Target: tPA

      Since 1963, local governments in Japan have had to establish emergency medical services. These governments manage fire stations as part of their emergency medical systems, and anyone can call an ambulance free of charge by dialing 1-1-9. Most governments use a one-tier system: Usually, the fire department dispatches the EMS team in an ambulance after receiving an emergency call. However, in some areas another ambulance, carrying a team that includes a doctor from a local hospital, may also arrive at the scene.

   In Japan, medical facilities are divided into three categories (primary, secondary, tertiary) from the standpoint of emergency care. Primary emergency medical facilities receive patients who are not in serious condition--who can walk in for treatment and do not need hospitalization, such as patients with flu or diarrhea. Secondary medical facilities receive patients who cannot walk on their own and need hospitalization, but who are not in critical condition, such as those with pneumonia, appendicitis or fractures. Tertiary medical facilities, such as lifesaving emergency centers, receive patients in critical conditions, such as patients in shock, unconsciousness, hypoxia, acute myocardial infarction or with severe multiple trauma.

   When a central fire station receives an emergency call, the nearest substation dispatches an EMS team in an ambulance. The EMS team consists of three members: one driver and two emergency medical technicians and/or emergency lifesaving technicians. Emergency lifesaving technicians can secure airways with instruments, secure peripheral venous access and administer 1 mg of epinephrine intravenously for patients with cardiopulmonary arrest after obtaining permission from doctors by telephone. When the EMT team accepts a patient into an ambulance, they must select and transport to a medical facility that agrees to treat the patient. The medical facility can deny acceptance of the emergency patient for various reasons: All beds are fully occupied, they have no specialist for the patient's problem or the physician on duty is too busy to treat any other patients. In this case, the EMT team cannot move until they can find a medical facility that agrees to receive the patient.

   Recombinant tissue plasminogen activator (tPA) can dissolve thrombi during an ischemic stroke. tPA must be administered intravenously within the first three hours of the event to reduce the mortality and morbidity of cerebral ischemia.¹ Accordingly, early detection, dispatch, delivery and location are important in the prehospital setting.²

   Although stroke mortality is decreasing in Japan, it is still the third-leading cause of death, and the number of patients with strokes is increasing as the population ages.³ tPA could not be used for ischemic stroke until 2005, when it was approved by the Ministry of Health, Labour and Welfare. In 2007, guidelines for the prehospital management of stroke were published by the Japanese Society of Emergency Medicine, to which most Japanese emergency medical services belong. Due to a lack of stroke specialists in many communities, some hospitals cannot be prepared to provide intravenous thrombolytic therapy around the clock, and time lost transporting patients to tertiary centers may mitigate the benefits of thrombolysis.⁴ Accordingly, candidates for tPA with ischemic stroke should be transported directly to a proper medical facility.

   The difficulty of clinically diagnosing stroke in the prehospital and primary care settings has been evaluated;^5,6 however, the quality of prehospital management provided by the emergency medical system has not. Therefore, our study investigated whether local EMS provided proper management of candidates for tPA for ischemic stroke.

METHODS

   For the study, we retrospectively reviewed transportation records written by EMTs from January to December 2007 that described the characteristics of prehospital management for ischemic stroke patients in the Tokorozawa city fire station in the Saitama prefecture. All patients who were transported by EMS and received diagnoses of ischemic stroke from physicians after admission to hospitals were eligible for the study.

   The EMS of the Tokorozawa city fire station has one central station and five substations, with about 70 EMTs (including emergency lifesaving technicians) and eight ambulances. The Tokorozawa city fire station is medically controlled by the National Defense Medical College, which is located in the same city. There are about 340,000 people and 20 hospitals in this area. Of these, only three hospitals--and four others near Tokorozawa--can provide tPA therapy. When the central station receives an emergency call, the nearest substation dispatches an EMS team in an ambulance. After checking the patient, the head of the EMTs selects a hospital for delivery after obtaining permission to transport the patient to the hospital.

   After use of tPA was approved, all EMTs in the Tokorozawa city fire station attended lectures concerning the indications for it and the hospitals that could provide tPA therapy. They had learned methods of stroke evaluation in training school, being educated that patients who had lost consciousness and/or had focal neurological deficits such as hemiparesis, aphasia or dysarthria, similar to the Cincinnati Prehospital Stroke Scale, and an onset of symptoms within two hours should be transported to a hospital where they can undergo emergency CT examinations, tPA therapy and neurosurgical treatment. In addition, EMTs are practically educated by physicians after transporting patients by reviewing tomography results. Further, EMS examination symposia--case studies of problem patients transported by EMTs--are regularly performed in the Tokorozawa city fire station to help improve prehospital care and management. These contents are published on computer disk so every EMT in Tokorozawa can inspect them.

   The primary aim was to investigate whether candidates for treatment of ischemic stroke with tPA were transported to hospitals where they could receive tPA therapy. In this study, the definition of a candidate for treatment for acute ischemic stroke using tPA was a patient with a new symptom induced by ischemic stroke, a duration from onset to first call under 90 minutes, age under 76 and Japan Coma Scale (JCS)⁷ score under 100 (JCS is the standard scale for evaluation of consciousness disturbances by EMS; see Figure 1). If a tPA candidate was transported to a hospital that could provide tPA therapy, it was judged to be a favorable result. The average duration from door (arrival at hospital) to drug (tPA infusion) in Japan is one hour,⁸ and the average duration from first call to hospital door in Tokorozawa is over 30 minutes. Therefore, 90 minutes was chosen as the target window for administration of tPA.

   Among eligible subjects, we analyzed age, sex, past history, JCS, Kurashiki prehospital stroke scale (KPSS) score,⁹ duration from onset to first call, the medical facility to which the patient was transported, and the duration from onset to arrival at hospital. The KPSS was constructed using four items, including consciousness level, consciousness disturbance, motor weakness and language, with scores ranging from 0 (fully neurologically intact) to 13. The KPSS can identify stroke patients and also assess stroke severity. The KPSS correlates well with National Institutes of Health Stroke Scale and is widely used in prehospital EMS in Japan.

   The data are presented as the mean ± standard error.

RESULTS

   There were 157 ischemic stroke cases that underwent emergency ambulance transport by the Tokorozawa Fire Department. The average duration from onset to arrival at the hospital was 38.3 ± 11.9 minutes. The average age was 74 ± 10 years. The patients included 94 males (60%). Hypertension was the most frequent prior medical condition among the subjects (30%). The JCS showed 86 patients with scores of 0 (clear consciousness), while 51 were 1-3 (spontaneous eye opening with disorientation), 13 were 10-30 (eye opening by stimulation) and 7 were 100-300 (closed eyes to any stimulation; coma). The average KPSS was 4.7. The frequency of duration under 90 minutes from onset to first call was 48%, and there were 32 tPA candidates (20%) based on age and consciousness level.

   Among the 32 tPA candidates, 29 were transported to hospitals where they could receive tPA treatment, a neurosurgical operation and rehabilitation. The remaining three were transported to a local hospital where tPA treatment was impossible. Two of those three were denied receiving by multiple hospitals that could provide tPA therapy because all those hospitals' beds were occupied, and one patient was ordered by a physician who treated the patient as an outpatient and lacked sufficient knowledge of the indications for tPA. These three cases were recommended by EMTs for transport to hospitals that could provide tPA therapy.

DISCUSSION

   In this area, ischemic stroke candidates for tPA were appropriately selected by EMTs for transport to hospitals that could provide tPA therapy.

   Prehospital care of stroke patients depends on adequate EMS education and evidence-based protocols.¹⁰ In this area, EMTs learn the methods of stroke evaluation in an education curriculum when they obtain qualification as EMTs in training school. In addition, Tokorozawa Fire Department provides information to EMTs on the indications for tPA and hospitals that provide tPA. Furthermore, EMTs routinely receive instructions concerning stroke patients based on results of head CTs at the hospitals where the EMTs deliver the patients. Finally, physicians in a medical control system retrospectively check transports performed by the EMTs, and discuss problem cases with them monthly at EMS examination symposia most off-duty EMTs attend. Tokorozawa EMTs surveyed regarding the importance of education in order to maintain and improve their skills in carrying out prehospital care for stroke victims found obtaining information from the fire station on the indications for tPA and the hospitals that provide tPA, on-the-job training based on the results of head CT scans and sharing knowledge by participating in EMS examination symposia beneficial. Having such educational programs in this area might therefore contribute to favorable results in the prehospital treatment of stroke victims.

   One weakness of this study was that it was not possible to investigate EMTs' diagnoses at scenes, because they were not recorded on the transportation records. Accordingly, many overtriaged cases for ischemic stroke may have been transported to hospitals providing tPA therapy. However, it is difficult to make a precise diagnosis of stroke in the prehospital setting, and the most important thing is to avoid undertriage of tPA candidates. Thus overtriage is unavoidable.^11,12

   Another weakness of this study was the absence of controls, such as comparison to an area without education and/or protocols in this arena. Such a control would have been useful in comparing the results of transportation. Further studies are warranted to demonstrate the significance of current education and/or protocols.

CONCLUSION

   In this area, ischemic stroke candidates for tPA were appropriately transported to hospitals that could provide tPA therapy. Therefore, providing EMTs with sufficient education on stroke evaluation, self-instruction based on case studies of the results of head CTs, knowledge and understanding of acute stroke management through conferences, and instruction on the indications for tPA treatment and hospitals that can provide tPA therapy might lead to favorable results.

Figure 1: Japan Coma Scale Scoring

0: Clear

1: Almost fully conscious

2: Unable to recognize time, place and person

3: Unable to recall name or DOB

10: Rousable by being spoken to but reverts to previous state if stimulus stops

20: Rousable with loud voice but reverts to previous state if stimulus stops

30: Rousable only by repeated mechanical stimuli

100: Unrousable using any forceful stimuli but responds to avoid the stimuli

200: Unrousable using any forceful stimuli but responds with slight movements, including decerebrate or decorticate postures

300: Unrousable using any forceful stimuli and does not respond at all

References

1. Lopez-Yunez AM, Bruno A, Williams LS, Yilmaz E, Zurrú C, Biller J. Protocol violations in community-based rTPA stroke treatment are associated with symptomatic intracerebral hemorrhage. Stroke 32: 12-16, Jan 2001.

2. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Part 9: Stroke. Circ v112: IV-111-IV-120, 2005.

3. Ma E, Takahashi H, Mizuno A, Okada M, Yamagishi K, Iso H. Stratified age-period-cohort analysis of stroke mortality in Japan, 1960 to 2000. J Stroke Cerebrovasc Dis 16: 91-102, 2007.

4. Switzer JA, Hess DC. Development of regional programs to speed treatment of stroke. Curr Neurol Neurosci Rep 8: 35-42, 2008.

5. Fischer CE, Barnung S, Nielsen SL, Rasmussen LS. Prehospital identification of stroke--room for improvement. Eur J Neurol 15: 792-6, 2008.

6. Ng CL. Diagnostic challenge--is this really a stroke? Aust Fam Physician 35(10): 805-8, 2006.

7. Ohta T, Kikuchi H, Hashi K, Kudo Y. Nizofenone administration in the acute stage following subarachnoid hemorrhage. J Neurosurg 64: 420-6, 1986.

8. Inatomi Y, Yonehara T, Hashimoto Y, Hirano T, Uchino M. Pre-hospital delay in the use of intravenous rt-PA for acute ischemic stroke in Japan. J Neurol Sci 270: 127-32, 2008.

9. Kimura K, Inoue T, Iguchi Y, Shibazaki K. Kurashiki prehospital stroke scale. Cerebrovasc Dis 25: 189-91, 2008.

10. Brice JH, Evenson KR, Lellis JC, Rosamond WD, Aytur SA, Christian JB, Morris DL. Emergency medical services education, community outreach, and protocols for stroke and chest pain in North Carolina. Preh Emerg Care 12: 366-71, 2008.

11. Kilner T. Triage decisions of prehospital emergency health care providers, using a multiple casualty scenario paper exercise. Emerg Med J 19: 348-53, 2002.

12. Sherck JP, Garland A, et al. Validation of a prehospital trauma triage tool: A 10-year perspective. J Trauma 65: 1,253-7, 2008.

   Youichi Yanagawa and Toshihisa Sakamoto are emergency physicians with the Department of Traumatology and Critical Care Medicine, National Defense Medical College in Tokorozawa, Saitama, Japan.

   Kazuo Koyama and Jihei Ohkawara are EMTs with the Tokorozawa City Fire Department, Saitama, Japan.