Management of Intraoperative Fluid Balance and Blood Conservation Techniques in Adult Cardiac Surgery

Abstract

Blood transfusions are associated with adverse physiologic effects and increased cost, and therefore reduction of blood product use during surgery is a desirable goal for all patients. Cardiac surgery is a major consumer of donor blood products, especially when cardiopulmonary bypass (CPB) is used, because hematocrit drops precipitously during CPB due to blood loss and blood cell dilution. Advanced age, low preoperative red blood cell volume (preoperative anemia or small body size), preoperative antiplatelet or antithrombotic drugs, complex or re-operative procedures or emergency operations, and patient comorbidities were identified as important transfusion risk indicators in a report recently published by the Society of Cardiovascular Anesthesiologists. This report also identified several pre- and intraoperative interventions that may help reduce blood transfusions, including off-pump procedures, preoperative autologous blood donation, normovolemic hemodilution, and routine cell saver use.A multimodal approach to blood conservation, with high-risk patients receiving all available interventions, may help preserve vital organ perfusion and reduce blood product utilization. In addition, because positive intravenous fluid balance is a significant factor affecting hemodilution during cardiac surgery, especially when CPB is used, strategies aimed at limiting intraoperative fluid balance positiveness may also lead to reduced blood product utilization.This review discusses currently available techniques that can be used intraoperatively in an attempt to avoid or minimize fluid balance positiveness, to preserve the patient's own red blood cells, and to decrease blood product utilization during cardiac surgery.

Conventional hemofiltration during cardiopulmonary bypass increases the serum lactate level in adult cardiac surgery

“…[ 30 ] Therefore, some authors recommend to add crystalloids to the circuit and increasing the pump flow to maintain adequate circulating volume, oxygen supply and demand better than to give phenylephrine but may counteract the favorable hemofiltration effect on hemodilution. [ 31 32 ]…”

Monitoring of brain oxygen saturation (INVOS) in a protocol to direct blood transfusions during cardiac surgery: a prospective randomized clinical trial

“…However, even though transfusions are clearly necessary in many cases, blood product use has been associated with increased morbidity [4] and long-term mortality [3] in cardiac surgery, and therefore attempts to reduce blood transfusions may contribute to reduced complications and improved outcomes. Consequently, several measures have been evaluated in an attempt to reduce blood transfusions during cardiac surgery [12], including tolerating lower hemoglobin values [5] and restricting parenteral fluids in order to avoid hemodilution [16]. Studies evaluating the effectiveness of restrictive fluid administration strategies in mitigating the precipitous intraoperative hematocrit drop, rather than restrictive blood transfusion strategies, are scarce.…”

“…Hematocrit and hemoglobin values are markedly affected by positive fluid balance while on CPB without true loss of erythrocytes. Existing guidelines underline the importance of limiting hemodilution [11,12]. …”

Role of a perfusionist in patient blood management

“…At our centre, blood prime (Table ) is used for such patients whose prebypass haematocrit value is also often found to be <35%. Even though the absolute lowest threshold for haematocrit cannot be determined, many clinicians and institutions, including ours, rely on ‘transfusion triggers’ , which is the haemoglobin or haematocrit level at which red blood cells are transfused . As high‐level evidence is still lacking on this topic, clinical practice is often based on expert consensus and recommendations provided by published guidelines.…”