Intraoperative Cell Salvage and Hemodilution Technique in Scoliosis Surgery
Condition: Adolescent Idiopathic Scoliosis
MeSH terms: Scoliosis
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      Patients who meet the inclusion criteria are enrolled in the study. They are assigned to 2
      arms of study group using concealed allocation method. A computerized random-number generator
      will be used to formulate an allocation schedule. Group A will receive cell salvage and acute
      normovolemic hemodilution during operation; Group B will only receive cell salvage as sole
      autologous transfusion strategy.

      Members of the research team should attend all operations and record all data. Anaesthetic
      technique including drugs usage, equipments and monitoring devices are standardized as per
      protocol. Intraoperative fluid management is recorded in details.

      All patients enrolled in the study (group A and B) underwent cell saver technique during
      surgery using Cell Saver® 5+ autologous blood recovery system-Haemonetics devices. All
      patients allocated in group A also received additional acute normovolemic hemodilution (ANH)
      after induction of anaesthesia. As a standardization measure, before starting skin incision,
      500ml blood will be collected from the radial artery to a standard blood collection bag and
      stored as CPD blood at ambient temperature. Simultaneously, 500ml Voluven® (6% hydroxyethyl
      starch 130/0.4 in 0.9% sodium chloride) will be infused through a peripheral vein.

      All autologous blood will be re-infused back to patient at surgery completion or within 6
      hours of withdrawal. Autologous blood will be given to patient during surgery at any point if
      there are 30% or more body blood volume loss.

      Allogenic blood will be administered when the intraoperative hemoglobin concentration fell
      below 8g/dl despite completion of autologous blood transfusion or when autologous blood not
      available; adequate volume correction by mean of collected autologous blood and crystalloid
      fluid administration, or when presence of ischemic electrocardiogram changes (2mV ST segment
      elevation or depression on 3 leads monitoring); persistent hypotension or tachycardia >20%
      from baseline.
    

Intervention name(s): cell salvage technique; acute normovolemic hemodilution
Intervention type(s): Procedure; Procedure
Intervention description(s): blood from the surgical field is collected, anti-coagulated, filtered, centrifuged, washed and re-suspended in saline to produce autologous blood with a resultant haematocrit of 50-80% for transfusion back to the patient using specific cell saver device; Removal of 500ml whole blood from the patient after induction of anesthesia, with restoration of blood volume with acellular fluid using equivolume of 6% hydroxyethyl starch 130/0.4 in 0.9% sodium chloride (voluven) to maintain isovolemia
Other intervention name(s): intraoperative blood salvage using cell saver; intraoperative hemodilution technique
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Adolescent idiopathic scoliosis; scoliosis corrective surgery; autologous blood transfusion; cell salvage; acute normovolemic hemodilution; hemoglobin level