Although the nature of procedures performed in orthopedic and urologic surgery differ, they have in common the potential to be often associated with blood loss, and hence the need for allogeneic transfusion. In addition, procedures in urologic and orthopedic surgery are often elective, and many such patients express interest in predeposit autologous blood donation. These similarities are shown in Table 11.1.
First, the potential to over-crossmatch allogeneic blood is prominent in both types of surgery. In orthopedic surgery, spinal, hip, and knee surgery, (particularly re-do's or bilateral procedures), and in urologic surgery, radical nephrectomies, retropubic prostatectomies, and extensive transurethral resections, there can be substantial blood loss with the subsequent need for allogeneic transfusion. On account of this potential, excessive amounts of crossmatched blood are frequently requested preoperatively for many orthopedic or urologic procedures. However, preoperatively crossmatching between 1-4 units should be acceptable, in most cases, depending on the type of procedure. For these procedures, in which blood transfusion is uncommon, a type and screen should suffice. In the event of unexpected hemorrhage, a procedure should be in place in order that blood can be dispensed expeditiously. Agreement on a maximum surgical blood ordering system (Chapter 9) is important for all of these procedures.
The practice of predeposit autologous blood (Chapter 3) increased sharply for both orthopedic and urologic elective surgical procedures throughout the 1980s, but has leveled or may be declining in the late 1990s. The elective nature of many of these procedures, the real or perceived need for allogeneic blood transfusion, and concern regarding disease transmission by blood transfusion was largely responsible for this increase. It should be noted however, that predeposit blood is over collected for these procedures, in many instances. Overall, only about 50% of all such predeposit blood is transfused perioperatively, depending on the assessment of perioperative blood loss and the tolerance of the surgeon for postoperative normovolemic anemia (Chapter 26). Opinions differ with regard to the appropriate threshold hemoglobin or hematocrit at which autologous blood should be transfused in the postoperative normovolemic patient. It has been contended that autologous blood should be transfused using the same clinical criteria as allogeneic blood. Alternatively, since autologous blood is inherently "safer" than allogeneic blood (although not without risk), it has been suggested that the threshold be different, i.e., a more liberal policy. There is no general agreement of this. It is important to appreciate that predeposit autologous blood is not completely safe
Table 11.1. Similar transfusion considerations in orthopedic and urologic surgery
1. Potential to over-cross-match allogeneic blood (Chapter 9)
2. Practice of predeposit autologous blood (Chapter 3)
3. Practice of intraoperative salvage (Chapter 3)
4. Practice of acute normovolemic hemodilution (Chapter 3)
6. Tolerance of postoperative normovolemic anemia and reactions such as hemolysis and bacterial contamination have been reported, with potential for fatal outcome (Chapter 35).
Both types of surgery may be suitable for intraoperative salvage. Orthopedic surgery, spinal surgery and joint revisions (particularly bilateral) are appropriate indications. Intraoperative salvage should require a washing phase for the salvaged blood prior to reinfusion since particulate contaminants are common. In addition, bone chips also can sometimes clog the filter of the reservoir or the intraoperative salvage device, and aspiration should be discontinued during this phase. Importantly, aspiration should never be performed when new cement (methacrylate) has been placed. For urological surgery, a different issue arises regarding the use of intraoperative salvage in patients undergoing procedures for cancer, such as radical nephrectomies or retropubic prostatectomies. Under these circumstances, it has been suggested that blood should be reinfused using a specialized filter designed to remove leukocytes from allogeneic red cell products (R100 filter, PALL Corporation). Although, these filters have been shown by electromicroscopy to be effective in removing tumor cells, there is no data to indicate that the routine use of such filters is clinically useful, i.e., prevent metastatic spread. Avoidance of aspirating from the tumor bed itself is, however, prudent. Used appropriately, intraoperative salvage has great potential in orthopedic and urologic surgery to reduce the need for allogeneic blood transfusion.
Acute normovolemic hemodilution (Chapter 3) has been practiced on many of these patients, generally removing 2-3 units of whole blood. Although several studies in the 1980s were reported to show a reduction in allogeneic transfusion, it has been suggested that, in most instances, normovolemic dilution in itself does not result in an actual reduction in allogeneic blood transfused, but rather that increased tolerance by the surgeon for perioperative or postoperative anemia explains the observed differences. Deep hemodilution (to an immediate preoperative Hct of 20) may be useful in situations where a large blood loss (4 or more units) is likely, such as spinal fusion, but anesthesiologists are often reluctant to attempt to achieve this target dilutional hematocrit.
In both types of surgery there is a limited need for the use of plasma or platelets. The one likely exception is spinal fusion surgery in which a blood loss of 0.5-1
blood volumes or more may occur intraoperatively. Under these circumstances microvascular oozing may be encountered intraoperatively, and the use of plasma in a dose of 10-15 ml/Kg is appropriate. Procedures requiring platelet transfusions are uncommon, and this should be reserved for hemorrhage in excess of 1 blood volume (8-12 units RBC).
Last, the use of allogeneic blood in these patients will be determined to some extent by the tolerance of the surgeon for postoperative normovolemic anemia. There is a tendency to transfuse these patients, many of whom are elderly, whenever the hemoglobin falls below an arbitrary threshold of 10 g/dl. It is uncertain that these patients actually benefit from allogeneic blood transfusion in the postoperative setting at this threshold, and a threshold of 8 g/dl may be a better trigger in the absence of symptoms ofhypoxemia (Chapter 26). Further studies are needed to clarify this situation.
Orthopedic surgery also presents some different clinical scenarios from uro-logic surgery. First, postoperative drainage and reinfusion of postoperative salvage blood continues to be practiced in orthopedic surgery. Devices are available which accompany the patient from the operating room to the postoperative area, in order to continue the collection of postoperative blood from the surgical drain. This salvage blood is unprocessed (unwashed), but routinely transfused using a filter. Although theoretically of concern because of the presence of cellular debris, this product has not been associated clinically with adverse reactions. It needs to be emphasized however, that this practice has not been shown to have an important role in reducing allogeneic exposure and it is doubtful as to whether the small amount of red cells actually harvested under these conditions effects any significant reduction in postoperative allogeneic transfusions. Second, there has been a recent interest in the treatment of patients undergoing orthopedic surgery with preoperative erythropoietin. Erythropoietin may be given in any one of a number of regimens as shown in Table 11.2. Administration may be intravenous or
Table 11.2. Erythropoietin in orthopedic surgery a) To increase predeposit autologous donations
250-300 IU/Kg IV twice weekly x 2-3 weeks preoperatively 600 IU/Kg Sc weekly x 2-3 weeks preoperatively Ferrous sulphate 200 mg daily.
b) To increase red cell mass perioperatively in anemic patients 100 IU/Kg - 300 IU/Kg SC daily x 15 doses,
10 days pre surgery and for 4 days post surgery c) Consider in anemic patients, Jehovah's Witnesses, rare blood groups or allosensitized patients.
subcutaneous, on a weekly regimen preoperatively, or combined preoperatively and postoperatively. Published studies show that these erythropoietin treatment regimens have been associated with a reduction in the use of allogeneic red cells. Erythropoietin, when given in this situation, requires routine use of supplementary elemental oral iron. Erythropoietin will increase red cell mass and thus, increase the number of predeposited autologous blood units which can be collected; also, the increase in red cell mass will reduce the extent of postoperative normovolemic anemia thus, potentially averting the transfusion of allogeneic cells. It remains to be shown however, that, while technically feasible, this expensive intervention will translate into a patient benefit, as measured in a cost-effective analysis, given the safety of the current blood supply and the expense associated with this form of treatment. Third, European studies have recently shown a benefit of aprotinin at a dose of two million KIU in reducing acute blood loss and allogeneic transfusion in orthopedic surgery (Chapter 23). This interesting observation will require confirmation, however, in additional studies.
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