Abstract
BACKGROUND: Diabetes mellitus (DM) is associated with vascular endothelial dysfunction, which may impair perioperative responsiveness to vasoactive drugs such as nitroglycerin. OBJECTIVE: This study aimed to assess vasodilatory dysfunction in diabetic patients using high-resolution ultrasound, compare their nitroglycerin response with non-diabetics during anesthesia emergence, and evaluate how endothelial impairment affects nitroglycerin-mediated vasodilation to guide personalized dosing. METHODS: This prospective cohort study compared 40 non-diabetic (Group A) and 40 diabetic patients (Group B). Preoperative brachial artery ultrasound assessed flow-mediated dilation (FMD) and nitroglycerin-induced dilation (NID). Following extubation, the total nitroglycerin dose required to restore blood pressure to baseline was recorded as the primary endpoint. Secondary endpoints comprised FMD and NID values, ED(50)/ED(90) of nitroglycerin, and perioperative hemodynamic changes. RESULTS: Compared with Group A, the nitroglycerin dose was significantly higher in Group B (48.47±5.11 µg vs 39.74±4.15 µg; mean difference: 8.73 µg, 95% CI: 6.82-10.64; P<0.001). Group B showed significantly lower FMD (3.68±1.70% vs 8.45±1.77%; mean difference: -4.77%, 95% CI: -5.65 to -3.89; P<0.001) and NID (5.07±2.63% vs 9.15±2.99%; mean difference: -4.08%, 95% CI: -5.27 to -2.89; P<0.001). Both FMD and NID correlated negatively with nitroglycerin dose (r=-0.653 and r=-0.610, respectively; both P<0.001). Diabetic patients required higher effective doses (ED(50): 0.292[0.268-0.316] vs 0.272[0.250-0.294]µg/kg/min; ED(90): 0.329[0.302-0.356] vs 0.312[0.288-0.336] µg/kg/min). Multivariate analysis identified higher HbA1c and lower FMD/NID as independent predictors of increased nitroglycerin requirement. CONCLUSION: This prospective cohort study demonstrated that impaired vascular endothelial function in diabetic patients significantly reduced sensitivity to nitroglycerin perioperatively. This was manifested by the requirement for higher nitroglycerin doses to achieve target baseline blood pressure levels during hemodynamic management following extubation. These findings suggest that preoperative vascular ultrasound may provide an individualized nitroglycerin dosing framework for diabetic patients.