Anesthetic Considerations for Endovascular Treatment in Stroke Therapy

Introduction:

Stroke, also known as cerebrovascular accident, is a condition in which there is an interruption of blood supply to the brain. Stroke can precipitate symptoms like paralysis of the face, legs, or arms, numbness in these areas, walking or speaking trouble, or problems with understanding and memory. Endovascular treatment is one of the non-surgical management protocols for loss of brain function suddenly due to clots.

What Is Endovascular Surgery?

EVT (endovascular therapy) involves inserting microcatheters (thin tubes which are visible under X-rays) into the body where the clot is located to remove the blood clot. The arrival of the EVT era has helped revolutionize the field of vascular surgery. EVT is a minimally invasive procedure. It is also advantageous as it has decreased perioperative mortality and significant morbidity. Many patients benefit from this as there is a shorter hospital and intensive care stays and quicker return to daily activities, especially for the elderly. Like a cherry on the cake, there has been a lower level of surgical stress, and EVT may eliminate the necessity for general anesthesia.

How Is Endovascular Treatment Helpful?

Endovascular treatment is a life-saving strategy against loss of brain function in stroke-affected patients. Timely restoration of the brain's blood supply will help prevent further damage. The removal of blood clots from the blood vessel is known as thrombectomy. Thrombectomy has been proven effective between 16 to 24 hours, a lapse after the patient was last known to be well. Another procedure, thrombolysis, is carried out, which involves liquefying the clot using drugs that are delivered through a catheter if the clot is challenging to remove.

What Is the Anesthesia Regimen for an Endovascular Treatment?

The clinical outcome of this treatment depends on various factors, including the anesthetic regimen employed. EVT can be performed under general anesthesia (GA) or with MAC (monitored anesthesia care). Local anesthesia (LA) is administered for vascular access and may or may not be accompanied by sedation. Acute stroke patients in a study demonstrated improved outcomes in selected patients who underwent thrombectomy as long as 24 hours after the onset of stroke symptoms. There has been an ongoing debate in recent years about which is the best anesthetic type, GA versus MAC, for this procedure.

Which Is the Better Anesthesia Between General and Monitored Care?

Many retrospective studies have found some kind of association between GA and worse neurologic outcomes in patients who underwent acute thrombectomy procedures. MAC has been known to hasten vascular access time, which is the difference between imaging and puncture time. But these studies failed to demonstrate an advantage in the time to revascularization (procedure to restore blood flow). However, it should be noted that both MAC and GA have remarkably reduced blood pressure, which has subsequently led to an increased risk of infarction. Aggressive treatment by the anesthesiologist to minimize the potential risk of GA-induced hypotension.

In selected patients who are cooperative, MAC will help assist in a neurologic examination throughout the procedure. Currently, there is insufficient evidence to recommend one anesthetic technique over another routinely. Instead, the technique employed should be based upon a quick clinical assessment of the patient, the comfort level of the anesthesiologist with various methods, and local practice. If GA is selected, extra attention must be given to avoid undue delay in endovascular treatment and maintenance of cerebral circulation.

What Is a WADA Test?

A WADA test is done to determine which is the dominant side for cognitive functions like speech, thinking, and memory. It is done by injecting a small dose of an anesthetic drug or barbiturates into the internal carotid artery. It can be done before surgery in patients with non-threatening conditions like epilepsy. The super selective anesthesia functional examination (SAFE) is an extension of the WADA test. It is also performed before permanent embolization by injecting anesthetic into the vessels. Angiographically occult vessels that supply normal brain tissue are identified. But these tests can also lead to complications like anaphylaxis (anaphylaxis refers to a life-threatening severe allergic reaction to an allergen exposure), contrast hypersensitivity, and hemorrhage (bleeding).

What Is the Protocol for a COVID Positive Patient?

Many patients receive MAC for endovascular treatment, but an urgent conversion to GA may be required in patients with suspected positive COVID infection. Arterial ischemic stroke refers to a condition in which there is blockage or narrowing of the artery that supplies the brain due to blood clot formation. During an AIS (arterial ischemic stroke) immediately requiring EVT, conversion from MAC to GA is undesirable due to the risk of contamination or infection to the healthcare personnel.

Based on the data from randomized control trials, general anesthesia (GA) is non-inferior to monitored anesthesia care (MAC) as long as hemodynamic stability is maintained. Endovascular treatment for acute ischemic stroke has provided better neurological outcomes. If the anesthesiologist finds any difficulties in the urgent conversion of MAC to GA, it is better to start with GA. The choice of the anesthetic and technique to be used should be planned uniquely for each patient, accounting for the patient's neurological and medical status as well as the risk of infection to healthcare personnels.

The following are the preferred candidates for GA in case of suspected COVID:

• Patients with acute respiratory distress.

• Patients require a high flow of oxygen or hypoxemia.

• Those who have an active cough.

• Active vomiting.

• Severe stroke.

• Uncooperative or agitated patients.

Irrespective of the implicated anesthetic technique, hemodynamic stability, ventilation, or oxygenation should be maintained in the recommended range. Blood pressure should be maintained between 140 and 180 mmHg, and oxygen saturation should be more than 94 percent.

What Is the Downside of Endovascular Treatment?

Despite EVT having shown overall improvements in short-term outcomes, the long-term consequences have not been everlasting. Moreover, endovascular repairs have been shown to be less durable, and there might be a need for reintervention. This is infrequent in traditional open repairs. Endovascular surgery has its own unique set of complications. This requires a lifetime of mandatory surveillance of the patients.

Conclusion:

Successful therapy for ischemic stroke is unforeseeable on a time window of multiple possibilities. Urgent assessment and rapid treatment are crucial for better clinical outcomes. In conjunction with imaging advances, endovascular therapy has led to significant outcome benefits. However, the anesthetic regimen that is most apt for this procedure is still a topic of debate and needs further investigation to derive a conclusion.

ADVERTISEMENT