The Brain Attack Coalition (BAC) and more recently the American Heart Association have offered consensus guidelines for criteria designating a primary stroke center, including acute stroke teams, stroke units, written care protocols, an integrated emergency response system, around-the-clock availability, and interpretation of computed tomography (CT) and rapid laboratory testing.3,12 However, a recent U.S. survey revealed that less than 10% of hospitals met the BAC criteria for a primary stroke center, although 75% of responding neurologists, neurosurgeons and emergency physicians believed that their own hospital did meet guidelines....
If a community hospital cannot provide the radiological and clinical stroke expertise to meet these guidelines, participation in a telestroke network may help a hospital to meet guidelines for stroke center designation. As a telestroke-networked stroke center, a community hospital can seek to increase the access to and appropriateness of rt-PA delivery, reducing peristroke complications without the costly addition of equipment or personnel.
Triage, evaluation and treatment at local centers prior to transportation would provide rapid management with an efficient use of resources. In a fraction of the time that sick and unstable patients can travel to a center of expertise, telemedicine collapses the boundaries of time and space to permit the expertise itself to travel instantaneously over great distances….
The telemedicine-based evaluation of acute stroke is especially challenging. It requires a rapid neurological assessment, CT image acquisition and review, and a detailed history for rt-PA exclusion criteria. Low-cost teleradiology systems are now available for the transmission of compressed CT images viewable on a conventional personal computer (PC) monitor, in accordance with published standards.16,17
The decreased cost of professional videoconferencing equipment can now empower a physician with clinical and imaging stroke expertise to conduct a remote history, physical exam and radiological interpretation in real time for the purpose of diagnosing and managing patients with stroke symptoms.18
The architecture of a telestroke service
At the Massachusetts General Hospital, a videoconferencing link is established between a community hospital (emergency physician) and a tertiary care hospital (stroke neurologist). All patients are examined on a stretcher in the community hospital's ED using a commercial videoconferencing system on a mobile cart (Polycom Inc.).
Our current system supports multiple users on a single call, which enables supervised consultation, digital archiving and creation and delivery of medical education content throughout the network. Data are transmitted encrypted over public Internet or multiple Integrated Services Digital Network (ISDN) lines at speeds of 384 kbps; video transmission occurs at 30 frames per second.
Most studies on stroke treatment have used ISDN but some have used Internet Protocol (IP) over a virtual private network. ISDN at a bandwidth of less than 384 kbps has not been evaluated for acute neurological management and may not be suitable for clinical applications. The initial capital expense for a commercially available, standards-based videoconferencing infrastructure in a community hospital (i.e., spoke site) is estimated in 2006 at less than $10,000.
Telestroke consultations permit side-by-side clinical and radiological evaluation by the consulting stroke neurologist.
In our system, CT scans are transmitted between hospitals in Digital Imaging and Communication in Medicine (DICOM) format and are then evaluated within browser-based image software (AMICAS Inc.) on a conventional desktop PC connected to a monitor set at 1024 x 768 pixel resolution or higher.
Telestroke consultations permit side-by-side clinical and radiological evaluation by the consulting stroke neurologist. For hospitals with a digital picture archiving and communication system…there is no additional capital expense to transmit images; for those without PACS, low-cost, secure, HIPAA-compliant, image transmission systems are readily available for under $5,000.
Performance of a validated examination
Studies have directly compared the telemedicine-enabled high bandwidth (384 kbps) video observations of a neurologist with the bedside examination of a house officer and the gold standard examination of a panel of six neurologists.19 The observations of the telemedicine-enabled neurologist were as good as the examination performed in person by the house officer and were in almost perfect agreement with the gold standard panel (k score 0.81–1.00) for many components of the neurological examination....
Accurate evaluation of transmitted radiology images
The rapid transmission and accurate interpretation of radiological images are essential in determining eligibility for IV thrombolysis among patients with stroke symptoms. Because the accuracy of interpreting these radiological studies affects outcomes after thrombolytic therapy, the person interpreting these images must be able to detect exclusion criteria for the administration of IV rt-PA....
To treat acute stroke patients, CT exclusions to rt-PA eligibility must be accurately identified. A team of experienced acute stroke specialists remotely linked by telestroke systems may provide "on call" acute stroke consultation to multiple hospitals without each facility having to maintain its own continuously available stroke consultation service with clinical and imaging expertise....
Low-cost teleradiology systems enable the distribution of images without an expensive PACS. A web browser can display images for viewing on a conventional PC monitor located in the hospital or remotely. One pilot study compared stroke neurologists’ reading of CT images via teleradiology to gold standard readings of hard-copy film radiographs on a view box. Each neurologist read one half of the CT scans via teleradiology in a blinded fashion, and the other half using a view box. Using the official reading by a neuroradiologist as the gold standard, there was perfect agreement between groups and 100% sensitivity and specificity for the determination of rt-PA eligibility by the stroke neurologist.29
We also have validated that the stroke neurologist’s review by telemedicine of DICOM compressed brain CT images can accurately identify candidates for IV rt-PA. Thus, for a patient with acute stroke symptoms, real-time interpretation of CT scans on a desktop computer during a telestroke consultation can favorably compare to image interpretation performed on a view box or on a PACS workstation by a neuroradiologist.
To make the process practical for community hospitals, this technology must be inexpensive and easily operated in the ED. Transmission of CT images to experienced radiologists for formal and final interpretation is essential for quality control and feedback. As a result, systems that permit remote decision-making by expert physicians reduce the manpower needed to provide acute stroke team coverage in ED without around-the-clock access to in-house stroke neurology.
3. Alberts MJ, Hademenos G, Latchaw RE, Jagoda A, Marler JR, Mayberg MR, Starke RD, Todd HW, Viste KM, Girgus M, Shephard T, Emr M, Shwayder P, Walker MD. "Recommendations for the establishment of primary stroke centers. Brain Attack Coalition." Journal of the American Medical Association 2000; 283: 3102-3109.
12. Schwamm LH, Pancioli A, Acker 3rd, JE, Goldstein LB, Zorowitz RD, Shephard TJ, Moyer P, Gorman M, Johnston SC, Duncan PW, Gorelick P, Frank J, Stranne SK, Smith R, FederspielW, Horton KB, Magnis E, Adams RJ. "Recommendations for the establishment of stroke systems of care: recommendations from the American Stroke Association’s task force on the development of stroke systems." Stroke 2005; 36: 690-703.
16. Pysher L, Harlow C. "Teleradiology using low-cost consumer-oriented computer hardware and software." American Journal of Roentgenology 1999; 172: 1181-1184.
17. Apple SL, Schmidt JH. "Technique for neurosurgically relevant CT image transfers using inexpensive video digital technology." Surgical Neurology 2000; 53: 411-416.
18. Levine SR, Gorman M. "'Telestroke': the application of telemedicine for stroke." Stroke 1999; 30: 464-469.
19. Craig JJ, McConville JP, Patterson VH,Wootton R. "Neurological examination is possible using telemedicine." Journal of Telemedicine and Telecare 1999; 5: 177-181.
29. Johnston KC,Worrall BB. "Teleradiology assessment of computerized tomographs online reliability study (tractors) for acute stroke evaluation." Telemedicine Journal and E-Health 2003; 9: 227-233.
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