8. Assessment and diagnostics
Early assessment and diagnosis are vital to ensuring that people can receive prompt and appropriate treatment, thus improving their chances of positive outcomes.
8.1 Interface between stroke services and emergency departments
Seamless joint working between stroke services and emergency departments is paramount for optimal patient care and outcomes in the acute stage of the stroke pathway.
To minimise delays to assessment and treatment for people with stroke, emergency department services should include:
- Systems supporting pre-registered imaging requests from the stroke team clinicians.
- Staff competent in acute stroke management and familiar with thrombolysis and thrombectomy eligibility criteria and pre-transfer procedures, checklists and processes.
- Video links for optimal virtual communication between the emergency department and stroke teams, where required.
- Senior stroke decision maker and senior leadership involvement at the front door to minimise door-to-needle times for thrombolysis e.g., straight to CT protocols.
- Systems and resources agreed with SAS to minimise door in, door out times for patients eligible for thrombectomy.
- Goal of minimising inappropriate or futile transfers to the CSC for thrombectomy.
- "Straight to MRI protocols" for some strokes where this is the most appropriate imaging modality.
- Agreed stroke mimic pathways where non stroke patients are cared for out with the stroke service, when possible, enabling efficient use of stroke beds and workforce.
Performance and protocols should be audited, and cases reviewed.
8.2 Assessment of eligibility for hyperacute treatment
People with suspected acute stroke should be assessed immediately to determine the best approach to treatment. This is particularly important for identifying people who would benefit from specific hyperacute stroke treatments such as thrombolysis and/or thrombectomy.
Assessment for emergency hyperacute stroke treatments should be undertaken by a stroke specialist clinician without delay. In locations where that specialist clinician is not available on site then telestroke services should provide access to specialist assessment and decision making.
Telestroke involves the use of mobile technologies to provide audio and/or video calls between patients and local and remote healthcare professionals. It has a major role in improving access to hyperacute specialist care, decision making and the safe delivery of hyperacute treatments.
Electronic documentation for remote consultation outcomes (e.g., Clinical Portal) should be established. An audit trail of referrals, decisions and outcomes will help inform practice development and processes.
Telestroke can be used to support filtering and triage of referrals from remote sites into designated stroke units and reduce delays in time critical decisions, including on the delivery of appropriate treatments and identification of patients not suitable for specific interventions or transfer to another site.
Eligibility for thrombolysis should be guided by available clinical support tools. Further information on thrombolysis is included in Section 8.1: Intravenous Thrombolysis.
Eligibility for thrombectomy should be guided by available clinical support tools. Patients who are identified as eligible for thrombectomy should be transferred to the relevant CSC for further assessment to confirm eligibility and to receive this intervention. They should then be admitted to a stroke unit to receive appropriate post intervention monitoring and care. Further detail on the core components of the delivery of thrombectomy are outlined in Section 8.2: Thrombectomy
The majority of patients with acute stroke will not be eligible for thrombolysis or thrombectomy. The key focus for these patients is ensuring access to the stroke bundle, including care within a designated stroke unit. Full information on this is included in Section 9: Acute Stroke Care.
8.3 Access to brain and vascular imaging and cardiac investigations
The role of diagnostic imaging and other investigations in stroke management is integral to achieving the best outcomes by supporting time critical decision making.
8.3.1 Brain imaging
For people with acute stroke Computed Tomography (CT) of the brain is a useful tool in detecting recent bleeding in and around the brain and can sometimes detect ischaemic changes present as a result of thrombotic stroke. CT Angiography (CTA) and CT Perfusion (CTP) are important in identifying large vessel occlusion, collateral circulation and salvageable tissue for reperfusion interventions. Magnetic Resonance Imaging (MRI) is particularly useful in detecting early or minor ischaemic changes, previous bleeding and can also be used to assess the blood vessels and salvageable brain tissue.
Decision support systems based on Artificial Intelligence (AI) can provide clinicians and radiologists with very early access to the results of imaging, on laptops or even mobile phones. These platforms support them in the immediate interpretation of the images to confirm the diagnosis and identify a large vessel occlusion and thus speed up the appropriate decision making to refer a patient for hyperacute treatment or not,.
However, it is important to recognise that AI is not a standalone decision-making technology and therefore, the process of using AI for decision support should be closely supported by radiology professionals. Formal reporting of images within 24 hours is important as a governance and learning tool.
The additional logistical link in delivering thrombectomy (patients are transferred to a CSC for this treatment) requires a clear plan between the ASC (spoke) and CSC (hub) regarding investigations to avoid duplication and minimise time to treatment. It also requires effective acquisition, transfer and interpretation of images between the ASC and CSCs.
There is also a need to ensure adequate imaging resources in ASCs and CSCs to cope with increasing numbers of patients needing assessments to determine eligibility for thrombolysis or thrombectomy. Improved access to advanced imaging will maximise the number of patients who present on waking, or present late, to receive thrombolysis and/or thrombectomy.
8.3.2 Vascular imaging
Imaging of the arteries and veins supplying the brain is not only important to determine suitability for thrombectomy but also guides the use of medication, interventional neuro radiology and surgery to reduce risks of stroke recurrence.
All ASCs and CSCs should have a pathway for carotid vascular imaging (using Carotid Doppler and/or CTA or MRA), enabling early identification of vascular pathology and rapid access to the vascular Multi-Disciplinary Team (MDT) to inform secondary prevention strategies where indicated.
- Carotid Ultrasound +/- CTA or MRA should be used for carotid imaging when required
- Where carotid stenosis is detected, there should be rapid access to a vascular MDT
- Carotid intervention should be performed within the standard time as recommended and monitored by the Scottish Stroke Care Audit – a Carotid Co-ordinator role may help this process
8.3.3 Cardiac investigations
Post-stroke cardiac investigations are important for identifying an underlying cardiac cause of stroke, such as AF or Patent Foramen Ovale (PFO). When judged to be required by the stroke specialist there should be early access to prolonged cardiac monitoring to detect paroxysmal AF. Prolonged cardiac monitoring should be carried out and reported within two weeks.
Cardiac rhythm monitoring systems should, where technically possible, have real-time reporting of paroxysmal AF with immediate notification of the service to allow verification of the diagnosis and, if appropriate, immediate anticoagulation. Where patients need anticoagulation, there should be a pathway in place for early anticoagulation with counselling and monitoring systems.
For patient work up for PFO, there should be 'soon' access to contrast transthoracic echocardiography or transcranial doppler and transoesophageal echocardiography with a pathway in place ensuring that PFO closure is carried out within six months of the index stroke.
Monitoring of Boards' ability to perform cardiac investigations for people with stroke within these time frames will be via the Stroke Action Plan and Scottish Stroke Improvement Programme team.
1. People with suspected acute stroke should be assessed for hyperacute stroke treatments by a specialist clinician without delay.
2. Where telemedicine is used for the rapid assessment of people with suspected stroke, the system should include the option of a high-quality video link.
3. Staff providing care via telemedicine should be appropriately trained in hyperacute stroke assessment, the delivery of thrombolysis and the use of this approach and technology.
4. All stroke services should have access to CT, CTA, and CTP on a 24/7 basis whether the patient is an inpatient or outpatient.
5. Departments offering CT, CTA, CTP and MRI should have systems in place which ensure that patients with stroke or TIA are prioritised appropriately in order to enable rapid access to these time-sensitive investigations.
6. When the stroke specialist feels that brain imaging is required in patients attending the TIA service, there should be same day access to this. MRI will usually be the preferred imaging modality in TIA/minor stroke patients who require a brain scan.
7. Where the above investigations are not delivered within one location, stroke services should have a clear plan for a) assessing the gain in outcome if a transfer takes place, and b) enabling a transfer for investigations where the outcome would be improved.
8. Where AI is used to support interpretation of imaging and enable timely decisions around transfer for thrombectomy, formal reporting of all radiology investigations should take place the following working day after the investigation is conducted.
9. Each stroke service should have a pathway in place enabling same day access to MRI in instances where this would be the most appropriate imaging modality.
10. There should be nationally agreed imaging protocols to be followed by ASCs and CSCs for non-contrast CT, CT Angiography (CTA) and CT perfusion (CTP) to avoid duplication.
11. All stroke centres should have a clear pathway ensuring that carotid imaging and intervention is performed within the standard time as recommended and monitored by the Scottish Stroke Care Audit. A Carotid Co-ordinator role is recommended to support delivery of this pathway.
12. People who have experienced stroke should have access to cardiac investigations including:
- Prolonged cardiac monitoring to identify paroxysmal AF (within two weeks)
- Access to contrast transthoracic echocardiography or transcranial doppler and transoesophageal echocardiography with a pathway in place ensuring that PFO closure is carried out within six months of the index stroke.
13. IT systems should be in place which highlight that the results of tests are available to the referring clinician. This enables prompt action to be taken on the results of the investigation.
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