Effect of dilutional anemia that can be treated with only one unit of red blood cell transfusion on tissue oxygenation in cardiac surgery patients

Abstract

Introduction Maintenance of microcirculatory homeostasis is essential for the preservation of organ function [1]. Cardiac surgery is associated with an inflammatory reaction that may promote alterations in the microcirculatory level, in addition to the general impact on hemodynamic status [2]. The use of cardiopulmonary bypass (CPB) additionally causes a broad range of changes in microcirculatory perfusion and oxygenation [1]. Anemia and transfusion not only make patients more prone to the deleterious effects of CPB but also aggravate the inflammatory response, oxidative stress, and renal hypoxia [3,4]. An intraoperative transfusion of red blood cells (RBCs) increases the risk of mortality and several morbidities. These risks are substantial for even one unit in general surgery patients [5]. The aim of this study was to compare tissue oxygenation, which was evaluated by blood lactate concentration, central venous oxygen saturation (S cv O 2), and venoarterial carbon dioxide pressure difference (ΔpCO 2), between patients who had dilutional anemia resulting from CPB and could be treated with a minimal RBC transfusion (1-2 units) and the patients who did not. Our hypothesis was that a minimal transfusion would lead to normalized Background/aim: Cardiac surgery, especially in the presence of cardiopulmonary bypass (CPB), is associated with an inflammatory reaction that may promote microcirculatory alterations, in addition to the general impact on system hemodynamics. Anemia and transfusion make patients more susceptible to the deleterious effects of CPB. In this study, it was aimed to evaluate the effect of dilutional anemia, which is caused by CPB and can be treated with 1-2 units of red blood cell (RBC) transfusion, on global tissue oxygenation parameters in cardiac surgery patients. Materials and methods: This prospective observational study comprised 127 patients who had a relatively stable operation period without any major anesthetic or surgical complications (e.g., operation duration >5 h, bleeding or hemodilution requiring more than 1-2 units of RBCs, or unstable hemodynamics, requiring inotropic support of more than 5 µg/kg/min dopamine). Patients were observationally divided into two groups: minimally transfused (Group Tr) and nontransfused (Group NTr). Global tissue oxygenation parameters were evaluated after anesthesia induction (T 1) and at the end of the operation (T 3) and compared between the groups. Results: Group Tr consisted of patients who had significantly lower preoperative hemoglobin values than Group NTr patients. The dilutional anemia of all Group Tr patients could be corrected with 1 unit of RBCs. The lactate levels at T 3 , increment rates of lactate, and venoarterial carbon dioxide pressure difference (ΔpCO 2) levels [(T 3-T 1) : T 1 ] in Group Tr were significantly higher than those in Group NTr. Conclusion: Dilutional anemia as a result of CPB mostly occurs in patients with borderline preoperative hemoglobin concentrations and its correction with RBC transfusion does not normalize the de...

STS/SCA/AmSECT/SABM Update to the Clinical Practice Guidelines on Patient Blood Management

“…Importantly, preoperative and intraoperative correction of anemia with RBC transfusion has not been demonstrated to mitigate the risks of endorgan dysfunction. Preventing dilutional anemia and avoiding transfusion in CPB operations are supported as the most effective means of preserving end-organ function 25.…”

Initial Clinical Experience with Implantation of a New Left Ventricular Assist Device HeartCon

“…When weaning from CPB, we routinely perform ultrafiltration to further filter out the water in the tissue space, to reduce the patient's weight closer to the standard weight (97% of preoperative weight), and to restore the levels of coagulation factors including platelets and proteins by supplementing plasma with the goal to make the activity equal to 56%-60% of the preoperative levels. It has been reported [18] that this level of the activity of the coagulation factors will prevent additional blood loss following surgery and therefore reduce the use of blood products during perioperative period.…”

STS/SCA/AmSECT/SABM Update to the Clinical Practice Guidelines on Patient Blood Management

“…Preventing dilutional anemia and avoiding transfusion in CPB operations are supported as the most effective means of preserving end-organ function. 25 The interplay of anemia and transfusion is complex, especially in the perioperative setting where multiple components of the hemostatic mechanism are required for control of bleeding and for optimal outcomes 26 (Figure 1 27 ). Preoperative anemia, especially in the absence of preoperative transfusions or other treatments, seems to be a risk factor for morbidity and mortality after cardiac operations, 10,28,29 but there is conflicting evidence that preoperative transfusion to higher hemoglobin levels impacted this risk.…”