Effect of induced hypotensive anaesthesia vs isovolaemic haemodilution on blood loss and transfusion requirements in orthognathic surgery: a prospective, single-blinded, randomized, controlled clinical study

Induced hypotensive anaesthesia and isovolaemic haemodilution are well-established blood-sparing techniques in major surgery. This prospective study compared them for blood loss, transfusion requirements, and surgical field quality during standardized orthognathic operations. In a surgeon-blinded trial, 60 healthy patients requiring either Le Fort I osteotomy or bimaxillary surgery were randomly allocated to receive normotensive anaesthesia, induced hypotensive anaesthesia, or induced hypotensive anaesthesia combined with isovolaemic haemodilution. Blood loss and haemoglobin level were measured intraoperatively and calculated on postoperative day 3. The surgeons rated surgical field quality. Mean blood loss was 1021.63, 392.38 (p < 0.05) and 1191.65 ml in the normotensive, hypotensive and haemodilution groups, respectively. Mean haemoglobin level immediately after surgery was 9.3, 10.3, and 7.4 g/dl (p < 0.05), respectively. No hypotensive group patients received transfusions; four normotensive group patients required allogenic transfusions; seven haemodilution group patients needed autogenous retransfusions (p < 0.05). Surgical field quality was significantly better in the hypotensive than in the normotensive (p < 0.05) or haemodilution (p < 0.05) groups. In orthognathic surgery, hypotensive anaesthesia significantly reduces blood loss and transfusion requirements and minimizes allogenic transfusions risks. Induced hypotensive anaesthesia combined with isovolaemic haemodilution has no additional blood-sparing effects but impairs surgical field quality.