Effect of controlled hypotension combined with low-pressure tourniquet on hemoglobin reduction after total knee arthroplasty

BACKGROUND: Blood loss is common in total knee arthroplasty (TKA). Tourniquet use and controlled hypotension are standard interventions to minimize intraoperative bleeding and avoid transfusions. This study compared the effects of conventional tourniquet use versus controlled hypotension combined with a low-pressure tourniquet on postoperative hemoglobin reduction in TKA. METHODS: In this single-center retrospective cohort study, 90 patients undergoing unilateral TKA under general anesthesia were assigned to either the conventional tourniquet group (n = 49) or the controlled hypotension-low-pressure tourniquet group (n = 41). Primary outcomes included postoperative red blood cell (RBC) count, hemoglobin levels, reductions in RBC and hemoglobin, drainage volume, estimated total blood loss, and transfusion rate. Secondary outcomes were intraoperative duration, duration of hospitalization, and incidence of lower extremity deep venous thrombosis (DVT). RESULTS: The controlled hypotension-low-pressure tourniquet group exhibited higher postoperative RBC count and hemoglobin levels. Reductions in RBC, hemoglobin, and cumulative drainage volume were lower, while estimated total blood loss, transfusion requirements, intraoperative duration, and duration of hospitalization were significantly reduced compared with the conventional tourniquet group. DVT incidence was similar between the two groups. CONCLUSION: Controlled hypotension with a low-pressure tourniquet effectively reduced postoperative blood loss without increasing the risk of lower limb DVT.