Prediction of hypotension in the beach chair position during shoulder arthroscopy using pre-operative hemodynamic variables

Abstract

Since hypotension in beach chair position (BCP) can lead to catastrophic neurologic complications, the prediction of hypotension is a matter of concern in the BCP under general anesthesia. We investigated whether pre-induction values of mean arterial pressure (MAP), stroke volume variation (SVV), cardiac index (CI), and stroke volume index (SVI) can predict hypotension in BCP during general anesthesia. Forty healthy adult patients, aged 18-65 years, undergoing elective arthroscopic shoulder surgery, were enrolled. At 5 min after anesthesia induction, patients were placed in the 70° upright position. Receiver operating characteristic (ROC) curves were plotted for preoperative hemodynamic variables, including MAP, SVV, CI and SVI, and their abilities to predict hypotension were investigated. Fifteen patients developed hypotension after being moved from the supine to the BCP. The areas under the ROC curves for pre-induction values of MAP, CI, and SVI and post-induction value of SVV before a positional change were 0.556 (95% CI 0.373-0.739; p = 0.557), 0.735 (0.576-0.894; p = 0.014), 0.787 (0.647-0.926; p = 0.003), and 0.691 (0.525-0.857; p = 0.046), respectively. In this study, pre-induction values of CI and SVI and post-induction value of SVV before a positional change predicted hypotension in the BCP under general anesthesia. Our findings suggest that not only preload but also preoperative cardiac performances might be the important factors for the development of hypotension after a repositioning supine to the sitting during general anesthesia.