Preventing Strokes: Surgery's Silent Danger

Stroke during surgery, or perioperative stroke, is a rare but serious complication that can negatively impact a patient's recovery and increase their risk of death. Perioperative stroke is defined as a stroke occurring during surgery or within 30 days after surgery. The risk of perioperative stroke depends on the type of surgery, with cardiac, neurologic, and vascular procedures carrying a higher risk. Age, sex, history of stroke or transient ischemic attack, and certain pre-existing health conditions are also risk factors for perioperative stroke. Preventive strategies should be tailored to individual patient factors to reduce the risk of perioperative stroke.

Perioperative stroke risk factors: age, sex, history of stroke, cardiac surgery, neurosurgery

Perioperative stroke is a brain infarction of ischemic or hemorrhagic etiology that occurs during surgery or within 30 days after surgery. It is an uncommon but devastating complication, negatively impacting recovery and functional outcomes. The risk of perioperative stroke varies with the type of surgery, with an incidence of 0.1–1.9% in non-cardiac, non-neurological, and non-major surgery, and up to 10% in high-risk cardiac or brain surgery.

Non-Modifiable Risk Factors

Age

The risk of perioperative stroke increases with age, with octogenarians having a six-fold higher risk compared to younger patients. Older age is an independent risk factor, and as the average age of surgical patients increases, the incidence of perioperative stroke is expected to rise.

Sex

Being female is a risk factor for perioperative stroke in both cardiovascular and non-cardiovascular surgeries. The reason for this sex difference is not well understood, but it may be related to the more rapid progression of atherosclerosis in elderly women after menopause.

History of Stroke or Transient Ischemic Attack

A history of stroke or transient ischemic attack is an established risk factor for perioperative stroke. The risk of perioperative stroke is highest within the first nine months after a stroke, and it is recommended to delay elective surgery for at least six to nine months after a stroke to minimize this risk.

Modifiable Risk Factors

Cardiac Surgery

Cardiac surgeries, such as coronary artery bypass grafting, aortic valve replacement, and mitral valve replacement, are associated with a higher risk of perioperative stroke due to the manipulation of the aorta and other surgical techniques. The risk of cerebral embolism is higher in these procedures, and the use of certain devices and techniques may help reduce this risk.

Neurosurgery

Neurosurgical procedures, such as carotid endarterectomy and intracranial aneurysm clipping, also carry a high risk of perioperative stroke. The risk is particularly elevated in direct extracranial-intracranial bypass surgery for Moyamoya disease, with a 30-day ipsilateral perioperative stroke risk of 14.4%.

Other Considerations

Intraoperative Hypotension and Hypoxia

Intraoperative hypotension and hypoxia are risk factors for perioperative stroke, especially in patients with significant large vessel stenosis. A sudden drop in blood pressure can decrease cerebral perfusion, leading to brain ischemia and stroke. Poor systemic oxygenation during cardiopulmonary bypass has also been associated with an increased risk of perioperative stroke.

Perioperative Beta-Blockade

The use of beta-blockers in the perioperative period has been associated with an increased risk of stroke, especially in patients with anemia. The combination of beta-blockade and anemia may impair cerebral vasodilation and cardiac output, leading to cerebral tissue hypoxia and an increased risk of stroke.

Perioperative stroke prevention: pre-screening, intraoperative imaging, blood pressure control, blood loss monitoring

Pre-screening

The risk of perioperative stroke can be reduced by identifying high-risk patients through pre-screening. Risk factors include age, sex, history of stroke or transient ischaemic attack, atrial fibrillation, renal failure, diabetes, hypertension, and previous cardiac surgery. Pre-screening allows for the development of individualised preventive strategies, such as carotid artery revascularisation and the optimisation of modifiable risk factors.

Intraoperative Imaging

Intraoperative imaging techniques, such as transesophageal echocardiography, can identify atherosclerotic disease of the ascending aorta, a risk factor for perioperative stroke. Other imaging techniques, such as multimodal CT and MRI, can help differentiate between ischaemic stroke and intracranial haemorrhage, aiding in prompt diagnosis and treatment.

Blood Pressure Control

Low blood pressure during surgery is a risk factor for perioperative stroke. Therefore, blood pressure control and monitoring are crucial to prevent excess strokes. However, aggressive blood pressure reduction in severely hypertensive patients may also precipitate ischaemic stroke, so cautious management is necessary.

Blood Loss Monitoring

While intracerebral haemorrhage accounts for a small proportion of perioperative strokes, it can occur due to coagulopathy, the use of antiplatelet or anticoagulant agents, or a sudden surge in blood pressure. Thus, blood loss monitoring and the management of anticoagulant therapy are essential to prevent perioperative intracerebral haemorrhage.

Perioperative stroke diagnosis: complete neurological exam, fast-track anesthesia protocol, CT and CT angiography

Perioperative Stroke Diagnosis

Complete Neurological Exam

The National Institutes of Health Stroke Scale (NIHSS) is considered the gold standard for acute stroke assessment. It is a systematic assessment tool that provides a quantitative measure of stroke-related neurological deficits. It is used to evaluate and document neurological status in acute stroke patients, predict lesion size, and determine appropriate treatment. The NIHSS can also be used to predict both short and long-term patient outcomes and serves as a data collection tool for planning patient care.

Other neurological assessment scales include the Scandinavian Stroke Scale (SSS), the Canadian Neurological Scale (CNS), and the European Stroke Scale (ESS). These scales are used to evaluate stroke severity, monitor neurological status, and predict patient outcomes.

Fast-Track Anesthesia Protocol

Fast-track surgery, also known as enhanced recovery after surgery, is a multidisciplinary approach to perioperative care that aims to facilitate earlier patient discharge from the hospital. This approach involves patient education and motivation, early feeding and mobilization, and a multimodal analgesic regimen.

In the context of anesthesia, fast-track protocols typically involve the use of short-acting anesthetic and analgesic agents to facilitate rapid recovery. Total intravenous anesthesia (TIVA) is often favoured to minimize the incidence of postoperative nausea and vomiting (PONV). For major abdominal surgery, thoracic epidural analgesia is recommended as it provides better pain relief, reduces postoperative pulmonary complications, and improves exercise capacity when compared to intravenous opioid-based analgesia.

CT and CT Angiography

Computed tomography (CT) and CT angiography (CTA) are essential tools in the diagnosis and management of acute stroke. CT is used to rule out hemorrhage before administering intravenous tissue plasminogen activator (IV tPA), a standard treatment for acute ischemic stroke. CTA, on the other hand, aids in the diagnosis of acute ischemic stroke by identifying carotid stenosis, intracranial atherosclerosis, and large vessel occlusions.

CTA is quick, safe, and relatively inexpensive. It has a short additional procedure time of approximately 5 minutes and a similar radiation exposure to a chest or abdominal CT. While there may be financial costs associated with performing CTA, these are outweighed by the potential benefits of improved stroke diagnosis and treatment.

Perioperative stroke treatment: intensive care, brain oxygenation and perfusion, clot-busting therapy, speech and swallow evaluation

Perioperative Stroke Treatment

Intensive Care

Perioperative stroke is a well-recognised complication of cardiac, carotid, and neurological surgery, but it can also occur during non-cardiac and non-neurological surgery. The risk of perioperative stroke varies depending on the type of surgery, with cardiac and brain surgery carrying a higher risk.

The most important predictor of perioperative stroke is a previous history of stroke, and the outcomes associated with such an event are extremely poor. Thus, the perioperative management of patients with a history of stroke needs careful consideration to minimise the thrombotic risk. A comprehensive, individualised approach is crucial, and should include a preoperative assessment of the patient's history of stroke or transient ischaemic attack (TIA), type of stroke, secondary prevention medications, and residual deficit from the stroke.

The timing of elective surgery following a stroke is also important. In the days following a stroke, cerebral autoregulation is impaired, and the area of infarcted cerebral tissue is vulnerable to the haemodynamic stresses of anaesthesia and surgery. A sufficient time period should be allowed before elective surgery for the patient’s neurological and haemodynamic status to stabilise and cerebral autoregulation to be restored. Current evidence suggests that non-urgent surgery should be delayed by at least 3 months following a stroke or TIA.

Brain Oxygenation and Perfusion

Oxygen delivery is a critical component of stroke treatment, as it can salvage ischaemic brain tissue. High-flow oxygen started promptly after stroke symptom onset can increase the time window for thrombolysis with intravenous tissue plasminogen activator (IV tPA). However, there is a theoretical risk of worsening stroke outcome due to hyperoxia-induced oxygen free radical injury.

Clot-Busting Therapy

Clot-busting drugs, or thrombolytics, can effectively stop ischemic strokes and improve patient outcomes if specialists trained in administering the drugs are immediately available. Ischemic strokes are caused by a blockage in an artery supplying the brain, and thrombolytics can be used to dissolve the clot and restore blood flow to the brain.

Speech and Swallow Evaluation

Dysphagia (difficulty swallowing) is a common complication of stroke. The American Heart Association recommends early screening for dysphagia after stroke to help reduce the risk of developing adverse health consequences, such as weight loss, dehydration, malnutrition, and pneumonia. Therapies designed to improve swallowing focus on strengthening muscles and building coordination of the nerves and muscles involved in swallowing.

Perioperative stroke and surgery delay: understanding the risk and ramifications for patient care

Perioperative stroke, defined as a stroke occurring during surgery or within 30 days after surgery, is an uncommon but devastating complication for patients and surgeons alike. The risk of perioperative stroke is influenced by various factors, including patient characteristics, type of surgery, and intraoperative events. Understanding these risk factors is crucial for implementing preventive strategies and optimizing patient care. This article will discuss the risk factors, ramifications, and strategies to mitigate the impact of perioperative stroke.

Risk Factors for Perioperative Stroke

The risk of perioperative stroke is generally low for non-cardiac, non-neurologic, and non-major surgeries, ranging from approximately 0.1% to 1.9%. However, the risk increases significantly for high-risk cardiac or brain surgery, with rates of up to 10%. Age is a critical factor, as the risk of perioperative stroke increases exponentially among older adults. Being female is also a risk factor, possibly due to the more rapid progression of atherosclerosis after menopause. A history of stroke or transient ischemic attack is another important consideration, as it elevates the risk of perioperative stroke.

Certain types of surgery carry a higher risk of perioperative stroke. Cardiac surgery, particularly aortic surgery, mitral valve surgery, and coronary artery bypass graft surgery, is associated with an increased risk. Neurosurgery, such as external carotid-internal carotid bypass surgery, carotid endarterectomy, or aneurysm clipping, also poses a higher risk. Concomitant carotid and cardiac surgery further elevate the likelihood of perioperative stroke.

Ramifications of Perioperative Stroke

Perioperative stroke can have significant negative consequences for patient recovery and functional outcomes. Patients who experience a perioperative stroke are less likely to achieve a good functional recovery and have an eight-fold higher mortality rate compared to those who do not. The impact of perioperative stroke is not limited to the immediate postoperative period but can also affect long-term neurological outcomes.

Strategies to Mitigate Risk

Preventive strategies should be tailored to individual patient factors, including cerebrovascular reserve capacity and the time interval since the previous stroke. Pre-screening for perioperative stroke risk, including an assessment of age, high blood pressure, high cholesterol, Type 2 diabetes, smoking status, and history of stroke or transient ischemic attack, is essential. During surgery, monitoring blood flow to the brain, intraoperative imaging of the aorta, tight blood pressure control, and close monitoring of blood loss are crucial.

In the event of a perioperative stroke, early diagnosis and rapid treatment are critical. Performing a complete neurological exam as soon as possible after surgery and having a stroke team on standby are essential components of the response. Thrombolytic therapy or endovascular thrombectomy may be considered, but the challenge of ascertaining the exact time of stroke onset can limit the use of these interventions.

Perioperative stroke is a rare but serious complication of surgery, carrying a substantial risk of mortality and long-term disability. By understanding the risk factors and implementing preventive and diagnostic strategies, it is possible to reduce the incidence and impact of perioperative stroke. Additionally, ongoing research is vital to further enhance our understanding and management of this complex condition.

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