PREOPERATIVE Establish baseline laboratory studies CBC hemoglobin & hematocrit platelets prothrombin time (PT) determines clotting time for the extrinsic coagulation cascade login to view 4 more bullets not correlated with increased transfusion rates partial thromboplastin time (PTT) assesses clotting time of the intrinsic clotting cascade factors XII, XI, IX, VIII, X, V, and II normal 25-39 seconds not correlated with increased transfusion rates fibrinogen also known as factor I normal 200-400 mg/dL below normal ranges have been associated with increased transfusion rates Preoperative blood loss estimation allows for cost-effective treatment with cell salvage systems, allogenic blood transfusions, and antifibrinolytic agents factors associated with increased blood loss: increased body mass index lower body weight login to view 3 more bullets advanced age bleeding diathesis number of spinal levels undergoing surgery login to view 1 more bullet use of instrumentation revision spine surgery iliac crest bone graft harvest interbody fusions trauma or tumor surgery Cobb angle >50° longer expected surgical time neuromuscular scoliosis >6 levels fused for deformity surgery Ponte osteotomies vertebral column resection login to view 1 more bullet recommend obtaining a preoperative hemoglobin level of 5 g/dL greater than the treating surgeon's transfusion trigger Hemoglobin optimization goal is to reduce allogenic blood transfusion intraoperatively and postoperatively vitamin supplementation login to view 13 more bullets erythropoietin (EPO) login to view 16 more bullets preoperative autologous blood donation login to view 10 more bullets preoperative embolization login to view 5 more bullets Discontinue anticoagulation medications goal is to decrease risk of intraoperative bleeding without causing adverse events NSAIDs inhibit COX-1 and COX-2 non-aspirin platelet inhibitors (clopidogrel) commonly prescribed after cardiac stenting login to view 6 more bullets long-term anticoagulants risks of discontinuing login to view 1 more bullet warfarin login to view 4 more bullets low-molecular-weight heparin or unfractionated heparin login to view 1 more bullet supplements should be discontinued 14 days prior to surgery to minimize intraoperative blood loss login to view 13 more bullets Anticoagulation Medications Drug Plasma Half-Life (Hours) Effect on Bleeding Minimum Cessation Prior to Surgery (Days) Diclofenac 1-2 Inhibits COX (reversibly) 1 Ibuprofen 2 Inhibits COX (reversibly) 1 Indomethacin 4-10 Inhibits COX (reversibly) 3 Ketorolac 5-7 Inhibits COX (reversibly) 3 Etodolac 6-7 Inhibits COX (reversibly) 3 Sulindac 8-16 Inhibits COX (reversibly) 3 Naproxen 12-17 Inhibits COX (reversibly) 3 Piroxicam 50 Inhibits COX (reversibly) 7 Celecoxib 11 Inhibits COX-2 (reversibly) 1 Aspirin 6 Inhibits COX (irreversibly) 7 Clopidogrel 1 Irreversibly inhibits platelet ADP receptors 7 Prasugrel 2-15 Irreversibly inhibits platelet ADP receptors 7 Ticagrelor 7-9 Reversibly inhibits platelet ADP receptors 5 Ticlopidine 20-50 Irreversibly inhibits platelet ADP receptors 14 Warfarin 20-60 Inhibits vitamin K-dependent clotting factor synthesis 5 Enoxaparin (LMWH) 3-5 Binds antithrombin and irreversibly blocks thrombin 1 Unfractionated heparin 0.5-2 Binds antithrombin and irreversibly blocks thrombin 4-5 hours Dabigatran 7-14 Reversibly blocks thrombin 3 Rivaroxaban 5-13 Reversibly blocks factor Xa 3 Apixaban 9-14 Reversibly blocks factor Xa 3 Edoxaban 10-14 Reversibly blocks factor Xa 3 Intraoperative Management Hypotensive anesthesia administration of vasodilating agents to a goal systolic blood pressure of 50-80 mm Hg or MAP of 60 mm Hg well validated in pediatric scoliosis surgery has been shown to decrease intraoperative blood loss by 55% without sequelae reduces blood extravasation through the surgical wound does not affect bone bleeding (mostly venous bleeding) complications: concern for possible cord transfusion login to view 2 more bullets ischemic optic neuropathy Maintenance of normothermia ideal to keep body temperature >36°C decrease in body temperature >1°C can increase blood loss by 16% and increase transfusion rates by 22% hypothermia decreases platelet function and coagulation enzyme activity increase OR temperature if needed minimize exposed skin surface area until draping Patient positioning reverse Trendelenburg positioning decrease central venous pressure Jackson frames that allow abdomen to hang freely decrease intra-abdominal pressure and pressure on inferior vena cava login to view 1 more bullet Tranexamic acid (TXA) lysine derivative that competitively blocks plasmin binding sites on fibrin results in a decrease in fibrinolysis and stabilized clot formation 6 to 10 times more potent than epsilon aminocaproic acid multiple studies have demonstrated a significant reduction in operative blood loss and transfusion rates with perioperative administration no increased risk of DVT and PE does not alter PT and PTT times multiple dosing regimens and routes of administration utilized IV, oral, and topical all appear equally efficacious contraindications: history of CVA allergy severe CAD side effects: seizures login to view 1 more bullet Desmopressin vasopressin analog increases factor VIII and von Willebrand factor limited data in spine surgery useful for treating patients with von Willebrand disease Surgical techniques local anesthetic with epinephrine can prevent dermal bleeding over long cases login to view 1 more bullet subperiosteal elevation preserves vasculature of paraspinal muscles electrocautery monopolar login to view 3 more bullets bipolar login to view 3 more bullets saline-irrigated radiofrequency bipolar hemostatic sealers login to view 4 more bullets wound packing surgical areas that are not being addressed should be packed login to view 1 more bullet saline-soaked sponges or patties login to view 1 more bullet Aminocaproic acid lysine derivative that competitively inhibits plasmin results in decreased fibrinolysis studies have demonstrated decreased blood loss with aminocaproic acid in arthroplasty lower cost than TXA does not decrease seizure threshold Topical hemostatic agents collagen agents stimulate the intrinsic pathway of coagulation cascade to promote hemostasis microfibrillar collagen login to view 2 more bullets fibrin sealant consists of two separate mixtures login to view 2 more bullets combining the mixtures creates a fibrin seal where it is sprayed platelet-rich plasma centrifugation of the patient's blood to isolate plasma with high contents of platelets, growth factors, and clotting factors proposed benefit of improved hemostasis, wound healing, and recovery platelet-poor plasma isolated from centrifugation process combined with thrombin and calcium to provide an autologous fibrin sealant Gelfoam sponges manufactured from animal-skin gelatin and processed into sponge-form isolated use exerts mostly mechanical hemostasis against low-pressure bleeders can be soaked with thrombin, which can act as scaffold for the coagulation cascade excess Gelfoam should be removed as it may interfere with bone healing topical hemostatic agents do not appear to be cost-effective in total joint arthroplasty cases beneficial in spine surgery to promote hemostasis without inflicting harm to adjacent neural structures topical TXA typically administered near the end of the procedure to control postoperative bleeding decreases fibrinolysis and stabilizes clot formation )may be an alternative route of administration in patients with higher risk of complications (history of MI, CAD, or CVA) gelatin-thrombin matrix commonly used in spine surgery to control epidural bleeding login to view 1 more bullet consists of porcine or bovine gelatine matrix combined with human derived thrombin acts of the end stage of the coagulation cascade → fibrin formation Reinfusion systems (Cell Saver) recycles intraoperative blood loss for later transfusion can be transfused intraoperatively during longer procedure suctioned blood is filtered, washed, and transfused within 6 to 8 hours of the procedure serves as an alternative to allogenic blood transfusion theoretical benefits of minimizing wound complications and hematoma formation need to avoid suctioning antibiotic irrigation, povidone-iodine solution, and irrigation >42°C into the circuit indications: religious beliefs that preclude allogenic blood transfusion large number of autoantibodies that makes allogenic blood stock incompatible contraindications: surgeries for malignancy and infection not recommended for routine use in lumbar spine surgery not cost effective unless blood loss ≥500 cc complications: coagulopathy login to view 4 more bullets transient hemoglobinuria pulmonary complications login to view 1 more bullet contamination cost Postoperative Management Allogenic blood transfusion preoperative hemoglobin is the strongest risk factor for postoperative blood transfusion <13 g/dL more likely to require other risk factors female gender increased age larger patient size longer procedures lateral releases in total knee arthroplasty 1 unit increases Hb by 1 g/dL no absolute criteria for transfusion transfusion should be considered for anyone with Hb <6 g/dL transfusion should be considered for postoperative patients with Hb 7-8 g/dL routine transfusion should be avoided for Hb >8 g/dL login to view 4 more bullets transfusion for Hb levels between 6-8 g/dL should be based on patient factors login to view 4 more bullets complications increased risk of nosocomial infections login to view 3 more bullets viral transmission login to view 3 more bullets transfusion-related acute lung injury (TRALI) login to view 2 more bullets acute hemolytic reaction login to view 2 more bullets Allogenic platelet transfusion blood product most likely to be contaminated stored at room temperature infections in 10 cases per million units transfused gram-positive organisms most common thrombocytopenia platelet count below 5,000/mm^3 login to view 1 more bullet platelet count below 50,000/mm^3 login to view 1 more bullet platelet count above 100,000/mm^3 login to view 1 more bullet Postoperative iron supplementation daily oral iron replacement for mild acute blood loss anemia Drains theoretically prevents surgical site hematomas potential site for infection or neural compression concern for increased post-operative blood negates the tamponade effect by decreasing intra-wound pressure Special Considerations Jehovah's Witness (JW) hold beliefs that blood transfusions are forbidden by the bible some patients may still consent to a blood transfusion some patients may consider the use of Cell Saver as an alternative to allogenic blood transfusion use of colloids and coagulation factors are not forbidden and a matter of personal choice bovine-derived hemostatic agents are generally approved by JW products derived from human plasma are a personal decision of JW login 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