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Controlled, deliberate hypotension during anesthesia for major spinal surgery reduces intraoperative blood loss and transfusion requirement. Hypotension may be achieved with increased doses of volatile anesthetic agents or by continuous infusion of vasodilating drugs. Safe application of this technique requires knowledge of the physiology of hemorrhagic shock and close intraoperative monitoring to avoid vasoconstriction and endorgan ischemia.

Patients and physicians continue to be motivated to find methods to reduce the use of allogeneic blood. Even though donor screening has increased the safety of donated blood products, autologous blood is the most desirable source of red cells during the perioperative period. The methods commonly used to obtain autologous blood during the perioperative period can be initiated prior to the operative procedure (autologous preoperative donation, acute normovolemic hemodilution) or during surgery (cell scavenging). Acute normovolemic hemodilution (ANH) involves a controlled removal of whole blood immediately prior to the operation. The patient’s intravascular volume is maintained with solutions that contain non-red cells. The operative procedure is conducted with a normal blood volume, but with a reduced red cell mass. At the conclusion of the operation, the stored autologous blood is restored to the patient. If operative blood loss is not excessive, the replacement of autologous blood may provide an acceptable red cell mass. In addition to surgical blood loss, some of the key factors in determining how effective acute normovolemic hemodilution will be in limiting allogeneic transfusion are: the patient’s initial hematocrit and blood volume; the volume of autologous blood removed prior to the operation; the effectiveness of the hemodilution; and the timing of autologous blood replacement. In contrast to autologous pre-donation, autologous blood removed during acute normovolemic hemodilution is usually stored and re-infused in the operating room.

Orthopaedic patients frequently require blood transfusions to treat peri-operative anemia. Research in the area of hemoglobin substitutes has been of great interest since it holds the promise of reducing the reliance on allogeneic blood transfusions. The three categories of hemoglobin substitutes are (1) cell-free, extracellular hemoglobin preparations made from human or bovine hemoglobin (hemoglobin-based oxygen carriers or HBOCs); (2) fluorinesubstituted linear or cyclic carbon chains with a high oxygen-carrying capacity (perfluorocarbons); and (3) liposome-encapsulated hemoglobin. Of the three, HBOCs have been the most extensively studied and tested in preclinical and clinical trials that have shown success in diminishing the number of blood transfusions as well as an overall favorable side-effect profile. This has been demonstrated in vascular, cardiothoracic, and orthopaedic patients. HBOC- 201, which is a preparation of cellfree bovine hemoglobin, has been approved for clinical use in South Africa. These products may well become an important tool for physicians treating peri-operative anemia in orthopaedic patients.

This article focuses on our current understanding of the role of activated coagulation factor VII (FVIIa) in coagulation, the current evidence regarding the efficacy and safety of recombinant FVIIa (rFVIIa), and thoughts regarding the use of rFVIIa in spine surgery. rFVIIa is approved in many countries (including the European Union and the USA) for patients with hemophilia and inhibitors (antibodies) to coagulation factors VIII or IX. High circulating concentrations of FVIIa, achieved by exogenous administration, initiate hemostasis by combining with tissue factor at the site of injury, producing thrombin, activating platelets and coagulation factors II, IX and X, thus providing for the full thrombin burst that is essential for hemostasis. This “bypass” therapy has led some clinicians to use rFVIIa “off-label” for disorders of hemostasis other than hemophilia. Based on clinical experience, case reports and limited information from clinical trials, rFVIIa may be efficacious in states of decreased concentration of coagulation factors, thrombocytopenia, and at least some states of altered platelet function. The former two can occur intra-operatively during spinal surgery as a consequence of substantial blood loss and normal consumption. Preliminary reports have indicated that rFVIIa does not increase the perioperative incidence of thromboembolic events. However, full reports from large clinical trials regarding the efficacy and safety of rFVIIa in settings other than hemophilia have yet to appear in peer-reviewed publications. Until adequate data demonstrating safety and efficacy are fully reported, it would seem appropriate to reserve the use of rFVIIa in spinal surgery to those instances where conventional therapy cannot provide adequate hemostasis, and “rescue” therapy is required.

The use of local agents to achieve hemostasis is an old and complex subject in surgery. Their use is almost mandatory in spinal surgery. The development of new materials in chemical hemostasis is a continuous process that may potentially lead the surgeon to confusion. Moreover, the more commonly used materials have not changed in about 50 years. Using chemical agents to tamponade a hemorrhage is not free of risks. Complications are around the corner and can be due either to mechanical compression or to phlogistic effects secondary to the material used. This paper reviews about 20 animal and clinical published studies with regard to the chemical properties, mechanisms of action, use and complications of local agents.

Advances in anaesthesiology and intensive care therapy as well as improved instrumentation have been responsible for the rapid development of spinal surgery during the past 15 years. Pathological lesions of the spinal column often demand partial or complete resection of the vertebral body, which in turn requires its replacement. The extraordinary vascular supply of the vertebral body and of the spinal canal often results in profuse bleeding in the environs of sensitive structures such as the spinal cord. Electrocoagulation is of limited use, for fear of causing thermal injury. While preoperative embolisation can considerably reduce the tendency to bleed in such instances, bleeding from the epidural venous plexus may be unavoidable, e.g., in spondylitis and tumour surgery. In such instances, fibrin sealants have proved to be an excellent means of controlling diffuse bleeding. Fibrin sealants have also proved to be effective in controlling diffuse bleeding during cervical disc surgery, which occasionally necessitates preparation and identification of the vertebral artery. The resulting spectrum of applications of fibrin sealants are presented here.

There are various electrical, mechanical and chemical methods used to achieve haemostasis in spine surgery. Chemical haemostatic agents are often preferable to bipolar cautery in intraspinal procedures, because these products control bleeding without occluding the vessel lumen and cause no thermal injuries to adjacent structures. A topical haemostat is the often the technique of choice to control bleeding from bone and to diffuse capillary and epidural venous oozing. This paper focuses on technical aspects of the application of absorbable porcine gelatine and regenerated, oxidised cellulose. These haemostats have been used in neurosurgical intraspinal procedures for more than 30 years; however, new application forms like Surgicel fibrillar and Surgifoam powder imply different handling options, which are discussed in this paper.

A possible strategy to promote the wound-healing cascade in both soft and hard tissues is the preparation of an autologous plateletrich plasma (PRP) to encourage the release of growth factors from activated platelets. In this process, PRP combines the advantage of an autologous fibrin clot that will aid in hemostasis as well as provide growth factors in high concentrations to the site of a tissue defect. The PRP preparation can be used as a biological enhancer in the healing of fractures and lumbar fusions. The local application of growth factors seems to promote initiation and early maturation of bone formation. Autologous bone or bone substitutes can be added to this mixture to increase the volume of grafting material. A simplified technique utilizing a commercially available separation system (GPS - Gravitational Platelet Separation System) is described. This system provides a less costly alternative to other previously described augmentation techniques and also presents a patient-friendly and operator-safe alternative. Further experimental studies of the actual concentrations of the growth factors in the PRP samples are necessary in order to validate the platelet concentration and growthfactor activation by laboratory evidence. In further prospective clinical trials, the safety and efficacy of PRP, in combination with autologous bone or bone graft substitutes, must be evaluated.

Increased awareness of the potential hazards of allogenic blood transfusion, such as incompatibility reactions, metabolic and immunologic disorders, or transmission of viral diseases, has led to an emphasis on allogeneic blood alternatives. For orthopaedic surgery, several autologous transfusion modalities have emerged as alternatives to allogeneic blood transfusion, avoiding its immunomodulatory effects. Among them, transfusion or return of post-operative salvaged shed blood has become popular in major orthopaedic procedures. However, although the effectiveness of this blood-saving method is well documented, several authors have questioned its safety and recommended the use of washed blood. Therefore, this review analyses the haematologic characteristics of unwashed filtered shed blood, including metabolic status and survival of red blood cells, the components of the haemostatic system, the content of fat particles, bacterial and tumour cells and the possibility of their removal, the content of inflammatory mediators, and the effects on the patient’s immune system. From data reviewed in this paper, it can be concluded that post-operative salvage of blood seems to be an excellent source of functional and viable red cells without many of the transfusion-related risks and with some immuno-stimulatory effects. In addition, from our experience, postoperative re-infusion of unwashed shed blood after major spine procedures has proved to reduce post-operative homologous transfusion requirements and to complement preoperative autologous blood donation, without any clinically relevant complication.