Prolonged Bleeding Time In Patients Research Articles

Use of a Von Willebrand Factor/Coagulation Factor VIII Complex for Treatment of Refractory Inherited Platelet Disorders

Inherited platelet disorders are recognized as an important cause of mild to severe bleeding in both children and adults. Patients with platelet disorders may present with mucocutaneous bleeding, gastrointestinal bleeding, menorrhagia, postsurgical, and/or excessive bleeding from traumatic injury. Delta storage pool deficiencies (delta-SPD) are among the most frequent platelet disorders, characterized by dysfunctional dense platelet granules. Bernard Soulier syndrome (BSS) is an autosomal recessive platelet disorder caused by mutations in various polypeptides in the GpIb/IX/V complex, which is the principal receptor for von Willebrand factor (VWF). Treatment of platelet disorders is mainly supportive. Normal hemostasis requires VWF and factor VIII (FVIII) to support platelet adhesion and aggregation at sites of vascular injury. von Willebrand factor is a large multimeric glycoprotein present in human plasma as a series of polymers called multimers. Molecular weights for multimers ranges from 500 kDa for the dimer to over 10,000 kDa for the high molecular weight multimers (HMWM) forming the largest known protein present in human plasma. Each multimeric subunit of VWF has binding sites for the receptor GpIb on nonactivated platelets and the receptor GpIIb/IIIa to facilitate platelet adhesion and platelet aggregation, respectively, making the VWF HMWM important for normal platelet function. Desmopressin (DDAVP), which is known to stimulate the release of VWF and FVIII, is commonly used for treatment of platelet disorders. Potentiation of platelet aggregation at high shear rate may be one mechanism by which DDAVP shortens the prolonged bleeding time of patients with congenital platelet defects. For severe bleeding, platelet transfusion may be required, but patients may develop isoantibodies, rendering this therapy ineffective. For this reason, it may be prudent to reserve platelet transfusion in this patient population for emergent situations, such as trauma. Other patients and/or clinical situations may require recombinant active factor VII (rFVIIa), but this therapy is very costly and not always effective and/or available. Antifibrinolytics may also be used but are not always effective. In four (4) patients with platelet disorders (delta-SPD [n=3]; BSS [n=1]), common supportive therapies were not effective, tolerable, and/or available. It was postulated that off-label infusions of a cost-effective von Willebrand factor/coagulation factor VIII (VWF/FVIII) complex (Wilate, Octapharma SA) might be of benefit in these refractory patients (Table 1). The mechanism of action of DDAVP treatment efficacy relies on the release of existing, stored, functional VWF. In refractory patients with suboptimal VWF functionality, it was reasoned that infusion of exogenous, functional VWF and FVIII could potentially encourage platelet adhesion and aggregation. All refractory patients studied were treated successfully with the VWF/FVIII complex with positive clinical outcomes. As mentioned, the adhesive activity of VWF depends on the size of its multimers, and HMWM are the most effective in supporting interaction with collagen and platelet receptors and in facilitating wound healing under conditions of shear stress in the human vascular system. The VWF/FVIII complex utilized in these patients is known to have minimal amounts of the plasma metalloproteinase ADAMTS13. The HMWM of VWF are, under normal conditions, cleaved by ADAMTS13 to smaller, less adhesive multimers. During the manufacturing process, if the ADAMTS13 is not filtered out of the product almost entirely, the VWF in the vial may become highly proteolyzed. Therefore, a reduction or lack of HMWM resulting from inclusion of ADAMTS13 in the manufactured product is believed to reduce product functionality. Multimeric analysis of the VWF/FVIII complex has shown that it exhibits a physiological triplet structure which resembles normal plasma. In addition, the product has a high safety profile and tolerability as protein impurities are eliminated in the manufacturing process. In summary, the use of a VWF/FVIII complex in four (4) patients with inherited platelet disorders, who were refractory to conventional treatments, provided beneficial, cost-effective clinical outcomes with resolution of bleeding. Disclosures Federizo: Octapharma: Consultancy, Honoraria, Other: Publication support, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; American Thrombosis and Hemostasis Netowrk: Research Funding; Aptevo: Consultancy, Speakers Bureau; National Hemophilia Foundation: Consultancy, Honoraria. OffLabel Disclosure: von Willebrand/FVIII concentrate is currently approved for the treatment of Hemophilia A and von Willebrand. This abstract will review the off-label use of this medication in the treatment of inherited platelet dysfunction.

Infusion of DDAVP Does Not Improve Primary Hemostasis in Patients with Cirrhosis

Rationale: Cirrhosis frequently affects multiple components of hemostasis. Reversal of the coagulopathy of these patients is frequently required in case of bleeding episodes, or as prophylaxis before invasive procedures. A simple and cost-effective way to correct a prolonged bleeding time in patients with cirrhosis is administration of 1-deamino-8-D-arginine vasopressin (DDAVP). Although DD AVP is widely used as a pro-hemostatic agent in patients with cirrhosis, it is unclear whether DDAVP truly enhances the hemostatic potential in these patients. We investigated the hemostatic effects of a single bolus dose of DDAVP in patients with cirrhosis.Methods: Ten patients with cirrhosis (n=6 Child-Pugh score B, n=4 Child-Pugh score C) and ten patients with mild hemophilia A (FVIII 0.05-0.40 IU/ml) were included in this study. All patients received an intravenous single bolus of 0.3 microgram/kg DDAVP. Plasma was collected prior to and at 1, 3, 6, and 24 hours after DDAVP administration. Levels of Von Willebrand factor (VWF:Ag), VWF propeptide, Factor VIII (FVIII), and ADAMTS13 were measured in all plasma samples, whereas VWF multimers and functional VWF-dependent platelet adhesion were determined in the samples pre- and 1 hour after DDAVP administration. VWF-dependent platelet adhesion was studied under flow conditions in a reconstituted blood model.Results: The median age of patients with cirrhosis was 55 years (IQR 47-58) and 46 years (IQR 40-55) in patients with haemophilia. Baseline values of coagulation parameters are shown in table 1. Following DDAVP administration, VWF:Ag, FVIII levels and VWF propeptide increased in patients with hemophilia, while patients with cirrhosis only showed a modest increase in VWF propeptide and FVIII levels (figure 1). Only in those patients with low Child-Pugh scores, VWF:Ag slightly increased following DDAVP. The proportion of high molecular weight VWF multimers and VWF-dependent platelet adhesion increased in patients with hemophilia one hour after DDAVP administration, but did not change in the patients with cirrhosis. Levels of ADAMTS13 were unaffected in both patient groups after DDAVP.Conclusion: DDAVP administration in patients with cirrhosis did not have effect on VWF:Ag and ADAMTS13, but VWF propeptide and FVIII did increase. The lack of relevant hemostatic effects of DDAVP in patients with cirrhosis may be the explanation for the limited value in previous clinical studies in these patients.Table 1Baseline levels of VWF:Ag and related proteinsPatient groupHemophilia ACirrhosisp-valueVWF:Ag (IU/dl)114 (94.5-164.3)521 (238-643.8)<0.001ADAMTS13 (%)76.6 (57.3-87.9)93.9 (59.2-130.4)0.247VWF propeptide (IU/dl)108.5 (97.3-121.3)284 (236.5-392.8)<0.001FVIII (IU/dl)20 (12.3-38)152.5 (117.3-193.8)<0.001Data are presented as medians with IQR; VWF:Ag= Von Willebrand factor antigen; ADAMTS13= a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; FVIII= Factor VIII [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The effect of magnesium sulfate treatment on blood biochemistry and bleeding time in patients with severe preeclampsia

Objective. The objective of this study was to observe the effects of magnesium sulfate on various blood biochemical parameters and coagulation status of patients with preeclampsia.Methods. During a period of 4 years, 50 patients with severe or mild preeclampsia progressing to severe preeclampsia were included in the cross-sectional study. Prothrombine (PT), activated limited thromboplastin time (aPTT), magnesium level, biochemistry parameters, systolic, and diastolic blood pressure (BP) were measured. These parameters were remeasured in the second hour of magnesium sulfate treatment.Results. After magnesium sulfate therapy; creatinine levels are decreased (p < 0.05), bleeding time is increased and serum magnesium levels are increased (p < 0.01), systolic and diastolic BP values decreased significantly (p < 0.01). PT, aPTT, platelet levels, and coagulation time did not change after treatment.Conclusion. Magnesium sulfate infusion prolonged bleeding time in patients with severe preeclampsia. This is clinically important because it worsens the present condition and causes possible complications.

The effect of magnesium sulfate treatment on blood biochemistry and bleeding time in patients with severe preeclampsia

The objective of this study was to observe the effects of magnesium sulfate on various blood biochemical parameters and coagulation status of patients with preeclampsia. During a period of 4 years, 50 patients with severe or mild preeclampsia progressing to severe preeclampsia were included in the cross-sectional study. Prothrombine (PT), activated limited thromboplastin time (aPTT), magnesium level, biochemistry parameters, systolic, and diastolic blood pressure (BP) were measured. These parameters were remeasured in the second hour of magnesium sulfate treatment. After magnesium sulfate therapy; creatinine levels are decreased (p < 0.05), bleeding time is increased and serum magnesium levels are increased (p < 0.01), systolic and diastolic BP values decreased significantly (p < 0.01). PT, aPTT, platelet levels, and coagulation time did not change after treatment. Magnesium sulfate infusion prolonged bleeding time in patients with severe preeclampsia. This is clinically important because it worsens the present condition and causes possible complications.

Prolonged Bleeding Time in Patients with Lupus Anticoagulant

Platelet adhesion to collagen under flow conditions was studied in 18 patients with lupus anticoagulant, seven of which showed a prolonged bleeding time in the presence of a normal platelet count. The effect of patient plasma, IgG and purified anticardiolipin antibodies on platelet adhesion was also examined. We found a significant reduction of platelet adhesion in patients with lupus anticoagulant, which was more evident in patients with prolonged bleeding time. This platelet adhesion defect could be attributed to a plasma factor. In fact, patients' platelets regained normal adhesion when mixed with normal plasma, whereas controls' platelets showed abnormal adhesion in the presence of patient plasma. A causative role of antiphospholipid antibodies was demonstrated in experiments using purified immunoglobulins and anticardiolipin antibodies.

Oral estrogens decrease bleeding time and improve clinical bleeding in patients with renal failure

purpose: A prolonged bleeding time is associated with platelet dysfunction and clinical bleeding in patients with renal failure. Parenteral estrogens have been shown to shorten the prolonged bleeding time in patients with chronic renal failure, although the mechanism of action is unknown. We conducted a study to evaluate the efficacy of oral conjugated estrogens in this setting. patients and methods: Four patients with renal failure, prolonged bleeding time, and clinical bleeding were given 50 mg of conjugated estrogen (Premarin) daily. results: Bleeding time normalized in two cases and was reduced to less than 50% of the pretreatment value in one of the remaining two cases. Bleeding stopped in all patients within two days. Ten dialysis patients with prolonged bleeding time were randomized to a course of 50 mg of Premarin daily or placebo. The bleeding time in all five patients in the Premarin group normalized or decreased to below 50% of the pretreatment value after 7.0 ± 4.2 days of therapy. The bleeding time did not normalize in the five patients treated with placebo. No side effects attributable to therapy were reported. conclusion: We conclude that orally administered conjugated estrogens effectively improve the bleeding tendency in patients with chronic renal failure.

Effect of 1-desamino-8-D-arginine vasopressin (DDAVP) on human platelets

Intravenous infusion of 1-desamino-8-D-arginine vaso-pressin (DDAVP), an analog of arginine vasopressin (AVP), results in a rise in plasma levels of factor VIII coagulant activity and the von Willebrand factor. DDAVP infusion has been shown to shorten the prolonged bleeding time of patients with inherited platelet defects but the mechanism for this has not been fully clarified. There is little information available on the direct effect of DDAVP on platelets. We examined the effect of DDAVP on platelet responses, including Ca 2+ mobilization, to understand the mechanisms by which DDAVP shortens the bleeding time in patients with primary platelet defects. In normal human platelets, DDAVP alone upto 100 μM did not induce aggregation, secretion or a rise in the intracellular Ca 2+ concentration, monitored using quin2. In contrast AVP induced all three responses in a dose dependent manner. Interestingly, preincubation of platelets with DDAVP at a 100-fold greater concentration inhibited the responses to AVP indicating that DDAVP does interact with the platelets. Moreover, DDAVP did not either potentiate or inhibit the responses to thrombin or ADP. These studies indicate that it is unlikely that the beneficial effect of DDAVP in patients with primary platelet defects is related to a direct stimulatory effect on platelets.

Subcutaneous Desmopressin (DDAVP) Shortens the Prolonged Bleeding Time in Patients with Liver Cirrhosis

The intravenous infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) shortens the prolonged bleeding time in patients with congenital or acquired bleeding disorders, including patients with uremia or liver cirrhosis. We carried out a double-blind, placebo-controlled crossover study in ten patients with liver cirrhosis to evaluate whether or not their prolonged bleeding times could be shortened by subcutaneous injections of DDAVP (0.3 microgram/kg), a more practical route of administration than intravenous infusions. One hour after DDAVP injection the bleeding time was significantly shortened (p less than 0.05). After 4 h, however, the bleeding time shortening was no longer statistically significant. There was no bleeding time change after placebo. Plasma levels of von Willebrand factor antigen (vWF:Ag) did not significantly increase after DDAVP or placebo. The study shows that subcutaneous DDAVP is an alternative method for short-term shortening of the bleeding time in liver cirrhosis.

DDAVP shortens the prolonged bleeding times of patients with severe von Willebrand disease treated with cryoprecipitate. Evidence for a mechanism of action independent of released von Willebrand factor

After infusion of cryoprecipitate, the very prolonged bleeding time of patients with severe von Willebrand disease (vWD) is shortened but not always normalized in spite of normalization of plasma von Willebrand factor (vWF) levels. Therefore treatments that further improve primary hemostasis in severe vWD patients are needed. Since DDAVP shortens the bleeding time in a variety of bleeding disorders, we investigated in a double-blind, placebo-controlled crossover study the effects of the intravenous (IV) infusion of DDAVP (0.3 microgram/kg) on the bleeding times of 10 patients with severe vWD treated with cryoprecipitate. Their very prolonged bleeding times (greater than 30 minutes), partially corrected by the infusion of cryoprecipitate (14 +/- 2 minutes, mean +/- SEM), were further shortened by the administration of DDAVP (9 +/- 2 minutes, P less than .01) but not of saline (15 +/- 3 minutes, ns). Plasma vWF levels, raised from unmeasurable to normal values by cryoprecipitate, were not changed after DDAVP or saline. The defective deposition of platelets from eight patients onto human umbilical artery subendothelium was increased but not normalized by cryoprecipitate and was not significantly affected by DDAVP or saline. Therefore the infusion of DDAVP after cryoprecipitate may be of clinical benefit for management of bleeding episodes in severe vWD patients. Since severe vWD patients do not have releasable tissue stores of vWF, DDAVP must shorten their prolonged bleeding times independently of released vWF.

DDAVP Shortens the Prolonged Bleeding Times of Patients With Severe von Willebrand Disease Treated With Cryoprecipitate. Evidence for a Mechanism of Action Independent of Released von Willebrand Factor

After infusion of cryoprecipitate, the very prolonged bleeding time of patients with severe von Willebrand disease (vWD) is shortened but not always normalized in spite of normalization of plasma von Willebrand factor (vWF) levels. Therefore treatments that further improve primary hemostasis in severe vWD patients are needed. Since DDAVP shortens the bleeding time in a variety of bleeding disorders, we investigated in a double-blind, placebo-controlled crossover study the effects of the intravenous (IV) infusion of DDAVP (0.3 microgram/kg) on the bleeding times of 10 patients with severe vWD treated with cryoprecipitate. Their very prolonged bleeding times (greater than 30 minutes), partially corrected by the infusion of cryoprecipitate (14 +/- 2 minutes, mean +/- SEM), were further shortened by the administration of DDAVP (9 +/- 2 minutes, P less than .01) but not of saline (15 +/- 3 minutes, ns). Plasma vWF levels, raised from unmeasurable to normal values by cryoprecipitate, were not changed after DDAVP or saline. The defective deposition of platelets from eight patients onto human umbilical artery subendothelium was increased but not normalized by cryoprecipitate and was not significantly affected by DDAVP or saline. Therefore the infusion of DDAVP after cryoprecipitate may be of clinical benefit for management of bleeding episodes in severe vWD patients. Since severe vWD patients do not have releasable tissue stores of vWF, DDAVP must shorten their prolonged bleeding times independently of released vWF.

Ddavp-induced correction of prolonged bleeding time in patients with congenital platelet function defects

In 37 patients with prolonged bleeding time, where thrombocytopenia, von Willebrand's disease or deficiency of other coagulation factors could be excluded, we have evaluated the effect of a DDAVP-infusion (0.2 ug/kg) together with tranexamic acid (10 mg/kg). Patients with acquired impairment of primary hemostasis were not included, except two cases where this could have been a contributing factor: The bleeding time was completely normalized in 27 cases and partially corrected in three more patients . The predominant feature among those, who did not respond, was a pattern compatible with thrombasthenia or cyclooxygenase deficiency, as assessed by platelet aggregation studies. Among the patients, in whom DDAVP was effective, this drug was thereafter successfully used as an alternative to blood products in 8 cases during and after surgery or delivery.

Platelet aggregation in iron deficiency anemia.

In-vitro platelet aggregation with ADP, adrenaline and collagen was studied in pediatric patients with iron deficiency before and after iron therapy, and in normal controls. Hyporeactivity of platelets to all agonists was seen in the untreated patients. This returned to normal following correction of anemia by iron therapy. There was a significant correlation between hemoglobin or serum iron and transferrin saturation on the one hand, and parameters of platelet aggregation on the other (P<0.001). Results of zero order correlation coefficient however, showed that platelet reactivity was actually dependent on the hemoglobin levels rather than the iron parameters per se. This may explain the prolonged bleeding time in patients with iron deficiency, particularly those associated with thrombocytopenia. Anemic individuals may be protected against thrombotic disorders due to this reduced platelet reactivity.

Human blood platelet adhesion to artery subendothelium is mediated by factor VIII–Von Willebrand factor bound to the subendothelium

ONE of the early events in the haemostatic process is the adherence of blood platelets to collagen of the subendothelium. Subsequent platelet-to-platelet adhesion then leads to the formation of a haemostatic plug. The role of a plasma factor in this process was recognised after the discovery1,2 that the prolonged bleeding time of patients with Von Willebrand disease could be corrected by transfusion of plasma or cryoprecipitate. This plasma factor, then named Von Willebrand factor, was later identified as factor VIII (anti-haemophilic factor A (ref. 3)). The current concept is that Von Willebrand factor and factor VIII are present in a complex, which can be dissociated in certain conditions. Despite this progress, little is yet known about the role of the factor VIII-Von Willebrand factor complex (factor VIII–VWF) in the haemostatic plug formation. Tschoppet al. showed that the Von Willebrand factor was required for normal adhesion of platelets to rabbit subendothelium in a perfusion chamber using blood from patients with Von Willebrand disease4. The role of factor VIII–VWF in platelet adhesion is also important for the development of atherosclerosis. In this process, adherence of platelets is followed by degranulation and concomitant secretion of factors causing intimai migration and proliferation of smooth muscle cells5,6. Defective adherence of platelets was shown to protect against experimental atherosclerosis7,8. We present here evidence that factor VIII–VWF binds to subendothelium of human arteries and that subendothelium-bound factor VIII–VWF mediates the platelet adhesion.