Preoperative Thromboelastographic Profile of Patients with Congenital Heart Disease: Association of Hypercoagulability and Decreased Heparin Response

Finding a common definition of heparin resistance in adult cardiac surgery: communication from the ISTH SSC subcommittee on perioperative and critical care thrombosis and hemostasis

Ensuring adequate anticoagulation for patients requiring cardiac surgery and cardiopulmonary bypass (CPB) is important due to the adverse consequences of inadequate anticoagulation with respect to bleeding and thrombosis. When target anticoagulation is not achieved with typical doses, the term heparin resistance is routinely used despite the lack of uniform diagnostic criteria. Prior reports and guidance documents that define heparin resistance in patients requiring CPB and guidance documents remain variable based on the lack of standardized criteria. As a result, we conducted a review of clinical trials and reports to evaluate the various heparin resistance definitions employed in this clinical setting and to identify potential standards for future clinical trials and clinical management. In addition, we also aimed to characterize the differences in the reported incidence of heparin resistance in the adult cardiac surgical literature based on the variability of both target-activated clotting (ACT) values and unfractionated heparin doses. Our findings suggest that the most extensively reported ACT target for CPB is 480 seconds or higher. Although most publications define heparin resistance as a failure to achieve this target after a weight-based dose of either 400 U/kg or 500 U/kg of heparin, a standardized definition would be useful to guide future clinical trials and help improve clinical management. We propose the inability to obtain an ACT target for CPB of 480 seconds or more after 500 U/kg as a standardized definition for heparin resistance in this setting.

Comparison of thromboelastographic profiles in pediatric patients with congenital heart disease according to existence of cyanosis

PURPOSE

Congenital heart disease (CHD) is divided into two groups according to cyanosis status. Cyanotic CHD has a low level of systemic oxygenation and is accompanied by increased erythropoiesis. We hypothesized that pediatric patients with CHD would exhibit different thromboelastographic profiles according to their cyanosis status.

METHODS

The study recruited 70 pediatric patients younger than 12 months who were undergoing surgery for CHD. Patients were allocated to the acyanotic group or cyanotic group after preoperative evaluations of their diagnosis and peripheral oxygen saturation in the operating room on room air. After inducing anesthesia, blood samples were collected. Hematologic and thromboelastographic profiles were evaluated.

RESULTS

Demographic data were similar between groups. The thromboelastographic profiles did not differ significantly between the groups. Hematologic profiles generally did not significantly differ between groups, except hematocrit (Hct) was higher in the cyanotic group (41.7 ± 6.8% vs. 35.3 ± 5.3%, p < 0.001). In patients under 3 months of age, prothrombin time (PT) (cyanotic group 15.4 ± 1.1 s vs. acyanotic group 14.2 ± 2.4 s, p = 0.02) and international normalized ratio (INR) (cyanotic group 1.24 ± 0.12 vs. acyanotic group 1.12 ± 0.27, p = 0.01) were significantly greater in the cyanotic group.

CONCLUSION

There were no differences in thromboelastographic profiles between the patients with or without cyanosis, regardless of age. The Hct was higher in the cyanotic group in patients under 12 months, while the PT was prolonged and the INR was increased in the cyanotic group in patients under 3 months.

Transfusion therapy of neonatal and paediatric patients: They are not just little adults

Patient blood management (PBM) strategies are needed in the neonate and paediatric population, given that haemoglobin thresholds used are often higher than recommended by evidence, with exposure of children to potential complications without meaningful benefit. A literature review was performed on the following topics: evidence-based transfusions of blood components and pharmaceutical agents. Other topics reviewed included perioperative coagulation assessment and perioperative PBM. The Transfusion and Anaemia Expertise Initiative (TAXI) consortium published a consensus statement addressing haemoglobin (Hb) transfusion threshold in multiple subsets of patients. A multicentre trial (PlaNeT-2) reported a higher risk of bleeding and death or serious new bleeding among infants who received platelet transfusion at a higher (50 000/μl) compared to a lower (25 000/μl) threshold. Recent data support the use of a restrictive transfusion threshold of 25 000/μl for prophylactic platelet transfusions in preterm neonates. The TAXI-CAB consortium mentioned that in critically ill paediatric patients undergoing invasive procedures outside of the operating room, platelet transfusion might be considered when the platelet count is less than or equal to 20 000/μl and there is no benefit of platelet transfusion when the platelet count is more than 50 000/μl. There are limited controlled studies in paediatric and neonatal population regarding plasma transfusion. Blood conservation strategies to minimise allogenic blood exposure are essential to positive patient outcomes neonatal and paediatric transfusion practices have changed significantly in recent years since randomised controlled trials were published to guide practice. Additional studies are needed in order to provide practice change recommendations.

Anesthesia Considerations in Infective Endocarditis

The management of infective endocarditis is complex and inherently requires multidisciplinary cooperation. About half of all patients diagnosed with infective endocarditis will meet the criteria to undergo cardiac surgery, which regularly takes place in urgent or emergency settings. The pathophysiology and clinical presentation of infective endocarditis make it a unique disorder within cardiac surgery that warrants a thorough understanding of specific characteristics in the perioperative period. This includes, among others, echocardiography, coagulation, bleeding management, or treatment of organ dysfunction. In this narrative review article, the authors summarize the current knowledge on infective endocarditis relevant for the clinical anesthesiologist in perioperative management of respective patients. Furthermore, the authors advocate for the anesthesiologist to become a structural member of the endocarditis team.

Use of Coagulation Point-of-Care Tests in the Management of Anticoagulation and Bleeding in Pediatric Cardiac Surgery: A Systematic Review

Bleeding and coagulation management are essential aspects in the management of neonates and children undergoing cardiac surgery. The use of point-of-care tests (POCTs) in a pediatric setting is not as widely used as in the adult setting. This systematic review aims to summarize the evidence showed by the literature regarding the use of POCTs in children undergoing cardiac surgery. We included all studies examining the pediatric population (<18 years old) undergoing cardiac surgery in which the coagulation profile was assessed with POCTs. Three electronic databases (PubMed, Embase, and the Cochrane Controlled Clinical Trials register) were searched. Tests involved were heparin effect tests, viscoelastic tests, and platelet function tests. Due to the wide heterogeneity of the patients and tests studied, a formal meta-analysis was impossible, and the results are therefore presented through a systematic review. Eighty articles were found, of which 47 are presented in this review. At present, literature data are too weak to define POCTs as a "gold standard" for the treatment of perioperative bleeding in pediatric cardiac surgery. Nevertheless, introduction of POCTs into postoperative algorithms has shown to improve bleeding management, patient outcome, and cost efficiency.

Non-Antithrombin-Mediated Heparin Resistance During Cardiac Surgery: Two Case Reports

It is well known that antithrombin (AT) deficiency results in decreased heparin sensitivity, also known as "heparin resistance." However, non-AT-mediated causes of heparin resistance are generally poorly characterized and less prevalent in the literature. We present 2 case reports of non-AT-mediated heparin resistance during cardiac surgery due to paraproteinemia and hyperfibrinogenemia. These cases highlight the challenges posed by unusual conditions in achieving adequate anticoagulation for cardiopulmonary bypass (CPB). The pros and cons of the treatment selections for these cases are discussed, and the potential complications of large doses of unfractionated heparin are considered.