A conversation with Alexandros Rentzos, MD, Diagnostic and Interventional Neuroradiology, Sahlgrenska University Hospital, and Pia Löwhagen Hendén, MD, PhD, Anesthesiology and Intensive Care department, Sahlgrenska University Hospital, about the role of anesthesia and conscious sedation for patients undergoing embolectomy for stroke.
Interviewed by José G. Merino, MD, Associate Professor of Neurology, University of Maryland School of Medicine.
They will be discussing the paper, “General Anesthesia Versus Conscious Sedation for Endovascular Treatment of Acute Ischemic Stroke: The AnStroke Trial (Anesthesia During Stroke),” published in the June 2017 issue of Stroke.
Dr. Merino: Could you please summarize the key findings of your study and put them in context of what was known on the topic?
Drs. Rentzos and Löwhagen: Since a number of retrospective studies showed that general anesthesia during endovascular stroke treatment was associated with poor neurological outcome, conscious sedation became the main method in most neurointerventional centers after 2010. However, the retrospective studies were limited by important selection bias, such as inclusion of posterior strokes (in some of the series) and, importantly, more severe stroke in patients treated under GA. Furthermore, most retrospective studies on anesthesia technique did not describe the anesthesia technique, nor the anesthetic management!
At our institute, we have used mainly general anesthesia since 1991 when we started with endovascular stroke treatment, and, in our experience, patients treated with GA did not have worse neurological outcome. That is why we started the randomized trial AnStroke in 2013. The results were presented in ESOC 2017 in Prague on May 18. In our trial, general anesthesia did not lead to worse neurological outcome compared to conscious sedation.
Dr. Merino: At what time point did you enroll patients into your study? After CT? After IV-tPA was started?
Drs. Rentzos and Löwhagen: Patients were included after the NCCT scan if no contraindications to endovascular treatment existed. The iv rtPA was initiated as soon as possible if no contraindications existed independently of study inclusion.
The oral informed consent was obtained either from the patient or next of kin. An important exclusion criteria was if the patient had a medical indication or contraindication for general anesthesia or conscious sedation.
Dr. Merino: How do your results compare to those of the SIESTA trial?
Drs. Rentzos and Löwhagen: Both AnStroke and SIESTA randomized patients to general anesthesia or conscious sedation groups, but the primary outcomes differ. In the SIESTA trial, the primary outcome was early neurological recovery (NIHSS 24 hours after treatment), which was similar in both groups. In the AnStroke trial, early neurological recovery was a secondary outcome. As in SIESTA, we did not detect a difference between the groups.
The primary outcome of the AnStroke trial was the modified Rankin scale (mRS) at 3 months from treatment. We did not find a difference between the general anesthesia and conscious sedation groups. In contrast, in the SIESTA trial, the general anesthesia group showed better neurological outcome, measured as mRS 3 months, although the trial was not powered for that outcome measure.
Dr. Merino: How do you implement the findings of your trial in your clinical practice? What clinical features do you take into account when deciding between general anesthesia or conscious sedation?
Drs. Rentzos and Löwhagen: The first think that we changed is that we do not avoid general anesthesia anymore. In a difficult case, such as when a patient has a tandem occlusion or a difficult anatomy, is agitated or has some other medical conditions, we prefer general anesthesia. There are many anesthesiological aspects to consider regarding anesthesia form in addition to NIHSS, level of consciousness and airway defense, including co-morbidities, difficult airway and fasting status. It is mandatory to have available anesthesiology personnel experienced in the care of stroke patients during endovascular treatment if we want to avoid periprocedural hypotension and delays during intubation. This is unfortunately not always the case in our institute, especially during on-call hours, and then conscious sedation is preferred.
Dr. Merino: Is further research needed to help us guide treatment decisions? What is the next step?
Drs. Rentzos and Löwhagen: The GA group in our study had higher NIHSS on arrival, higher incidence of carotid T occlusions and higher incidence of left sided occlusions, but still showed no difference in the primary or secondary outcomes compared to conscious sedation group. As we also mention in our article, this could mean that a general anesthesia has a neuroprotective effect and further research is needed. Furthermore, the appropriate blood pressure during endovascular stroke treatment is a field that needs further research. Maybe instead of trying to avoid blood pressure fall, increasing the blood pressure or tailored blood pressure for the individual patient is the way to go.
Dr. Merino: How do you think your findings will affect current treatment guidelines?
Drs. Rentzos and Löwhagen: We hope that general anesthesia will no longer be considered a method associated with poor outcome, but as one tool for the management of stroke patients that should be used properly and whenever indicated. Our study cannot be generalized, as it a single-center randomized study and reflects the current practice in our institute. We are awaiting other multicenter studies in the same area, and we have discussions about collaboration with the other single-center studies that recently presented their data for a pooled analysis.
Dr. Merino: What were the major challenges that you faced when doing the study? How did you overcome them?
Drs. Rentzos and Löwhagen: Obtaining an informed consent from a patient presenting with a major stroke or from a worried and distressed relative without delaying the stroke workflow was the most challenging task. It took a lot of effort from all physicians who first met the patient to obtain the consent while the workflow remained uninterrupted.
The study protocol required good cooperation between neuroradiology, anesthesiology and neurology personnel, a situation we actually have at Sahlgrenska University Hospital. Taking into account that the study was unfinanced, we want to mention the huge effort from all the staff; they made the study feasible!
Dr. Merino: What advice do you have for trainees interested in learning about and doing multidisciplinary clinical trials in the acute setting?
Drs. Rentzos and Löwhagen: Financing makes it easier, but most importantly you have to be sure that all specialties/disciplines and all the staff enter the study with the same mindset and one common goal! The stroke team mentality is important even in stroke research.