Mustafa Kemal SAHIN, Eda C. CAFEROGLU, M. Burak CALISICI, Burak DINCER
Van Medical Journal - 2026;33(4):503-510
Introduction: Methylene blue (MB) is widely used for sentinel lymph node biopsy (SLNB) in breast cancer surgery, but its potential systemic hemodynamic effects after local administration remain unclear. This study evaluated intraoperative hemodynamic patterns associated with intradermal MB use under standardized general anesthesia. Materials and Methods: This prospective observational study included 254 adult patients undergoing elective breast surgery, categorized according to intraoperative MB exposure (MB group, n = 137; comparison group, n = 117). General anesthesia was standardized using bispectral index monitoring. Mean arterial pressure (MAP) and heart rate (HR) were recorded via invasive arterial monitoring at baseline and predefined time points up to 60 minutes. Secondary outcomes included intraoperative hypotension incidence and vasopressor requirements. Results: Baseline characteristics were comparable between groups. The MB group showed higher MAP at 5, 10, 15, and 60 minutes (p < 0.05) and higher HR at all post-injection time points (p < 0.01). Intraoperative hypotension did not differ significantly between groups (48.9% vs. 60.7%, p = 0.060), and vasopressor requirements were comparable . In adjusted linear regression, MB exposure remained associated with higher MAP at 5, 10, 15, and 60 minutes after adjustment for age, BMI, ASA physical status, baseline MAP, and operation duration. Conclusions: Intradermal MB during SLNB was associated with higher MAP at several time points and higher HR early intraoperatively. However, similar hypotension incidence and vasopressor requirements suggest limited overall clinical relevance under standardized general anesthesia. Because systemic absorption was not assessed, these findings should be interpreted as associations, not evidence of a direct mechanistic or causal effect.
