Transfusion medicine : support of patients undergoing cardiac surgery

Effect of Desmopressin on Bleeding After Heart Surgeries: A Narrative Review

Desmopressin is an analog of the antidiuretic hormone (vasopressin), which causes anticoagulant activity by increasing plasma factor 8. The use of desmopressin dates back to 1977, when this hormone was used to prevent bleeding during tooth extraction and surgery in patients with hemophilia A and von Willebrand disease. After that, this hormone was expanded to prevent bleeding in congenital defects and conditions such as chronic kidney and liver failure. Also, this hormone is used to prevent bleeding in major surgeries such as heart surgery, where the patient loses much blood and needs a blood transfusion. Considering the importance of desmopressin in bleeding control, the present study was conducted to investigate the possible effect of this hormone in heart surgery.

Bleeding Following Deep Hypothermia and Circulatory Arrest in Children

Deep hypothermic circulatory arrest (DHCA) is a technique of extracorporeal circulation commonly used in children with complex congenital heart defects undergoing surgical repairs. The use of profound cooling (20°C) and complete cessation of circulation allow adequate exposure and correction of these complex lesions, with enhanced cerebral protection. However, the profound physiologic state of DHCA results in significant derangement of the coagulation system and a high incidence of postoperative bleeding. This review examines the impact of DHCA on bleeding and transfusion requirements in children and the pathophysiology of DHCA-induced platelet dysfunction. It also focuses on possible pharmacologic interventions to decrease bleeding following DHCA in children.

Antiplatelet drugs: mechanisms and risks of bleeding following cardiac operations

Preoperative antiplatelet drug use is common in patients undergoing coronary artery bypass grafting (CABG). The impact of these drugs on bleeding and blood transfusion varies. We hypothesize that review of available evidence regarding drug-related bleeding risk, underlying mechanisms of platelet dysfunction, and variations in patient response to antiplatelet drugs will aid surgeons as they assess preoperative risk and attempt to limit perioperative bleeding. The purpose of this review is to (1) examine the role that antiplatelet drugs play in excessive postoperative blood transfusion, (2) identify possible mechanisms to explain patient response to antiplatelet drugs, and (3) formulate a strategy to limit excessive blood product usage in these patients. We reviewed available published evidence regarding bleeding risk in patients taking preoperative antiplatelet drugs. In addition, we summarized our previous research into mechanisms of antiplatelet drug-related platelet dysfunction. Aspirin users have a slight but significant increase in blood product usage after CABG (0.5 U of nonautologous blood per treated patient). Platelet adenosine diphosphate (ADP) receptor inhibitors are more potent antiplatelet drugs than aspirin but have a half-life similar to aspirin, around 5 to 10 days. The American Heart Association/American College of Cardiology and the Society of Thoracic Surgeons guidelines recommend discontinuation, if possible, of ADP inhibitors 5 to 7 days before operation because of excessive bleeding risk, whereas aspirin should be continued during the entire perioperative period in most patients. Individual variability in response to aspirin and other antiplatelet drugs is common with both hyper- and hyporesponsiveness seen in 5 to 25% of patients. Use of preoperative antiplatelet drugs is a risk factor for increased perioperative bleeding and blood transfusion. Point-of-care tests can identify patients at high risk for perioperative bleeding and blood transfusion, although these tests have limitations. Available evidence suggests that multiple blood conservation techniques benefit high-risk patients taking antiplatelet drugs before operation. Guidelines for patients who take aspirin and/or thienopyridines before cardiac procedures include some or all of the following: (1) preoperative identification of high-risk patients using point-of-care testing; (2) withdrawal of aspirin or other antiplatelet drugs for a few days and delay of operation in patients at high risk for bleeding if clinical circumstances permit; (3) selective perioperative use of evidence-based blood conservation interventions (e.g., short-course erythropoietin, off-pump procedures, and use of intraoperative blood conservation techniques), especially in high-risk patients; and (4) platelet transfusions if clinical bleeding occurs.

2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

The relationship among thromboelastography, hemostatic variables, and bleeding after cardiopulmonary bypass surgery in children

BACKGROUND

Mediastinal bleeding is common after pediatric cardiopulmonary bypass (CPB) surgery. Thromboelastography (TEG) may predict bleeding and provide insight into likely mechanisms. We aimed to (a) compare perioperative temporal profiles of TEG and laboratory hemostatic variables between patients with significant hemorrhage (BLEED) and those without (CONTROL), (b) investigate the relationship between TEG variables and routine hemostatic variables, and (c) develop a model for prediction of bleeding.

METHODS

TEG and laboratory hemostatic variables were measured prospectively at 8 predefined times for 50 children weighing <20 kg undergoing CPB.

RESULTS

Patients who bled demonstrated different TEG profiles than those who did not. This was most apparent after protamine administration and was partly attributable to inadequate heparin reversal, but was also associated with a significantly lower nadir in mean (sd) fibrinogen for the BLEED group compared with CONTROL group: 0.44 (0.18) and 0.71 (0.40) g/L, respectively (P = 0.01). Significant nonlinear relationships were found between the majority of TEG and laboratory hemostatic variables. The strongest relationship was between the maximal amplitude and the platelet-fibrinogen product (logarithmic r(2) = 0.71). Clot strength decreased rapidly when (a) fibrinogen concentration was <1 g/L, (b) platelets were <120 x 10(9)/L, and (c) platelet-fibrinogen product was <100. A 2-variable model including the activated partial thromboplastin time at induction of anesthesia and TEG mean amplitude postprotamine discriminated well for subsequent bleeding (C statistic 0.859).

CONCLUSIONS

Hypofibrinogenemia and inadequate heparin reversal are 2 important factors contributing to clot strength and perioperative hemorrhage after pediatric CPB. TEG may be a useful tool for predicting and guiding early treatment of mediastinal bleeding in this group.

The use of desmopressin in open-heart surgery

Desmopressin (l-deamino-8-D-arginine vasopressin, DDAVP) is a synthetic analogue of the antidiuretic hormone vasopressin. Like the natural antidiuretic hormone, desmopressin increases the plasma levels of factor VIII and von Willebrand factor (vWF), with the advantage, compared to vasopressin, that it produces little or no vasoconstriction, no increase in blood pressure, and no contraction of the uterus or gastrointestinal tract, so that it is well tolerated when administered to humans. In 1977, desmopressin was used for the first time in patients with mild hemophilia A and von Willebrand disease (vWD) for the prevention and treatment of bleeding, first during dental extractions and then during major surgical procedures. The clinical indications for desmopressin rapidly expanded beyond hemophilia and vWD. The compound was shown to be efficacious even in bleeding disorders not involving a deficiency or dysfunction of factor VIII or vWF, including congenital and acquired defects of platelet function and such frequent abnormalities of hemostasis as those associated with chronic kidney and liver diseases. Desmopressin has also been used prophylactically in patients undergoing surgical operations characterized by large blood loss and transfusion requirements.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Clinical strategies in the medical care of Jehovah's Witnesses

Jehovah's Witnesses are primarily known to physicians for their refusal of blood transfusions. Conflict arises at times with the medical staff concerning how best to manage their care. This article will begin with a brief description of the beliefs of Jehovah's Witnesses and will then recommend specific clinical strategies highlighting newer potential therapies according to the principles of bloodless medicine. The scenarios of bleeding and acute and chronic anemia will be discussed in detail for the care of these patients refusing red blood cell transfusions. An update in the use of blood substitutes will be mentioned as well as the surgical advances used today that can minimize blood loss for all patients. The experience of organ transplantation in Jehovah's Witnesses will be detailed. Further resources for physicians with questions in the care of these patients will be listed. Stressed throughout the article will be the need for a team approach and good communication between physicians to successfully care for their patients who are Jehovah's Witnesses.

Costs associated with blood transfusions in Sweden - the societal cost of autologous, allogeneic and perioperative RBC transfusion

Anaemia is characterised by an insufficient number of red blood cells (RBCs) and might occur for different reasons, e.g. surgical procedures are often with associated blood loss. Patients who suffer from anaemia have the option of treatment with blood transfusion or medical treatment. In this study, the societal cost, for the case of Sweden, of RBC transfusion using three different techniques, i.e. allogeneic, autologous and intraoperative transfusion, was estimated. The analysis was based on information from interviews with hospital staff at large Swedish hospitals and from published data. The average cost for a 2 units transfusion was found to be Swedish kronor (SEK) 6330 (702 Euro) for filtered allogeneic RBCs and SEK 5394 (598 Euro) for autologous RBCs for surgery patients. Transfusion reactions accounted for almost 35 per cent of the costs of allogeneic RBC transfusions. The administration cost was found to be much higher for autologous transfusions compared with allogeneic transfusions. The cost of intraoperative erythrocyte salvage was calculated to be SEK 2567 (285 Euro) per transfusion (>4 units).