Processing of small volumes in blood salvage devices

Advances in automated cell washing and concentration

The successful commercialization of cell therapies requires thorough planning and consideration of product quality, cost and scale of the manufacturing process. The implementation of automation can be central to a robust and reproducible manufacturing process at industrialized scales. There have been a number of wash-and-concentrate devices developed for cell manufacturing. These technologies have arisen from transfusion medicine, hematopoietic stem cell and biologics manufacturing where operating mechanisms are distinct from manual centrifugation. This review describes the historical origin and fundamental technologies underlying each currently available wash-and-concentrate device as well as their relative advantages and disadvantages in cell therapy applications. Understanding the specific attributes and limitations of these technologies is essential to optimizing cell therapy manufacturing.

Extracellular Vesicles in Autologous Cell Salvaged Blood in Orthopedic Surgery

(1) Background: Cell salvage is highly recommended in orthopedic surgery to avoid allogeneic transfusions. Preparational steps during cell salvage may induce extracellular vesicle (EV) formation with potential thrombogenic activity. The purpose of our study was to assess the appearance of EVs at retransfusion. (2) Methods: After ethics committee approval and informed consent, blood was withdrawn from the autotransfusion system (Xtra, Sorin, Germany) of 23 patients undergoing joint arthroplasty. EVs were assessed by flow cytometry in two times centrifugated samples. EVs were stained with specific antibodies against cellular origins from platelets (CD41), myeloid cells (CD15), monocytes (CD14), and erythrocytes (CD235a). The measured events/µL in the flow cytometer were corrected to the number of EVs in the retransfusate. (3) Results: We measured low event rates of EVs from platelets and myeloid origin (<1 event/µL) and from monocytic origin (<2 events/µL). Mean event rates of 17,042 events/µL (range 12–81,164 events/µL) were found for EVs from red blood cells. (4) Conclusion: Retransfusate contains negligible amounts of potentially thrombogenic EVs from platelet and monocytic origin. Frequent EVs from erythrocytes may indicate red blood cell destruction and/or activation during autologous cell salvage. Further research is needed to investigate the clinical relevance of EVs from salvaged red blood cells.

[Cell salvage : Scientific evidence, clinical practice and legal framework]

Cell salvage is an efficient method to reduce the transfusion of homologous banked blood, as documented by several meta-analyses detected in a systematic literature search. Cell salvage is widely used in orthopedics, trauma surgery, cardiovascular and abdominal transplantation surgery. The retransfusion of unwashed shed blood from wounds or drainage is not permitted according to German regulations. Following irradiation of wound blood, salvaged blood can also be used in tumor surgery. Cell salvage makes a valuable contribution to providing sufficient compatible blood for transfusions in cases of massive blood loss. Certain surgical procedures for Jehovah's Witnesses are only possible with the use of cell salvage. Another possible use is the washing of homologous banked blood, e. g. to prevent potassium-induced arrhythmia or sequestration of autologous platelets. Other advantages besides a good compatibility are the high vitality and functionality of the unstored autologous red blood cells. These have been declared a pharmaceutical product by the German transfusion task force in 2014, so that the autologous red blood cells are now under the control of the Pharmaceutical Products Act (AMG). The new hemotherapy guidelines, however, tolerate cell salvage only under strict rules, whereby the production of autologous blood during or after surgery is still possible without additional special permits. The new guidelines now require the introduction of a quality management system for cell salvage and regular quality controls. These quality controls include a control of the product hematocrit for every application, monthly controls of the protein and albumin elimination rates and the erythrocyte recovery rate for each cell salvage device. Testing for infection markers is not required. The application of cell salvage has to be reported to the appropriate authorities.

Traditional and emerging technologies for washing and volume reducing blood products

Millions of blood components including red blood cells, platelets, and granulocytes are transfused each year in the United States. The transfusion of these blood products may be associated with adverse clinical outcomes in some patients due to residual proteins and other contaminants that accumulate in blood units during processing and storage. Blood products are, therefore, often washed in normal saline or other media to remove the contaminants and improve the quality of blood cells before transfusion. While there are numerous methods for washing and volume reducing blood components, a vast majority utilize centrifugation-based processing, such as manual centrifugation, open and closed cell processing systems, and cell salvage/autotransfusion devices. Although these technologies are widely employed with a relatively low risk to the average patient, there is evidence that centrifugation-based processing may be inadequate when transfusing to immunocompromised patients, neonatal and infant patients, or patients susceptible to transfusion-related allergic reactions. Cell separation and volume reduction techniques that employ centrifugation have been shown to damage blood cells, contributing to these adverse outcomes. The limitations and disadvantages of centrifugation-based processing have spurred the development of novel centrifugation-free methods for washing and volume reducing blood components, thereby causing significantly less damage to the cells. Some of these emerging technologies are already transforming niche applications, poised to enter mainstream blood cell processing in the not too distant future.

Performance of a new-generation continuous autotransfusion device including fat removal and consequences for quality controls

BACKGROUND AND OBJECTIVES

Cell salvage plays a key role in blood conservation. To maintain high performance, quality management is recommended. Accordingly, a new-generation autotransfusion device was tested for its performance and compared with its predecessor. Two different calculations of quality parameters were applied.

MATERIALS AND METHODS

In an experimental study, the continuous autotransfusion devices CATSmart and Continuous Autotransfusion System (C.A.T.S) plus were tested using banked blood adjusted to a haematocrit of 20% and anticoagulated with heparin 5 U/L. Test blood was processed using an emergency programme, a high-quality programme/smart wash programme and a low-volume wash programme. Samples were taken after the production of 200 mL of red blood cells (RBC) and after the final emptying of the separation chamber. In an additional set of tests, blood containing 1·25% fat was processed with both devices to examine fat removal.

RESULTS

Both devices demonstrated an equally high performance with regards to product hematocrit (Hct); RBC recovery; and elimination rates of protein, heparin and fat. The high fat elimination rate (>99·8%) reported for C.A.T.S plus was confirmed for CATSmart, regardless of the used programme. Samples taken during the ongoing process show a higher haematocrit and RBC recovery rate than samples taken after the final emptying of the separation chamber. Interface sensors were not affected by fat in the blood.

CONCLUSIONS

The new-generation autotransfusion device CATSmart is not inferior to its predecessor and shows high performance with regards to RBC recovery, plasma and fat elimination in all programme modes. Samples for quality controls should be taken during blood processing.

Pediatric Patient Blood Management Programs: Not Just Transfusing Little Adults

Red blood cell transfusions are a common life-saving intervention for neonates and children with anemia, but transfusion decisions, indications, and doses in neonates and children are different from those of adults. Patient blood management (PBM) programs are designed to assist clinicians with appropriately transfusing patients. Although PBM programs are well recognized and appreciated in the adult setting, they are quite far from standard of care in the pediatric patient population. Adult PBM standards cannot be uniformly applied to children, and there currently is significant variation in transfusion practices. Because transfusing unnecessarily can expose children to increased risk without benefit, it is important to design PBM programs to standardize transfusion decisions. This article assesses the key elements necessary for a successful pediatric PBM program, systematically explores various possible pediatric specific blood conservation strategies and the current available literature supporting them, and outlines the gaps in the evidence suggesting need for further/improved research. Pediatric PBM programs are critically important initiatives that not only involve a cooperative effort between pediatric surgery, anesthesia, perfusion, critical care, and transfusion medicine services but also need operational support from administration, clinical leadership, finance, and the hospital information technology personnel. These programs also expand the scope for high-quality collaborative research. A key component of pediatric PBM programs is monitoring pediatric blood utilization and assessing adherence to transfusion guidelines. Data suggest that restrictive transfusion strategies should be used for neonates and children similar to adults, but further research is needed to assess the best oxygenation requirements, hemoglobin threshold, and transfusion strategy for patients with active bleeding, hemodynamic instability, unstable cardiac disease, and cyanotic cardiac disease. Perioperative blood management strategies include minimizing blood draws, restricting transfusions, intraoperative cell salvage, acute normovolemic hemodilution, antifibrinolytic agents, and using point-of-care tests to guide transfusion decisions. However, further research is needed for the use of intravenous iron, erythropoiesis-stimulating agents, and possible use of whole blood and pathogen inactivation. There are numerous areas where newly formed collaborations could be used to investigate pediatric transfusion, and these studies would provide critical data to support vital pediatric PBM programs to optimize neonatal and pediatric care.

Fat removal during cell salvage: an optimized program for a discontinuous autotransfusion device

BACKGROUND

Fat in wound blood observed in orthopedic or cardiac surgery might pose a risk for fat embolism during blood salvage. Fat removal was optimized in the washing process.

STUDY DESIGN AND METHODS

In an experimental study blood from fresh donations was adjusted to a hematocrit (Hct) of 25% and an admixture of 1.25% human tissue fat. This blood was processed with the cell salvage device XTRA in a modified program mode. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From the volumes, the Hct levels and the concentrations of fat and other variables elimination rates and RBC recovery were calculated.

RESULTS

Pretests showed wash volume, wash flow, and process interruptions affecting fat elimination. With the new optimized fat elimination program Pfat removal rate of fat increased to 98.5 ± 0.9% for the 225-mL bowl. The product had a mean Hct of 48.7 ± 1.2% and a RBC recovery rate of 93.5 ± 2.3%. The program conserved the high elimination rates for albumin, heparin, potassium, and free plasma hemoglobin (98.8, 99.3, 95.3, and 94.9%, respectively). Similar high fat removal was also observed with bowls of smaller size, namely, 98.1% for the 175-mL bowl and 98.2% for the 125- and the 55-mL bowls. With test blood of Hct 10% a mean fat elimination of 99.6 ± 01% was observed.

CONCLUSIONS

A special program modification Pfat involving extra washing and RBC concentration steps significantly improves fat removal by the Latham bowl-based autotransfusion device XTRA, thus yielding results equivalent to the continuous cell salvage system.

The Reinfusion of Autogenous Shed Blood After Unilateral Total Knee Arthroplasty Using the Perioperative Autologous Transfusion System OrthoPAT

This study aims to explore the use of postoperative autogenous shed blood reinfusion using Orthopedic Perioperative Autotransfusion System (OrthoPAT) system in treating patients undergoing unilateral total knee arthroplasty (TKA). Fifty patients undergoing unilateral TKA were enrolled as the experimental group A and were treated with reinfusion of autologous shed blood within 6 hours after unilateral TKA using OrthoPAT. Accordingly, 50 patients undergoing unilateral TKA were selected as the experimental group B and were treated with allogeneic blood transfusion. Different indexes were observed at different times. Patients in both groups had relatively stable hemodynamics, and there was no postoperative coagulopathy. Prothrombin time, thrombin time, and activated partial thromboplastin time were lower, and fibrinogen was higher in group A than that in group B 24 hours after surgery (all P < 0.05). White blood cell, red blood cell, hemoglobin, hematocrit (Hct), and platelet count levels in group A were lower than those in group B 12 hours after surgery (all P < 0.05). The postoperative complications of the 2 groups have significant difference (P < 0.05). Postoperative autogenous shed blood reinfusion using OrthoPAT system in the treatment of patients undergoing unilateral TKA may improve the coagulation function of patients and reduce the rejection caused by standard allogeneic blood transfusion.

Evaluation of the minimum volume of salvage blood required for the successful use of two different autotransfusion devices

BACKGROUND

Autotransfusion in pediatric anesthesia is beneficial in several clinical settings; however, more frequent usage is deterred by process-related costs and the fact that the absolute volume of blood returned may be minimal.

OBJECTIVE

Two autotransfusion devices (CATS, Fresenius Kabi AG, and Sorin Xtra, Sorin GmbH) with different technologies were evaluated to determine the minimum volume necessary to efficiently process salvage blood.

METHODS

Banked blood was diluted to simulate different clinical scenarios. Volume and red cell mass in returned blood were analyzed as a function of initial volume and red cell mass in the collection reservoir using incremental increases in the volume of blood added to the reservoir.

RESULTS

The volume of the returned processed blood for infusion was dependent on degree of dilution and blood volume in the reservoir. The CATS required a smaller initial minimum volume to process and successfully return; however, the Xtra provided a more efficient recovery at low initial collected volumes. Using test blood of various degrees of dilution, the CATS and Xtra were able to return blood for retransfusion after a mean initial red cell mass of 48.7 ml (±4.9 ml) and 53.7 ml (±5.0 ml) were processed, respectively.

CONCLUSIONS

Red cell mass rather than salvaged blood volume represents a reliable predictor of the successful use of an autotransfusion device. Measuring the hematocrit of the salvaged blood could improve the use of the devices. The investigated devices are likely to be roughly equivalent in effectiveness.

Fat removal during cell salvage: a comparison of four different cell salvage devices

BACKGROUND

Fat embolism is a possible risk factor for pulmonic and cerebral dysfunction after orthopedic and heart surgery. It is unknown whether fat occasionally observed during cell salvage adds to the risk of fat embolism after retransfusion. We have examined the fat removal capacities of different cell salvage devices including discontinuous and a continuous system under various conditions.

STUDY DESIGN AND METHODS

In an experimental study ABO-matched banked blood was adjusted to a hematocrit of 20%, and 1.25% of human fat was added. This blood was processed with the cell salvage devices XTRA and Electa, CATS, or Cell Saver 5 plus. Fat in the blood samples was quantified by volumetric measurement after centrifugation in Pasteur pipettes and by gravimetric measurement after extraction of fat in organic solvents and phase partition. Performance in fat removal was tested with different programs, bowl sizes, and additional filtration.

RESULTS

The continuous system consistently showed a high fat removal rate of 99.8 ± 0.2%. Fat accumulated in the wash disposal, but not in the product. In the Latham bowl-based discontinuous systems, fat removal varied from 69.2 to 92.8 ± 4.4% depending on the program mode, but not on the bowl size. Additional filtration increased fat removal to 96.7 ± 2.2%, but also increased red blood cell loss.

CONCLUSIONS

Fat contamination of wound blood can be detected by volumetric and gravimetric measurements. Continuous salvage systems remove fat to a higher extent than discontinuous systems. The fat removal capacities of discontinuous systems depend on the program mode and can be improved by filtration.