LAUSR

After years of investigation, including substantial studies, opinions continue to shift regarding conscious sedation (CS) versus general anesthesia (GA) utilization in mechanical thrombectomy for emergent large vessel occlusion (ELVO) stroke. Early retrospective studies demonstrated that CS was superior, but subsequent randomized controlled trials failed to show the superiority of one method. Current research continues to explore the best use of anesthesia in acute ischemic stroke therapy. While consensus does not exist on whether CS or GA is safer and/or more beneficial for stroke interventions, there are strong arguments to support having an anesthesia team involved in all mechanical thrombectomy procedures, whatever method is chosen. The clearest reason an anesthesia team should be involved is that patient motion is not routinely predictable before a case. A person may appear calm, but when stimulated, patients can become agitated or even combative, making the procedure difficult to perform. If this occurs when catheters are already close to the clot, it can be difficult to decide whether to pause the procedure for the time it takes to request anesthesia and wait for them to join. The risk of losing significant time may not outweigh the benefit of a still patient. Conversion to GA from CS during stroke intervention is associated with worse outcomes. Post hoc analysis of data from three randomized controlled trials of CS versus GA for stroke intervention showed a large shift towards worse outcomes when conversion from CS to GA was required during the procedure. They found no factor that predicted which patients would require conversion to GA. These trials were conducted with anesthesia services performing both arms, so it is likely that this negative effect would have been even worse if anesthesia was not already present, adding a time delay before the required intubation. Research has shown that maintaining a patient’s blood pressure during stroke intervention near presentation values results in improved outcomes, whether using GA or CS. 11 Anesthesia support is beneficial or perhaps even necessary for this level of control. Furthermore, once the thrombus is removed, anesthesia has the ability to quickly lower blood pressure accordingly to reduce the risk of reperfusion hemorrhage. Complete reperfusion makes a difference to clinical outcomes, and this is aided by having a still patient. With motion on angiograms, it can be difficult to clearly identify downstream secondary medium vessel occlusions (MeVOs). These secondary MeVOs may result in worse functional outcomes than primary MeVOs. It is intuitive that thrombectomy in smaller arteries in a moving patient has an increased risk of vessel injury, so attempts to remove distal M2 or large M3 emboli may not be performed. When Thrombolysis in Cerebral Infarction (TICI) grade 3 reperfusion is achieved instead of TICI 2B, studies have shown improved outcomes, significant cost savings, and quality adjusted life year benefits for patients. In many ways, administering CS for interventional stroke cases is more complex and challenging than administering GA. The ability to maintain analgesia and anxiolysis to a level that allows the patient to remain still during intervention, but awake enough to follow commands and protect their airway, represents a fine balance which is only complicated by the neurological compromise created by any ELVO. The quality of CS is highly dependent on the abilities and training of the sedation provider. An anesthesia team consisting of an anesthesiologist or certified registered nurse anesthetist can use additional medications and higher medication doses because of their superior techniques for airway management compared with interventional nurses. In some centers, it is common for interventional nurses to give only one agent or nothing at all because of the risk of over sedating an uncooperative, ELVO patient. This may lead to inadequate levels of sedation and more frequent motion. Mechanical thrombectomy has a very low number needed to treat to improve neurologic outcomes, so a thrombectomy is likely the most potentially impactful and time sensitive procedure occurring in the hospital at any given time. It would be uncommon for anesthesia to have more important or more indicated cases over an acute stroke intervention. Anesthesia departments should understand this opportunity to take part in our patient successes. We believe that having immediate access to anesthesia for all interventional stroke cases should be a new requirement for comprehensive stroke center certification. The percentage of cases performed using an anesthesia team should be a metric routinely reported in stroke committees, similar to other safety measures. There are other certification requirements and metrics collected which are arguably less important for the success of our stroke service. While there is no consensus on GA versus CS, having an anesthesia team in the procedural suite may be one of the most critical points for a successful outcome. It is important to have a consistent workflow in acute stroke care that notifies anesthesia early in the process to achieve timely services without delaying the procedure. Strong cooperation and education between neurointerventional physicians and their anesthesia colleagues is, in our opinion, key to a successful interventional stroke program. While in 2023 the optimized approach to providing anesthesia in the interventional suite may give strongly differentiated opinions that appear to leave the neurointerventional practitioner betwixt and between, it is fair to say there is little to argue for leaving our anesthesia colleagues out of the procedural equation.