. The patient with extant heart problems will often have valuable information.
Current 12-lead EKG machines provide a variety of outputs to the EMS providers. Most monitors will print off a hard copy of the EKG, along with an interpretation provided the machine software’s sophisticated algorithms.
When the machine provides an interpretation of the electrocardiogram, it will add to the paramedic’s analysis. Some machines will transfer the EKG to the local designated cardiac hospital, and some will transfer it to the cardiologist directly.
A computer EKG interpretation of “acute MI” or similar language will usually activate a specific treatment and transport protocol, which usually specifies that EMS transport the patient to the nearest PCI center if it is timely; that patient may be bypassing a closer non-PCI facility.
The protocols also should say that the EKG interpretation and past medical history need to be shared with online medical direction. An EKG transmission system may supplement this by sending the image to the hospital and/or the cardiologist.
With the correct activation, the hospital can immediately activate the PCI intervention system. A patient with a suspected or definitive MI will be managed and transported to the appropriate ED, with the ED staff directing care from that point.
If a patient is PCI-ready, EMS personnel may be asked to move the patient on the EMS stretcher to the lab, with guidance from the hospital staff. In some cases, the patient may pause in the ED to have a portable chest X-ray, registration and patient ID applied and blood drawn.
EMS providers need to perform and interpret the 12-lead EKG in light of the patient’s past medical history and chief complaint. A normal prehospital EKG does not mean there isn’t a heart problem. It is wise to communicate to the patient that the EKG, along with any additional tests, will need to be read again by the emergency physician. Hospital personnel often have access to prior EKGs, key information for interpreting the present one.
The 12-lead EKG improves prehospital treatment. It also yields improved documentation of patients’ conditions, leaving a copy of the EKG for the hospital and one to submit with the written or electronic patient care report. Finally, the 12-lead EKG monitors EMS system performance — on correct patient selection, proper and timely transport, correct EKG reading and appropriate communication.
