Intraoperative Cell Salvage and Hemodilution Technique in Scoliosis Surgery

Surgical correction of scoliosis with instrumentation carries significant blood loss and needs for blood transfusion with its inherent risk and cost. In recent years, there is an increased interest in utilizing autologous blood as part of perioperative blood conservation strategy. The foremost mechanical methods of perioperative conservation of red blood cells including intraoperative cell salvage (ICS) and acute normovolemic hemodilution (ANH). They should be considered in all cases where significant blood loss (\>1000 ml) or \>20% estimated blood volume is expected, in patients with multiple antibodies or rare blood types and those who refuse allogenic blood products. Literature search has revealed that both cell salvage method and ANH utilized in elective surgeries are capable of minimizing allogenic blood transfusion respectively. Surgeries which are of significant relevance are aortic surgery, cardiac surgery and arthroplasty orthopaedic surgery. Combining the above two techniques such as in ATIS trial 2002 also shows that it is safe and significantly reduced allogenic blood requirements in aortic surgery. However till date, there is still lack of strong evidence that autologous blood transfusion technique is beneficial for scoliosis surgery in reducing allogenic blood transfusion. Hypothesis: The investigators hypothesize that the addition of ANH to ICS would confer additional benefit than using cell saver alone. By combining cell saver with hemodilution technique, the difference between pre-operative and post-operative Hemoglobin level will be smaller than using cell saver technique alone, hence minimizing the variation in perioperative Hemoglobin level - a predictor of allogenic blood transfusion.