Role of Viscoelastic and Conventional Coagulation Tests for Management of Blood Product Replacement in the Bleeding Patient.

An important aim of viscoelastic testing (VET) is to implement transfusion algorithms based on coagulation test results to help reduce transfusion rates and improve patient outcomes. Establishing a rapid diagnosis and providing timely treatment of coagulopathy is the cornerstone of management of severely bleeding patients in trauma, postpartum hemorrhage, and major surgery. As the nature of acute bleeding and trauma leads to an unstable and tenuous physiologic state, conventional coagulation tests (CCTs) are too slow to diagnose, manage, and also course correct any hemostatic abnormalities that accompany an acute critical illness. Viscoelastic point-of-care tests strongly correlate with results from standard laboratory tests but are designed to enable clinicians to make timely, informed bleeding management decisions when time to intervene is critical. These assays provide an individualized and goal-oriented approach to patient blood management and are increasingly becoming involved in transfusion algorithms. The scope of this review aims to evaluate the current literature on VETs and their impact on actionable outputs in clinical decision making and their relationship to CCT.

RHD genotyping to resolve weak and discrepant RhD patient phenotypes.

BACKGROUND: We instituted RHD genotyping in our transfusion service for obstetrical patients and transfusion candidates. We sought to examine how RHD genotyping resolved weak or discrepant automated microplate direct agglutination (MDA) RhD phenotypings and impacted needs for Rh Immune Globulin (RhIG) and D-negative RBCs. STUDY DESIGN AND METHODS: We investigated RhD phenotypes with equivocal or reagent-discrepant automated MDA (Immucor, Norcross, GA), weak-2+ immediate-spin tube typings, historically discrepant RhD typings, or D+ typings with anti-D. We performed microarray RHD genotyping (RHD BeadChip, Immucor BioArray Solutions, Warren, NJ). Patients were managed as D+ with weak-D types 1, 2, and 3, and as D-negative with all other results. RESULTS: Our weak-D prevalence was 0.14%. Among 138 patients (73 obstetrics, 65 transfusion candidates), 38% had weak-D types 1, 2 or 3, 25% weak partial type 4.0, 21% other partial-D variant alleles, and 15% no variant detected. One novel allele with weak partial type 4.0 variants plus c.150T>C (Val50Val) was discovered. Weak D types 1, 2 or 3 were identified in 66% (48/73) of Whites versus 3% (2/62) of diverse ethnic patients (p < .0001). RHD genotyping changed RhD management in 60 patients (43%) (49 to D+, 11 to D-negative), resulting in net conservation of D-negative RBCs (98 avoided, 14 given) and RhIG (8 avoided, 3 given). CONCLUSION: In our patient population, equivocal or reagent-discrepant MDA RhD phenotypes were highly specific for weak-D or partial-D RHD genotypes. Resolution of RHD genotype status reduced our use of D-negative RBCs and RhIG.

Antiplatelet Medications and Biomarkers of Hemostasis May Explain the Association of Hematoma Appearance and Subsequent Hematoma Expansion After Intracerebral Hemorrhage.

BACKGROUND: To test the hypothesis that appearances of intracranial hematomas on diagnostic computed tomography (CT) are not idiosyncratic and reflect a biologically plausible mechanism, we evaluated the association between hematoma appearance on CT, biomarkers of platelet activity, and antiplatelet or anticoagulant medication use prior to admission. METHODS: We studied 330 consecutively identified patients from 2006 to 2019. Biomarkers of platelet activity (platelet aspirin assay) and medication history (aspirin, clopidogrel) were prospectively recorded on admission. A blinded interpreter recorded the presence of hematoma appearances from the diagnostic scan. Associations were tested with parametric or nonparametric statistics, as appropriate. RESULTS: The black hole sign (101, 30%) was most prevalent, followed by the island sign (57, 17%) and blend sign (32, 10%). There was reduced platelet activity in patients with a black hole sign (511 [430-610] vs. 562 [472-628] aspirin reaction units, P = 0.01) or island sign (505 [434-574] vs. 559 [462-629] aspirin reaction units, P = 0.004). Clopidogrel use prior to admission was associated with the black hole sign (odds ratio 2.25, 95% confidence interval 1.02-4.98, P = 0.04). CONCLUSIONS: In patients with acute intracerebral hemorrhage, hematoma appearances on CT are associated with biomarkers of platelet activity and clopidogrel use prior to admission. Appearances of intracranial hematomas on CT may reflect reduced hemostasis from antiplatelet medication use.

The Central Role of Fibrinolytic Response in COVID-19-A Hematologist's Perspective.

The novel coronavirus disease (COVID-19) has many characteristics common to those in two other coronavirus acute respiratory diseases, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). They are all highly contagious and have severe pulmonary complications. Clinically, patients with COVID-19 run a rapidly progressive course of an acute respiratory tract infection with fever, sore throat, cough, headache and fatigue, complicated by severe pneumonia often leading to acute respiratory distress syndrome (ARDS). The infection also involves other organs throughout the body. In all three viral illnesses, the fibrinolytic system plays an active role in each phase of the pathogenesis. During transmission, the renin-aldosterone-angiotensin-system (RAAS) is involved with the spike protein of SARS-CoV-2, attaching to its natural receptor angiotensin-converting enzyme 2 (ACE 2) in host cells. Both tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) are closely linked to the RAAS. In lesions in the lung, kidney and other organs, the two plasminogen activators urokinase-type plasminogen activator (uPA) and tissue plasminogen activator (tPA), along with their inhibitor, plasminogen activator 1 (PAI-1), are involved. The altered fibrinolytic balance enables the development of a hypercoagulable state. In this article, evidence for the central role of fibrinolysis is reviewed, and the possible drug targets at multiple sites in the fibrinolytic pathways are discussed.

Passive Immunity for Coronavirus Disease 2019: A Commentary on Therapeutic Aspects Including Convalescent Plasma.

In the ongoing pandemic of coronavirus disease 2019 (COVID-19), the novel virus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is infecting a naïve population. The innate immunity of the infected patient is unable to mount an effective defense, resulting in a severe illness with substantial morbidity and mortality. As most treatment modalities including antivirals and anti-inflammatory agents are mostly ineffective, an immunological approach is needed. The mechanism of innate immunity to this viral illness is not fully understood. Passive immunity becomes an important avenue for the management of these patients. In this article, the immune responses of COVID-19 patients are reviewed. As SARS-CoV-2 has many characteristics in common with two other viruses, SARS-CoV that cause severe acute respiratory syndrome (SARS) and MERS-CoV (Middle East respiratory syndrome coronavirus) that causes Middle East respiratory syndrome (MERS), the experiences learned from the use of passive immunity in treatment can be applied to COVID-19. The immune response includes the appearance of immunoglobulin M followed by immunoglobulin G and neutralizing antibodies. Convalescent plasma obtained from patients recovered from the illness with high titers of neutralizing antibodies was successful in treating many COVID-19 patients. The factors that determine responses as compared with those seen in SARS and MERS are also reviewed. As there are no approved vaccines against all three viruses, it remains a challenge in the ongoing development for an effective vaccine for COVID-19.

Blood transfusion utilization in hospitalized COVID-19 patients.

BACKGROUND: The acute respiratory illness designated coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, in December 2019 and caused a worldwide pandemic. Concerns arose about the impact of the COVID-19 pandemic on blood donations and potential significant blood transfusion needs in severely ill COVID-19 patients. Data on blood usage in hospitalized COVID-19 patients are scarce. STUDY DESIGN AND METHODS: We performed a retrospective observational study of blood component transfusions in the first 4 weeks of COVID-19 ward admissions. The study period began 14 days before the first COVID-19 cohort wards opened in our hospital in March 2020 and ended 28 days afterward. The number of patients and blood components transfused in the COVID-19 wards was tabulated. Transfusion rates of each blood component were compared in COVID-19 wards versus all other inpatient wards. RESULTS: COVID-19 wards opened with seven suspected patients and after 4 weeks had 305 cumulative COVID-19 admissions. Forty-one of 305 hospitalized COVID-19 patients (13.4%) received transfusions with 11.1% receiving red blood cells (RBCs), 1.6% platelets (PLTs), 1.0% plasma, and 1.0% cryoprecipitate (cryo). COVID-19 wards had significantly lower transfusion rates compared to non-COVID wards for RBCs (0.03 vs 0.08 units/patient-day), PLTs (0.003 vs 0.033), and plasma (0.002 vs 0.018; all p < 0.0001). Cryo rates were similar (0.008 vs 0.009, p = 0.6). CONCLUSIONS: Hospitalized COVID-19 patients required many fewer blood transfusions than other hospitalized patients. COVID-19 transfusion data will inform planning and preparation of blood resource utilization during the pandemic.

Thrombosis Risk in Cancer Patients Receiving Red Blood Cell Transfusions.

Patients with cancer have increased risk of thrombosis and often need red blood cell (RBC) transfusions. However, RBC transfusions may also promote thrombosis because of raised hematocrit and viscosity, storage-related RBC damage, and exposure to thrombogenic mediators from obsolescent RBCs. The authors conducted a literature survey for studies examining whether RBC transfusions were associated with increased risk of venous thromboembolism (VTE) in cancer patients. In perioperative cancer surgery patients with categorical comparisons of any versus no RBC transfusion, increased risk of VTE with RBC transfusion was found in 11 of 31 studies, 5 by univariate correlation only and 6 in multivariate analysis. All six multivariate-positive studies had intermediate overall rates of thrombosis (1.4-6.0%), and three were in urological surgery series. In the larger studies of > 2,000 patients (range: 2,219-44,656), the maximum odds ratio among the multivariate-positive studies was 1.3. Perioperative RBC transfusion volume was more strongly associated with VTE risk, with a positive association in six of seven studies. One large registry-based study of hospitalized cancer patients, not restricted to the perioperative setting, found an adjusted odds ratio of 1.60 (95% confidence interval: 1.53-1.67) for VTE risk in patients receiving RBCs compared with nontransfused patients.

Fibrin and Fibrinolysis in Cancer.

In 1878, Billroth discovered that tumor cells invest themselves in a fibrin thrombus, and he hypothesized that fibrin promotes tumor growth and invasion. Since then, many observations have supported this concept, showing that many hemostatic factors including fibrinogen, fibrin, and components of the fibrinolytic system have indeed a complex interaction with cancer growth and metastasis. Fibrin promotes cell migration by providing a matrix for tumor cell migration and by interactions with adhesive molecules and integrins. Fibrin-containing vascular endothelial growth factor promotes angiogenesis. Fibrin interacts with platelets and leukocytes, and promotes their respective carcinogenic properties. Fibrinolytic components exert different effects on tumors. Plasmin activates latent growth factors, and breaks down extracellular matrix (ECM), while urokinase plasminogen activator (uPA) and the uPA receptor (uPAR) form complexes with vitronectin and integrins to promote tumor cells to adhere to the ECM. This complex also binds the epidermal growth factor receptor on the tumor cell membrane, and signals the RAF-MEK-ERK pathway. The complex also binds to the G protein-coupled receptors leading to cell proliferation. Plasminogen activator inhibitor 1 (PAI-1) inhibits apoptosis, and increases tumor cell survival. PAI-1 also enhances cell senescence, leading to production of tumorigenic cytokines by the senescence secretome. The presence of uPA/uPAR and PAI-1 represents a strong biomarker for tumor aggressiveness and poor prognosis. Multiple attempts by blocking various carcinogenic steps have shown tumor-suppressing effects in experimental animals, but human responses are uncertain without clinical trials.

Mixing Studies in Patients With Prolonged Activated Partial Thromboplastin Time or Prothrombin Time.

BACKGROUND: Patients presenting for surgery may have isolated or combined prolonged activated partial thromboplastin time (aPTT) and/or prothrombin time (PT). In patients not receiving anticoagulants or with no identifiable cause for abnormal clot formation, a mixing study is performed. The index of circulating anticoagulant (ICA) has been used to predict the presence of an inhibitor, usually a lupus anticoagulant. METHODS: We retrospectively reviewed the results of mixing studies performed at Northwestern Memorial Hospital, between January 1, 2010 and February 29, 2012. We determined the number of samples that normalized or remained prolonged, the clotting factors associated with prolonged test results, and the presence of coagulation inhibitors. We calculated the ICA in the samples with prolonged aPTT and PT to determine its ability to predict a lupus anticoagulant. The primary comparison of interest was the diagnostic utility of the ICA at cutoff values of 11% for predicting the presence of lupus anticoagulant. RESULTS: There were 269 mixing studies performed: 131 samples with prolonged aPTT; 95 with prolonged PT; and 43 with both prolonged aPTT and prolonged PT. Of the samples with a prolonged aPTT, 55 of 131 (42%) normalized, 36 of 131 (27%) partially corrected, and 40 of 131 (31%) remained prolonged. Thirty-three of 95 samples (35%) with prolonged PT normalized, while 62 of 95 (65%) remained prolonged. Eight of 43 (19%) mixing studies of patients with prolonged PT and aPTT normalized; the aPTT normalized, but the PT remained prolonged in 17 of 43 (39%); the PT normalized, but the aPTT remained prolonged in 7 of 43 (16%); and both tests remained prolonged in 11 of 43 (26%) samples. Prolongations in the aPTT were primarily associated with low activities of CF XII, while the majority of the prolongations in PT were secondary to low activities in CF VII. Combined prolongations were secondary to deficiencies in both the intrinsic and extrinsic as well as the common pathways. An ICA >11% had 100% (95% CI, 59%-100%) sensitivity, 53% (95% CI, 35%-70%) specificity, and 77% (95% CI, 62%-92%) accuracy in predicting the presence of lupus anticoagulant in patients with prolonged aPTT. CONCLUSIONS: Normalization of the aPTT and PT in a mixing study was associated with low clotting factor activity. The ICA may be helpful in predicting the presence of a lupus anticoagulant. As anesthesiologists take ownership of the perioperative surgical home, we need to understand the clinical implications of the results of mixing studies.

Lysophosphatidic acid activates the RhoA and NF-κB through Akt/IκBα signaling and promotes prostate cancer invasion and progression by enhancing functional invadopodia formation.

We have demonstrated previously that increased RhoA and nuclear factor (NF)-κB activities are associated with increased PC-3 prostate cancer cell invasion and that lysophosphatidic acid (LPA) significantly increases cancer invasion through RhoA and NF-κB activation. In this study, we identified the intermediate signaling molecules and specialized cell structures which are activated by LPA, resulting in enhanced cellular invasion. LPA-induced Akt and IκBα signaling pathways were necessary for RhoA and NF-κB activation, and these LPA effects were abolished by RhoA inhibition. Mice injected with PC-3 cells expressing dominant-negative RhoA N19 developed significantly less tumor growth compared with those injected with control (pcDNA 3.1). In addition, LPA treatment increased functional invadopodia formation. Activation of RhoA and NF-κB through the Akt and IκBα signaling pathway was required for LPA-stimulated gelatin degradation activity. LPA administration increased tumor growth and osteolytic lesions in a mouse xenograft model. These results indicate that LPA promotes PC-3 cell invasion by increasing functional invadopodia formation via upregulating RhoA and NF-κB signaling which contributes to prostate cancer progression. Therefore, the LPA and RhoA-NF-κB signaling axis may represent key molecular targets to inhibit prostate cancer invasion and progression.

A Caucasian JK*A/JK*B woman with Jk(a+b-) red blood cells, anti-Jkb, and a novel JK*B allele c.1038delG.

The Kidd blood group on the red blood cell (RBC) glycoprotein urea transporter-B has a growing number of weak and null alleles in its gene SLC14A1 that are emerging from more widespread genotyping of blood donors and patients. We investigated a 64-year-old Caucasian woman of Polish-Czech descent who developed anti-Jkb detected in solid-phase RBC adherence testing within 12 days after 7 units of RBCs were transfused. Her RBCs subsequently typed Jk(a+b­) by licensed reagents and human antisera. Nevertheless, in RBC genotyping (BioArray HEA BeadChip, Immucor, Warren, NJ) performed in our transfusion service on all patients with alloantibodies, her Kidd typing was JK*A/JK*B based on the Jka/Jkb single nucleotide polymorphism in exon 9 (c.838G>A, p.Asp280Asn). Genomic analysis and cDNA sequencing of her JK*B allele revealed a novel single-nucleotide deletion of c.1038G in exon 11, predicting a frameshift and premature stop (p.Thr346Thrfs*5) after translation of nearly 90 percent of the expressed exons 4­11. This allele has been provisionally named JK*02N.14, subject to approval by the International Society of Blood Transfusion Working Party. The site of this variant is closer to the C-terminus than that of any allele associated with the Jk(a­b­) phenotype reported to date. Routine genotyping of patients with RBC alloantibodies can reveal variants posing potential risk of alloimmunization. Continuing investigation of Kidd variants may shed light on the structure of Kidd antigens and the function of urea transporter-B.

Desmopressin improves platelet activity in acute intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Minimizing hematoma growth in high-risk patients is an attractive strategy to improve outcomes after intracerebral hemorrhage. We tested the hypothesis that desmopressin (DDAVP), which improves hemostasis through the release of von Willebrand factor, improves platelet activity after intracerebral hemorrhage. METHODS: Patients with reduced platelet activity on point-of-care testing alone (5), known aspirin use alone (1), or both (8) received desmopressin 0.4 µg/kg IV. We measured Platelet Function Analyzer-epinephrine (Siemens AG, Germany) and von Willebrand factor antigen from baseline to 1 hour after infusion start and hematoma volume from the diagnostic to a follow-up computed tomographic scan. RESULTS: We enrolled 14 patients with of mean age 66.8±14.6 years, 11 (85%) of whom were white and 8 (57%) were men. Mean Platelet Function Analyzer-epinephrine results shortened from 192±18 seconds pretreatment to 124±15 seconds (P=0.01) 1 hour later, indicating improved plate activity. von Willebrand factor antigen increased from 242±96% to 289±103% activity (P=0.004), indicating the expected increase in von Willebrand factor. Of 7 (50%) patients who received desmopressin within 12 hours of intracerebral hemorrhage symptom onset, changes in hematoma volume were modest, -0.5 (-1.4 to 8.4) mL and only 2 had hematoma growth. One patient had low blood pressure and another had a new fever within 6 hours of desmopressin administration. CONCLUSIONS: Intravenous desmopressin was well tolerated and improved platelet activity after acute intracerebral hemorrhage. Larger studies are needed to determine its potential effects on reducing hematoma growth versus platelet transfusion or placebo. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00961532.

P2Y12 inhibitor use predicts hematoma expansion in patients with intracerebral hemorrhage.

OBJECTIVE: Hematoma expansion (HE) predicts disability and death after acute intracerebral hemorrhage (ICH). Aspirin and anticoagulants have been associated with HE. We tested the hypothesis that P2Y12 inhibitors predict subsequent HE in patients. We explored laboratory measures of P2Y12 inhibition and dual antiplatelet therapy with aspirin (DAPT). METHODS: We prospectively identified patients with ICH. Platelet activity was measured with the VerifyNow-P2Y12 assay. Hematoma volumes for initial and follow-up CTs were calculated using a validated semi-automated technique. HE was defined as the difference between hematoma volumes on the initial and follow-up CT scans. Nonparametric statistics were performed with Kruskal-Wallis H, and correction for multiple comparisons performed with Dunn's test. RESULTS: In 194 patients, 15 (7.7%) were known to take a P2Y12 inhibitor (clopidogrel in all but one). Patients taking a P2Y12 inhibitor had more HE compared to patients not taking a P2Y12 inhibitor (3.5 [1.2-11.9] vs. 0.1 [-0.8-1.4] mL, p = 0.004). Patients taking DAPT experienced the most HE (7.2 [2.6-13.8] vs. 0.0 [-1.0-1.1] mL, p = 0.04). The use of P2Y12 inhibitors was associated with less P2Y12 activity (178 [149-203] vs. 288 [246-319] P2Y12 reaction units, p = 0.005). INTERPRETATION: Patients taking a P2Y12 inhibitor had more HE and less P2Y12 activity. The effect was most pronounced in patients on DAPT, suggesting a synergistic effect of P2Y12 inhibitors and aspirin with respect to HE. Acute reversal of P2Y12 inhibitors in acute ICH requires further study.

Improving Judicious Use of Heparin-Induced Thrombocytopenia Testing Through Electronic Health Record-Based Intervention.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is an immune-mediated drug reaction that can cause thromboembolism in the setting of thrombocytopenia. An enzyme-linked immunosorbent assay (ELISA)-based assay to screen for HIT antibodies (HAb) is available but has relatively low specificity and a correspondingly high false positive rate. The 4Ts score has been validated to determine the pretest probability of HIT. The authors hypothesized that an electronic health record (EHR)-based clinical decision support (CDS) tool incorporating the 4Ts score would reduce the volume of HAb orders. METHODS: After implementing a CDS tool into the EHR, the researchers retrospectively evaluated the impact from November 2019 to October 2021, compared to a preintervention period (January to October 2019). The primary outcome was average tests per month. Secondary outcomes included rates of tests ordered per total inpatient encounters and proportion of HAb sent despite low 4Ts score in the postintervention study period. RESULTS: Of 1,833 HAb sent during the study period, 1,217 occurred in the postintervention period. In the postintervention period compared with the preintervention period, the average orders per month was 50.5 (standard deviation [SD] 9.7) vs. 61.6 (SD 7.2) (p = 0.003), and the order incidence rate was 8.0 per 1,000 patient encounters postintervention vs. 9.2 per 1,000 patient encounters preintervention (rate ratio [RR] 0.87, 95% confidence interval [CI] 0.79-0.96, p = 0.002). Postintervention, 252 (20.7%) had a 4Ts score calculated as low probability, 759 (62.4%) as intermediate probability, and 131 (10.8%) as high probability, and 75 had no associated 4Ts score. CONCLUSION: Implementation of a simple CDS tool reduced the rate of HAb orders, reducing unnecessary HAb testing.