Clinical and experimental studies of intraoperative autotransfusion using a new filtration device

Blood salvage with a continuous autotransfusion system compared with a haemofiltration system

Background: Red blood cells may be destroyed by autotransfusion processing during intraoperative salvage. The aim of the present study was to evaluate the blood component recovery rate of techniques built on either continuous centrifugation and washing, or haemofiltration (HF).

Methods: Two different methods used in blood salvage - red cell salvage with continuous processing with centrifugation and saline washing (Continuous Auto Transfusion System, CATS) and whole blood recirculation through a 30000-Da filter, i.e., HF - were compared in a randomized laboratory study using donor whole blood activated by cobra venom factor. The recovery of red blood cells, haemoglobin, free haemoglobin, leucocytes, platelets, albumin, total protein and potassium was measured.

Results: The recovery of red cells was 86% with CATS and 76% with HF. HF had a significantly higher recovery of leucocytes (CATS 20%, HF 63%), platelets (CATS 4%, HF 37%), albumin (CATS 0.2%, HF 70%), total protein (CATS 1.3%, HF 71%) and potassium (CATS 2%, HF 17%). Less than 1% haemolysis was obtained in processed blood from both groups.

Conclusion: Both methods caused little destruction of the red blood cells during processing. There was a larger reinfusion of leucocytes, platelets, albumin, total protein and extracellular potassium when HF was used compared with the ‘CATS’ method.

Cell salvage does not minimize perioperative allogeneic blood transfusion in abdominal vascular surgery: a systematic review

PURPOSE

To determine whether the use of cell salvage reduces the proportion of patients receiving at least one unit of allogeneic packed red blood cells during the perioperative period of an elective vascular surgery.

SOURCE

We identified all relevant articles through the combined use of electronic searches of the MEDLINE and EMBASE databases, the Cochrane library as well as hand searching of all randomized clinical trials and review articles. The electronic search included articles published between 1966 and April 2001. The search included textword searches using "autotransfusion," "cell salvage," "device," or Medical Subject Headings "autologous blood transfusion" or a "randomized controlled trials" filter.

PRINCIPAL FINDINGS

Five randomized controlled trials (RCT) were identified involving cell salvage and vascular surgeries. In infra renal abdominal aortic aneurysm surgery the risk ratio (the risk of receiving at least one unit of allogeneic red cells) was 0.37 [95% confidence intervals (CI) of 0.06 to 2.36]. In elective aorto-femoral bypass surgery the risk ratio was 0.97 (95% CI of 0.66 to 1.42). The pooled risk ratio for cell salvage in vascular surgery was 0.67 (95% CI of 0.35 to 1.28).

CONCLUSION

Cell salvage, a commonly used technique to recover red cells from the operative field, has been the subject of several studies in vascular surgery. There is insufficient evidence to recommend the routine use of cell salvage in elective abdominal aortic aneurysm and aorto-femoral bypass surgeries. A large RCT would elucidate whether cell salvage is effective as a blood conservation technique.

Intraoperative use of platelet-plasmapheresis in vascular surgery

STUDY OBJECTIVE

To determine, in a pilot study, whether pheresis of plasma and platelets before surgical blood loss, with reinfusion of the autologous plasma and platelets after completion of the aortic reconstruction, will result in decreased bleeding and decreased transfusion of allogenic blood components in patients undergoing elective aortic reconstruction.

DESIGN

Randomized study.

SETTING

University medical center.

INTERVENTIONS

Patients were randomized to perioperative (acute) platelet plasmapheresis (APP group) versus conventional blood component therapy (control group). In the APP group, blood was withdrawn after induction of anesthesia, to sequester approximately 300 mL of platelet rich plasma (PRP); platelet poor plasma (PPP) and red blood cells (RBC) were sequestered as well. An autotransfusion device was used to collect and re-infuse autologous RBC during the course of the operation in both groups. After completion of the aortic reconstruction, autologous PRP and PPP were re-infused in the APP group. Blood loss, volume of blood component transfusions, and preoperative and postoperative hemoglobin (Hb), hematocrit (Hct), platelet, international normalized ratio (INR), and activated partial thromboplastin time (aPTT) were recorded.

MEASUREMENTS AND MAIN RESULTS

There was no difference between groups in demographics, preoperative laboratory values, or surgical procedures, although more patients were treated for aneurysms (73% vs. 60%) and fewer for occlusive disease (20% vs. 40%) in the control versus APP group. Also, there were no differences between the control and APP groups in duration of operation, blood loss, volume of colloid infused, or volume of allogenic RBC and plasma transfused. Patients in the APP group received a greater volume of crystalloid solution (9.1 +/- 3.4 L vs. 6.8 +/- 3.0 L; p = 0.002), but fewer units of allogenic platelets than the control group (0.7 +/- 1.0 units vs. 0.2 +/- 0.4 units; p < 0.04). There were no differences in postoperative Hb, Hct, INR, aPTT, or fibrinogen. The platelet count was lower in the APP group than in the control group (123 +/- 40 x 10(3)/mm(3) vs. 182 +/- 51 x 10(3)/mm(3); p = 0.004).

CONCLUSIONS

Perioperative platelet plasmapheresis led to fewer allogenic platelet transfusions in patients undergoing elective aortic reconstruction. However, there was no decrease in blood loss and no reduction in transfusion of allogenic RBC or plasma. Perioperative platelet plasmapheresis is not recommended for routine use in elective aortic reconstruction.

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.