<p>Intraoperative arterial hypotension (IAH) increases the risk of complications. Norepinephrine is often used to treat IAH, but its effects on stroke volume (SV) are highly variable. The perfusion index (PI), a non-invasive marker measured via pulse oximetry, may help monitor hemodynamic changes. This study aims to evaluate the ability of changes in the perfusion index (∆PI), a non-invasive marker measured via pulse oximetry, to identify patients experiencing a decrease in SV in response to norepinephrine bolus. This is a prospective observational study in the cardiac surgery. Hemodynamic variables, including SV assessed via transesophageal echocardiography and PI, were measured before and after a 4–8 μg norepinephrine bolus. The relationship between ΔPI and ΔSV was assessed using Pearson’s correlation test, and the ability of ΔPI to detect a ≥ 10% decrease in SV was evaluated using receiver operating characteristics curve (ROC) analysis (DeLong method). Twenty-seven patients undergoing cardiac surgery who required norepinephrine for IAH were included. Thirty-one measurements were analyzed. A &gt; 10% decrease in SV was observed in 45% of the cases. The ROC curve for ∆PI detecting a ≥ 10% decrease in SV had an area under the curve of 0.94 (95% CI [0.86–1]). A correlation was found between ∆PI and ∆SV, with a Pearson correlation coefficient of 0.81 (95% CI [0.65–0.91], p &lt; 0.001). This prospective study confirms that some cardiac surgery patients experience SV fall in response to NE bolus and is a proof-of-concept that the PI might be a useful tool for tracking these patients. Further research is needed to confirm these findings in larger cohort and broader surgical populations.</p>