Oxidative stress and rheologic properties of stored red blood cells before and after transfusion to surgical patients.

BACKGROUND: The loss of structural and functional integrity of red blood cells (RBCs) during storage, collectively referred to as "storage lesion," has been implicated in reduced oxygen delivery after transfusion. RBCs are highly susceptible to oxidative damage from generation of reactive oxygen species by autoxidation of hemoglobin. Therefore, we examined whether increased oxidative stress (OS) in stored RBCs is associated with impaired cell membrane deformability before or after transfusion. STUDY DESIGN AND METHODS: Thirty-four patients undergoing multilevel spine fusion surgery were enrolled. OS in RBCs was assessed by the presence of fluorescent heme degradation products and methemoglobin, which were measured with fluorimetric and spectrophotometric methods, respectively. Deformability and aggregation were determined by ektacytometry in stored RBCs, autologous salvaged RBCs, and posttransfusion blood samples. RESULTS: OS in stored RBCs was significantly increased with longer storage (R = 0.54, p = 0.032) and significantly higher than that in fresh RBCs (9.1 ± 1.3 fluorescent arbitrary units vs. 7.7 ± 0.9 fluorescent arbitrary units, p < 0.001). Deformability decreased (R = -0.60, p = 0.009) with increasing storage duration. OS was elevated (p < 0.05) and deformability was decreased (p < 0.05) in postoperative blood from patients who had undergone moderate (≥4 RBC units) but not minimal or no transfusion. Neither the decrease in deformability of RBCs nor the aggregation changes were correlated with OS. CONCLUSIONS: Although stored RBCs show signs of increased OS and loss of cell membrane deformability, these changes were not directly correlated and were only evident after moderate but not lower dose transfusion in postoperative surgical patients. These findings suggest that factors other than OS may contribute to impaired rheology with stored RBCs in the clinical setting.

2,3-Diphosphoglycerate Concentrations in Autologous Salvaged Versus Stored Red Blood Cells and in Surgical Patients After Transfusion.

BACKGROUND: Stored red blood cells (RBCs) are deficient in 2,3-diphosphoglycerate (2,3-DPG), but it is unclear how autologous salvaged blood (ASB) compares with stored blood and how rapidly 2,3-DPG levels return to normal after transfusion. Therefore, we compared levels of 2,3-DPG in stored versus ASB RBCs and in patients' blood after transfusion. METHODS: Twenty-four patients undergoing multilevel spine fusion surgery were enrolled. We measured 2,3-DPG and the oxyhemoglobin dissociation curve (P50) in samples taken from the ASB and stored blood bags before transfusion and in blood samples drawn from patients before and after transfusion. RESULTS: The mean storage duration for stored RBCs was 24 ± 8 days. Compared with fresh RBCs, stored RBCs had decreased 2,3-DPG levels (by approximately 90%; P < 0.0001) and a decreased P50 (by approximately 30%; P < 0.0001). However, ASB RBCs did not exhibit these changes. The mean 2,3-DPG concentration decreased by approximately 20% (P < 0.05) in postoperative blood sampled from patients who received 1 to 3 stored RBC units and by approximately 30% (P < 0.01) in those who received ≥4 stored RBC units. 2,3-DPG was unchanged in patients who received no stored blood or ASB alone. After surgery, 2,3-DPG levels recovered gradually over 3 postoperative days in patients who received stored RBCs. CONCLUSIONS: Stored RBCs, but not ASB RBCs, have decreased levels of 2,3-DPG and a left-shift in the oxyhemoglobin dissociation curve. Postoperatively, 2,3-DPG levels remain below preoperative baseline levels for up to 3 postoperative days in patients who receive stored RBCs but are unchanged in those who receive only ASB RBCs.

Radiofrequency bipolar hemostatic sealer reduces blood loss, transfusion requirements, and cost for patients undergoing multilevel spinal fusion surgery: a case control study.

BACKGROUND: A relatively new method of electrocautery, the radiofrequency bipolar hemostatic sealer (RBHS), uses saline-cooled delivery of energy, which seals blood vessels rather than burning them. We assessed the benefits of RBHS as a blood conservation strategy in adult patients undergoing multilevel spinal fusion surgery. METHODS: In a retrospective cohort study, we compared blood utilization in 36 patients undergoing multilevel spinal fusion surgery with RBHS (Aquamantys, Medtronic, Minneapolis, MN, USA) to that of a historical control group (n = 38) matched for variables related to blood loss. Transfusion-related costs were calculated by two methods. RESULTS: Patient characteristics in the two groups were similar. Intraoperatively, blood loss was 55% less in the RBHS group than in the control group (810 ± 530 vs. 1,800 ± 1,600 mL; p = 0.002), and over the entire hospital stay, red cell utilization was 51% less (2.4 ± 3.4 vs. 4.9 ± 4.5 units/patient; p = 0.01) and plasma use was 56% less (1.1 ± 2.4 vs. 2.5 ± 3.4 units/patient; p = 0.03) in the RBHS group. Platelet use was 0.1 ± 0.5 and 0.3 ± 0.6 units/patient in the RBHS and control groups, respectively (p = 0.07). The perioperative decrease in hemoglobin was less in the RBHS group than in the control group (-2.0 ± 2.2 vs. -3.2 ± 2.1 g/dL; p = 0.04), and hemoglobin at discharge was higher in the RBHS group (10.5 ± 1.4 vs. 9.7 ± 0.9 g/dL; p = 0.01). The estimated transfusion-related cost savings were $745/case by acquisition cost and approximately 3- to 5-fold this amount by activity-based cost. CONCLUSIONS: The use of RBHS in patients undergoing multilevel spine fusion surgery can conserve blood, promote higher hemoglobin levels, and reduce transfusion-related costs.