Role of the peripheral intravenous catheter in false-positive D-dimer testing

Assessment of Coagulation and Hemostasis Biomarkers in a Subset of Patients With Chronic Cardiovascular Disease

Measurement of a single marker of coagulation may not provide a complete picture of hemostasis activation and fibrinolysis in patients with chronic cardiovascular diseases. We assessed retrospective orders of a panel which included prothrombin fragment 1.2 (PF1.2), thrombin: antithrombin complexes, fibrin monomers, and D-dimers in patients with heart assist devices, cardiomyopathies, atrial fibrillation and intracardiac thrombosis (based on ordering ICD-10 codes). During 1 year there were 117 panels from 81 patients. Fifty-six (69%) patients had heart assist devices, cardiomyopathy was present in 17 patients (21%) and 29 patients (36%) had more than 1 condition. PF1.2 was most frequently elevated in patients with cardiomyopathy (61.1%) compared to those with cardiac assist devices (15.7%; P = 0.0002). D-dimer elevation was more frequent in patients with cardiac assist devices (98.8%) compared to those patients with cardiomyopathy (83.3%; P = 0.014). Patients with cardiomyopathy show increases of PF1.2 suggesting thrombin generation. In contrast, elevations of D-dimers without increase in other coagulation markers in patients with cardiac assist devices likely reflect the presence of the intravascular device and not necessarily evidence of hemostatic activation.

Retrospective Analyses Associate Hemostasis Activation Biomarkers With Poor Outcomes in Patients With COVID-19

OBJECTIVES

Patients with coronavirus disease 2019 (COVID-19) have thromboembolic complications. Assessment of coagulation and other markers could be useful to understand their coagulopathy.

METHODS

We performed a retrospective study of inflammatory and coagulation parameters, including prothrombin fragment 1.2 (PF1.2), thrombin-antithrombin complexes (TATs), fibrin monomers, and D-dimer, in hospitalized patients with COVID-19. We compared the markers in patients with thrombosis, admission to the intensive care unit (ICU), and poor outcome.

RESULTS

Of the 81 patients, 9 (11%) experienced an acute thrombotic event (4 with pulmonary embolism, 3 with venous thrombosis, and 2 with stroke). PF1.2 was elevated in 32 (39%) patients, TATs in 54 (67%), fibrin monomers in 49 (60%), and D-dimer in 76 (94%). Statistically significant elevation in PF1.2 and TATs was seen in patients admitted to the ICU, while D-dimer and fibrin monomers were significantly elevated in patients with poor outcomes. The presence of multiple abnormal coagulation parameters was associated with ICU admission. Other parameters with statistically significant results included abnormal WBC counts and elevated C-reactive protein, which were associated with ICU admission and poor outcomes.

CONCLUSIONS

Our data demonstrate that abnormalities of biomarkers of hemostasis activation and inflammatory markers are associated with poor outcomes in patients with COVID-19.

Effects of Oritavancin on Coagulation Tests in the Clinical Laboratory

Previous studies have shown that some lipoglycopeptide and lipopeptide antimicrobial agents may cause falsely elevated values for some phospholipid-dependent coagulation tests. The effect of oritavancin, a lipoglycopeptide antibiotic, on coagulation test results was explored using pooled human plasma samples spiked with drug and in a clinical study after an infusion of a single 1,200-mg intravenous dose of oritavancin in normal healthy volunteers. Pooled plasma with oritavancin added ex vivo showed concentration-dependent prolongation of prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and dilute Russell viper venom time (DRVVT) test results. In contrast, oritavancin had no effect on the activated protein C resistance assay, chromogenic anti-factor Xa assay (anti-FXa), thrombin time, and an immunoassay for the laboratory diagnosis of heparin-induced thrombocytopenia. In participants that received a single dose of oritavancin, elevations in PT/INR result, aPTT, DRVVT, activated clotting time, and silica clotting time occurred, with the maximum times to resolution of test interference determined to be 12, 120, 72, 24, and 18 h, respectively. The anti-FXa assay was unaffected, whereas transient elevations in D dimer levels were observed in 30% of participants, with a maximum time to resolution of 72 h. Although oritavancin has no impact on the coagulation system in vivo, a single dose of oritavancin can produce falsely elevated values of some coagulation tests used to monitor hemostasis. The interference of oritavancin on affected tests is transient, and the test results revert to normal ranges within specified times after dosing.

Porcine traumatic lung injury model induced by hilum clamping

OBJECTIVE

To establish a temporary pulmonary hilum clamping model for thoracic damage control surgery, as well as to determine the safety time latitude of this manipulation.

METHODS

Pigs were anaesthetised and instrumented with a thermodilution cardiac output catheter. The left pulmonary hilum was clamped with a urethral catheter after thoracotomy, maintained for three different time periods (n=6 for each group), 90min (C90), 120min (C120) and 150min (C150) and then unclamped. Haemodynamic data were recorded and the serum samples were collected for D-dimer detection and other haematological analysis. A 1-cm(3) pulmonary tissue of the left lower lobe was also obtained for histological study before clamping, at the end of clamping and at 0.5, 1, 1.5, 2 and 4h after unclamping.

RESULTS

Postoperative survival rate in each group of the pigs was as follows: 100% (all six) of C90, 83.3% (five of six) of C120, and 33.3% (two of six) of C150. Blood pressure (BP) and heart rate (HR) increased after clamping and gradually declined after unclamping. The animals of C150 group suffered highest BP and HR, respiratory index, pulmonary dynamic compliance and cardiac output. Platelet count showed no significant changes between the C90 and C120 groups, whereas a decline was noticed in the C150 group. Pulmonary vascular resistance increased significantly after pulmonary hilum clamping; when unclamped, there were minor changes in animals of C90 and C120 groups while there was a persistent elevation in the C150 group. An elevated D-dimer was detected in the C150 group, whereas it was normal in the C90 and C120 groups. There was significantly serious inflammatory cell infiltration, perivascular oedema and haemorrhagic infiltration in the C150 group compared with the C90 and C120 groups.

CONCLUSIONS

We established a pulmonary hilum clamping animal model for investigating pulmonary damage. By studying the haemodynamic and lung function changes of three different unilateral pulmonary hilum clamping time, it was determined that 120min was the longest safety time for hilum clamping without lethal pulmonary injury in porcine models.

The dynamic changes of LDH isoenzyme 3 and D-dimer following pulmonary thromboembolism in canine

INTRODUCTION

To investigate the time course of changes of lactic acid dehydrogenase (LDH), LDH isoenzymes and D-dimer levels following acute pulmonary thromboembolism (PTE).

MATERIALS AND METHODS

Eighteen dogs were randomly divided into three groups. Acute PTE was induced by injection of preformed blood clots into pulmonary artery through femoral vein. Thrombin and human fibrinogen were delivered into blood clots in embolism group I. Only thrombin was delivered into blood clots in embolism group II. The control group received normal saline and human fibrinogen in the same manner. Series of blood samples were collected pre-embolism and post-embolism. LDH isoenzymes proportion and D-dimer levels were measured.

RESULTS

At 30 min, 1 h, 2 h, 4 h, 24 h post-embolism, the plasma D-dimer levels from embolism group I were significantly higher than pre-embolism and those from control group at the same intervals (p<0.05). The peak appeared at 2 h post-embolism (2.336+/-0.326 vs. 0.016+/-0.013, p<0.05). At 4 h, 24 h and 48 h post-embolism, total serum LDH activity and LDH-3 proportion from two embolism groups were significantly higher than pre-embolism (p<0.05). The peak of LDH-3 proportion in two embolism groups both appeared at 24 h post-embolism (0.225+/-0.021 vs. 0.108+/-0.030, 0.214+/-0.011 vs. 0.096+/-0.031, respectively. p<0.05).

CONCLUSIONS

The LDH-3 and D-dimer levels were changed dynamically with a relative specificity manner during the course of acute massive PTE. Combination the D-dimer assay with LDH-3 may have a potential value in diagnosing acute massive PTE.

D-Dimer Concentrations in Normal Pregnancy: New Diagnostic Thresholds Are Needed

Background: Pregnancy is known to increase the D-dimer concentration above the conventional normal threshold of 0.50 mg/L, leading to an increased false-positive D-dimer test when venous thromboembolism (VTE) is clinically suspected in a pregnant patient. Our aim was to determine the effect of normal pregnancy on the D-dimer concentration.

Methods: Healthy women who were seeking to become pregnant and had no preexisting condition known to increase the D-dimer concentration were identified. Quantitative D-dimer measurements (MDA turbidimetric assay) and fibrinogen assays were performed before conception, at each trimester, and at 4 weeks postpartum. Patients were excluded for fetal loss or preeclampsia.

Results: A total of 50 women were enrolled in the study, and blood samples were obtained at preconception and all trimesters from 23 women. The mean (SD) preconception D-dimer concentration was 0.43 (0.49) mg/L, and 79% of women had a D-dimer concentration &lt;0.50 mg/L. D-Dimer increased with each trimester such that only 22% of women in the second trimester and none (of 23) in the third trimester (95% confidence interval, 0–14%) had a D-dimer concentration &lt;0.50 mg/L. We found no correlation between either the D-dimer and fibrinogen concentrations or between the increases in D-dimer and fibrinogen with pregnancy.

Conclusions: Normal pregnancy causes a progressive increase in circulating D-dimer. The D-dimer test has no use in ruling out VTE in the third trimester if a cutoff of 0.50 mg/L is used. A large management study is needed to establish new thresholds for the D-dimer to rule out VTE in each trimester.

False-positive D-dimer result in a patient with Castleman disease

In suspected cases of disseminated intravascular coagulation, concurrent elevation of both fibrin(ogen) degradation products (FDPs) and D-dimer levels aids in confirming the diagnosis. This pattern of results reflects the action of plasmin proteolysis of cross-linked fibrin polymers as well as fibrinogen. We report the case of a patient with human immunodeficiency virus (HIV) and Castleman disease who presented with a high-positive D-dimer level and a negative FDP level in the course of a workup for disseminated intravascular coagulation. This finding suggested the possibility of either a false-positive D-dimer or a false-negative FDP level. To investigate the former, a Western blot was performed on the patient's serum to determine the presence of the D-dimer. No D-dimer band was visualized on the Western blot, confirming the false-positive nature of the D-dimer result. Insufficient quantity of patient serum, however, prevented further investigation into the etiology of this result. The false-positive D-dimer result is likely attributable to interference caused by the patient's Castleman disease-associated monoclonal gammopathy, a phenomenon that has been reported in other immunoassays. As the development of lymphoproliferative disorders is especially common within the HIV population, and hypergammaglobulinemia in Castleman disease is particularly common, clinicians should be aware of this phenomenon when the laboratory findings do not fit the clinical picture. Although it is rare, recognition of potential paraprotein interference in immunoassays will help avoid undertreatment or overtreatment of patients based on erroneous laboratory results.