Abstract
<title>Abstract</title> <p>Background Dynamic arterial elastance (Eadyn) has been proposed as a predictor of arterial pressure responsiveness following fluid loading. We evaluated the ability of Eadyn and conventional hemodynamic indices to predict arterial pressure responsiveness during prone spine surgery. Methods Thirty-eight adult patients undergoing elective spine surgery in the prone position received a 500-mL crystalloid fluid challenge when volume expansion was clinically indicated. Arterial pressure responders were defined by a ≥ 15% increase in mean arterial pressure (MAP). Baseline Eadyn, effective arterial elastance (Ea), arterial compliance (C), systemic vascular resistance (SVR), pulse pressure variation (PPV), and stroke volume variation (SVV) were compared between responders and non-responders. Receiver operating characteristic (ROC) curve analysis was performed. Results Ten patients were classified as responders and twenty-eight as non-responders. Baseline Eadyn, Ea, C, SVR, PPV, and SVV were comparable between groups. Stroke volume increased significantly after fluid loading in both groups, whereas MAP increased only in responders. None of the evaluated variables demonstrated clinically useful predictive performance, with AUCs ranging from 0.516 to 0.577. Conclusions Neither Eadyn nor conventional hemodynamic indices reliably predicted arterial pressure responsiveness following fluid loading during prone spine surgery. These findings suggest that preload-dependent variables alone are insufficient to predict arterial pressure response in this surgical setting, highlighting the need for more comprehensive hemodynamic assessment strategies.</p>