title: Sedimentation method for preparation of postoperatively salvaged unwashed shed blood in orthopaedic surgery.
abstract: BACKGROUND
  Salvage and return of unwashed shed blood (USB) after total knee replacement (TKR) is an established blood-saving technique, but some authors question its efficacy and safety and suggest that the shed blood be washed before returning. We evaluated a colloid-based sedimentation method for improving and standardizing the quality of USB collected after TKR without the need for washing.
  
  
  METHODS
  Experiments were performed to find the optimal colloid dose and sedimentation time using diluted donated venous blood. USB samples (n=52) were drawn from the reinfusion bag and mixed with hydroxyethyl starch or gelatine solutions (15-30%, colloid solution volume/total volume × 100). USB red blood cells (RBCs) were allowed to settle by gravity for 30 min, supernatant was evacuated from the syringe, and RBC concentrate was analysed. RBC recovery and other blood cell and chemical removal were calculated according to changes in USB volume and haematocrit. Twenty-five samples from leucodepleted packed RBCs were analysed as a comparator group.
  
  
  RESULTS
  Mean haemoglobin (Hb) of USB was 10.9 g dl(-1). After colloid treatment, 90% of RBCs were recovered, and USB Hb was similar to that of leucodepleted packed RBCs (n=25) (18.9 vs 19.6 g dl(-1), respectively; P=NS). In addition, the procedure reduced USB content of leucocytes (60%), platelets (48%), total protein (76%), cytokines (70-77%), and plasma-free haemoglobin (53%), without major differences between colloids.
  
  
  CONCLUSIONS
  Sedimentation of USB with colloid solutions provides a low-cost alternative for improving and standardizing the quality of salvaged USB after TKR.
authors.affiliation: Transfusion Medicine, School of Medicine, University of Málaga, Campus de Teatinos, 29071 Málaga, Spain. mmunoz@uma.es
authors.forename: M
authors.initials: M
authors.lastname: Muñoz
authors.forename: S
authors.initials: S
authors.lastname: García-Segovia
authors.forename: D
authors.initials: D
authors.lastname: Ariza
authors.forename: A
authors.initials: A
authors.lastname: Cobos
authors.forename: J A
authors.initials: JA
authors.lastname: García-Erce
authors.forename: D
authors.initials: D
authors.lastname: Thomas
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D016063:Blood Loss, Surgical; D001799:Blood Sedimentation; D001804:Blood Transfusion, Autologous / Q000379:methods*; D003102:Colloids; D016207:Cytokines / Q000097:blood; D006438:Hemodilution / Q000379:methods; D006801:Humans; D047589:Leukocyte Reduction Procedures / Q000379:methods; D016131:Lymphocyte Subsets; D011182:Postoperative Care / Q000379:methods; D020858:Tissue and Organ Harvesting / Q000379:methods*
chemical_list: D003102:Colloids; D016207:Cytokines