The influence of dead space in blood sampling needle on FVIII level and pharmacokinetic profiles in children with hemophilia

OBJECTIVE

To investigate the influence of the dead space in disposable blood sampling needle on activated partial thromboplastin time (APTT), FVIII level and pharmacokinetic (PK) profiles in children with hemophilia.

METHODS

Children (<18 years) with severe hemophilia A were enrolled. After three days' washout-period, blood samples were collected at pre-dose, 1 h, 3 h, 9 h, 24 h and 48 h post-infusion. At each timepoint, two 2 mL vacuum tubes with 3.2% trisodium citrate were used. The first tube was signed as 'non-standard' (NS) and the second tube was signed as 'standard' (S). FVIII activities were evaluated by one-stage assay. WAPPS-Hemo was used to generate PK profiles like half-life time (t1/2), clearance (CL), trough level and time to 1, 2 and 5IU/dL after a dose of 50 ± 10IU/dL. The FVIII activities at 9 h and 24 h post-infusion were put into WAPPS and thus brought four combinations by true or biased FVIII level that used.

RESULT

Compared with standard-collected blood samples, prolonged APTT results (P-values < 0.01) and decreased FVIII activity (P-values < 0.05) were revealed in those non-standard blood samples. The corresponding bias was in positive relation to both APTT-S (r = 0.44, P < 0.0001) and FVIII-S level(r = 0.68, P < 0.001). The FVIII bias percentage got larger as FVIII-S level reduced (r = -0.24, P < 0.01). During the four combinations of FVIII activity at 9 h and 24 h, statistically longer t1/2, lower CL and longer time to 1, 2 or 5IU/dL were observed in 9H-S&24H-S group and 9H-NS&24H-S group.

CONCLUSION

While using vacuum tubes for clotting indicators and PK profiles, the dead space of blood sampling needle should be eliminated in advance.

CA125-Associated Activated Partial Thromboplastin Time and Thrombin Time Decrease in Patients with Adenomyosis

Objective

Adenomyosis patients are in a hypercoagulable state, and studies have shown that carbohydrate antigen125 (CA125) may relate to the hypercoagulability and thrombosis of patients with adenomyosis, but there is still a lack of clarity regarding the changes in CA125-related coagulation indicators. This study was to explore the changes and influencing factors of CA125-related coagulation parameters in patients with adenomyosis.

Methods

Retrospective observational study conducted on 200 patients with adenomyosis (AM group), 240 patients with uterine leiomyoma (LM group) and 81 patients with cervical intraepithelial neoplasia (CIN)-III (control group), of which the coagulation parameters were detected by clinical blood sample collection and statistical method analysis and informed consent was obtained.

Results

The level of CA125 in the AM group was significantly higher than that in the LM group and control group. However, thrombin time (TT) shortened in the AM group when compared with the LM and control group. Activated partial thromboplastin time (APTT) in the AM group was shorter than in the control group. Multivariate logistic regression analysis found that adenomyosis was associated with CA125 level (OR=323.860, 95% CI 90.424-1159.924, P<0.001), APTT (OR=1.295, 95% CI 1.050-1.598, P=0.016), TT (OR=0.642, 95% CI 0.439-0.938, P=0.022), menorrhagia (OR=7.363, 95% CI 2.544-21.315, P<0.001), dysmenorrhea (OR=22.590, 95% CI 8.185-62.347, P<0.001). Correlation analysis revealed that APTT (r= -0.207) and TT (r = -0.174) were negatively correlated with the level of CA125.

Conclusion

The shortening of CA125-related APTT and TT indicates that it is meaningful to detect coagulation parameters of patients with elevated CA125 levels early, dysmenorrhea and menorrhagia, and maybe further discover the hypercoagulability and prevent the occurrence of thrombus in adenomyosis.

Detection of a Prethrombotic State in Patients with Hepatocellular Carcinoma, Using a Clot Waveform Analysis

Background: Although hepatocellular carcinoma (HCC) is frequently associated with thrombosis, it is also associated with liver cirrhosis (LC) which causes hemostatic abnormalities. Therefore, hemostatic abnormalities in patients with HCC were examined using a clot waveform analysis (CWA). Methods: Hemostatic abnormalities in 88 samples from HCC patients, 48 samples from LC patients and 153 samples from patients with chronic liver diseases (CH) were examined using a CWA-activated partial thromboplastin time (APTT) and small amount of tissue factor induced FIX activation (sTF/FIXa) assay. Results: There were no significant differences in the peak time on CWA-APTT among HCC, LC, and CH, and the peak heights of CWA-APTT were significantly higher in HCC and CH than in HVs and LC. The peak heights of the CWA-sTF/FIXa were significantly higher in HCC than in LC. The peak times of the CWA-APTT were significantly longer in stages B, C, and D than in stage A or cases of response. In the receiver operating characteristic (ROC) curve, the fibrin formation height (FFH) of the CWA-APTT and CWA-sTF/FIXa showed the highest diagnostic ability for HCC and LC, respectively. Thrombosis was observed in 13 HCC patients, and arterial thrombosis and portal vein thrombosis were frequently associated with HCC without LC and HCC with LC, respectively. In ROC, the peak time×peak height of the first derivative on the CWA-sTF/FIXa showed the highest diagnostic ability for thrombosis. Conclusion: The CWA-APTT and CWA-sTF/FIXa can increase the evaluability of HCC including the association with LC and thrombotic complications.

Comparative Assessment of APTT Reagents for Evaluating Anticoagulant Sensitivity of Fucosylated Glycosaminoglycans (FGs) Derived from Sea Cucumbers

Fucosylated glycosaminoglycans (FGs) derived from sea cucumbers exhibit potent intrinsic Xase (iXase) inhibition, anticoagulation, and antithrombosis. Plasma activated partial thromboplastin time (APTT), a widely used screening test worldwide, is crucial for evaluating anticoagulant efficacy. However, the applicability of these commercially available APTT reagents for assessing anticoagulation of FGs remains unreported. In this study, we investigated the disparity between ellagic acid and colloidal silica APTT reagents in evaluating anticoagulation of dHG-5 and dHLFG-4, two depolymerized FGs, and elucidated the underlying rationale. The results demonstrated that dHG-5 and dHLFG-4 exhibited heightened sensitivity to the ellagic acid APTT reagent both in vitro and in vivo, and did not significantly affect the activation of APTT reagents for plasma. In addition, both ellagic acid and colloidal silica APTT reagents inhibited the anti-iXase of dHG-5 and dHLFG-4, and the inhibition of the ellagic acid APTT reagent was less pronounced compared to the colloidal silica APTT reagent. These findings suggest that the reduced impact of the ellagic acid APTT reagent on the anti-iXase activity of dHG-5 and dHLFG-4 is responsible for the increased sensitivity in plasma APTT analysis. This study offers valuable insights into the characteristics of two APTT reagents applied for assessing the anticoagulant activity of FG-related compounds.

The Evaluation of Clot Waveform Analyses for Assessing Hypercoagulability in Patients Treated with Factor VIII Concentrate

BACKGROUND

Regular prophylactic therapy has become an increasingly common treatment for severe hemophilia. Therefore, hypercoagulability-a potential risk factor of thrombosis-is a cause for concern in hemophilic patients treated with a high dose of FVIII concentrate. In clot waveform analysis (CWA)-thrombin time (TT), a small amount of thrombin activates clotting factor VIII (FVIII) instead of fibrinogen, resulting in FVIII measurements using CWA-TT with a small amount of thrombin.

METHODS

The coagulation ability of patients treated with FVIII concentrate or emicizumab was evaluated using activated partial thromboplastin time (APTT), TT and a small amount of tissue factor-induced FIX activation assay (sTF/FIXa) using CWA.

RESULTS

The FVIII activity based on CWA-TT was significantly greater than that based on the CWA-APTT or chromogenic assay. FVIII or FVIII-like activities based on the three assays in plasma without emicizumab were closely correlated; those in plasma with emicizumab based on CWA-TT and chromogenic assays were also closely correlated. CWA-APTT and CWA-TT showed different patterns in patients treated with FVIII concentrates compared to those treated with emicizumab. In particular, CWA-TT in patients treated with FVIII concentrate showed markedly higher peaks in platelet-rich plasma than in platelet-poor plasma. CWA-APTT showed lower coagulability in hemophilic patients treated with FVIII concentrate than in healthy volunteers, whereas CWA-sTF/FIXa did not. In contrast, CWA-TT showed hypercoagulability in hemophilic patients treated with FVIII concentrate.

CONCLUSIONS

CWA-TT can be used to evaluate the thrombin bursts that cause hypercoagulability in patients treated with emicizumab. Although routine APTT evaluations demonstrated low coagulation ability in patients treated with FVIII concentrate, CWA-TT showed hypercoagulability in these patients, suggesting that the evaluation of coagulation ability may be useful when using multiple assays.

Hematological findings in COVID-19 and their correlation with severity of Disease

Objective

To evaluate the efficacy of hematological parameters to predict severity of COVID-19 patients.

Method

This was a cross-sectional comparative study conducted at Central Park Teaching Hospital, Lahore in COVID ward and COVID ICU between April 23, 2021 to June 23, 2021. Patients of all ages and both genders with positive PCR admitted in the COVID ward and ICU during this time span of two months were included in the study. Data was collected retrospectively.

Results

This study included 50 patients with male to female ratio of 1.38:1. Though males are more affected by COVID-19 but the difference is not statistically significant. The mean age of the study population was 56.21 and the patients in the severe disease group have higher age. It was observed that in severe/critical group the mean values of total leukocyte count 21.76×103 μI (p-value= 0.002), absolute neutrophil count 71.37% (p-value=0.045), neutrophil lymphocyte ratio (NLR) 12.80 (p-value=0.00) and PT 11.9 seconds (p-value=0.034) and the difference was statistically significant. While in severe/critical group, the mean values of hemoglobin 12.03g/dl (p-value=0.075), lymphocyte count 28.41% (p-value=0.8), platelet count 226×103 μI (p-value=0.67) and APTT 30.7 (p-value=0.081) and the difference was not significantly different between groups.

Conclusion

It can be concluded from the study that total leucocyte count, absolute neutrophil count and neutrophil lymphocyte ratio can predict in-hospital mortality and morbidity in COVID-19 patients.

Major Bleeding During Thrombolytic Therapy for Acute Lower Limb Ischaemia: Value of Laboratory Tests for Clinical Decision Making, 17 Years of Experience

OBJECTIVE

Regular measurement of fibrinogen as dose guidance in catheter directed thrombolysis (CDT) for acute limb ischaemia (ALI) has recently been dropped from European guidelines based on inconsistent literature. This study aimed to determine whether low fibrinogen levels and high activated partial thromboplastin time (APTT) are associated with an increased major bleeding risk during CDT.

METHODS

All consecutive patients treated with CDT for ALI in two Dutch hospitals between January 2004 and April 2021 were analysed retrospectively. Patients were treated with two dosing regimens (low dose: 50 000 IU/hour; high dose: 100 000 IU/hour) of urokinase and, after 2018, with a single low dose regimen of alteplase (rtPA) due to urokinase manufacturing problems. The incidence of major bleeding and associated APTT and fibrinogen levels were reviewed from patient charts.

RESULTS

Of the 443 included cases, 277 underwent CDT with urokinase and 166 with rtPA. The incidence of major bleeding in the whole cohort was 7%. Patients with a fibrinogen levels < 1.0 g/L developed more major bleeding than those in whom the fibrinogen level did not drop below 1.0 g/L (15% vs. 6%; p = .041). Systemic heparinisation during CDT or high (> 80 seconds) APTT were not significantly associated with major bleeding. Angiographic success (47% vs. 72%; p = .003) and 30 day amputation free survival (53% vs. 82%; p < .001) were lower for cases with major bleeding. Older age (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.02 - 1.11), cardiac history (OR 3.35, 95% CI 1.39 - 8.06), high dose regimens (≥ 75 000 IU/hour urokinase; OR 2.67, 95% CI 1.18 - 6.04), and fibrinogen values < 1.0 g/L (OR 5.59, 95% CI 1.98 - 15.77) were independent predictors for major bleeding during CDT.

CONCLUSION

High dose thrombolytic regimens and fibrinogen levels of ≤ 1.0 g/L are associated with more major bleeding during thrombolytic therapy. Major bleeding significantly worsened the clinical outcome. A prospective comparative study is needed to assess the benefit of monitoring fibrinogen levels.

Assays to Monitor Bivalirudin

Bivalirudin (Angiomax, Angiox) is a parenteral direct thrombin inhibitor (DTI) that is used for patients with heparin-induced thrombocytopenia (HIT), where heparin cannot be used due to the risk of thrombosis. Bivalirudin is also licensed for use in cardiology procedures (e.g., percutaneous transluminal coronary angioplasty; PTCA). Bivalirudin is a synthetic analogue of hirudin found in the saliva of the medicinal leech and has a relatively short half-life of ~25 min. Several assays can be used to monitor bivalirudin; these include the activated partial thromboplastin time (APTT), activated clotting time (ACT), ecarin clotting time (ECT), an ecarin-based chromogenic assay, thrombin time (TT), the dilute TT, and the prothrombinase-induced clotting time (PiCT). Drug concentrations can also be measured using liquid chromatography tandem mass spectrometry (LC/MS) and clotting or chromogenic-based assays with specific drug calibrators and controls.

The Detection of Hypercoagulability in Patients with Acute Cerebral Infarction Using a Clot Waveform Analysis

A few studies concerning hypercoagulable states have sufficiently been reported in patients with acute cerebral infarction (ACI), as ACI is generally considered to be caused by platelet activation. Clot waveform analyses (CWA) for activated partial thromboplastin time (APTT) and small amount of tissue factor FIX activation assay (sTF/FIXa) were examined in 108 patients with ACI, 61 patients without ACI, and 20 healthy volunteers. CWA-APTT and CWA-sTF/FIXa showed that the peak heights were significantly higher in ACI patients without anticoagulant therapy than in healthy volunteers. Absorbance exceeding 78.1 mm on the 1^st DPH in the CWA-sTF/FIXa showed the highest odds ratio for ACI. The peak heights were significantly lower in the CWA-sTF/FIXa of ACI patients receiving argatroban therapy than in those of ACI patients without anticoagulant therapy. CWA can suggest a hypercoagulable state in ACI patients and may be useful for monitoring the need for anticoagulant therapy.

A Patient with Severe Fever with Thrombocytopenia Syndrome, Activated Partial Thromboplastin Time Prolongation, and Transient Antiphospholipid Antibodies

A prolonged activated partial thromboplastin time (APTT) is observed in patients with severe fever with thrombocytopenia syndrome (SFTS) and is one of the risk factors for severe disease. The mechanism underlying a prolonged APTT is largely unknown. The presence of antiphospholipid (aPL) antibodies in various viral infections has been documented but never reported in a patient with SFTS. We herein report the first SFTS patient with APTT prolongation and concurrent transiently positive aPL antibodies (lupus anticoagulants and anticardiolipin antibodies) with no coagulation factor deficiency.

Meriandra dianthera Aqueous Extract and Its Fraction Prevents Blood Coagulation by Specifically Inhibiting the Intrinsic Coagulation Pathway: An in vitro Study

Background

Currently, cardiovascular disorders are the primary cause of mortality in the world and constitute a serious medical problem. Blood coagulation is an essential process to prevent excessive blood loss through injured blood vessels; however, abnormal blood clotting in the blood vessels can result in fatal cardiovascular disorders. This study investigated the in vitro anticoagulant activity of Meriandra dianthera crude extract and its fractions and their erythrocyte membrane stabilizing activity.

Methods

The plant leaves were extracted by a decoction method and were further fractionated by a liquid–liquid partition with a solvent of crescent polarity. The in vitro anticoagulant activity of the plant extract and its fractions was assessed by PT and APTT assays, while the membrane stabilizing activity was determined through hypotonic induced hemolysis.

Results

The crude aqueous leaf extract of Meriandra dianthera significantly (P < 0.001) prolonged the intrinsic clotting pathway measured by APTT by specifically acting on the intrinsic coagulation pathway. By using liquid–liquid fractionation, the residual aqueous fraction was identified as the fraction responsible for the anticoagulant activity of the crude extract as it significantly (P<0.001) prolonged APTT while the other fractions failed. Both the crude extract and its aqueous residue fraction did not affect the extrinsic coagulation pathway measured by PT. In the membrane stabilizing assay, crude extract and aqueous residue fraction showed the highest membrane stabilizing activity.

Conclusion

The crude extract and its aqueous residue fraction showed a potent in vitro anticoagulant and membrane stabilizing activity, which shows the potential of the plant’s leaves as a new source of bioactive molecules for coagulation-related disorders.

Risk Factors for Bleeding Complications during Venovenous Extracorporeal Membrane Oxygenation as a Bridge to Recovery

Background

Bleeding complications during venovenous extracorporeal membrane oxygenation (V‐V ECMO) can be critical. However, there is limited information on the associated risk factors. This study investigated the risk factors for bleeding complications during V‐V ECMO as a bridge to recovery.

Methods

This single‐center retrospective study enrolled 59 patients (bleeding and non‐bleeding groups) who received V‐V ECMO from 2012 to 2020, to evaluate whether peak activated partial thromboplastin time (APTT) value, lowest platelet count, and mobilization to sitting on the edge of the bed during V‐V ECMO were risk factors for bleeding complications, defined according to the Extracorporeal Life Support Organization guidelines. Age, sex, body mass index, Sequential Organ Failure Assessment score, and ECMO duration before bleeding complications were covariates in the multivariate logistic regression analysis.

Results

Thirty‐one (53%) participants experienced 36 bleeding complications; the ECMO cannulation site, gastrointestinal tract, and nasopharyngeal region were the most common bleeding sites. The use of transfusion products and length of ECMO and intensive care unit stay were significantly and medical costs were non‐significantly increased in the bleeding group. Peak APTT (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.05, p < 0.01) was significantly associated whereas the lowest platelet count (OR 0.96, 95% CI 0.82–1.13, p = 0.66) was unassociated with bleeding complications during ECMO. Achieving mobilization (OR 0.14, 95% CI 0.02–1.17, p = 0.07) decreased the trend of risk for bleeding complications.

Conclusions

Peak APTT might be an independent modifiable factor for bleeding complications during V‐V ECMO. The protective effect of mobilization during V‐V ECMO requires further investigation.

Monitoring of Unfractionated Heparin Therapy in the Intensive Care Unit Using a Point-of-Care aPTT: A Comparative, Longitudinal Observational Study with Laboratory-Based aPTT and Anti-Xa Activity Measurement

Continuous intravenous unfractionated heparin (UFH) is administered routinely in the intensive care unit (ICU) for the anticoagulation of patients, and monitoring is performed by the activated partial thromboplastin time (APTT) or anti-Xa activity. However, these strategies are associated with potentially large time intervals before dose adjustments, which could be detrimental to the patient. The aim of the study was to compare a point-of-care (POCT) version of the APTT to (i) laboratory-based APTT and (ii) measurements of anti-Xa activity in terms of correlation, agreement and turnaround time (TAT). Thirty-five ICU patients requiring UFH therapy were prospectively included and followed longitudinally for a maximum duration of 15 days. UFH was administered according to a local adaptation of Raschke and Amanzadeh’s aPTT nomograms. Simultaneous measurements of POCT-APTT (CoaguCheck® aPTT Test, Roche Diagnostics) on a drop of fresh whole blood, laboratory-based APTT (C.K. Prest®, Stago) and anti-Xa activity (STA®Liquid anti-Xa, Stago) were systematically performed two to six times a day. Antithrombin, C-reactive protein, fibrinogen, factor VIII and lupus anticoagulant were measured. The time tracking of sampling and analysis was recorded. The overall correlation between POCT-APTT and laboratory APTT (n = 795 pairs) was strongly positive (rs = 0.77, p < 0.0001), and between POCT-APTT and anti-Xa activity (n = 729 pairs) was weakly positive (rs = 0.46, p < 0.0001). Inter-method agreement (Cohen’s kappa (k)) between POCT and laboratory APTT was 0.27, and between POCT and anti-Xa activity was 0.30. The median TATs from sample collection to the lab delivery of results for lab-APTT and anti-Xa were 50.9 min (interquartile range (IQR), 38.4−69.1) and 66.3 min (IQR, 49.0−91.8), respectively, while the POCT delivered results in less than 5 min (p < 0.0001). Although the use of the POCT-APTT device significantly reduced the time to results, the results obtained were poorly consistent with those obtained by lab-APTT or anti-Xa activity, and therefore it should not be used with the nomograms developed for lab-APTT.

An Analysis of the Sensitivity of the Activated Partial Thromboplastin Time (APTT) Assay, as Used in a Large Laboratory Network, to Coagulation Factor Deficiencies

OBJECTIVES

To advance knowledge in using the ex vivo method to identify factor sensitivity of the activated partial thromboplastin time (APTT), using data from a hemophilia and reference hemostasis laboratory; to evaluate application of inclusion and exclusion criteria to eliminate data outliers; and to discuss outcomes with reference to comparable studies.

METHODS

An ex vivo, retrospective analysis was performed on patient samples with conjointly ordered APTT and intrinsic pathway factors (VIII, IX, XI, XII) for application to a large network of laboratories. The relationship between factor levels and APTT, before and after application of exclusion criteria, is demonstrated.

RESULTS

Curvilinear relationships were found between all factor levels and APTTs, which demonstrated both similarities and differences with available studies. Factor sensitivity data are presented. Study strengths include large sample size and use of real-world data. Limitations include inability to exclude all residual outliers and paucity of patient samples singularly deficient in factors other than FVIII.

CONCLUSIONS

This ex vivo, retrospective analysis of the sensitivity of the APTT assay to intrinsic pathway factor deficiencies using real-world data from a hemophilia and reference hemostasis laboratory contains the largest sample size using this approach to date. The outcomes assist in informing practice in this area and can be used as a reference for further studies.

Clot Waveform Analysis Demonstrates Low Blood Coagulation Ability in Patients with Idiopathic Thrombocytopenic Purpura

BACKGROUND

Although platelets, which contain large amounts of phospholipids, play an important role in blood coagulation, there is still no routine assay to examine the effects of platelets in blood coagulation.

METHODS

Hemostatic abnormalities in patients with thrombocytopenia, including those with idiopathic thrombocytopenic purpura (ITP), were examined using clot wave analysis (CWA)-small-amount tissue-factor-induced FIX activation (sTF/FIXa) and thrombin time (TT).

RESULTS

Although there were no marked differences in the three parameters of activated partial thromboplastin time (APTT) between normal healthy volunteers and typical patients with ITP, the peak heights of the CWA-sTF/FIXa were markedly low in patients with ITP. The three peak times of the CWA-sTF/FIXa in patients with a platelet count of ≤8.0 × 10¹⁰/L were significantly longer than those in patients with a platelet count > 8.0 × 10¹⁰/L and the peak heights of the CWA-sTF/FIXa in patients with a platelet count of ≤8.0 × 10¹⁰/L were significantly lower than those in patients with >8.0 × 10¹⁰/L. The peak heights of the CWA-APTT in patients with ITP were significantly lower than in patients with other types of thrombocytopenia. The three peak heights of the CWA-sTF/FIXa in ITP patients were significantly lower than those in patients with other types of thrombocytopenia. The CWA-TT showed lower peak heights and longer peak times in patients with ITP in comparison to patients with other types of thrombocytopenia.

CONCLUSIONS

The CWA-sTF/FIXa and CWA-TT results showed that blood coagulation is enhanced by platelets and that the blood coagulation ability in ITP patients was low in comparison to healthy volunteers and patients with other types of thrombocytopenia.

Caution in Using the Activated Partial Thromboplastin Time to Monitor Argatroban in COVID-19 and Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT)

Introduction

Argatroban is licensed for patients with heparin-induced thrombocytopenia and is conventionally monitored by activated partial thromboplastin time (APTT) ratio. The target range is 1.5 to 3.0 times the patients’ baseline APTT and not exceeding 100 s, however this baseline is not always known. APTT is known to plateau at higher levels of argatroban, and is influenced by coagulopathies, lupus anticoagulant and raised FVIII levels. It has been used as a treatment for COVID-19 and Vaccine-induced Immune Thrombocytopenia and Thrombosis (VITT). Some recent publications have favored the use of anti-IIa methods to determine the plasma drug concentration of argatroban.

Methods

Plasma of 60 samples from 3 COVID-19 patients and 54 samples from 5 VITT patients were tested by APTT ratio and anti-IIa method (dilute thrombin time dTT). Actin FS APTT ratios were derived from the baseline APTT of the patient and the mean normal APTT.

Results

Mean APTT ratio derived from baseline was 1.71 (COVID-19), 1.33 (VITT) compared to APTT ratio by mean normal 1.65 (COVID-19), 1.48 (VITT). dTT mean concentration was 0.64 µg/ml (COVID-19) 0.53 µg/ml (VITT) with poor correlations to COVID-19 baseline APTT ratio r² = 0.1526 p <0.0001, mean normal r² = 0.2188 p < 0.0001; VITT baseline APTT ratio r² = 0.04 p < 0.001, VITT mean normal r² = 0.0064 p < 0.001.

Conclusions

We believe that dTT is a superior method to monitor the concentration of argatroban, we have demonstrated significant differences between APTT ratios and dTT levels, which could have clinical impact. This is especially so in COVID-19 and VITT.

A Clot Waveform Analysis Showing a Hypercoagulable State in Patients with Malignant Neoplasms

(1) Objective: hypercoagulability in patients with malignant neoplasm were evaluated to examine the relationship with thrombosis. (2) Methods: clot waveform analysis (CWA)—activated partial thromboplastin time (APTT) and CWA—small amount of tissue factor induced FIX activation (sTF/FIXa) assays were performed in 92 patients with malignant neoplasm and the relationship between hypercoagulability and thrombosis was retrospectively examined. (3) Results: The study population included 92 patients with malignant neoplasms. Twenty-six (28.3%) had thrombotic diseases and 9 (9.8%) patients died within 28 days after the CWA. The peak time of the CWA-APTT could not show hypercoagulability in patients with malignant neoplasms. There were almost no significant differences in the peak times of the sTF/FIXa among patients with malignant neoplasms and healthy volunteers. In contrast, the peak heights of the CWA-sTF/FIXa in patients with various malignant neoplasms were significantly higher than those in healthy volunteers. Furthermore, among patients with malignant neoplasms, the peak heights of the sTF/FIXa in patients with thrombosis were significantly higher than those in patients without thrombosis. (4) Conclusions: although the routine APTT cannot evaluate the hypercoagulability, the peak heights of CWA-sTF/FIXa were significantly high in patients with malignant neoplasms, especially in those with thrombosis, suggesting that an elevated peak height of the CWA-sTF/FIXa may be a risk factor for thrombosis.

Laboratory methods for monitoring argatroban in heparin-induced thrombocytopenia

INTRODUCTION

The Summary of Product Characteristics for the direct thrombin inhibitor argatroban states monitoring should be by activated partial thromboplastin time (APTT), with a target range of 1.5-3.0 times the patients' baseline APTT. APTT may be influenced by coagulopathies, lupus anticoagulant and raised FVIII levels. Previous studies have shown sensitivity differences of APTT reagents to argatroban. Some recent publications have favoured the use of anti-IIa methods to determine the plasma drug concentration of argatroban. This study aims to compare the anti-IIa assays: Hemoclot thrombin inhibitor assay (HTI) and Ecarin chromogenic assay (ECA) alongside the APTT.

METHODS

Residual plasma of 25 samples from 8 patients (3 with COVID-19 and HIT: n = 18, 5 with HIT: n = 7) was tested at two sites: site A: Sysmex CS5100 by HTI and APTT (Actin FS and SynthASil), and also on Stago STA Compact Max: ECA and APTT (CK Prest); and site B: Stago STA R Max 2 by ECA and APTT (Cephascreen).

RESULTS

Mean APTT ratio was 1.96 (Actin FS), 1.84 (SynthASil), 1.59 (CK Prest) and 2.48 (Cephascreen). Mean argatroban concentration by HTI was 0.60 µg/mL and by ECA was 0.65 µg/mL (site A) and 0.70 µg/mL (site B). There was a poor correlation to HTI in APTT ratios (range r²  = .0235-0.4181) with stronger correlations between ECA methods to HTI (r²  = .8998 site A, r²  = .8734 site B).

CONCLUSION

This study confirms previous publications on the unsuitability of APTT and expands this by being multisited and included APTT reagents that use mechanical clot detection. Both anti-IIa methods are more suitable.

[Reagent-dependent pseudo-prolongation of activated partial thromboplastin time]

We report a case of pseudo-prolongation of activated partial thromboplastin time (APTT), which was suspected to be caused by an animal-derived phospholipid. A 78-year-old woman was referred to our hospital because of an unexplained APTT prolongation. She had compensated alcoholic liver cirrhosis, with modestly decreased platelet count and normal prothrombin time, and no bleeding tendency. The APTT was 66 seconds in a test using phospholipid extracted from rabbit brain but was 34.9 seconds with synthetic phospholipids. The artifactual pseudo-prolongation of the APTT was seemingly attributable to the susceptibility of the test reagents to low factor XII levels. Thus, tests with different APTT reagents would be useful to physicians in the diagnosis of similar cases.

Verification of the ACL Top 50 Family (350, 550, and 750) for Harmonization of Routine Coagulation Assays in a Large Network of 60 Laboratories

OBJECTIVES

To verify a single platform of hemostasis instrumentation, the ACL TOP 50 Family, comprising 350, 550, and 750 instruments, across a large network of 60 laboratories.

METHODS

Comparative evaluations of instrument classes (350 vs 550 and 750) were performed using a large battery of test samples for routine coagulation tests, comprising prothrombin time/international normalized ratio, activated partial thromboplastin time (APTT), thrombin time, fibrinogen and D-dimer, and using HemosIL reagents. Comparisons were also made against existing equipment (Diagnostica Stago Satellite, Compact, and STA-R Evolution) and existing reagents to satisfy national accreditation standards. Verification of manufacturer normal reference ranges (NRRs) and generation of an APTT heparin therapeutic range were undertaken.

RESULTS

The three instrument types were verified as a single instrument class, which will permit standardization of methods and NRRs across all instruments (n = 75) to be deployed in 60 laboratories. In particular, ACL TOP 350 test result data were similar to ACL TOP 550 and 750 and showed no to limited bias. All manufacturer NRRs were verified with occasional minor variance.

CONCLUSIONS

This ACL TOP 50 Family (350, 550, and 750) verification will enable harmonization of routine coagulation across all laboratories in the largest public pathology network in Australia.

Challenges of biological monitoring in a hemophilia A patient without inhibitors on emicizumab undergoing major orthopedic surgery: a case report

A man with severe hemophilia A (HA) without factor VIII (FVIII) inhibitors was admitted for total arthroplasty of his elbow. The patient was being treated with emicizumab, with his last administration given 8 days before surgery. Preoperatively, he received a bolus of 4000 international units (IU) of recombinant (r)FVIII. Throughout the operation, a continuous infusion of 4 IU/kg/h was administered and maintained over 24 hours. On the first postoperative day, the FVIII infusion rate was reduced to 225 IU/h for 4 days and stopped on the fifth day. Under this treatment, no bleeding complications occurred. Emicizumab is known to interfere with a wide range of coagulation assays, thereby challenging replacement therapy monitoring before, during, and after surgery. In this case study, we report on the assessment of FVIII levels at different time points using various reagents. We conclude that for both hematologists and non-hematology clinicians, it is crucial to be aware of emicizumab interferences with routine coagulation tests so as to avoid misinterpretation. In addition, laboratory specialists must be familiar with this treatment in order to select appropriate coagulation tests and provide rapid and reliable result interpretations.

Update on the Clot Waveform Analysis

The activated partial thromboplastin time (APTT)–clot waveform analysis (CWA) was previously reported to be associated with the early detection of disseminated intravascular coagulation and was also reported to be able to measure very low levels of coagulation factor VIII activity. The software program for the analysis for the APTT-CWA allows the associated first and second derivative curves (first and second DCs) to be displayed. The first and second DC reflect the velocity and acceleration, respectively. The height of the first DC reflects the “thrombin burst” and bleeding risk, while that of the second DC is useful for detecting any coagulation factor deficiency and abnormal enhancement of coagulation by phospholipids. Activated partial thromboplastin time-CWA aids in making a differential diagnosis which is difficult to do using only the routine APTT. The CWA is currently used for many applications in the clinical setting, including the monitoring of hemophilia patients and patients receiving anticoagulant therapy and the differential diagnosis of diseases.

The Evaluation of Hemostatic Abnormalities Using a CWA-Small Amount Tissue Factor Induced FIX Activation Assay in Major Orthopedic Surgery Patients

We analyzed the utility for a clot waveform analysis (CWA) of small tissue factor induced FIX activation (sTF/FIXa) assay in patients with major orthopedic surgery (including total hip arthroplasty [THA] and total knee arthroplasty [TKA]) receiving edoxaban for the prevention of venous thromboembolism (VTE). The sTF/FIXa assay using recombinant human TF in platelet-rich plasma (PRP) and platelet-poor plasma (PPP) was performed using a CWA in the above patients to monitor the efficacy of edoxaban administration. Of 147 patients (109 THA and 38 TKA), 21 exhibited deep vein thrombosis (DVT), and 15 had massive bleeding. Increased peak heights of the CWA-sTF/FIX were observed in almost patients after surgery and prolonged peak heights of the CWA-sTF/FIX were observed in almost patients treated with edoxaban. The peak heights and times of the CWA-sTF/FIX were significantly higher and shorter, respectively, in PRP than in PPP. There were no significant differences in parameters of the CWA-sTF/FIXa between the patients with and without DVT or between those with and without massive bleeding. The peak time of CWA-sTF/FIXa were significantly longer in TKA patients than in THA patients on day 1 after surgery. The second derivative peak height of the CWA-sTF/FIXa was significantly lower in TKA patients than in THA patients on day 4. The CWA-sTF/FIX reflected hemostatic abnormalities after surgery and the administration of edoxaban, and the results were better in PRP than PPP. Further studies separately analyzing the THA and TKA subgroups should be conducted.

Evaluation of hemostatic abnormalities in patients who underwent major hepatobiliary pancreatic surgery using activated partial thromboplastin time-clot waveform analysis

INTRODUCTION

Bleeding after major hepatobiliary pancreatic (HBP) surgery may be serious. Although postoperative abnormality of the hemostatic system are important elements that affect bleeding, routine activated partial thromboplastin time (APTT) assessment is considered inadequate to predict massive bleeding (MB). Recently, APTT-clot waveform analysis (CWA) was reported to be useful for detecting coagulation disorders.

METHODS

APTT-CWA was performed using the ACL-TOP analyzer in 188 patients who underwent four major HBP surgeries (distal pancreatectomy, hepatectomy, subtotal stomach-preserving pancreatoduodenectomy (SSPPD), and SSPPD with combined resection and reconstruction of the portal vein) to analyze its usefulness in predicting the risk of bleeding.

RESULTS

Seventy (37.2%) patients developed MB and the incidence of MB was highest among patients who underwent hepatectomy. There were no significant differences in routine APTT, the first derivative peak (DP) time and 1/2 fibrin formation peak time between patients with MB and those without MB, throughout the postoperative course. On the other hand, the first and second DP heights were significantly lower in patients with MB than in those without MB and lowest in patients who underwent hepatectomy.

CONCLUSION

APTT-CWA was able to detect the detailed changes in the hemostatic system after major HBP surgery. The patterns of APTT-CWA after major HBP surgery differed among various surgical procedures according to invasiveness. The lower first and the second DP height, which were frequently observed in hepatectomy patients, may be useful for predicting the risk of MB.

Prediction of Poor Outcomes in Patients with Colorectal Cancer: Elevated Preoperative Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)

Background and Objective

Tools for the non-invasive assessment of colorectal cancer (CRC) prognosis have profound significance. Although plasma coagulation tests have been investigated in a variety of tumours, the prognostic value of the prothrombin time (PT) and activated partial thromboplastin time (APTT) in CRC has not been discussed. Our study objective was to explore the prognostic significance of preoperative PT and APTT in CRC patients.

Patients and Methods

A retrospective analysis of preoperative coagulation indexes including PT, PTA, INR, APTT, FIB, TT, PLT, NLR and PLR in 250 patients with CRC was performed. Kaplan–Meier and multivariate Cox regression analysis were used to demonstrate the prognostic value of these preoperative coagulation indexes.

Results

The overall survival (OS, p<0.05) and disease-free survival (DFS, p<0.05) of CRC patients with lower PT and APTT levels were significantly prolonged. Based on univariate analysis, PT levels (p<0.001, p<0.001), PTA levels (p=0.001, p=0.001), APTT levels (p=0.001, p<0.001), INR levels (p<0.001, p<0.001), fibrinogen levels (p=0.032, p=0.036), tumour status (p=0.005, p=0.003), nodal status (p<0.001, p<0.001), metastasis status (p<0.001, p<0.001) and TNM stages (p<0.001, p<0.001) were remarkably associated with DFS and OS. Multivariate Cox regression analysis suggested that the levels of PT (HR: 2.699, p=0.006) and APTT (HR: 1.942, p=0.015), metastasis status (HR: 2.091, p= 0.015) and TNM stage (HR: 7.086, p=0.006) were independent predictors of survival in CRC. In the whole cohort, the enrolled patients were then divided into three groups according to their PT and APTT levels. The OS and DFS differed notably among the low-risk (PT<11.85 sec and APTT<25.85 sec), medium-risk (PT≥11.85 sec or APTT≥25.85 sec), and high-risk (PT≥11.85 sec and APTT≥25.85 sec) groups.

Conclusion

Elevated levels of preoperative PT and APTT were predictors of poor outcomes in CRC patients. Moreover, the combination of preoperative PT and APTT can be a new prognostic stratification approach for more precise clinical staging of CRC.

Effects of platelet and phospholipids on clot formation activated by a small amount of tissue factor

INTRODUCTION

Physiological coagulation is considered to activate coagulation factor IX (FIX) by a small amount of tissue factor (TF) and activated coagulation factor VII (FVIIa) with the presence of platelets. A Clot waveform analysis (CWA) may be useful for evaluating physiological coagulation.

MATERIAL AND METHODS

A CWA using a small amount of TF (CWA/sTF) was performed in platelet-rich plasma (PRP), platelet-poor plasma (PPP), several phospholipids (PLs) and patients with lupus anticoagulant (LA), idiopathic thrombocytopenic purpura (ITP) or inhibitor for FVIII.

RESULTS

The CWA/sTF without PLs showed a shorter peak time and higher peak height in PRP than in PPP. The effect of PRP on the CWA/sTF depended on the platelet count, and PLs showed a similar effect on the CWA/sTF results in PPP. The peak time of the CWA/sTF in PRP was prolonged in patient with ITP. The CWA/sTF in PRP showed a prolonged peak time and decreased peak height of the second derivative in patient with LA. Both a shortened peak time and elevated peak height were observed in the CWA/sTF of patient with inhibitor after treatment with activated recombinant human FVII.

CONCLUSION

A CWA can be conducted using a small amount of TF and platelets or PL without contact activation and may be able to detect not only hemostatic abnormalities but also changes in platelet counts.

Effects of the ketogenic diet on platelet counts and global coagulation tests in childhood epilepsy

PURPOSE

Several antiseizure drugs (ASD), especially Valproic acid (VPA), influence platelet counts and coagulation parameters. The ketogenic diet (KD), established in drug-resistant epilepsy, is combined with ASDs. Bruising and prolonged bleeding times during KD have been described, but whether hemostatic changes result from the KD or from concomitant ASDs, remains unclear. Aim of the present study was to evaluate bleeding, platelet counts and global coagulation tests prior to and during KD in childhood epilepsy.

METHOD

Consecutive children treated with KD were systematically observed for bleeding. Serial measurements of platelet counts and global coagulation tests (APTT, PT and fibrinogen) were obtained at baseline and during KD (at 1, 3, 6 and 12 months). Children with KD monotherapy, concomitant VPA, or other ASDs were compared.

RESULTS

Among 162 children receiving KD, we observed neither bleeding in daily life nor perioperative bleeding in those undergoing surgery (n = 25). Most children had normal platelet counts and coagulation parameters. Only a few had transient mild thrombocytopenia and mildly prolonged APTT values, not indicative of a bleeding risk. Even KD combined with VPA did not cause relevant coagulopathy. Unexpectedly, we found mild thrombocytosis in 24 % of patients prior to KD, which was most pronounced in yet untreated epilepsy. Thrombocytosis steadily resolved during KD.

CONCLUSIONS

During KD treatment of childhood epilepsy, we observed neither bleeding symptoms nor laboratory results indicating a bleeding risk. Unexpectedly, mild thrombocytosis was present in 24 % at baseline, normalising during KD. Thrombocytosis may reflect the underlying inflammatory process of untreated epilepsy and requires further study.

The spatial distribution of the normal reference values of the activated partial thromboplastin time based on ArcGIS and GeoDA

We explored the variation and spatial distribution of the activated partial thromboplastin time (APTT) reference values of healthy people at different altitudes in China in order to develop a scientific basis for a unified standard. The APTT reference values of 49,020 healthy males (41-75 years old) and 32,447 healthy females (41-75 years old) were collected from 601 work units and 546 work units in China, respectively. The relationship between the APTT reference values and altitude was tested by correlation analysis. Linear regression analysis and curve analysis were employed to predict the APTT reference values in the whole country. Trend surface analysis, the variation function, kriging interpolation, and Getis-Ord Gi* statistic were utilized to reveal the spatial characteristics of the values. The result showed a significant positive correlation between the APTT reference values and altitude. The APTT values for females were prolonged for a greater amount of time than the males in several same areas in China. The spatial contact forms of the APTT reference values of healthy Chinese were mainly "high-high" and "low-low," which was in accord with the first law of geography. The APTT reference values still showed spatial autocorrelation and regional variation. The values were higher in the western and northern areas than in the eastern and southern areas of China. The APTT reference values of people aged 41-75 in China showed regional differences. The APTT reference values in one area can be estimated by using the best prediction model or can be obtained by the geographical distribution.

Coagulation tests on admission correlate with mortality and morbidity in general ICU patients: An observational study

BACKGROUND

It is well known that low platelet count on admission to intensive care units (ICU) is associated with increased mortality. However, it is unknown whether prothrombin time (PT-INR) and activated partial thromboplastin time (APTT) on admission correlate with mortality and organ failure. Therefore, the aim of this study was to investigate whether PT-INR and APTT at admission can predict outcome in the critically ill patient after adjusting for severity of illness measured with Simplified Acute Physiology Score 3 (SAPS 3).

MATERIALS AND METHODS

Data were retrospectively collected. APTT and PT-INR taken on admission and SAPS 3 score were independent variables in all regression analyses. Survival analysis was done with Cox regression. Organ failure was reported as days alive and free (DAF) of vasopressors and invasive ventilation, need of continuous renal replacement therapy (CRRT) and Acute Kidney Injury Network creatinine score (AKIN-crea).

RESULTS

A total of 3585 ICU patients were included. Prolonged APTT correlated with mortality with 95% confidence interval (CI) of hazard ratio 1.001-1.010. Prolonged APTT also correlated with DAF vasopressor, CRRT and AKIN-crea with 95% CI of odds ratio (OR) 1.009-1.034, 1.016-1.037 and 1.009-1.028, respectively. Increased PT-INR correlated with DAF vasopressor and DAF ventilator with 95% CI of OR 1.112-2.014 and 1.135-1.847, respectively.

CONCLUSIONS

Activated partial thromboplastin time prolongation was associated with mortality and all morbidity outcomes except the DAF ventilator. PT-INR increase at admission was associated with DAF vasopressor and DAF ventilator. APTT and PT-INR at admission correlate with morbidity, which is not accounted for in the SAPS 3 model.

[Effect of lead pollution on anticoagulant effect of Whitmania pigra based on in vitro anticoagulation experiment]

Leech has a good anticoagulant activity and is one of the raw materials for treatment of many cardiovascular and cerebrovascular diseases. This study was based on in vitro anticoagulant experiments( APTT and PT) to investigate the effects of lead contamination on the anticoagulant effect of leech. At present,the Hirudo circulating in the market are dominated by Whitmania pigra,therefore Wh. pigra were cultivated under a different lead pollution for 50 days. Then,the effects of Wh. pigra extract,extracting from different cultivating environment,on activated partial thrombin time( APTT) and prothrombin time( PT) were determined by automatic coagulation instrument. The results showed that the Wh. pigra extract significantly prolonged the APTT compared with the saline group.The APTT of the lead-high residual Wh. pigra was shorter than that of the blank Wh. pigra. The Wh. pigra extracts from different treatment groups had little effect on PT. The results showed that the lead residue in the Wh. pigra increased with the increase of lead in the cultured soil,the lead residual of the Pb-H group was( 10. 66±2. 79) mg·kg~(-1),which exceeded the lead limit specified in the 2015 edition of the Chinese Pharmacopoeia. The results indicated that growth environment pollution is one of the important factors causing excessive lead in Wh. pigra. Lead pollution will reduce the anticoagulant effect of Wh. pigra and affect its clinical efficacy.

Polysaccharide composition of an anticoagulant fraction from the aqueous extract of Marsypianthes chamaedrys (Lamiaceae)

Marsypianthes chamaedrys (Lamiaceae) is a medicinal plant popularly used against envenomation by snakebite. Pharmacological studies have shown that extracts of M. chamaedrys have antiophidic, anti-inflammatory and anticoagulant properties, supporting the ethnopharmacological use. In this study, an aqueous extract of aerial parts of M. chamaedrys showed anticoagulant activity in the activated partial thromboplastin time assay (0.54 IU/mg). The bioassay-guided fractionation using ethanol precipitation and gel filtration chromatography on Sephadex G-50 and Sephadex G-25 resulted in a water-soluble fraction with increased anticoagulant activity (Fraction F2-A; 2.94 IU/mg). A positive correlation was found between the amount of uronic acids and the anticoagulant potential of the active samples. Chemical and spectroscopic analyses indicated that F2-A contained homogalacturonan, type I rhamnogalacturonan, type II arabinogalactan and α-glucan. UV and FT-IR spectra indicated the possible presence of ferulic acid. Pectic polysaccharides and type II arabinogalactans may be contributing to the anticoagulant activity of the aqueous extract of M. chamaedrys in the APTT assay.

The association of coagulation indicators with in-hospital mortality and 1-year mortality of patients with sepsis at ICU admissions: A retrospective cohort study

BACKGROUND

Coagulation activation is the host's response to pathogens during sepsis and is considered to be one of the reasons for tissue damage and multiple organ failure. This study is designed to evaluate whether the alterations of coagulation indicators are related to in-hospital mortality and 1-year mortality of patients with sepsis.

METHOD

Data of all 2258 patients were extracted from the database Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC III). The relationship between the in-hospital mortality of patients with sepsis and coagulation indicators was analyzed with a receiver operating characteristic (ROC) curve analysis and logistic regression model. Effects of coagulation indicators on patients' 1-year mortality were determined by using a Cox hazard regression model, and clinical experience or quintiles were used to classify the activated partial thromboplastin time (APTT) to determine the cutoff values to explore segmentation effects.

RESULT

International normalized ratio (INR) was positively associated with hospital mortality of patients with sepsis after adjusting confounders with an odds ratio (OR) of 1.86 [95% confidence interval (CI), 1.37-2.52], and a hazard ratio (HR) of 1.465[95%CI(1.24-1.74)] for 1-year mortality, respectively. 1-year mortality of patients with sepsis demonstrated a U-shaped relationship with APTT, ranging from 25 to 37, indicating the lowest risk. The adjusted HR (95% CI) values for 1-year mortality of septic patients with risk values <25 and >37 were 1.493 (1.02, 2.19) and 1.379 (1.06, 1.79), respectively.

CONCLUSION

Increased INR in critically ill septic patients is related to greater in-hospital mortality and 1-year mortality. A U-shaped relationship was found between APTT and 1-year mortality of patients with sepsis.

A cost-effective approach to factor assay calibration using a truncated live calibration curve

INTRODUCTION

The measurements of clotting factor activities are usually performed using a one-stage clotting assay (OSA) or chromogenic substrate assay (CSA). Advances in automated coagulation analysers have led to the utilization of stored calibration curves. There are sometimes substantial intervals between test calibration and analysis of samples. Variability in results can be influenced by calibrant and methodology. Several guidelines recommend calibration and patient samples be performed together in parallel; this incurs costs, but reliance on a stored calibration curve may lead to inaccuracy of results over time.

METHODS

We evaluated inclusion of a live truncated (3 point) calibration curve using calibrator plasma alongside test samples and compared results calculated against the stored calibration curves and live truncated calibration to assess the impact on precision and accuracy. The feasibility of this was tested on two hospital sites in the UK; OSA and CSA were performed on Sysmex CS5100 using Actin FS, SynthASil, Innovin, Biophen chromogenic VIII and Rossix chromogenic IX.

RESULTS

Results of two batches of IQC were compared for FII, FV, FVII, FX, FIX:C, FXI, FXII and OSA FVIII (FVIII:C1) and CSA FVIII:C (FVIII:CR) and FXI:C. By utilizing a live truncated calibration, precision improved with the most striking examples: FXII %CV 23.1% to 3.1% (site A) FXI 7.3% to 2.4% (site B). The improvement in other clotting factors was more modest.

CONCLUSION

To the best of our knowledge, this is the first study that demonstrates that the use of a live truncated calibration curve will improve precision and accuracy.

Haemostatic Changes in Five Patients Infected with Ebola Virus

Knowledge on haemostatic changes in humans infected with Ebola virus is limited due to safety concerns and access to patient samples. Ethical approval was obtained to collect plasma samples from patients in Sierra Leone infected with Ebola virus over time and samples were analysed for clotting time, fibrinogen, and D-dimer levels. Plasma from healthy volunteers was also collected by two methods to determine effect of centrifugation on test results as blood collected in Sierra Leone was not centrifuged. Collecting plasma without centrifugation only affected D-dimer values. Patients with Ebola virus disease had higher PT and APTT and D-dimer values than healthy humans with plasma collected in the same manner. Fibrinogen levels in patients with Ebola virus disease were normal or lower than values measured in healthy people. Clotting times and D-dimer levels were elevated during infection with Ebola virus but return to normal over time in patients that survived and therefore could be considered prognostic. Informative data can be obtained from plasma collected without centrifugation which could improve patient monitoring in hazardous environments.

Association of coagulation profile with microvascular complications and glycemic control in type 2 diabetes mellitus - a study at a tertiary care center in Delhi

Introduction

Type 2 diabetes mellitus, characterized by insulin resistance, corresponds to approximately 90% of cases of diabetes worldwide. Hyperglycemia in diabetes contributes to hyperfibrinogenemia and activates the coagulation cascade thereby producing atherothrombotic events.

Objectives

This study was designed to evaluate the coagulation profile (activated partial thromboplastin time, prothrombin time and fibrinogen) in Type 2 diabetes and to analyze correlations between body mass index, fasting blood glucose, glycated hemoglobin and duration of diabetes with coagulation parameters.

Methods

This study included 60 type 2 diabetics and 30 controls. Diabetic patients were grouped in two sets based on the presence or absence of microvascular complications. The demographic profile and clinical details were recorded. Fasting blood glucose, glycated hemoglobin, coagulation parameters such as prothrombin time, activated partial thromboplastin time and fibrinogen along with other biochemical parameters were investigated.

Results

There were statistically significant differences in the coagulation parameters between the two groups of diabetics (with and without complications). The present study also found significant correlations between age and the duration of diabetes with and without complications and coagulation parameters such as the activated partial thromboplastin time, which was found to be significantly lower, and fibrinogen, which was found to be significantly higher in subjects with complications compared to subjects without complications.

Conclusion

Clinical tests for prothrombin time, activated partial thromboplastin time and fibrinogen are relatively inexpensive and readily available. The present study shows that shortened prothrombin time, activated partial thromboplastin time and increased fibrinogen levels might be useful hemostatic markers in diabetic patients, especially in those at high-risk for thrombotic complications.

Routine Preoperative Coagulation Tests in Children Undergoing Elective Surgery or Invasive Procedures: Are They Still Necessary?

Introduction:

Preoperative coagulation screening tests in pediatric patients was once routine clinical practice globally and still used as standard practice in some countries before surgical procedures to assess of perioperative bleeding risk.

Objective:

The study aimed to evaluate unselected routine preoperative coagulation testing in children undergoing elective or invasive surgery to predict abnormal perioperative bleeding. The study also aimed to provide a rational approach of determining bleeding and family history of coagulation disorders as a predictive risk for bleeding.

Methods:

This retrospective study conducted between 2014 and 2015 (1 year) on normal healthy children aged under 15 years admitted to the hospitals for elective mild to intermediate surgery or invasive procedures. We reviewed and collected the details of the clinical history, previous surgery, trauma, family history, detail of anti-thrombotic medication and coagulation tests performed (prothrombin time (PT), the activated partial prothrombin time (APTT), and international normalized ratio (INR)) at the time of admission.

Results:

Among 2078 cases, 1940 cases had normal coagulation tests (93.4%), 77 cases had abnormal coagulation results (3.7%), and 61 patients underwent surgery without preoperative coagulation screening (2.9%). In 15 of 77 patients, coagulation tests were normal on repeat testing. A total of 52 were confirmed to have abnormal screening testing. Among these 52 cases, 45 had normal factors assay; where seven patients had abnormal factors assay. Postoperative bleeding occurred only in three cases (0.14%), two cases due to surgical procedures with normal preoperative testing and one due to hemophilia A which was detected postoperatively as no preoperative testing was performed.

Conclusions:

Routine coagulation screening before surgery or invasive procedures to predict perioperative bleeding in unselected patients is not recommended. Our study emphasizes that selective preoperative testing is more appropriate. Selective criteria for consideration of the latter includes physical examination, type of surgery, family and bleeding history, and concomitant use of antiplatelet and anti-thrombotic therapy.

Comparison of Rapid Centrifugation Technique with Conventional Centrifugation for Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) Testing

Prothrombin Time (PT) and activated partial thromboplastin time (APTT) are frequently performed coagulation tests in patients with coagulation disorders especially in critical care areas and in monitoring patients on anticoagulation therapy. In coagulation testing, sample processing especially centrifugation is one of the most critical steps that affect turnaround time (TAT). This study was carried out over a period of 1 year. Three hundred paired samples from patients sent for PT and APTT estimation were included. One sample was centrifuged in a regular bench top centrifuge at 1500g for 20 min. The other sample was divided into two polypropylene aliquots and centrifuged in a microcentrifuge at 13000g for 3 min. The plasma obtained from both methods was tested for PT and APTT using the automated method on STA Compact coagulometer (Stago) using commercial thromboplastin STA^R-Neoplastine^R C1 Plus and phospholipid (cephalin), STA^R-C K PREST^R 5 respectively. Data were analyzed using descriptive statistics, Student t test, correlation coefficient and Bland-Altman plots. Mean PT, INR and APTT for both centrifugation methods was comparable with no statistically significant difference (p > 0.05). PT, INR and APTT also showed good correlation (r > 0.98) when compared between the two methods of centrifugation. Bland-Altman comparison between rapid and conventional methods of centrifugation for PT, INR and APTT also showed acceptable agreement. Rapid centrifugation technique for routine coagulation testing can be used safely with a significant reduction in the TAT. This can benefit patients in critical care settings and those on outpatient oral anticoagulant therapy.

What should be the laboratory approach against isolated prolongation of a activated partial thromboplastin time?

BACKGROUND

This study is a retrospective evaluation of patients who were subject to mixing study in our laboratory due to prolonged APTT. The preliminary diagnoses, clinical manifestations, and results of additional ordered tests were reviewed. The study aims to investigate whether repeating APTT test with a different assay prior to performing mixed study in patients with prolonged APTT would be a better alternative algorithmic approach in order to save both time and costs.

METHODS

We retrospectively evaluated 166 patients (65 females and 101 males) who were subject to mixing study due to isolated prolonged APTT. Additional ordered tests to identify the etiology and clinical findings were reviewed. All patients who had prolonged APTT as a result of testing with Hemosil Synthasil APTT reagent in ACL TOP analyzer were repeated with Stago Cephascreen APTT reagent in STA-R coagulation analyzer.

RESULTS

APTT test was requested preoperatively in 72.2% of cases. Only 6.6% of the cases had history of bleeding. Correction with mixing study was achieved in 122 (73.5%) cases, among which 75 (45%) cases were found to have APTT test results within reference range when tested with Cephascreen reagent. In 44 (26.5%) cases, mixing study did not result in correction. Only 4 cases were confirmed to have lupus anticoagulants (LA), while 4 cases were diagnosed with hemophilia with inhibitors.

CONCLUSION

Prolonged APTT results should always be retested using a different assay prior to mixing study. The clinician and the laboratory specialist should collaborate at the postanalytical phase.

An Evaluation of Hemostatic Abnormalities in Patients With Hemophilia According to the Activated Partial Thromboplastin Time Waveform

The usefulness of the waveform of activated partial thromboplastin time (APTT) in various diseases has been evaluated in recent years. The APTT waveform was examined in patients with hemophilia and patients positive for lupus anticoagulant (LA). The correlation with the FVIII activity was highest for the height of acceleration peak. The peak time of acceleration, velocity, and ½ fibrin formation, and the width of acceleration and velocity were significantly long and the height of acceleration was significantly low in patients with hemophilia. The height of velocity was significantly low in patients with hemophilia with inhibitor. There were no significant differences in the APTT waveform between patients with hemophilia and patients with LA, but the peak of acceleration and ½ fibrin formation were significantly longer and the height of acceleration and velocity were significantly lower in patients with hemophilia with inhibitor than in the patients with LA. Wave changes in the APTT were observed in all 22 patients positive for LA, while a biphasic waveform was observed in patients with hemophilia with FVIII activity <10.0%. The APTT waveform is useful for the analysis of hemostatic abnormalities in patients with hemophilia.

Therapeutic monitoring of unfractionated heparin - trials and tribulations

INTRODUCTION

Heparin is one of the oldest biological medicines with an established role in prevention and treatment of arterial and venous thromboembolism. Published therapeutic ranges for unfractionated heparin (UFH) mostly precede the large increase in the number of activated partial thromboplastin time (APTT) reagent/instrument combinations that now show wide variability. Areas covered: This paper explores the use of UFH, the development of heparin therapeutic ranges (HTRs), and the strengths and limitations of the methods used to monitor heparin's anticoagulant effect. Expert commentary: Despite longstanding use of UFH for management of thromboembolic conditions, the optimal test for monitoring UFH remains undetermined. Although used extensively for monitoring UFH, routine APTT-derived HTRs are based on limited science that may have little relevance to current laboratory practice. Anti-FXa levels may provide better and more reliable HTRs; however, even these levels show considerable inter-laboratory variation, and there are insufficient clinical studies proving improved clinical efficacy. Alternative tests for monitoring UFH reported over time have not been proven effective nor feasible, secondary to technical or cost issues, or lack of general adoption. Thus, despite limited evidence of clinical utility, an uncomfortable marriage of convenience represented by heparin laboratory monitoring is unlikely to be terminated in the immediate future.

An Evaluation of the Activated Partial Thromboplastin Time Waveform

The activated partial thromboplastin time (APTT) waveform includes several parameters that are related to various underlying diseases. The APTT waveform was examined in various diseases. Regarding the pattern of APTT waveform, a biphasic pattern of the first or second derivative curve (DC) was observed in patients with hemophilia and patients positive for antiphospholipid (aPL) antibodies or coagulation factor VIII (FVIII) inhibitors. The time of the first and second DC and fibrin formation at 1/2 height were prolonged in patients with hemophilia, patients with inhibitors, patients positive for aPL, patients treated with anti-Xa agents, and patients with disseminated intravascular coagulation (DIC). These values all tended to decrease in pregnant women (at 28-36 weeks' gestation). The height of the second derivative peak 1 was significantly lower in patients with hemophilia, patients with FVIII inhibitors, patients positive for aPL, patients treated with anti-Xa agents, and patients with DIC; these values tended to be significantly higher in pregnant women. The height of the first DC was significantly lower in patients who were positive for FVIII inhibitors and was significantly higher in patients treated with anti-Xa agents and pregnant women. The height of the first and second DC was useful for the analysis of hemophilia, FVIII inhibitor, and aPL.

Necessity of preoperative activated partial thromboplastin time test as a predictor for surgical hemorrhage in obstetric and gynecological patients in China

BACKGROUND

On an international scale, the necessity of preoperative coagulation screen remains controversial, yet in China, coagulation screen is still a routine test before surgery required by the Ministry of Health of China.

METHODS

A retrospective review of 26,807 patients >18y presenting with problems related to the areas of gynecology and obstetrics from March 2013 to July 2015 was performed, and the rate of major bleeding and the amount of blood lost during surgery were compared among groups of patients grouped according to the values of preoperative APTT, the departments the patients belonged to, or the measures for intervention.

RESULTS

Groups with increased APTT had higher rates of major bleeding (9.80% & 26.14% vs 2.77%, P<0.001) and more blood loss (862.9 and 1455.6ml vs 194.0ml, P<0.001). And the same conclusion could be induced in both the obstetric and gynecological patients when they were taken into account separately. For obstetric patients, once those with high bleeding risks, e.g., placental abruption, placental implantation, or preoperative massive hemorrhage were excluded, groups with increased APTT would no longer demonstrated the higher rate of major bleeding (0.91% & 2.38% vs 0%, P=0.409 & 0.833) and would even have a lower amount of blood loss (202.76 and 228.09ml vs 322.13ml, P=0.003 and 0.027). In increased APTT patients without bleeding or bleeding tendency, FFP intervention would not make a difference in the rate of major bleeding (7.69% vs 8.37%, P=0.203) and the amount of blood loss (271.35ml vs 306.63, P=0.865).

CONCLUSION

For Chinese patients from the Obstetrics and Gynecology Departments, APTT is a good screen test to predict surgical hemorrhage.

Anticoagulant Activity and Structural Characterization of Polysaccharide from Abalone (Haliotis discus hannai Ino) Gonad

In this study, we aimed at characterizing the structure and the anticoagulant activity of a polysaccharide fraction (AGP33) isolated from the gonads of Haliotis discus hannai Ino. AGP33 was extracted by enzymatic hydrolysis and purified by ion-exchange and gel-filtration chromatography. The backbone fraction of AGP33 (BAGP33), which appeared to contain of mannose, glucose and galactose, was prepared by partial acid hydrolysis. According to methylation and nuclear magnetic resonance (NMR) spectroscopy, the backbone of AGP33 was identified as mainly consisting of 1→3-linked, 1→4-linked, and 1→6-linked monosaccharides. AGP33 is a sulfated polysaccharide with sulfates occur at 3-O- and 4-O-positions. It prolonged thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) compared to a saline control solution in a dosage-dependent manner. AGP33 exhibited an extension (p < 0.01) of APTT compared to the saline group at concentrations higher than 5 μg/mL. AGP33 exhibited higher anticoagulant activity than its desulfated product (AGP33-des) and BAGP33. The results showed that polysaccharide with higher molecular weight and sulfate content demonstrated greater anticoagulant activity.

Elevated D-dimer and fibrinogen levels in serum of preoperative bone fracture patients

The changes of coagulation parameters in preoperative fracture patients reflect the coagulation status before surgery. We did retrospective assessment of preoperative fracture patients (n = 113) admitted to the hospital between September 2013 and September 2014. The control group were selected from healthy adults (n = 113) with matched age and gender. Platelet, PT INR, APTT, fibrinogen (FIB) and D-dimer values were collected and analyzed. PT INR level was 1.043 ± 0.119, APTT was 31.91 ± 7.56 s, FIB was 320.6 ± 71.8 mg/dl and D-dimer was 1283 ± 1582 ng/ml for the fracture patients. For the control group, PT INR level was 0.9976 ± 0.0602, APTT was 33.22 ± 2.55 s, FIB was 277.3 ± 44.7 mg/dl and D-dimer was 97.53 ± 63.90 ng/ml. Meanwhile, D-dimer levels of different sites of fractures were also measured: Femora 2448 ± 1961 ng/ml; Humerus 792.4 ± 691.2 ng/ml; Ulna/Radius 619.4 ± 843.7 ng/ml; Vertebra 647.7 ± 787.1 ng/ml; Tibia/Fibula 496.3 ± 268.8 ng/ml; Clavicle 260.9 ± 170.9 ng/ml; Ankle 415.4 ± 286.6 ng/ml. To conclude, D-dimer and fibrinogen levels get higher in preoperative fracture patients than controls. Besides, D-dimer levels are significantly different among different locations of fractures, and our data revealed that D-dimer levels of Femora fracture were higher than other sites.

Neutralisation of the anti-coagulant effects of heparin by histones in blood plasma and purified systems

Neutrophil extracellular traps (NETs) composed primarily of DNA and histones are a link between infection, inflammation and coagulation. NETs promote coagulation and approaches to destabilise NETs have been explored to reduce thrombosis and treat sepsis. Heparinoids bind histones and we report quantitative studies in plasma and purified systems to better understand physiological consequences. Unfractionated heparin (UFH) was investigated by activated partial thromboplastin time (APTT) and alongside low-molecular-weight heparins (LMWH) in purified systems with thrombin or factor Xa (FXa) and antithrombin (AT) to measure the sensitivity of UFH or LMWH to histones. A method was developed to assess the effectiveness of DNA and non-anticoagulant heparinoids as anti-histones. Histones effectively neutralised UFH, the IC50 value for neutralisation of 0.2 IU/ml UFH was 1.8 µg/ml histones in APTT and 4.6 µg/ml against 0.6 IU/ml UFH in a purified system. Histones also inhibited the activities of LMWHs with thrombin (IC50 6.1 and 11.0 µg/ml histones, for different LMWHs) or FXa (IC50 7.8 and 7.0 µg/ml histones). Direct interactions of UFH and LMWH with DNA and histones were explored by surface plasmon resonance, while rheology studies showed complex effects of histones, UFH and LMWH on clot resilience. A conclusion from these studies is that anticoagulation by UFH and LMWH will be compromised by high affinity binding to circulating histones even in the presence of DNA. A complete understanding of the effects of histones, DNA and heparins on the haemostatic system must include an appreciation of direct effects on fibrin and clot structure.

Lupus anticoagulants and anticardiolipin antibodies in Indian women with spontaneous, recurrent fetal loss

Spontaneous and recurrent pregnancy loss are common complications of pregnancy resulting from varied causes including antiphospholipid syndrome (APS). Treatment of women with APS increases the chance of a subsequent successful pregnancy. The study aimed to find the prevalence of lupus anticoagulants (LA) and anticardiolipin antibodies (ACAs) in women with spontaneous/recurrent fetal loss and compare with women with normal obstetric history. Hundred women with spontaneous/recurrent fetal loss and 50 healthy pregnant controls were tested for LA by complete blood counts, Prothrombin time, Activated partial thromboplastin time (APTT), LA sensitive APTT and dilute Russell viper venom time (dRVVT) (screening and confirmatory) and ACAs (ELISA). LA was detected in 15 % patients using dRVVT confirmatory test and ACA in 5 %, all controls being negative. Twenty one % patients were detected by LA sensitive APTT (sensitivity 92.9 %, specificity 100 %) and 100 % with dRVVT screening test (sensitivity 98.8 %, specificity 100 %). We recommend that screening for antiphospholipid antibodies must be done in women with spontaneous/recurrent foetal loss even in the absence of other clinical manifestations using a combination of tests.

Global assays and the management of oral anticoagulation

Coagulation tests range from global or overall tests to assays specific to individual clotting factors and their inhibitors. Whether a particular test is influenced by an oral anticoagulant depends on the principle of the test and the type of oral anticoagulant. Knowledge on coagulation tests applicable in monitoring status and reversal of oral anticoagulation is a prerequisite when studying potential reversal agents or when managing anticoagulation in a clinical setting. Specialty tests based on the measurement of residual activated factor X (Xa) or thrombin activity, e.g., are highly effective for determining the concentration of the new generation direct factor Xa- and thrombin inhibitors, but these tests are unsuitable for the assessment of anticoagulation reversal by non-specific prohemostatic agents like prothrombin complex concentrate (PCC) and recombinant factor VIIa (FVIIa). Global coagulation assays, in this respect, seem more appropriate. This review evaluates the current status on the applicability of the global coagulation assays PT, APTT, thrombin generation and thromboelastography in the management of oral anticoagulation by vitamin K antagonists and the direct factor Xa and thrombin inhibitors. Although all global tests are influenced by both types of anticoagulants, not all tests are useful for monitoring anticoagulation and reversal thereof. Many (pre)analytical conditions are of influence on the assay readout, including the oral anticoagulant itself, the concentration of assay reagents and the presence of other elements like platelets and blood cells. Assay standardization, therefore, remains an issue of importance.

Consequences for the APTT due to direct action of factor XIa on factor X, resulting in bypassing factors VIII-IX

BACK GROUND

It has recently been reported that factor XIa can activate factor X directly and can bypass factors VIII-IX. We evaluated the consequences for factor analysis with the one-stage APTT.

METHODS

APTT was performed with the Actin FS reagent with ellagic acid as the standard. Silica, high lipid (PTT-A) or low lipid (PTT-LA) were also tested. Factor depleted and deficient plasma's were obtained from commercial sources.

RESULTS

The APTT clotting times in factor XII, XI, High Molecular Weight Kininogen, factor X and factor V deficient plasma's were all significantly longer (>100s) than the clotting times of factor VIII- and IX-depleted or deficient plasma's (<100s). That the shorter times for factor VIII and IX deficient plasmas were due to contact activation was supported by biphasic inhibition of the clotting times with addition of Corn Trypsin Inhibitor and Trasylol. The role of factor XI and the by-passing of factor VIII/IX was shown by the use of quenching antibodies towards factor XI and VIII. Enriching factor VIII or IX depleted plasma with purified factor XI and addition of factor XIa showed a strong dependence on factor XI level. Calibration curves for factor analysis were steeper for factors FXII, HMWK, FX and FV, compared to those of both factors VIII and IX. Curves for VIII/IX were found steeper by the use of APTT-A/silica-based, 50% diluted substrate plasma and low factor XI in the substrate plasma.

CONCLUSIONS

In factors VIII and IX deficient plasmas, the APTT shows an activity which can be attributed to contact activation of factor X by factor XIa. This direct activity is lower with silica reagent compared to ellagic acid, dilution of plasma and low factor XI in substrate plasma.