Guidelines from the United Kingdom Association of Anaesthetists on perioperative cell salvage recommend using either heparinized saline or acid-citrate dextrose (ACD) as the anticoagulant. The red cells are washed using intravenous saline 0.9% and then pumped into a bag for re-infusion to the patient. While there are no absolute contraindications to cell salvage, a history of heparin-induced thrombocytopenia (HIT) is a contraindication to using heparin as the anticoagulant; an anticoagulant solution containing acid-citrate dextrose should be used instead. If heparinized saline is used as the anticoagulant solution, care must be taken to add the correct volume and concentration of heparin and label the bag clearly so that it is not accidentally given intravenously. [1]
A 2018 review discussed the use of various anticoagulants in the setting of plasma exchange, including clinical considerations for optimal management of these patients. The review was compiled based on discussion by 10 physicians from multiple institutions, with consensus data presented. Primarily, citrate or heparin are considered to prevent clotting in the extracorporeal circuit, with citrate generally preferred, but heparin is reserved as a secondary option due to the potential for clinically significant bleeding and risk of HIT. [2]
A 2023 case series described 11 patients who experienced severe hypotension following reinfusion of autologous blood processed with a cell saver and anticoagulated with acid-citrate-dextrose solution A (ACD-A) during off-pump coronary artery bypass surgery. These hypotensive episodes, distinct from those typically associated with bypass surgery, were immediate, necessitating the use of vasopressors or inotropic agents; two cases required cardiopulmonary resuscitation. The events were characterized by significant decreases in cardiac output and mixed venous oxygen saturation. A retrospective root cause and prospective healthcare failure mode and effect analysis failed to conclusively identify the underlying mechanism, though incomplete removal of ACD-A from salvaged blood was proposed as a plausible contributor. Patient characteristics and interventions were meticulously documented, revealing that all patients received ACD-A as the anticoagulant during cell salvage. Reinfusion volumes varied, with no leukocyte depletion filters used. Among the 11 cases, hypotension was associated with nadir mean blood pressures as low as 23 mmHg, with mixed venous oxygen saturations dropping to as low as 38%. Transitioning to a heparin-based anticoagulant for cell salvage during a subsequent 1.5-year period involving 513 cardiac procedures eliminated further occurrences of such complications. These observations align with reports from the United Kingdom’s "Severe Hazards of Transfusion," which documented 31 cases of hypotension after reinfusion of salvaged blood since 2010, 22 of which involved ACD-A. [3]
A 2016 ex-vivo study investigated the use of argatroban as an anticoagulant in a blood salvage system, comparing its efficacy and residual concentrations to unfractionated heparin (UFH). Blood from 23 surgical patients contraindicated for blood salvage use was processed using the Continuous-Auto-Transfusion-System (C.A.T.S.®; Fresenius Kabi) with anticoagulation provided by either 5 mg, 50 mg, or 250 mg of argatroban in 1000 mL saline, or 25,000 U of heparin. Patency of the system and the extent of anticoagulant removal through emergency and high-quality washing protocols were evaluated. In 3 of 8 (38%) cases using 5 mg of argatroban, clotting occurred, rendering the system ineffective. High-quality washing removed 89-95% of argatroban, whereas emergency washing resulted in a lower clearance of 60-90%. Clearance was higher in the group with 50 mg argatroban compared to 5 mg or 250 mg, but the relative clearance among the groups did not differ significantly. Heparin removal was inconsistent, with residual anti-Xa activity detected in 20% of samples. Residual argatroban concentrations ranged from 55 ng/mL to 6810 ng/mL, increasing proportionally with the initial dose. Using an initial concentration of 50 mcg/mL resulted in a red cell concentrate containing approximately 0.794 mcg/mL of argatroban after high-quality wash, which could lead to a plasma concentration of 132 ng/mL upon reinfusion (argatroban steady state reference values: 300-600 ng/mL). The 250 mg argatroban dose generated significantly higher residual levels, posing a risk of unintended anticoagulation upon transfusion. Hematocrit levels were comparable across groups both before surgery and in the reservoir bag. After washing, hematocrits in re-transfusion bags were about double the initial patient levels and were similar across both washing methods. Based on these findings, anticoagulation with 50 mg of argatroban maintained system patency while being reduced significantly during washing, though additional dose-finding studies are necessary to identify the optimal concentration for clinical use. Argatroban 50 mg was selected due to similar anticoagulant potency to heparin 25,000 U, with the other two argatroban doses attempting to find lower and upper dosing ranges. Argatroban 5 mg concentrations were inadequate due to clotting issues, indicating it was too low to maintain system patency. A concentration of 50 mcg/mL in the solution, after washing, resulted in a residual argatroban concentration that could be safely re-infused without causing significant anticoagulation. However, emergency washing yielded higher residual concentrations, potentially leading to full anticoagulation and posing bleeding risks. The highest concentration tested, 250 mcg/ml, resulted in excessive anticoagulation, especially after emergency washing, suggesting it should be avoided. The study concludes there is a need for further research to identify safe argatroban concentrations below 50 mcg/mL for anticoagulating salvaged blood. [4]