INTRODUCTION — Surgical blood conservation techniques are used to reduce patient exposure to allogeneic blood during and after surgery. Techniques include preoperative autologous donation, intraoperative hemodilution, and blood salvage (also called cell salvage) during surgery.
This topic will review the indications, advantages, and potential complications of intraoperative blood salvage (ie, intraoperative autologous transfusion or intraoperative autotransfusion) and postoperative blood salvage. Other perioperative blood conservation techniques are discussed in detail separately. (See "Surgical blood conservation: Preoperative autologous blood donation" and "Surgical blood conservation: Intraoperative hemodilution".)
INTRAOPERATIVE BLOOD SALVAGE — We suggest intraoperative blood salvage in surgical procedures having a high likelihood of significant blood loss (>1000 mL), based on evidence that allogeneic transfusion and associated complications can be avoided  with a very low incidence of adverse events .
Indications and benefits — Intraoperative blood salvage has the following potential benefits:
●Avoidance of allogeneic transfusion – The technique can be effective in avoiding or reducing allogeneic blood transfusion, with its attendant costs and risks (eg, transfusion reactions, transfusion-transmitted infections) . Thus, intraoperative blood salvage is presumed to be beneficial, although randomized trials have not demonstrated improved outcomes. In a 2010 systematic review including 75 trials (36 involving orthopedic procedures, 33 involving cardiac procedures, 6 involving vascular surgery), the absolute reduction in the use of allogeneic red blood cell (RBC) transfusion was 21 percent (95% CI 15-26 percent) . In a 2015 systematic review in emergency abdominal or thoracic trauma surgery (one trial; n = 44), the reduction in the use of allogeneic RBCs in the cell salvage group was 4.7 units (95% CI 1.31-8.09 units) . These systematic reviews concluded that cell salvage did not increase the risk of adverse events, including mortality and infection [1,3]. (See "Indications and hemoglobin thresholds for red blood cell transfusion in the adult", section on 'Risks and complications of transfusion'.)
Intraoperative blood salvage has been applied effectively in a variety of surgical procedures having a high likelihood of requiring a transfusion, whether elective or emergent, including cardiac, vascular, orthopedic, urologic, trauma, gynecologic, and transplantation procedures [1,3-16]. Intraoperative blood salvage has also been effective in neurosurgery and plastic surgery cases with a high likelihood of blood transfusion [17-20].
Intraoperative blood salvage may also be acceptable to some Jehovah's Witnesses, who will not accept allogeneic blood [21-23]. Requirements for acceptance by these patients may include assurance that the blood does not leave the operating room for processing and/or that the blood remains continuously connected to the patient via intravenous tubing. (See "The approach to the patient who refuses blood transfusion", section on 'Jehovah's Witnesses'.)
Intraoperative blood salvage may be lifesaving in patients with a rare blood type or multiple RBC alloantibodies when crossmatch-compatible blood cannot readily be obtained.
●Greater number of units available compared with other autologous blood conservation techniques – Intraoperative blood salvage complements other methods of blood conservation, but has the potential to deliver much larger amounts of blood than either preoperative autologous donation or intraoperative hemodilution, which generally only provide 1 to 3 units of autologous blood [24,25].
●Time and cost savings – Intraoperative blood salvage is usually done in the operating room without direct involvement of the transfusion service and also eliminates the need for the patient to provide autologous donations. Thus, intraoperative salvage may save time for the patient and the blood collection facility. The cost of intraoperative blood salvage is at least equivalent to allogeneic transfusion [3,4,26,27].
If there is uncertainty regarding the need for blood salvage, the collection disposables for a cell salvage device can be set up as a "standby" option, potentially saving the cost of the bowl and reinfusion bag, as well as personnel costs. This option has a similar cost to crossmatching 2 units of allogeneic blood .
Contraindications — There are both absolute and relative contraindications to the use of intraoperative blood salvage .
●Presence of contraindicated fluids – Salvaged blood must never be mixed with fluids, such as sterile water or any hypotonic solution because RBC hemolysis will occur [16,28]. Also, intraoperative blood salvage cannot proceed if solutions that would be toxic with intravascular administration could come into contact with the salvaged blood. Examples include antibiotic irrigation or hydrogen peroxide, alcohol, or povidone-iodine solutions.
●Admixture with hemostatic products or bone cement – Blood salvage cannot be used during suctioning of blood from the surgical field when there is any potential for simultaneous collection of hemostatic products such as topical thrombin, fibrin glue, or microfibrillar bovine collagen-based products (eg, Avitene, Actifoam Collagen Sponge, Ultrafoam Sponge, Instat, Helitene, or similar products), or any chance of admixture with methyl methacrylate (ie, bone cement) [16,28].
Relative contraindications — The following relative contraindications are controversial, in that there is no compelling evidence to suggest an association with adverse outcomes. Notably, use of intraoperative blood salvage in these settings has been expanded without clear-cut negative consequences .
●Bacterial infections – Decisions about using intraoperative blood salvage in patients with bacterial infections are made on a case-by-case basis, with consideration of relative risks and benefits for the individual patient, and with informed consent.
Bacterial contamination of the surgical wound has traditionally been a contraindication to use of intraoperative blood salvage. However, small studies support the appropriateness of more liberal use of intraoperative blood salvage in this setting. In a case series of intraoperative blood salvage in 11 hemorrhaging trauma patients with enterically contaminated wounds, rapid access to a large volume of autologous blood for reinfusion was potentially lifesaving; no patient developed intraabdominal sepsis, and no deaths were reported . A 2015 systematic review in emergency abdominal or thoracic trauma surgery (one trial; n = 44) noted no difference in sepsis (measured by blood cultures) or mortality in the cell salvage group compared with the control group receiving allogeneic blood . A study that retrospectively evaluated clinical outcomes in 36 patients who received salvaged blood during cardiac surgery found no clinical sequelae in the third of patients who were transfused with blood found to contain bacteria or endotoxin .
There are no reports of bacteremia and sepsis in otherwise healthy people who were transfused with salvaged blood containing bacteria in the intraoperative period. Absence of clinical sequelae may be attributable to the use of broad-spectrum antibiotics in surgical patients, irrigation of surgical wounds before resuming salvage procedures when contamination occurs, and the thorough washing and filtration process used for intraoperative cell salvage . Although washing blood that contains bacteria cannot completely sterilize it, processing blood via a cell salvage system and then filtering it using a leukocyte reduction filter has been associated with a 98 to 100 percent reduction in a variety of bacterial organisms [31,32]. Thus, decisions regarding reinfusion of salvaged blood in the setting of systemic infection should consider the potential infection risk of this technique compared with the known risk of postoperative infection after transfusion of allogeneic blood . (See "Indications and hemoglobin thresholds for red blood cell transfusion in the adult", section on 'Risks and complications of transfusion' and "Transfusion-transmitted bacterial infection".)
●Active malignancy – Decisions about using intraoperative blood salvage in patients with active malignancy are made on a case-by-case basis, with consideration of factors such as the risk of major intraoperative bleeding, the need for transfusion, the availability of allogeneic blood, and informed patient consent.
The successful use of intraoperative blood salvage in cancer surgery supports more liberal use of the technique in patients with active malignancy . Malignant cells have been observed in shed blood collected intraoperatively, and extensive cell washing does not remove these cells . However, leukocyte depletion filters have been shown to remove tumor cells from salvaged blood, similar to their ability to remove bacteria [35-40] (see 'Reinfusion' below). Importantly, in a 2012 systematic review and meta-analysis including 10 controlled but not randomized studies, patients who received salvaged autologous blood during oncology surgery had no increase in cancer recurrence or development of metastases compared with those receiving allogeneic blood .
Areas of uncertainty — Intraoperative blood salvage has been used successfully in the following settings, with continuing research to clarify its risks and benefits [16,28,41,42]:
●Obstetrics – Blood salvage, if available, can be helpful in managing patients with postpartum hemorrhage (PPH) during cesarean delivery [41-45]. Preoperative planning for its use is prudent in obstetric patients at high risk for significant PPH, such as those with placenta accreta. Blood salvage in this setting is discussed separately. (See "Postpartum hemorrhage: Management approaches requiring laparotomy", section on 'Role of intraoperative cell salvage'.)
●Hemoglobinopathies – There is uncertainty regarding the safety of intraoperative blood salvage for patients with sickle cell disease (eg, theoretical risk of increased sickling) or thalassemia (eg, theoretical risk of increased hemolysis) [16,28,46].
●Cold agglutinin disease – There is uncertainty regarding the safety of intraoperative blood salvage for patients with cold agglutinin disease, dependent on the thermal amplitude of the antibody and the temperature of the room. If intraoperative blood salvage is used in a patient with known cold agglutinin disease, the reinfused blood should be passed through a blood warmer.
Technology and procedural steps — The intraoperative cell salvage machine (commonly referred to as a "cell saver") separates, washes, and concentrates salvaged RBCs. Several steps are involved, including suctioning of shed blood from the surgical field, addition of an anticoagulant, separation and washing of RBCs (to remove the anticoagulant, free hemoglobin molecules, activated thrombogenic substances, and cellular stroma), concentration of the blood, and eventual reinfusion to the patient (figure 1) .
Aspiration of blood from the surgical field — Centrifuge-based RBC salvage with the intraoperative cell salvage machine starts with the surgeon aspirating blood from the surgical field through a suction wand. The blood is mixed with an anticoagulant as it is aspirated (eg, heparin or citrate) to prevent coagulation . Typically, heparin in saline with a concentration of approximately 30,000 units/L is used. This solution is slowly and automatically added to the aspirated blood at a rate of 15 mL per 100 mL of collected blood . During subsequent washing of the collected blood, all but a trace of heparin is removed [16,47].
If there is concern about heparin-induced thrombocytopenia (HIT), a citrate-based anticoagulant/preservative solution (eg, citrate-phosphate-dextrose [CPD] or citrate-phosphate-dextrose-adenine [CPD-A]) should be used instead of heparin. Citrate-containing solutions are administered at a rate of 15 mL per 100 mL of collected blood . Citrate is rapidly metabolized by the liver after transfusion. Therefore, iatrogenic anticoagulation is unlikely with intraoperative blood salvage techniques. However, if there is concern about citrate-induced hypocalcemia (eg, due to impaired liver function, changes consistent with hypocalcemia on the electrocardiogram, or a low measured ionized calcium level), intravenous calcium chloride or calcium gluconate can be administered . In patients with advanced liver disease who receive a large volume of salvaged blood, it is helpful to monitor calcium levels to detect hypocalcemia.
Processing of blood — The aspirated blood is collected in a sterile, filtered reservoir until the amount is sufficient for processing (typically 375 to 750 mL).
Centrifugation — The salvaged blood is then pumped into the centrifuge bowl, where the higher density RBCs are separated and concentrated. The plasma, platelets, and waste components are sent to the waste bag.
Washing — Salvaged blood has a high concentration of free hemoglobin, inflammatory mediators, and other cellular debris . Therefore, it is washed with an isotonic solution, usually normal (0.9 percent) saline. Some centers change to a balanced electrolyte solution (eg, PlasmaLyte-A) after administration of a large volume of normal saline (eg, after approximately 1500 mL of saline is reinfused with 3000 mL of salvaged blood) [16,49].
Cell salvage instruments can process a full reservoir of blood in approximately three minutes, resulting in 55 to 225 mL of RBCs with hemoglobin concentration >17 g/dL [16,50]. A "partial bowl" that is at least one-half full can be processed if necessary (eg, insufficient blood to process a full bowl), but the resulting hemoglobin concentration will be <17 g/dL.
Reinfusion — Finally, the processed red cell suspension is pumped from the centrifuge bowl into a cell salvage bag and is ready for reinfusion. Reinfusion is instituted as soon as the washed blood is available .
●Microaggregate filters – A 40-micron microaggregate filter is installed between the cell salvage bag and the patient to filter the final blood product as it is reinfused into the patient .
●Leukocyte depletion filters – A leukocyte depletion filter is an excellent alternative to a microaggregate filter when it is desirable to achieve optimal removal of bacteria, cancer cells, fat particles, or amniotic fluid [43,52] (see 'Relative contraindications' above and 'Areas of uncertainty' above). This type of filter must be changed after reinfusion of each 500 mL of blood .
Typically, leukocyte-reduced blood has <1x104 leukocytes/mL of blood, corresponding to approximately 99 percent leukocyte depletion [53,54]. (See "Leukoreduction to prevent complications of blood transfusion", section on 'Definition of leukoreduction'.)
Other components in the blood such as platelets and contaminants can also adhere to these filters, but at least 85 percent of RBCs pass through the filter and into the patient. Commonly used polyester or polyamide filters have a 40-micron pore size and promote relatively selective adhesion of negatively charged leukocytes via three passive mechanisms (blocking, bridging, and interception) and one active mechanism (adhesion). Adhesion-based filters are the most efficient, allowing >99.9 percent leukocyte depletion [55,56].
Washed versus unwashed blood — We recommend using washed blood for all patients undergoing intraoperative blood salvage, based on the likely lower risk of complications compared with infusing salvaged blood that has not been washed. Although washing reduces the platelet count, it mitigates the negative effects on platelet function after reinfusion of salvaged blood . The quality of salvaged, washed, autologous RBCs, as measured by posttransfusion RBC survival and enzymatic indices of RBC function, is equivalent, if not superior, to washed RBCs obtained by standard blood donation [49,58-60].
Salvaged washed red cells — Separation, washing, and concentration of RBCs is performed by the cell salvage machine (ie, "cell saver") in the operating room.
Separation and washing of RBCs removes added anticoagulant and virtually eliminates free hemoglobin, platelets, white blood cells, and cellular stroma products (which are potentially thrombogenic). Thus, patients who receive a large number of units of washed autologous RBCs may require treatment of dilutional coagulopathy with fresh frozen plasma and/or platelet infusion (see "Massive blood transfusion", section on 'Alterations in hemostasis'). Centrifuging salvaged blood concentrates the RBCs, which reduces the total fluid volume administered to the patient.
Salvaged unwashed blood — In rare intraoperative settings with extremely rapid sustained blood loss (>500 mL/min), it may be lifesaving to return the salvaged blood without separating or washing, until control of bleeding can be achieved. Returning whole blood in this setting allows the blood to be almost immediately available for reinfusion and may preserve some clotting factors and platelets. However, the risks and disadvantages of infusing unwashed blood are significant, including [61,62]:
●The anticoagulant that was added to the blood is not removed and may cause coagulopathy.
●The reinfused platelets may be dysfunctional after being suctioned from the surgical field .
●Thrombogenic substances (eg, inflammatory mediators and microaggregates consisting of white cell and platelet debris) may be introduced.
●Hemoglobin levels are low (range: 7 to 9 g/dL, versus 16 to 18 g/dL in processed washed blood).
●Free hemoglobin levels may be very high due to hemolysis.
●Fat may be present in the unwashed product, which increases the risk of fat embolism.
In these rare emergency circumstances, it is particularly important to use a 40-micron microaggregate filter for reinfusion. Also, the anticoagulant drip is increased due to the larger blood volume being processed; thus, a heparin-neutralizing agent, such as protamine, is administered to avoid coagulopathy.
Storage and handling — Blood collected by intraoperative blood salvage may be stored either at room temperature for up to six hours or at 1 to 6°C for up to 24 hours, provided that it is collected under aseptic conditions with a device that provides washing and that cold storage is begun within six hours of initiating the collection. Such stored blood must be properly labeled. Minimum requirements for labeling include the name and identifying number of the patient, the component name, the statement "For Autologous Use Only," and the expiration date and time.
Blood collected by intraoperative salvage should never be transfused to any patient other than the one from whom it was collected.
POSTOPERATIVE BLOOD SALVAGE — Postoperative blood salvage refers to the collection of blood from surgical drains and subsequent reinfusion through a 40-micron microaggregate filter, with or without a washing process. (See 'Washed versus unwashed blood' above.)
Major orthopedic procedures — Major orthopedic surgery is the main setting in which postoperative blood salvage is used. Randomized trials have demonstrated a reduction in allogeneic blood transfusion in joint replacement surgery [63-66].
The use of postoperative blood salvage after major orthopedic surgery is evolving and is individualized based upon institutional expertise and available technologies . Development of efficient systems for collecting, anticoagulating, and filtering blood for reinfusion has increased interest in salvaging blood after major orthopedic surgery, despite residual concerns regarding the safety of unwashed salvaged blood (see 'Washed versus unwashed blood' above). However, other techniques to reduce allogeneic blood transfusion may be equally effective in this setting (eg, use of an antifibrinolytic drug such as tranexamic acid or adhering to a restrictive transfusion protocol) .
Cardiac surgery — In agreement with the 2011 Update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines , we avoid reinfusion of unwashed shed mediastinal blood from postoperative chest tube drainage following cardiac surgery (see 'Washed versus unwashed blood' above). Shed mediastinal blood contains fibrinogen degradation products, tissue-type plasminogen activators, inflammatory cytokines, complement, and endotoxin, causing activation of the extrinsic coagulation pathway, and may be associated with postoperative bleeding tendency [70-74] and with sternal or systemic infections [75,76].
Washing reduces these abnormalities and risks [69,74,77,78]. Therefore, reinfusion after washing may be considered as part of a multimodal blood conservation strategy in institutions where this is practical and cost-effective, or in patients who will not accept allogeneic blood products [69,74]. A self-contained automated system has been developed to allow washing of both intraoperative and postoperative salvaged blood . Additional trials are needed to determine whether this approach is safe, effective, and cost-saving compared with intraoperative blood salvage alone.
POTENTIAL COMPLICATIONS — Perioperative blood salvage has some of the same potential complications that are associated with transfusion of allogeneic blood. These include the following:
●Coagulation defects – Since intraoperative blood salvage replaces only red blood cells (RBCs), dilutional coagulopathy is a frequent problem accompanying a large blood loss replaced solely by reinfusion of salvaged blood that does not contain plasma or platelets [66,79]. (See "Massive blood transfusion", section on 'Alterations in hemostasis'.)
●Transfusion-associated circulatory/volume overload – Pulmonary edema due to transfusion-associated circulatory/volume overload (TACO) may occur, especially in patients with compromised cardiac function. TACO may occur more frequently in surgical settings where large volumes of fluid and blood are administered. (See "Transfusion-associated circulatory overload (TACO)".)
●Infection – As with transfusion of any blood component, the risk of bacterial contamination is a possibility .
●Air embolism – Cell savers have the ability to pump massive amounts of air into the reinfusion bag [80,81] (see "Air embolism"). Safeguards to avoid air embolism include (1) transferring the blood into a separate bag or (2) disconnecting the bag from the cell saver equipment before giving it back to the patient [81,82]. Other standard safety precautions for intravenous infusions are also employed, including removing residual air from the bag containing the red cell product to be infused, avoiding the use of "pressure bags" to increase the reinfusion rate, and using inline air detectors when blood reinfusion is administered via an infusion pump.
●Embolism of microaggregates or fat – Embolism of microaggregates consisting of white blood cell and platelet debris in salvaged blood is preventable by use of a 40-micron microaggregate filter for reinfusion, which, in addition to RBC washing, is standard practice in blood salvage programs. Fat embolism is also possible but is preventable by extra washing and/or use of a leukocyte-reducing filter .
In one multicenter retrospective review of the autotransfusion and risk management system records for 33,351 patients receiving salvaged blood, only two potential adverse events were identified (one patient with acute tachycardia, hypertension, and dyspnea with rigors and another with acute hypotension and dyspnea) . There were no air emboli and no deaths in this large review.
ESTABLISHING A BLOOD SALVAGE PROGRAM — The AABB (formerly known as the American Association of Blood Banks) Standards for Perioperative Autologous Blood Collection and Administration recommend that hospitals with intraoperative blood salvage programs and blood centers providing the service should establish written policies and procedures for proper collection, labeling, and storage of the collected blood . All policies and procedures should be regularly reviewed by a clinician responsible for the program. Periodic quality control testing of collected blood is recommended to ensure that collection equipment and techniques result in an aseptic blood product.
Guidelines and training are essential for the quality assurance of intraoperative blood salvage, which was pointedly described in an editorial as a "largely unregulated cottage industry" . The technique can potentially be performed by a cross-trained operating room employee (eg, an anesthesia technician) or by a member of a specialist service (eg, an extracorporeal technologist or perfusionist). Cross-training employees as cell salvage technicians might be more economical than using an outsourced specialist service when the caseload exceeds 55 cases per year .
SUMMARY AND RECOMMENDATIONS
●Intraoperative blood salvage can be utilized throughout the surgical procedure to rapidly provide large quantities of autologous blood. (See 'Indications and benefits' above.)
●Blood salvage is contraindicated in the presence of solutions that are hypotonic (eg, sterile water) or toxic (eg, alcohol, hydrogen peroxide, or povidone-iodine solution), or when there is a possibility of simultaneous collection of hemostatic agents (eg, microfibrillar collagen-based products, topical thrombin, or fibrin glue) or methyl methacrylate (ie, bone cement). (See 'Contraindications' above.)
●Use of intraoperative blood salvage in patients with bacterial infections, active malignancy, or hemorrhage at cesarean delivery is decided on a case-by-case basis. (See 'Relative contraindications' above and 'Areas of uncertainty' above.)
●Processing of intraoperative salvaged blood involves separation, washing, and centrifuging (concentrating) blood aspirated from the surgical field and mixed with an anticoagulant. The result is a salvaged red blood cell (RBC) product with a hemoglobin >17 g/dL. (See 'Processing of blood' above.)
●A 40-micron microaggregate filter is installed between the cell salvage bag and the patient to filter the blood as it is reinfused into the patient. A leukocyte depletion filter is an excellent alternative when it is desirable to achieve optimal removal of bacteria, cancer cells, fat particles, or amniotic fluid. (See 'Reinfusion' above.)
●Salvaged washed RBCs have the same posttransfusion RBC survival as traditional washed RBC products. Neither product contains functional platelets, white blood cells, or coagulation factors. (See 'Salvaged washed red cells' above.)
●Blood collected by intraoperative blood salvage may be stored either at room temperature for up to six hours or at 1 to 6°C for up to 24 hours, provided that blood is collected under aseptic conditions with a device that provides washing and that cold storage is begun within six hours of initiating the collection. Such stored blood must be properly labeled. (See 'Storage and handling' above.)
●Potential complications of perioperative blood salvage include some of those associated with allogeneic blood transfusion (eg, coagulopathy, transfusional volume overload, bacterial contamination, and embolism of air, cellular microaggregates, or fat). (See 'Potential complications' above.)
●We suggest blood salvage in surgical procedures having a high likelihood of significant blood loss (>1000 mL), rather than relying on transfusion of allogeneic blood (Grade 2B). Blood salvage avoids or reduces allogeneic blood transfusion, with its attendant risks. (See 'Intraoperative blood salvage' above.)
●Salvaged blood should be washed. Salvaged blood that is not washed or otherwise processed (eg, centrifuged) has low hemoglobin levels (7 to 9 g/dL), residual anticoagulant, dysfunctional platelets, thrombogenic substances, free hemoglobin levels, and fat emboli that might lead to coagulation abnormalities. (See 'Salvaged unwashed blood' above.)
●Blood collected by intraoperative blood salvage should never be transfused to any patient other than the one from whom it was collected. (See 'Storage and handling' above.)
●After cardiac surgery, if shed mediastinal blood from chest tube drainage is to be reinfused, we suggest that it first be washed (Grade 2C). Postoperative blood salvage after major orthopedic surgery (eg, joint replacement surgery) is evolving and is individualized based upon institutional expertise and available technologies. (See 'Postoperative blood salvage' above.)