Medical and Surgical Part 7: Acute Stroke Protocol

Khoo Teck Puat Hospital adapted the  National Neuroscience Institute(NNI) guidelines in management of acute strokes and the administration of RTPA within the stroke window time.

Stroke is recognized early by GP and sent to hospital for early stroke care.

Attached is the protocol

Quoted from National Neuroscience Institute Singapore:

"Stroke is Singapore’s fourth leading cause of death, comprising 10–12% of all deaths¹. Its prevalence is estimated at 3.65% for adults > 50 years of age. Approximately three quarters of strokes are ischaemic in nature and one-quarter are haemorrhagic². Stroke is the largest cause of long-term physical disability in Singapore³ and with a rapidly ageing population, the burden of stroke is expected to increase exponentially in the none too distant future, posing challenges to the healthcare system and society."

What is rTPA and how does it work?

The three main components of a blood clot are platelets, thrombin, and fibrin; each of these components is a key therapeutic target. During thrombus formation, circulating prothrombin is activated to the active clotting factor, thrombin, by activated platelets. Fibrinogen is activated to fibrin by the newly activated thrombin. Fibrin is then formed into the fibrin matrix while Plasminogen gathers in the fibrin matrix.

Tissue Plasminogen Activator (TPA) is a naturally-occurring serine protease found in vascular endothelial cells and is involved in the balance between thrombolysis and thrombogenesis. It works by converting plasminogen to the natural fibrinolytic agent plasmin. Plasmin lyses clot by breaking down the fibrinogen and fibrin contained in a clot thereby dissolving the clot. Recombinant TPA is manufactured using recombinant biotechnology techniques and this synthetic form is the one used in acute stroke treatment. It should be kept in mind that the thrombolysis process works best on recently formed thrombi. Older thrombi have extensive fibrin polymerisation that makes them more resistant to thrombolysis; hence the importance of time for thrombolytic therapy. 

Who gets rTPA?

Stroke patients are triaged by the ambulance service and on arrival in hospital, if they appear suitable for this treatment, they are ‘fast-tracked’. They are very quickly assessed by a physician who is trained in stroke and thrombolysis. A history is taken and a clinical examination is made. The doctor has to be sure that the patient really has a stroke and not some other condition.

The severity of the stroke is assessed using a universal standard scale, the National Institute of Health Stroke Scale (NIHSS) score to determine the severity of the stroke (patients with very mild strokes or an extremely severe stroke may not be suitable for this treatment). Measurements of blood pressure, blood glucose and other observations are made. A checklist of conditions that make the treatment more dangerous is quickly run through. If eligible, a CT brain scan is done immediately to rule out intracranial haemorrhage (for which rTPA is contraindicated) and if the patient has no objection to receiving the treatment, the rTPA is administered as soon as possible.

At the National Neuroscience Institute, we currently administer intravenous rTPA in patients with acute stroke up to 4.5 hours after the onset of the stroke. We have accumulated several years of experience in treating acute stroke victims and have reached out to peripheral hospitals such as Changi Hospital and Khoo Teck Puat Hospital through a telestroke network so that i/v rTPA in conjunction with expert neurology input is available to these hospitals 24 hours a day to help such patients in different parts of Singapore.

How is TPA administered and what happens after?

The injection of rTPA is given intravenously. The dose is calculated based on 0.9mg/kg of estimated body weight. The first 10% is given as a bolus and the remaining 90% is given as an infusion via a pump over one hour. During the treatment, the patient is observed closely and monitored in the Neuro Intensive Care Unit (NICU) for the first 24 hours and is then transferred to the stroke unit the next day. The blood pressure, heart and oxygen levels are monitored and neurological observations are made every few minutes. A followup CT or MRI brain is performed at 24 hours to evaluate for haemorrhage. Anti-platelet therapy is resumed 24 hours after the rTPA is given if the follow-up CT brain does not show haemorrhage. Stroke rehabilitation and other routine treatments are continued as per standard stroke treatment.

What role do primary care physicians have in managing acute stroke?

Family physicians may be the first line of doctors that see patients with acute stroke or be called to see patients with acute stroke during house calls. The acronym FAST is a simple mnemonic used to help recognise acute strokes quickly so that the patient can get thrombolysis early at the hospital. F - Facial weakness, A - Arm weakness, S - Speech difficulty, and T - Time to act. Better results have been observed with patients who have had earlier administration of the drug compared with those who had it later. As 'Time is Brain', primary care physicians play a critical role in recognising stroke early and dispatching these patients with a neurological emergency off to the hospital's emergency department without delay. The primary care physician is also instrumental in educating his patients on the availability of acute stroke treatment options and the possibility of good outcomes on seeking early medical attention at the hospital.

Conclusion

Stroke disease still exacts a terrible burden of mortality and morbidity on the individual and society. Where in the past, only anti-thrombotic agents were available for treatment with mild benefits, currently i/v rTPA has revolutionised the way stroke can be treated and has given stroke victims a new lease of life and hope. The family physician’s role in early recognition (<4.5hrs) of stroke and prompt referral of the patient to a hospital is critical. At NNI, we have developed a holistic care plan for stroke patients which encompasses acute stroke rescue from admission all the way to rehabilitation and outpatient follow-up. Besides i/v rTPA, new and exciting treatment options on the horizon are being developed to extend the stroke window and may further alter the face of how doctors treat stroke patients in future with better outcomes.

References: http://www.singhealth.com.sg/DoctorsAndHealthcareProfessionals/Medical-News/2012/Pages/Stroke-in-Singapore-2.aspx