Keeping the Blood Pressure Up!
Duy Le, MD
Löwhagen Hendén PL, Rentzos A, Karlsson JE, Rosengren L, Sundeman H, Reinsfelt B, and Ricksten SE. Hypotension During Endovascular Treatment of Ischemic Stroke Is a Risk Factor for Poor Neurological Outcome. Stroke. 2015
With the advent of endovascular therapy becoming a standard of care for acute ischemic stroke (AIS), much work is being done on optimizing the procedure itself. How long is too long? Which patients are the most appropriate candidates? Which is better: general anesthesia (GA) or conscious sedation (CS)? Most recently, we were relayed information that CS portended to better outcomes in AIS patients undergoing endovascular therapy. However, the study was limited due to the inherent nature of being a retrospective study. Nonetheless, the results leave us wondering what, if not for potential confounding factors; could this be due to?
Lowhagen et al attempt to tackle this question by retrospectively evaluating 108, consecutive, AIS patients who underwent endovascular therapy with GA, between 2007-2012. They find that patients who had a MAP drop of greater than 40% during the procedure (when compared to induction MAP) had an OR of 2.8 worse outcome. From a physiology standpoint, this argument appears to make sense. Lowering blood pressure decreases perfusion to the penumbra and collateralization, leading to more ischemic infarct, hence a poorer outcome. While it is tempting to draw lines and conclude that GA may lead to worse outcomes because of a drop in blood pressure, this study is too limited to conclude such a process.
I applaud Lowhagen et al for not attempting to make conclusions that go beyond the scope of this study. Limitations include 1) a small sample size in light of an extensive logistic regression analysis 2) slightly outdated data (including patients from 2007-2012) and more importantly, outdated devices 3) evaluating patients who underwent GA only 4) ultimately being retrospective in nature. Nonetheless, this study raises a number of questions which must be answered; mainly on what optimal blood pressure should be during endovascular therapy; and whether GA vs CS affect this. Lowhagen et al point towards work that needs to be done in the future; that which we are all clamoring for: A prospective randomized trial evaluating GA vs. CS in AIS patients undergoing endovascular therapy.