Association Between Chronic Tamsulosin Therapy and Intraoperative Hemodynamics During Spinal Anesthesia: A Prospective Observational Study

Background: This prospective observational study investigated the association between chronic tamsulosin therapy and intraoperative hemodynamic changes in patients undergoing elective transurethral resection of the prostate (TUR-P) under spinal anesthesia. Methods: Adult patients scheduled for elective TUR-P under spinal anesthesia were prospectively enrolled. Patients receiving long-term tamsulosin therapy comprised the tamsulosin group, whereas those with no history of α1-adrenergic blocker use served as the control group. Hemodynamic variables, including mean arterial pressure (MAP) and heart rate, were recorded before spinal anesthesia and at predefined time points during the first 60 min after spinal anesthesia. Results: A total of 115 patients were analyzed (tamsulosin, n = 56; control, n = 59). Baseline MAP was comparable between groups. The adjusted linear mixed-effects model demonstrated a significant group × time interaction for MAP (F(5, 565.10) = 8.34, p < 0.001). Adjusted between-group MAP differences were −4.9 mmHg (95% CI, −8.8 to −1.0; p = 0.015) at 5 min, −17.0 mmHg (95% CI, −20.2 to −13.8; p < 0.001) at 30 min, and −16.4 mmHg (95% CI, −19.5 to −13.3; p < 0.001) at 60 min. Criteria-defined hypotension occurred in 21/56 (37.5%) patients in the tamsulosin group and 17/59 (28.8%) in the control group (p = 0.32). Conclusions: Chronic tamsulosin therapy was associated with lower intraoperative MAP values during spinal anesthesia, without a statistically significant increase in the incidence of clinically defined hypotension. These findings suggest that chronic tamsulosin use may be associated with a different intraoperative blood pressure response following spinal anesthesia.