LVO stroke: How to improve EMS response and patient survival
Here's how to understand the role of EMS in unraveling the pre-puncture problem for patients with large vessel occlusive stroke
By Robert L. Dickson, Guy R. Gleisberg, Lee S. Gillum, Kevin J. Crocker, Jordan L. Anderson, Coty C. Aiken,
MCHD paramedics are dispatched for a 59-year-old male patient who appears to have suffered a stroke. Per bystander history, the patient was shopping when he complained of feeling unwell. He sat down in a chair and shortly after slumped over to his left side; he was noted to have a facial droop.
After initial assessment, his vital signs are unremarkable with the exception of hypertension 170/98; his capillary blood glucose is normal; and per his family, there is no report of seizure, substance abuse or any trauma prior to his onset of symptoms.
A Rapid Arterial Occlusion Evaluation score is calculated at eight. Stabilization and rapid transport are initiated along with a stroke alert to the nearest primary stroke center.
On arrival the patient is taken directly to CT scan and diagnosed with suspected ischemic Large Vessel Occlusion stroke; tPA is initiated and an immediate transfer to a comprehensive stroke center is arranged for intra-arterial therapy.
After returning to the station, a discussion ensues regarding their decision to transport to a primary stroke center rather than a comprehensive stroke center 10 miles farther.
Stroke assessment and severity
The effectiveness of mechanical intra-arterial therapy procedure is very time sensitive with diminishing clinical outcomes as onset to treatment time increases. This time-to-therapy issue is a driving force for EMS systems to be an integral part of the solution of how appropriate patients are identified, assessed and expedited to receive the procedure.
This issue has been coined the "pre-puncture problem." Montgomery County Hospital District EMS and our hospital partners struggle to find the best solution.
MCHD is a non-fire based EMS service in Montgomery County, Texas. We respond to approximately 58,000 calls for service and identify stroke in over 500 patients per year. MCHD covers a 1,100-square-mile service area and has 190 medics, 900 EMTs among 15 first responder organizations.
At present, MCHD uses the South East Texas Region Advisory Council tool for identification and severity grading of stroke patients. The SETRAC tool uses a diagnostic component to identify stroke and a stroke severity component. The severity component serves as a guide to deciding a transportation destination of primary versus comprehensive stroke center.
Stroke identification: Signs and symptoms
To determine the presence of a stroke, prehospital providers look for one or more signs of a stroke.
- Sudden unilateral facial drooping/weakness.
- Sudden unilateral arm weakness.
- Sudden unilateral decreased grip strength.
- Sudden difficult speech/aphasia.
If a patient has one or more stroke signs, a stable airway and blood glucose level of greater than 60 mg/dl, the stroke severity is assessed to decide if a patient should be transported to the closest designated primary stroke center or to a comprehensive stroke center.
A) Patient has one or more of the following:
1) GCS less than 9
2) Asymmetric pupils
3) Sudden severe headache w/no known cause
4) Severe one-sided weakness or RACE ≥ 5
B) Diversion to comprehensive stroke center would NOT extend transport time by more than 15 minutes
Current evidence for therapy in LVO stoke includes mechanical thrombectomy in addition to tPA for eligible candidates. At MCHD we have added the RACE score to our prehospital guideline for assessing stroke signs, symptoms and severity. We are gathering data to validate our current guideline and examine the performance of RACE in identifying LVO.
Why EMS Matters to stroke care
EMS is involved in approximately three-quarters of strokes treated in the U.S. and is associated with decreased onset-to-treatment times and improved clinical outcomes .
The American Heart Association recommends door-to-puncture times of 120 minutes or less. However there is published expert opinion that the goal should mimic the 60-minute golden hour in trauma care .
The NAEMSP position statement on this matter has this to say.
"EMS systems and medical directors should develop local or regional strategies for triaging, treating and transporting patients with acute stroke symptoms. Each system should identify centers capable of treating acute LVO stroke patients and outline criteria for patients who should be transported to them."
Some of the best practices identified in the Target: Stroke recommendations are directly affected by EMS.
A reliable method of EMS pre-notification is crucial to give the receiving facility opportunity to activate a stroke response. This notification appears inconsistent and does not occur in about 25 percent of EMS stroke cases .
One way your EMS system can achieve best practices for stroke care is through coordination and guideline development with the stroke-ready hospitals in your area of responsibility. A systemized approach that includes the Target: Stroke best practices, listed below, demonstrates improved time to therapy in both stroke and STEMI.
- EMS pre-notification
- Stroke toolkit
- Rapid triage protocol and stroke team notification
- Single call activation
- Transfer directly to CT
- Rapid acquisition and interpretation of brain imaging
- Rapid laboratory testing (POC)
- Pre-mix tPA ahead of time
- Rapid administration of tPA
- Team based approach
- Prompt data feedback
Pulsara Stop Stroke is a mobile application to help systems improve performance in acute care coordination for STEMI and stroke. In previous reports, there was observed improvement in door-to-needle times in stroke of 28 to 46 percent, and 1.5 to 3.7 times improvement in the percentage of patients receiving therapy within the recommended 60 minutes or less [4-7].
There is ongoing research in a large EMS system in Florida to implement the app and measure improvement in care of LVO stroke patients . Whether your system opts for a mobile technology solution or a robust set of guidelines to coordinate the stroke systems, any solution should include appropriate assessment, EMS pre-notification, patient transfers, follow-up of clinical outcome and performance for continual quality improvements.
Best transport destination
Should the 59-year-old male with stroke symptoms and hypertension have been diverted to a comprehensive stoke center? If not, is there a process that could allow rapid transport to primary stroke centers with immediate transfer and parallel activation of a comprehensive stroke center when LVO is identified?
At MCHD we have a process to address this question built into our clinical guidelines. However, we have struggled with the performance of our existing tool in identifying LVO and appropriate disposition.
We are evaluating our process for identifying LVO and assessing the performance of the RACE score with the Validation of Integrating A Stroke Algorithm study. We expect to report preliminary results in late 2016.
Take home points on stroke
Here are four important take-home points for EMS providers and agencies on the assessment and treatment of stroke.
- EMS identification and disposition to a capable facility in suspected LVO strokes is crucial for improved onset to therapy times and patient outcomes.
- At present the Rapid Arterial Occlusion Evaluation is the best tool for EMS to identify LVO stroke.
- Implementing Target: Stroke best-practices guidelines improves patient outcome.
- Mobile technology is evolving to implement most of the Target: Stroke best-practice guidelines
About the authors:
Dr. Dickson is an assistant professor of emergency medicine at Baylor College of Medicine in Houston Texas. He serves as EMS medical director of Montgomery County Hospital District EMS and is board certified in emergency medicine. His academic interests include stroke, acute care coordination and resuscitation.
Guy R. Gleisberg, MBA, BSEE / Bio-Medical , NREMT-B, works for Montgomery County Hospital District EMS and the Baylor College of Medicine, Section of Emergency Medicine.
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