The Stroke Revolution and Pivotal Role of EMS
Over the past 20 years, the acute care of stroke patients has progressed and improved significantly. This is due to a number of seminal events and advances, including improved brain and vascular imaging, the use of IV alteplase up to 4½ hours after stroke onset, and confirmation that clot removal using endovascular therapy can reduce major disability in some patients with large-artery occlusions. These advances mainly impact patients with ischemic strokes.
For patients with intracerebral hemorrhage, we now know the use of prothrombin complex concentrate is a safe and effective therapy to correct the anticoagulant effects of warfarin. For patients taking the direct thrombin inhibitor dabigatran, the use of idarucizumab rapidly reverses the anticoagulant effects and restores normal hemostasis. Patients with aneurysmal subarachnoid hemorrhage can be effectively treated with early surgery (in some cases), endovascular coiling and even stenting in complex cases, along with surgical clipping of the aneurysm.
A network of primary and comprehensive stroke centers provides the core facilities in which the above therapies are provided to patients with acute strokes. The challenge is that in many cases, patients with acute strokes may not be rapidly identified and/or transported to a stroke center, thereby delaying timely therapy.
This is where the opportunities and challenges for prehospital care, including EMS, come into play. While the care of patients with acute stroke is of the utmost importance to many in the EMS and neuroscience communities, the reality is that calls for stroke make up only about 1%–2% of all EMS activity. The accuracy of EMS making field diagnoses of stroke is about 50% in some large series. This is understandable, since many common stroke symptoms (slurred speech, unsteady gait, confusion) can be caused by other common disease processes.
Several recent studies have reported the accuracy of various field triage tools for distinguishing large-artery strokes from other types of strokes. These scales make up an alphabet soup of acronyms that would require a laptop computer to be functionally useful in the field. Although there is currently no consensus on the optimal scale, the larger issue is that these tools are only useful for patients with strokes. Many patients screened for stroke and EVT do not qualify, not for lack of a severe stroke but because they have not even had a stroke. The converse issue is that if EMS initially takes a patient to a hospital without sophisticated stroke services, the patient may languish there for hours and then not qualify for endovascular or other appropriate therapies. Therefore, having EMS accurately identify patients with known or suspected stroke is a critical step.
Triage based on this diagnosis is made even more challenging due to the fragmentation of EMS care throughout the U.S. This lack of uniformity makes acute care inefficient in many cases and somewhat random in some areas.
We do, however, have a nationwide network of primary and comprehensive stroke centers. Several studies have shown that patients cared for at PSCs or CSCs have improved outcomes compared to those cared for at general hospitals. However, of the approximately 5,000 acute care hospitals in the U.S., about 1,500 are PSCs, and perhaps 200 or 250 are CSCs. Thus, without some type of preferential triage, most stroke patients will be transported to facilities that aren’t stroke centers.
In cases when the diagnosis of stroke is delayed or not obvious or the patient arrives at a hospital unable to make the correct diagnosis (or provide the proper acute therapy), the clinical outcome may be less than ideal. There is a certain randomness to this, since a host of factors are at play: where the patient has the event, the sophistication of EMS resources, proximity to a stroke center, time of day, etc. It is hoped that some degree of standardization of EMS systems and operations nationwide will help mitigate some of this uncertainty.
A number of ideas are being developed to solve these issues. As you will read in the following pages and coming months, stroke registries—such as the one recently passed into law in Florida—are using big data to improve outcomes. Other technologies include field triage using iPads or cellphone audiovisual assessments, mobile stroke units and point-of-care biomarkers of acute stroke.
What is still needed is a simple and reliable tool, analogous to a 12-lead EKG used for STEMI diagnosis in the field. Until we have such a resource, we will continue to use and refine our current tools, making diagnoses one patient at a time. Either way, EMS professionals will be the leaders in this endeavor.
Mark Alberts, MD, FAHA, is physician in chief at the Hartford HealthCare Neuroscience Institute and cochair of the Brain Attack Coalition. Reach him at Mark.Alberts@hhchealth.org.