Advanced Diagnostics of Acute Stroke (Biomarkers, Blood Analysis, Stroke Scales and Cerebral CT Examinations) and Initiation of rtPa Treatment in an Air Ambulance Model

Treat-NASPP is a prospective controlled intervention study. The main aim of this study is to prospectively compare patients with ischemic stroke (IS) who are diagnosed and treated prehospitally in the MSU (intervention), with those who receive conventional pre- and inhospital diagnostics and treatment (control). At the same time we will do an explorative study with the aim to further improve diagnostic- (the biomarker study) and outcome measures (the biomarker study and MRI infarction volume study). The MSU will be staffed with an anaesthesiologist, a paramedic-nurse and a paramedic while on call. On the weeks the MSU is not operating, the data collection will take place from the conventional ambulance on weekdays from 8 am to 8 pm. Only ambulances staffed with the paramedic-nurse and paramedic that work as staff on the MSU will participate in the study. All emergency calls to the central EMS dispatch center (AMK 113) from the catchment region of Ostfold county will be screened for stroke symptoms by the EMS dispatcher according to normal procedures: they will use the FAST scale (one or more of the following neurological deficits: paralysis of arm or leg, facial paralysis, aphasia or dysarthria) and in regard to the inclusion criteria (listed below) the MSU will be dispatched when the inclusion criteria are fulfilled on weeks when the MSU is on call. The same inclusion criteria apply for the ordinary ambulance on weeks when the MSU is not on call. The intervention (prehospital CT and thrombolytic treatment) can only be administered in the MSU. The control (in-hospital CT and thrombolytic treatment) can only be administered in the hospital.

MSU procedure On site the anesthesiologist will take the actual medical history and do a rapid screening using the ABCDE's of trauma care. If the patient is stable and further investigations can proceed including NIHSS scoring. The patient will get two venous lines, and blood samples will be collected. Blood samples for biomarkers (se details below) will be stored and delivered to the laboratory at the hospital for further analyses and storage in bio bank (related to REK 2014/1161). The patient will be taken into the stroke ambulance, where the CT scan is performed and blood tests are run in the point of care laboratory (POC). After completing the CT scan examination, the anesthesiologist will immediately get in contact with the on call neurologist (stroke team) at Ostfold Hospital. The anesthesiologist will provide the stroke team with clinical history, POC blood tests, NIHSS score, time of symptom onset and any known clinical contraindication of thrombolysis. The stroke team and the on call radiologist will interpret the CT scan by teleradiology and a treatment decision will eventually be made. If indication of thrombolytic treatment the stroke ambulance nurse will prepare and initiate iv. rtPa (Actilyse) as per protocol (appendix). The prehospital study data will be completed in an electronic study form by the anesthesiologist.

Conventional ambulance management Conventional ambulance data collection will only take place when the MSU is not on duty. The conventional ambulance is then staffed with the same personnel (except the anaesthesiologis) as the MSU. After the paramedic or nurse-paramedic has taken the patient's actual medical history, performed a physical examination including NIHSS, established a venous line and eventually given the emergency treatment needed, the patient will be transported to the Østfold hospital. The paramedic will contact EMS dispatcher to inform patient inclusion in the study and the EMS dispatcher will contact the hospital stroke team. The paramedic will withdraw a blood sample for the biomarker study, and an additional blood sample will be taken at the hospital for standard analysis.

Therapeutic decision In both the conventional and the MSU pathway a cerebral CT scan will be conducted as soon as possible after symptom onset. Images will in both pathways be registered in the hospital PACS system, and interpret by the on call stroke team (neurologist and radiologist). In the MSU pathway the anesthesiologist will decide which patients are eligible for CT scan, but in the conventional pathway the neurologist on call in the emergency department will make this decision. Prehospital clinical assessment will include the actual medical history, a stroke scale score, and ABCDE evaluation. The clinical information and scores will be completed in designated study forms, and in the specialized prehospital patient record system AMIS. Both paramedic/nurse in the conventional pathway and the anesthesiologist in the MSU will do a stroke scale score, and scores will be analyzed for research purposes.

If a thrombolytic treated patient shows signs of clinical detoriation, expressed as an increase of 4 or more points on the NIHSS scale, an intracranial hemorrhage is to be suspected and the thrombolytic infusion must be stopped immediately. If in the MSU, a new cerebral CT scan should be conducted if the driving distance to the hospital exceeds 20 minutes, and the CT findings should immediately be transferred and reported to the hospital. After identification of location and distribution of damage based on the CT image, treatment will either be initiated on site in accordance with in-hospital procedures, or the patient will be transported directly to location for neurosurgery (see attachment 3).