What matters during endovascular therapy for acute stroke: anesthesia technique or blood pressure management?

P ATIENTS who experience acute ischemic stroke increasingly are undergoing treatment with endovascular revascularization procedures. Davis et al. present a retrospective review encompassing their 6 yr experience treating 96 stroke patients with endovascular arterial revascularization, half receiving local anesthesia or sedation, and the remainder receiving general anesthesia. A number of recently published studies have implicated general anesthesia as a factor in poor outcome. All these studies have a common problem. The patients receiving general anesthesia had the confounding factor of being “sicker” at baseline than patients receiving local anesthesia and/or sedation: they had higher baseline values on their neurologic stroke scale, which would lead one to expect a higher postprocedure stroke volume, morbidity, and mortality. For example, in Davis et al., patients who received general anesthesia presented with higher baseline National Institutes of Health Stroke Scale scores (worse strokes), lower levels of consciousness, and higher rates of preprocedural aspiration. In this and other studies, general anesthesia was administered because of a lack of patient cooperation. Davis et al. postulated that “. [d]espite the likelihood that these patients are sicker . there may be additional factors that contribute to poor outcome . Specifically . that peri-procedural blood pressures may have been influenced by anesthetic management and could plausibly have contributed to the observed differences in neurologic outcome. ” In addition, the correlation analysis identified the possibility that general anesthesia and blood pressure were colinear variables. The authors present two models to examine the effect of either the type of anesthesia or the blood pressure nadir; they found both to correlate with poor outcome. This study underlines the importance of blood pressure management during anesthetic management in patients experiencing acute stroke. It is the first study to find that systolic blood pressures less than 140 mmHg significantly contributed to poor outcome. In our opinion, this is the most important result of this study. Induction of general anesthesia frequently causes a decrease in blood pressure. Intraoperative hypotension has been shown to affect cognitive outcome in patients undergoing cardiac surgery, and it may have effects on cognitive functioning that can be seen immediately after spine surgery in patients with a history of hypertension. In the studies published on the outcomes of anesthesia type in patients experiencing acute ischemic stroke, a decrease in blood pressure may have exaggerated consequences because of the loss of cerebral autoregulation and reliance on collateral circulation. Seventy percent (70%) of patients experiencing acute thromboembolic stroke present with hypertension, some without a history of hypertension, which gradually decreases during the next 24 h to various degrees depending on the type of stroke; a smaller percentage present with hypotension, which has a significantly worse prognosis. Data from the International Stroke Trial demonstrates a U-shaped relationship between baseline systolic blood pressure and death or dependency: “. early death increased by [18%] for every 10 mmHg below 150 mmHg (P less than 0.0001) and by [4%] for every 10 mmHg above 150 mmHg (P 0.023). ” As Davis et al. discuss, the hemodynamic goals for the care of patients experiencing acute stroke are controversial. Although hypotension during the acute phase of ischemic stroke is associated with poor neurologic outcome, induced hypertension is clearly not the remedy for every patient. There probably is a subgroup of