Using EMD for Acute Stroke Identification - Official Academy Position Statement
Stroke could become one of the defining elements of the driving force behind prioritized EMD. In recent years, thrombolytic therapy with tissue plasminogen activator (t-PA) to break down blood clots that precipitate “brain attacks,” has resulted in new hope for people who suffer stroke.
Clinical studies have shown that, if given during the early stages of a stroke, t-PA can indeed improve outcomes for many stroke victims. The National Institute of Neurological Disorders and Stroke (NINDS), t-PA Stroke Study Group, concluded in its 1995 paper, Tissue plasminogen activator for acute ischemic stroke, “Despite an increased incidence of symptomatic intracerebral hemorrhage, treatment with intravenous t-PA within three hours of the onset of ischemic stroke improved clinical outcome at three months.”77 Appropriate t-PA administration improves the long-term outcome in a significant number of patients. Overall, t-PA treatment is beneficial, despite the fact that it does cause serious intracranial bleeding in some patients. For 11 percent of patients, if they get to hospital rapidly, and are treated by a stroke team using thrombolytic drugs, they’ll go home rather than to a long-term care facility.”78
Earlier interventions lead to improved patient outcomes (as “time is muscle” during acute MI, “time is brain cells” during stroke) and the goal should be a 90-minute time to treatment, rather than the latest acceptable treatment time of
This short window for effective intervention has led to the widespread realization that, as stated in USA Today, “People having strokes should be treated with the same urgency as those suffering heart attacks.”
Patient groups are calling for “...a major overhaul of outmoded stroke responses nationwide, upgrading stroke to a time-dependent, urgent medical emergency.”79 This publicity has led to many agencies proposing that for all requests that report stroke-like symptoms, response be upgraded to an obligatory lights-and-siren mode both to the scene and during transport of the patient.
We believe that in most situations the small time savings of a L&S response to the scene will not alone make a significant difference in stroke outcomes and that the initial response should be the same as for chest pain in the absence of symptoms which suggest the patient is arresting.
For chest pain without these symptoms, charlie (not delta) determinants drive responses for the cardiac age-range patient. We believe the similarities between stroke and acute MI warrant changes in protocol 28: Stroke (CVA), now that there is an intervention that significantly improves the outcome for many stroke patients if given soon enough.
In stroke, the situation is in many ways analogous to acute MI. Therefore, we believe there should be more parity between the stroke and chest pain protocols by upgrading the Stroke dispatch protocol to drive determinants that are similar to the charlie determinants on the Chest Pain protocol. However, protocol 28: Stroke does not warrant the delta drivers we use in protocol 10 (chest pain). These delta determinants are driven by priority symptoms that suggest the patient is arresting and requires on-scene treatment within two or three minutes.
If a patient is arresting, effective on-scene intervention (defibrillation) by first responders can make an enormous difference, but the window of opportunity is extremely short. On-scene intervention for stroke patients is still very limited and will likely remain so until the on-scene use of neuroprotective drugs can be shown to be effective. In the meantime, the existing charlie determinants do not imply that stroke (or MI without evidence of arrest) is not time-sensitive, but rather that it is reasonable to respond to stroke and acute MI without L&S and to only respond with L&S when there is evidence that the chest pain patient is deteriorating or arresting.
A stroke patient should call 9-1-1 as soon as symptoms appear, hence a need for increased public awareness and education. Pepe, et al., in their 1998 paper, Ensuring the chain of recovery for stroke in your community, point out that, “The sheer logistics of reaching and retrieving patients, even in a ‘scoop and run’ mode, leads to significant time lapses, a concept often unappreciated by those unfamiliar with the delivery of emergency patient care in the out-of-hospital setting.”80 They show that typical delivery of a patient to the ED will not take place for at least 30 to 50 minutes after a stroke is recognized by the patient or bystander. (This breaks down to 15 minutes from caller recognition to EMS-professional identification of the stroke at the scene; 10 to 20 minutes on-scene time; and 5 to 15 minutes transport time.) The NINDS guidelines: Rapid identification and treatment of acute stroke,81 recommend that a physician should evaluate a stroke patient within 10 minutes of arrival at the ED, and that a stroke specialist should be available or notified within 15 minutes. In order to avoid giving thrombolytic treatment to a patient with a brain hemorrhage, a CT scan must be done. The CT scan should be started within 25 minutes, the results available within 45 minutes, and treatment (when appropriate) started within 60 minutes.
Hunt, et al.,36 measured that a typical L&S run saves, on average, 43 seconds over a cold run. While this saving seems surprisingly small, there are other studies that appear to confirm these results.11 Even allowing for rural versus metropolitan differences, it seems likely that a L&S response is probably only saving one or two minutes over a cold response time.
In a rapid (15 to 20 minute) “scoop and run” delivery to a facility where the CT turn-around is also fast, an extra couple of minutes for a cold ambulance journey to the scene is a small, but significant, portion of the time taken before the t-PA injection-but the total time is still likely to allow treatment of patients within a 90-minute window. In a conventional ALS response and delivery (30 to 50 minutes) to a facility that does not meet the NINDS guidelines for CT scanning, the time lost by a cold response will very likely still be less than one percent of the total time and is therefore probably not alone a major source of delay.
While these time constraints do not really suggest that the “time criticality” of thrombolytic stroke treatment warrants the extra risks of a L&S response, we do need a response mode that confers the same sense of urgency without the use of lights and sirens, i.e., one that gets the patient there quickly, but without creating unnecessary hazards for emergency personnel or civilians. Stroke is indeed a time-critical medical emergency, but it is saving hours (through public education) and minutes (through ED compliance with the NINDS time guidelines) that is important, not saving seconds that can place others at unnecessary risk.
In 1996, the Academy stated, “It is the temporary position of the Academy that, at this time, no changes are necessary within protocol 28’s key questions, post dispatch instructions, or determinant codes. However, in light of changing science, we recommend the addition of a new in additional information, to state:
‘The adoption of in-hospital administration of clot dissolving drug therapies may require special assignment of units equipped to evaluate patients for this therapy in areas adopting it for trial and on-going treatment. Based on the current consensus recommendation to provide this treatment within 3 hours of the occurrence of stroke symptoms, the use of lights-and-siren (hot) responses is generally not indicated at the present time unless priority symptoms are present.’”
More recently, at the 1998 Council of Research meeting the Council recommended several additional modifications that emphasize the availability of thrombolytic treatment, but also recognized that other elements in the survival chain (such as pre-notification of stroke response teams at the receiving hospital and eliminating unnecessary ALS procedures at the scene) will have greater impact on stroke survival. Further, the Council stood by the 1996 recommendation that L&S responses are not generally indicated for stroke when priority symptoms are not present.
Since the 1998 Council of Research meeting, the Academy has continued to examine the stroke issue in great detail. For a number of reasons, the Council of Standards has now established an age-dependent triage for stroke and stroke-like symptoms. The new determinants appear as follows:
C-1 Not alert
C-2 Abnormal breathing
C-3 Speech or movement problems
C-4 Numbness or tingling
C-5 Vision problems
C-6 Sudden onset of severe headache
C-7 STROKE history
C-8 Breathing normally ≥ 35
B-1 Unknown status (3rd party caller)
A-1 Breathing normally < 35
The version 10.3 changes have been approved by the Council of Research and then were formally ratified by the Council of Standards—effective July 20, 1998.
The 10.3 changes will improve the MPDS in several ways. Statistically, the age range given would only fail to upgrade less than three percent of all strokes, and less than one percent of all ischemic strokes, to the charlie response. The recommended ALS capability of the charlie response for stroke would increase the sense of urgency when compared to the BLS capability of the current alpha response, and might even improve the patient’s reception at the ED.82 Finally, upgrading stroke to an ALS-level response sets the scene for on-site intervention when new neuroprotective drugs gain approval.
As with all MPDS determinant-driven response modes, local medical control has the final word on who, when, and how field personnel actually respond. Due to differences in response configuration options, available facilities, and local driving conditions, this situation may be somewhat different among systems. While any delay in the stroke patient’s chain of recovery is undesirable, in most circumstances the extra time taken by a cold response to the scene is a very small portion of the total (call-to-treatment) time. Stroke is a time-sensitive medical emergency and should be responded to with a sense of urgency comparable to that used in response to chest pain suspected to be due to myocardial infarction.
Therefore in the absence of additional priority symptoms, for both Chest Pain and Stroke the Academy recommends dispatching an ALS-level response without the use of L&S (see “Response Determinant Methodology” protocol). As more data on thrombolytic treatment becomes available, the precise nature of t-PA’s time criticality will become clearer. For now, it appears that the benefits of the small time savings of an L&S response may not outweigh its additional risks.
Fig. 6-15. Priority dispatch evolves to accommodate changes in treatments and accepted standards of care. Stroke management has recently undergone radical changes due to the introduction of thromolytic therapies. This position statement presents the rationale for changes to the MPDS first released in version 10.3 (now updated to v11.2). “Using EMD for Acute Stroke Identification,” by Sinclair, R. and Marler, J. Reprinted from the JNAEMD.83