Anesthetic management of endovascular treatment of acute ischemic stroke (AIS) can have a significant impact on these patients’ long-term outcome. Lately, anesthetic management of AIS patients has received increasing interest with anesthesiologists, neurologists and neurointerventionalists. Because of the importance of anesthesiologists’ involvement in these procedures, and because the available literature does not provide adequate guidance to clinicians, the Society of Neuroscience in Anesthesiology and Critical Care (SNACC) formed a task force to write a consensus statement on anesthetic management of endovascular treatment of acute ischemic stroke. The following is a synopsis of a few of the topics worked on by the task force (Drs. Sergio Bergese, Eric Heyer, Deepak Sharma, Pekka Talke).
Each year, more than 400,000 people in the U.S. have an ischemic stroke. Endovascular treatment of AIS is a relatively new field of medicine. The first FDA-approved therapy (1996), which is still the first line of treatment today, is administration of intravenous tissue plasminogen activator (tPA). Endovascular treatment of AIS originated in the late 1990s, starting with selective intra-arterial infusion of tPA. Later (2004), mechanical devices were developed to retrieve blood clots from cerebral arteries. Two of the first devices to get FDA clearance were the Merci and Penumbra devices. More recently, a new class of devices has been approved to retrieve intracerebral blood clots – they are called stent retrievers and resemble self-expanding intracranial and cardiac endovascular stents.1,2
The goal of endovascular treatment of AIS is to remove a blood clot from a cerebral artery and to reperfuse the ischemic brain as soon as possible. For two key reasons, only a small portion of patients with AIS are eligible for endovascular treatments. First, in order to be eligible for endovascular treatment, the patient must have failed intravenous tPA treatment, or not be eligible for intravenous tPA treatment. Second, there is a relatively small time window for endovascular treatment of AIS from the onset of a stroke (up to eight hours). Unfortunately, for many of these patients the time of onset of the stroke is not known, making them ineligible for the treatment. Although it seems desirable to remove the blood clot and reperfuse the ischemic brain, expanding the treatment window beyond six to eight hours is associated with increasing incidence of symptomatic intracranial hemorrhage.
Endovascular treatment of AIS can be performed under sedation or general anesthesia. It is controversial whether sedation or general anesthesia is a better choice for this patient population. Proponents of sedation favor it because sedation has been associated with better long-term patient outcomes and because less hypotension has been reported during the procedures with sedation compared to general anesthesia. Proponents of sedation also feel that general anesthesia prolongs the procedure time. However, this is not supported by data. Proponents of general anesthesia prefer it because of lack of patient movement, which may increase patient safety, radiological image quality and possibly speed up the procedure. The proponents of general anesthesia also like to have an anesthesiologist present during the procedure to manage hemodynamics and potential complications.
Much of the available data relating to the sedation-versus-general anesthesia controversy are retrospective and somewhat biased, as patients with severe strokes (high NIHSS scores) are not good candidates for sedation.3 Patients with high NIHSS scores are more likely to receive general anesthesia and are also more likely to have worse-than-average outcomes – thus, the bias. There are no randomized trials relating to this subject, and quality of available data is not sufficient to guide clinical practice. Current practice is largely driven by institutional preferences. For example, at UCSF all endovascular stroke treatments are performed under general anesthesia.
Hemodynamic management is another area of anesthetic management of patients undergoing endovascular treatment of AIS that is in need of additional data. Available data suggest that low blood pressure may be harmful, which seems reasonable in view of an occluded cerebral artery. But how low is too low in this mostly elderly patient population, most of whom have a history of hypertension? Further complicating hemodynamic management is difficulty in assessment of “baseline” blood pressure. Stroke tends to cause an increase in blood pressure, and many of these patients arrive to the emergency room with elevated blood pressures. As anesthesiologists we are well versed in hemodynamic management, and I trust that we can avoid hypotension (even brief periods) in this patient population. However, we become involved with these patients several hours after the beginning of the stroke. This concerns me because we do not have control of hemodynamic management before these patients receive their endovascular treatment. “Ideal” hemodynamic management during the one- to two-hour procedure several hours after the onset of the stroke may not be enough to achieve an optimal outcome.
Although it is easy to be critical of the existing literature, especially in the areas that relate to anesthetic management, we as the anesthesia community must take responsibility for lack of sufficient involvement. What limited data exist relating to anesthesia and hemodynamic management during endovascular treatment of AIS has been mostly reported by intensivists or radiologists. Involvement of anesthesiologists is desperately needed in future studies to help with study design, data collection and interpretation of the data as it relates to anesthetic management. This area of research will provide anesthesiologists an excellent opportunity for clinical research that will have a significant impact on future anesthetic practice.
Due to the limited data on anesthetic management of these patients, SNACC formed a task force to develop a consensus statement that aims to provide us guidance. Consensus statements, as the name implies, are documents that rely heavily on expert opinion mainly because of the limited amount of data from clinical trials. This consensus statement addresses all aspects of periprocedural issues specifically focusing on anesthetic management of these patients. This document has been submitted for publication and we expect it to be published soon, including on the SNACC website.
While working on this consensus statement, results of three randomized clinical trials were published in the New England Journal of Medicine, all suggesting that endovascular treatment of AIS is no better than intravenous tPA.4-6 No doubt, this has raised several questions relating to utility of endovascular treatment of AIS. Since most recent studies show a high (90 percent) recanalization rate after endovascular treatment, but the impact of recanalization on outcome is not as positive as expected, questions have been raised regarding the timing of recanalization after endovascular treatment. Perhaps recanalization happens too late to prevent permanent damage. As anesthesiologists we have a significant impact on the timing of these procedures. We should do whatever we can do safely to facilitate these procedures and to minimize the time to treatment.
Should all of us be knowledgeable about these procedures? Yes. Although it would be ideal to have experienced neuroanesthesiologists familiar with these procedures at designated stroke centers to provide anesthesia for this patient population, the reality is that endovascular treatment of AIS is common at many hospitals and the treatments are performed 24/7. Any anesthesiologists taking call may need to provide anesthesia during endovascular treatment of AIS. Should anesthesiologists be involved with all endovascular treatments of AIS? In my opinion, absolutely. We are experts in hemodynamic management and management of potential complications during these procedures. Thus, we can have a significant role in improving the long-term outcome of these patients.
Anesthetic management of endovascular treatment of AIS needs more evidence-based data to provide guidance to anesthesiologists. Meanwhile, we hope that you find the upcoming consensus statement useful. This is a perfect time for anesthesiologists to get involved with clinical studies in this area. It is also a perfect time for those of you interested in neuroanesthesia to get involved with SNACC.
1. Saver JL, Jahan R, Levy EI, et al.; SWIFT Trialists. Solitaire flow restoration device versus the Merci Retriever in patients with acute ischaemic stroke (SWIFT): a randomised, parallel-group, non-inferiority trial. Lancet. 2012;380(9849):1241-1249.
2. Nogueira RG, Lutsep HL, Gupta R, et al.; TREVO 2 Trialists. Trevo versus Merci retrievers for thrombectomy revascularisation of large vessel occlusions in acute ischaemic stroke (TREVO 2): a randomised trial. Lancet. 2012;380(9849):1231-1240.
3. Davis MJ, Menon BK, Baghirzada LB, et al.; Calgary Stroke Program. Anesthetic management and outcome in patients during endovascular therapy for acute stroke. Anesthesiology. 2012;116(2):396-405.
4. Broderick JP, Palesch YY, Demchuk AM, et al.; Interventional Management of Stroke (IMS) III Investigators. Endovascular therapy after intravenous t-PA versus t-PA alone for stroke. N Engl J Med. 2013;368(10):893-903.
5. Ciccone A, Valvassori L, Nichelatti M, et al.; SYNTHESIS Expansion Investigators. Endovascular treatment for acute ischemic stroke. N Engl J Med. 2013;368(10):904-913.
6. Kidwell CS, Jahan R, Gornbein J, et al.; MR RESCUE Investigators. A trial of imaging selection and endovascular treatment for ischemic stroke. N Engl J Med. 2013;368(10):914-923.
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