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not severe and are completely resolved by medication, the ongoing transfusion is often canceled and over a third of patients must be transfused again. This not only strains the already scarce supply of blood products but also results in high costs [ 10 ]. At the SHOT( Serious Hazards of Transfusion) Symposium 2018, it emerged that over 85 % of complications during transfusions were caused by human error in the process, such as misunderstandings, incorrect assumptions, or inadequate handovers [ 8 ]. These errors could be reduced by intraoperative cell savers, as the blood product remains in the operating room and therefore no mix-ups can occur. However, the use of intraoperative cell savers is contraindicated in Germany in cases of suspected bacterial contamination of the operating field or bacteremia, as well as in tumor surgery. In contrast to other countries, the use of leucocyte depletion filters alone is not sufficient in Germany for tumor surgery, as the hemotherapy guideline recommends the irradiation of the processed autologous transfusion blood [ 11 ]. In Germany, intraoperatively prepared transfusion blood is subject to quality control, whereby the target hematocrit value must be above 50 % and the target elimination rate of total protein or albumin must be above 90 %. In previous studies, a hematocrit of over 50 % of the processed blood could not always be achieved by intraoperative cell salvage [ 12 – 15 ]. Since the recovery of erythrocytes is the main objective of cell savers, the question arises whether an absolute hematocrit target value of over 50 % is necessarily relevant for this objective. The hematocrit in autotransfusion blood was particularly low when a small volume of collected blood was processed [ 13 ], as the missing volume in the collection bowl must be filled with physiological saline solution before the washing process [ 14 ]. The hematocrit in the processed transfusion blood was also lower when using the emergency program, in which the collected blood is processed more quickly, resulting in a lower RBC yield [ 13, 15 ]. Nevertheless, the hemoglobin value of patients who receive an intraoperative autotransfusion increases significantly postoperatively [ 16 ] and even more than in patients who receive a homologous blood transfusion [ 17 ]. Previous studies have shown an average total protein elimination of over 90 % [ 13, 15 ].
Study aim
Previous studies have not yet described the influence of patient-dependent factors such as age, gender, and surgical diagnosis on compliance with the target values for the hematocrit value of the prepared transfusion blood and total protein elimination. Similarly, special clinical-surgical circumstances that result in lower hematocrit values have not yet been evaluated, which is the subject of this article. The age and gender of the patients were only recorded to better describe the patient collective under investigation. We did not expect these parameters to have any influence on quality control. Nevertheless, to complete the study, we aimed to investigate the influence of these parameters on total protein elimination and hematocrit.
Material and methods
Each time an intraoperative cell salvage is performed at Charité – Universitätsmedizin Berlin, a quality control check is carried out. This study includes all uses of the cell savers since January 2019 at Campus Charité Mitte and Campus Benjamin Franklin in which an autotransfusion of the processed blood took place. At Campus Charité Mitte, 107 cases were included until 1 March 2022 and at Campus Benjamin Franklin, 131 cases were included until 29 March 2022. The different end dates result from the different times of data collection at the cell savers. This results in a total patient collective of 238 cases. During the study period, only the 125 mL bowl size was used. The optimal default program( Popt) was used for each wash set. The emergency option was occasionally selected for larger quantities of collected blood in a short period of time. By activating the emergency option, the standard program( Pstd) was selected, which achieves a minimum hematocrit concentration and a minimum wash quality within the shortest possible processing time. The additional options“ No Wash” and“ Rapid Transfer” in this mode were not selected. The default factory program settings were not changed during usage. Medical cell salvage users were asked about possible reasons for deviations from the target values and acceptance criteria.
This study protocol was reviewed and approved by the Ethics Committee of the Charité – Universitätsmedizin Berlin( approval reference EA2 / 096 / 23). The data for quality control of the use of the cell saver is stored in a standard table in the SAP Ò hospital information system.
Outcome
The main aim of the evaluation was to assess whether the target values specified in the German hemotherapy guideline of hematocrit(> 50 %) and a total protein elimination(> 90 %) in the transfusion blood were not achieved in certain applications of cell salvage, and to investigate the influence of patient-dependent factors such as age, gender, surgical diagnosis, and special surgical circumstances on compliance with the target values.
Procedures
The cell saver Sorin LivaNova Xtra Ò is used for intraoperative autotransfusion at the Charité. The device is set up according to the manufacturer’ s instructions. The wound blood was aspirated from the surgical site, mixed with the anticoagulant simultaneously, and then stored in a sterile reservoir. Anticoagulation was carried out with heparin( 25,000 IU per 0.5 liter of NaCl 0.9 %) or alternatively with argatroban( 50 mg / L) according to the anesthesiologist’ s instructions. If sufficient blood volume was aspirated, the collected blood was transferred and processed in the Latham bowl. As it rotated, the erythrocytes reached the outer wall of the bowl due to their greater density. Plasma, waste components and other blood components, which had a lower density than erythrocytes, then flowed into a waste bag. This washing process continued until the buffy coat reached a certain level, indicating that there were sufficient red blood cells in the bowl. If a bowl could not be sufficiently filled with the available collected blood, the treating anesthesiologist could choose to either fill the rest of the volume with rinsing fluid and accept a low hematocrit, stop the washing process and pump the contents of the bowl back into the reservoir