title: Oxygen carrying capacity of salvaged blood in patients undergoing off-pump coronary artery bypass grafting surgery: a prospective observational study.
abstract: BACKGROUND
  Intraoperative cell salvage (ICS), hereby referred to 'mechanical red cell salvage', has been widely used and proven to be an effective way to reduce or avoid the need for allogeneic red blood cells (RBCs)transfusion and its associated complications in surgeries involving major blood loss. However, little is known about the influence of this technique on the functional state of salvaged RBCs. Furthermore, there are no articles that describe the change of free hemoglobin (fHb) in salvage blood during storage, which is a key index of the quality control of salvaged blood. Therefore, in this study, the influence of ICS on the function of salvaged RBCs and the changes of salvaged RBCs during storage were studied with respect to the presence of oxyhemoglobin affinity (recorded as a P50 value) and the level of 2, 3-diphosphoglycerate (2, 3-DPG) and fHb by comparing salvaged RBCs with self-venous RBCs and 2-week-old packed RBCs.
  
  
  METHODS
  Fifteen patients undergoing off-pump coronary artery bypass grafting (OPCAB) surgery were enrolled. Blood was collected and processed using a Dideco Electa device. The level of P50, 2, 3-DPG and fHB from salvaged RBCs, venous RBCs and 2-week-old packed RBCs was measured. We also measured the changes of these indicators among salvaged RBCs at 4 h (storage at 21-24 °C) and at 24 h (storage at 1-6 °C).
  
  
  RESULTS
  The P50 value of salvaged RBCs at 0 h (28.77 ± 0.27 mmHg) was significantly higher than the value of venous RBCs (27.07 ± 0.23 mmHg, p=0.000) and the value of the 2-week-old packed RBCs (16.26 ± 0.62 mmHg, p=0.000). P50 value did not change obviously at 4 h (p=0.121) and 24 h (p=0.384) compared with the value at 0 h. The 2, 3-DPG value of salvaged RBCs at 0 h (17.94 ± 6.91 μmol/g Hb) was significantly higher than the value of venous RBCs (12.73 ± 6.52 mmHg, p = 0.007) and the value of the 2-week-old packed RBCs (2.62 ± 3.13 mmHg, p=0.000). The level of 2, 3-DPG slightly decreased at 4 h (p=0.380) and 24 h (p=0.425) compared with the value at 0 h. Percentage of hemolysis of the salvaged blood at 0 h(0.51 ± 0.27 %) was significantly higher than the level of venous blood (0.07 ± 0.05 %, p=0.000) and the value of 2-week-old packed RBCs (0.07 ± 0.05 %, p=0.000), and reached 1.11 ± 0.42 % at 4 h (p=0.002) and 1.83 ± 0.77 % at 24 h (p=0.000).
  
  
  CONCLUSIONS
  The oxygen transport function of salvaged RBCs at 0 h was not influenced by the cell salvage process and was better than that of the venous RBCs and 2-week-old packed RBCs. At the end of storage, the oxygen transport function of salvaged RBCs did not change obviously, but percentage of hemolysis significantly increased.
authors.affiliation: Department of Pain Management, Xuanwu Hospital of Capital Medical University, No. 45, Changchun Street, Xicheng District, 100053, Beijing, China. lixiulianglxl@sina.com.
authors.forename: Xiu Liang
authors.initials: XL
authors.lastname: Li
authors.affiliation: Department of Anaesthesiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong'an Road, Xicheng District, 100050, Beijing, China. dongpen8001@hotmail.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Dong
authors.affiliation: Department of Anaesthesiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong'an Road, Xicheng District, 100050, Beijing, China. mzmgr@sohu.com.
authors.forename: Ming
authors.initials: M
authors.lastname: Tian
authors.affiliation: Department of Pain Management, Xuanwu Hospital of Capital Medical University, No. 45, Changchun Street, Xicheng District, 100053, Beijing, China. nijiaxiang@263.net.
authors.forename: Jia Xiang
authors.initials: JX
authors.lastname: Ni
authors.affiliation: Department of Anaesthesiology, the 2nd Affiliated Hospital & Yuying Children Hospital of Wenzhou Medical University, Wenzhou, China. f.g.smith@bham.ac.uk.|Perioperative, Critical Care and Trauma Trials Group, University of Birmingham, Edgbaston B15 2WB, Birmingham, UK. f.g.smith@bham.ac.uk.
authors.forename: Fang Gao
authors.initials: FG
authors.lastname: Smith
mesh_terms: D019794:2,3-Diphosphoglycerate / Q000097:blood; D000368:Aged; D047549:Coronary Artery Bypass, Off-Pump; D017707:Erythrocyte Transfusion / Q000379:methods*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D057725:Operative Blood Salvage; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies
chemical_list: D019794:2,3-Diphosphoglycerate; D010100:Oxygen