Cellular mechanisms of the hemostatic effects of desmopressin (DDAVP)

The use of DDAVP in children with bleeding disorders

Desmopressin (1-deamino-8-D-arginine vasopressin, DDAVP) has been used in children with von Willebrand disease (VWD) and Hemophilia A for almost 35 years. This treatment has substantially lowered the number of children exposed to human plasma derived products, with a good safety profile, and at very low cost. The response to DDAVP has been shown to be associated with age, baseline factor level, and genetic mutations. A DDAVP challenge test is recommended. DDAVP has also been used to prevent and treat bleeding episodes in children with platelet function defects and other disorders associated with bleeding tendency.

Phase II prospective open-label trial of recombinant interleukin-11 in desmopressin-unresponsive von Willebrand disease and mild or moderate haemophilia A

Desmopressin (DDAVP) is the treatment of choice in those with mild von Willebrand disease (VWD), yet 20% are unresponsive to DDAVP, and among the 80% who respond, the response is transient, as endothelial stores are depleted after three days. We, therefore, conducted a single-center Phase II clinical trial to determine safety and biologic efficacy of recombinant interleukin-11 (rhIL-11, Neumega®) in patients with VWD unresponsive or allergic to DDAVP, or mild or moderate haemophilia A (HA). Increases in VWF:RCo wer e observed by 48 hours after rhIL-11, with a 1.54-fold increase by Day 4, 1.30-fold in VWD and 1.73-fold in HA. Similarly, by 48 hours, increases in VIII:C were observed, with a 1.65-fold increase by Day 4, 1.86-fold in VWD and 1.48-fold in HA. Platelet VWFmRNA expression by qPCR increased 0.81-fold but did not correlate with plasma VWF:Ag responses. rhIL-11 was well tolerated, with grade 1 or less fluid retention, flushing, conjunctival erythema, except for transient grade 3 hyponatraemia in one subject after excess fluid intake for diabetic hyperglycaemia, which resolved with fluid restriction. In summary, rhIL-11 increases VWF levels in two of four DDAVP-unresponsive or allergic VWD and F.VIII levels in four of five mild or moderate haemophilia A subjects, suggesting its potential use in treatment of these disorders.

Current status of pharmacologic therapies in patient blood management

Patient blood management(1,2) incorporates patient-centered, evidence-based medical and surgical approaches to improve patient outcomes by relying on the patient's own (autologous) blood rather than allogeneic blood. Particular attention is paid to preemptive measures such as anemia management. The emphasis on the approaches being "patient-centered" is to distinguish them from previous approaches in transfusion medicine, which have been "product-centered" and focused on blood risks, costs, and inventory concerns rather than on patient outcomes. Patient blood management(3) structures its goals by avoiding blood transfusion(4) with effective use of alternatives to allogeneic blood transfusion.(5) These alternatives include autologous blood procurement, preoperative autologous blood donation, acute normovolemic hemodilution, and intra/postoperative red blood cell (RBC) salvage and reinfusion. Reviewed here are the available pharmacologic tools for anemia and blood management: erythropoiesis-stimulating agents (ESAs), iron therapy, hemostatic agents, and potentially, artificial oxygen carriers.

Von Willebrand disease: an overview

Most commonly inherited bleeding disorder, first described in Aland Islands by Erik von Willebrand. It occurs as a result of decrease in plasma levels or defect in von Willebrand factor which is a large multimeric glycoprotein. Monomers of this glycoprotein undergo N-glycosylation to form dimers which get arranged to give multimers. Binding with plasma proteins (especially factor VIII) is the main function of von Willebrand factor. The disease is of two forms: Inherited and acquired forms. Inherited forms are of three major types. They are type 1, type 2, and type 3; in which type 2 is sub-divided into 2A, 2B, 2M, 2N. Type 1 is more prevalent than all other types. Mucocutaneous bleeding is mild in type 1 whereas it is mild to moderate in types 2A, 2B, and 2M. Type 2N has similar symptoms of haemophilia. The pathophysiology of each type depends on the qualitative or quantitative defects in von Willebrand factor. The diagnosis is based on von Willebrand factor antigen, von Willebrand factor activity assay, FVIII coagulant activity and some other additional tests. Results should be analyzed within the context of blood group. von Willebrand factor multimer analysis is essential for typing and sub typing the disease. The management of the disease involves replacement therapy, non-replacement therapy and other therapies that include antifibrinolytics and topical agents.

Antiplatelet therapy in the management of cardiovascular disease in patients with CKD: what is the evidence?

Antiplatelet agents (APAs) are proven to reduce risk of major cardiovascular events in patients with cardiovascular disease and normal kidney function. With recent post hoc analyses of large trials questioning the safety and efficacy of APAs in CKD, major gaps exist in our understanding of platelet aggregability and the effects of APAs on thrombosis and bleeding in CKD. Clinical practice guidelines are ambiguous about use of such agents in CKD patients, because patients with moderate to advanced CKD were systematically excluded from clinical trials of APAs. CKD patients experience excessive rates of cardiovascular thrombotic events, yet paradoxically are at higher risk for major bleeding while receiving APAs. Furthermore, observational studies suggest that CKD patients may exhibit poor response to APAs. High residual platelet aggregability, as determined by inhibition of platelet aggregation, is associated with increased risk for cardiovascular events. In addition, metabolism of certain APAs may be altered in CKD patients. It is, therefore, imperative to explore the mechanisms responsible for poor response to APAs in CKD patients in order to use these drugs more safely and effectively. This review identifies the knowledge gaps and future trials needed to address those issues with the use of APAs in CKD patients.

Selective V(1a) agonism attenuates vascular dysfunction and fluid accumulation in ovine severe sepsis

Vasopressin analogs are used as a supplement to norepinephrine in septic shock. The isolated effects of vasopressin agonists on sepsis-induced vascular dysfunction, however, remain controversial. Because V(2)-receptor stimulation induces vasodilation and procoagulant effects, a higher V(1a)- versus V(2)-receptor selectivity might be advantageous. We therefore hypothesized that a sole, titrated infusion of the selective V(1a)-agonist Phe(2)-Orn(8)-Vasotocin (POV) is more effective than the mixed V(1a)-/V(2)-agonist AVP for the treatment of vascular and cardiopulmonary dysfunction in methicillin resistant staphylococcus aureus pneumonia-induced, ovine sepsis. After the onset of hemodynamic instability, awake, chronically instrumented, mechanically ventilated, and fluid resuscitated sheep were randomly assigned to receive continuous infusions of either POV, AVP, or saline solution (control; each n = 6). AVP and POV were titrated to maintain mean arterial pressure above baseline - 10 mmHg. When compared with that of control animals, AVP and POV reduced neutrophil migration (myeloperoxidase activity, alveolar neutrophils) and plasma levels of nitric oxide, resulting in higher mean arterial pressures and a reduced vascular leakage (net fluid balance, chest and abdominal fluid, pulmonary bloodless wet-to-dry-weight ratio, alveolar and septal edema). Notably, POV stabilized hemodynamics at lower doses than AVP. In addition, POV, but not AVP, reduced myocardial and pulmonary tissue concentrations of 3-nitrotyrosine, VEGF, and angiopoietin-2, thereby leading to an abolishment of cumulative fluid accumulation (POV, 9 ± 15 ml/kg vs. AVP, 110 ± 13 ml/kg vs. control, 213 ± 16 ml/kg; P < 0.001 each) and an attenuated cardiopulmonary dysfunction (left ventricular stroke work index, PaO(2)-to-FiO(2) ratio) versus control animals. Highly selective V(1a)-agonism appears to be superior to unselective vasopressin analogs for the treatment of sepsis-induced vascular dysfunction.

Metastasis: recent discoveries and novel perioperative treatment strategies with particular interest in the hemostatic compound desmopressin

Metastatic disease is responsible for most of cancer lethality. A main obstacle for therapy of advanced cancers is that the outcome of metastasis depends on a complex interplay between malignant and host cells. The perioperative period represents an underutilized window of opportunity for cancer treatment where tumor-host interactions can be modulated, reducing the risk of local recurrences and distant metastases. Blood-saving agents are attractive compounds to be administered during tumor surgery. Desmopressin (DDAVP) is a safe and convenient hemostatic peptide with proved antimetastastic properties in experimental models and veterinary clinical trials. The compound seems to induce a dual angiostatic and antimetastatic effect, breaking the cooperative function of cancer cells and endothelial cells during residual tumor progression. DDAVP is therefore an interesting lead compound to develop novel synthetic peptide analogs with enhanced antitumor properties.

Anaphylaxis on reperfusion during liver transplantation with coagulopathy

We present a case in which anaphylaxis on hepatic reperfusion during liver transplantation presented only with hypotension and coagulopathy. There were no cutaneous manifestations or clinical features distinguishing anaphylaxis from postreperfusion syndrome. The recipient regularly consumed seafood, and the organ donor died of anaphylaxis to shellfish. The trigger for anaphylaxis was postulated to be passive transfer of immunoglobulin to the recipient. Anesthesiologists should be notified of donor factors to anticipate anaphylaxis. In this report, we discuss coagulopathy of anaphylaxis and contrast it with disseminated intravascular coagulation.

Unlike arginine vasopressin, the selective V1a receptor agonist FE 202158 does not cause procoagulant effects by releasing von Willebrand factor

OBJECTIVE

To compare the effects on von Willebrand factor release of the mixed vasopressin type 1a and type 2 receptor agonist arginine vasopressin and the selective vasopressin type 1a receptor agonist FE 202158, [Phe2,Ile3,Hgn4,Orn(iPr)8]vasopressin, at doses required for the treatment of septic shock.

DESIGN

Prospective, randomized, controlled laboratory experiment.

SETTING

University animal research facility.

SUBJECTS

Twenty-four chronically instrumented sheep.

INTERVENTIONS

After a 5-day recovery from instrumentation, sheep were randomly assigned to receive a single intravenous bolus of the selective vasopressin type 2 receptor agonist desmopressin (1 nmol·kg(-1)) or continuous intravenous infusions of arginine vasopressin (3 pmol·kg(-1)·min(-1)), the selective vasopressin type 1a receptor agonist FE 202158 (10 pmol·kg(-1)·min(-1)), or vehicle (0.9% NaCl) (n = 6 each).

MEASUREMENTS AND MAIN RESULTS

The von Willebrand factor antigen activity relative to hemoglobin concentration (vWF:Ag/Hb ratio) was measured at different time points during the 120-min study period. Maximal vWF:Ag/Hb ratio expressed as percentage of baseline level was significantly increased compared to vehicle-infused animals (3 ± 2%) in the desmopressin (40 ± 6%, p < .001) and arginine vasopressin groups (25 ± 4%, p < .001). The ratio for the FE 202158 group was not statistically different from the sham group (9 ± 2%, p = .208). Notably, maximal vWF:Ag/Hb ratio was lower in the FE 202158 than the arginine vasopressin group (p < .005).

CONCLUSIONS

Unlike the mixed vasopressin type 1a receptor/vasopressin type 2 receptor agonist arginine vasopressin, the selective vasopressin type 1a receptor agonist FE 202158 does not release von Willebrand factor. Because von Willebrand factor is involved in coagulatory and inflammatory pathways during septic shock, future studies should clarify the role of the vasopressin type 2 receptor-mediated von Willebrand factor increase by arginine vasopressin and the potential benefit of selective vasopressin type 1a receptor-agonists like FE 202158.

Antiproliferative effect of 1-deamino-8-D-arginine vasopressin analogs on human breast cancer cells

BACKGROUND

Desmopressin (dDAVP), a synthetic nonapeptide derivative of arginine vasopressin, is a safe antidiuretic and hemostatic compound that acts as a selective agonist for the vasopressin V2 membrane receptor (V2R). It is known that dDAVP can inhibit progression of residual metastatic cells in preclinical models. Among other mechanisms, the compound induces an agonist effect on V2R present in tumor cells.

RESULTS/DISCUSSION

Looking for novel analogs with improved anti-tumor activity, positions 4 and 5, at the conformational peptide loop, were substituted. The analog [V(4)Q(5)]dDAVP ([4-valine 5-glutamine] desmopressin) exhibited a significantly higher antiproliferative effect than dDAVP in cultures of MCF-7, a V2R-expressing human breast carcinoma cell line. The chiral isomer of this analog and tetrapeptide fragments corresponding to the loop region were also assessed.

CONCLUSION

Preclinical evaluation of the anti-tumor activity of [V(4)Q(5)]dDAVP in animal models is warranted.

Management of children with inherited mild bleeding disorders undergoing adenotonsillar procedures

OBJECTIVE

To evaluate the incidence of perioperative bleeding among children with mild bleeding disorders who underwent adenotonsillar surgery in our hospital and were treated with our perioperative bleeding prophylaxis protocol.

METHODS

Retrospective chart review was aimed at determining the perioperative bleeding rate in children with mild bleeding disorders subjected to our prophylactic protocol while undergoing adenotonsillar procedures. Low von Willebrand factor (LVWF), unspecific platelet function disorders (UPFD) and mild factor VII deficiency were considered as mild bleeding disorders. The protocol utilizes intravenous desmopressin, tranexamic acid, NSAID avoidance, and overnight observation.

RESULTS

Between 2004 and 2009, 44 children with mild bleeding disorders underwent adenotonsillar procedures in our hospital and were treated with the protocol. One patient (LVWF+UPFD) developed perioperative bleeding (2.3%).

CONCLUSIONS

It is possible to obtain low rates of perioperative bleeding in children with mild bleeding disorders undergoing adenotonsillar procedures, provided there is a well-timed diagnosis and an adequate prophylaxis protocol. We believe that further efforts must be directed at preoperative diagnosis of mild bleeding disorders to ensure safer surgeries.

The bleeding child. Part I: primary hemostatic disorders

Mucocutaneous bleeding is common in childhood and may be the result of primary hemostatic disorders such as vascular abnormalities, von Willebrand disease, thrombocytopenia, and platelet dysfunction. A detailed bleeding history and physical examination are essential to distinguish between normal and abnormal bleeding and to decide whether it is necessary to perform further laboratory evaluation. Initial laboratory tests include complete blood count, peripheral blood smear, mean platelet volume, von Willebrand factor (VWF) antigen assay, VWF ristocetin cofactor activity, and factor VIII activity. Once thrombocytopenia and von Willebrand disease have been excluded, platelet function should be tested by platelet aggregation. Additional specific diagnostic tests, such as platelet secretion tests and flow cytometry for the detection of platelet surface glycoprotein expression, are needed to confirm the raised hypothesis.

New, potent, selective, and short-acting peptidic V1a receptor agonists

[Arg(8)]vasopressin (AVP) produces vasoconstriction via V(1a) receptor (V(1a)R)-mediated vascular smooth muscle cell contraction and is being used to increase blood pressure in septic shock, a form of vasodilatory hypotension. However, AVP also induces V(2) receptor (V(2)R)-mediated antidiuresis, vasodilation, and coagulation factor release, all deleterious in septic shock. The V(1a)R agonist terlipressin (H-Gly(3)[Lys(8)]VP) also lacks selectivity vs the V(2)R and has sizably longer duration of action than AVP, preventing rapid titration of its vasopressor effect in the clinic. We designed and synthesized new short acting V(1a)R selective analogues of general structure [Xaa(2),Ile(3),Yaa(4),Zaa(8)]VP. The most potent and selective compounds in in vitro functional assays (e.g., [Phe(2),Ile(3),Asn(Me(2))(4),Orn(8)]VP (31), [Phe(2),Ile(3),Asn((CH(2))(3)OH)(4),Orn(8)]VP (34), [Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]VP (45), [Phe(2),Ile(3),Asn(Et)(4),Dab(8)]VP (49), [Thi(2),Ile(3),Orn(iPr)(8)]VP (59), [Cha(2),Ile(3),Asn(4),Orn(iPr)(8)]VP (68)) were tested by intravenous bolus in rats for duration of vasopressive action. Analogues 31, 34, 45, and 49 were as short-acting as AVP. Compound 45, FE 202158, is currently undergoing clinical trials in septic shock.

Canine mammary tumours, an overview

Canine mammary tumours (CMTs) are the most common neoplasms in intact female dogs. Although the prevalence of these tumours decreases in regions where preventive ovari(ohyster)ectomy is performed, it remains an important disease entity in veterinary medicine. Moreover, treatment options are limited in comparison with human breast cancer. Nevertheless, recent human treatment protocols might have potential in bitches suffering from CMTs.

Pharmacological characterization of FE 202158, a novel, potent, selective, and short-acting peptidic vasopressin V1a receptor full agonist for the treatment of vasodilatory hypotension

FE 202158, ([Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]vasopressin, where Hgn is homoglutamine and iPr is isopropyl), a peptidic analog of the vasoconstrictor hormone [Arg(8)]vasopressin (AVP), was designed to be a potent, selective, and short-acting vasopressin type 1a receptor (V(1a)R) agonist. In functional reporter gene assays, FE 202158 was a potent and selective human V(1a)R agonist [EC(50) = 2.4 nM; selectivity ratio of 1:142:1107:440 versus human vasopressin type 1b receptor, vasopressin type 2 receptor (V(2)R), and oxytocin receptor, respectively] contrasting with AVP's lack of selectivity, especially versus the V(2)R (selectivity ratio of 1:18:0.2:92; human V(1a)R EC(50) = 0.24 nM). This activity and selectivity profile was confirmed in radioligand binding assays. FE 202158 was a potent vasoconstrictor in the isolated rat common iliac artery ex vivo (EC(50) = 3.6 nM versus 0.8 nM for AVP) and reduced rat ear skin blood flow after intravenous infusion in vivo (ED(50) = 4.0 versus 3.4 pmol/kg/min for AVP). The duration of its vasopressor effect by intravenous bolus in rats was as short as AVP at submaximally effective doses. FE 202158 had no V(2)R-mediated antidiuretic activity in rats by intravenous infusion at its ED(50) for reduction of ear skin blood flow, in contrast with the pronounced antidiuretic effect of AVP. Thus, FE 202158 seems suitable for treatment of conditions where V(1a)R activity is desirable but V(2)R activity is potentially deleterious, such as vasodilatory hypotension in septic shock. In addition to the desirable selectivity profile, its short-acting nature should allow dose titration with rapid onset and offset of action to optimize vasoconstriction efficacy and safety.

Vasopressin: Its current role in anesthetic practice

Vasopressin or antidiuretic hormone is a potent endogenous hormone, which is responsible for regulating plasma osmolality and volume. In high concentrations, it also raises blood pressure by inducing moderate vasoconstriction. It acts as a neurotransmitter in the brain to control circadian rhythm, thermoregulation and adrenocorticotropic hormone release. The therapeutic use of vasopressin has become increasingly important in the critical care environment in the management of cranial diabetes insipidus, bleeding abnormalities, esophageal variceal hemorrhage, asystolic cardiac arrest and septic shock. After 10 years of ongoing research, vasopressin has grown to a potential component as a vasopressor agent of the anesthesiologist's armamentarium in the treatment of cardiac arrest and severe shock states.

Von Willebrand factor and fibrinolytic parameters during the desmopressin test in patients with Cushing's disease

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Desmopressin is a known haemostatic agent and is also being used, albeit at lower doses, during the diagnostic work-up of Cushing's syndrome, a condition characterized by excess cortisol concentrations and frequent thromboembolic events. No study has yet evaluated whether administration of desmopressin for diagnostic purposes induces significant, adverse changes in endothelial cell markers in these patients.

WHAT THIS STUDY ADDS

Administration of desmopressin to patients with Cushing's disease induces changes in endothelial cell markers comparable with those observed in obese and normal weight subjects. It follows, that desmopressin testing does not induce disease-specific untoward changes in coagulatory markers in patients with endogenous hypercortisolism and its use in this context appears safe.

AIMS

Desmopressin, a vasopressin analogue, is used for various clinical purposes, including haemostasis and, in recent times, the diagnostic work-up of patients with Cushing's syndrome, a condition associated with a known prothrombotic profile. We decided to evaluate whether and to what extent a diagnostic dose of desmopressin induces significant changes in endothelial parameters in patients with Cushing's disease (CD) and obese and normal weight controls.

METHODS

Twelve patients with CD, 10 obese and five normal weight controls were studied. Von Willebrand antigen (VWF:Ag), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) were measured at baseline and up to 4 h after 10 µg desmopressin i.v.

RESULTS

Desmopressin 10 µg transiently increased VWF:Ag and t-PA and decreased PAI-1 in all subjects. The magnitude of the VWF:Ag and t-PA increases after desmopressin was comparable in the three groups (VWF:Ag peak-to-basal ratio 1.9 ± 0.17, 1.5 ± 0.11 and 1.8 ± 0.13 and t-PA peak-to-basal ratio 1.6 ± 0.18, 1.6 ± 0.20 and 1.8 ± 0.24 for CD, obese and controls, respectively, all NS). The PAI-1 decrease observed in patients with CD was comparable with obese (0.7 ± 0.07 and 0.6 ± 0.09, NS) and controls (0.7 ± 0.07 vs. 0.4 ± 0.09, P= 0.08).

CONCLUSIONS

Administration of desmopressin to patients with CD for diagnostic purposes induces a transitory increase in VWF:Ag counterbalanced by a decrease in PAI-1 and increase in t-PA. The magnitude of these changes is largely comparable with that observed in obese and normal weight controls. Our data show that testing with desmopressin does not induce disease-specific changes in endothelial markers in patients with CD.

Effect of adjuvant perioperative desmopressin in locally advanced canine mammary carcinoma and its relation to histologic grade

Desmopressin (DDAVP) is a vasopressin peptide analog with hemostatic properties that has been successfully used during surgery in patients with bleeding disorders. Recently published experimental and clinical data indicate that perioperative administration of DDAVP can minimize spread and survival of residual mammary cancer cells. The central aim of this study was to explore the effect of perioperative DDAVP and its relation to histologic grade in bitches with locally advanced mammary carcinoma. Of the 32 dogs initially recruited, 28 intact bitches with mammary carcinoma tumors stage III or IV were ultimately included. These dogs were randomized to receive DDAVP at intravenous doses of 1 μg/kg (n=18) or saline solution as placebo (n=10). En bloc mastectomy of the affected gland(s) was performed. Tumor malignancy was graded by the method of Elston and Ellis into well-differentiated (grade 1), moderately differentiated (grade 2), or poorly differentiated (grade 3). DDAVP therapy significantly prolonged the disease-free survival (P<0.001) and overall survival (P<0.01) in bitches with grade 2 or 3 carcinomas compared with bitches in the control group. No significant difference in disease-free period or overall survival was found between treatment groups in bitches with grade 1 tumors. The present data suggest that DDAVP may be an excellent candidate as a surgical adjuvant in the management of aggressive cancers in small animals. More research in this field is warranted.

Overview of bleeding disorders in adolescent females with menorrhagia

Women bleed with menses, during childbirth, and after childbirth. Women are more likely to manifest a bleeding disorder as they have more opportunities to experience bleeding challenges in their lifetime. Bleeding disorders such as hemophilia and von Willebrand disease affect 2.5-3 million American women. The most common inherited bleeding disorder in the population is von Willebrand disease with an estimated prevalence of 1-2%. von Willebrand factor (vWF) is required to adhere platelets to exposed subendothelium and protects factor VIII from proteolysis in the circulation. The prevalence of vWF rises in studies involving women with menorrhagia, with estimates ranging as high as 10-20% in white women, and 1-2% among African American women. Other bleeding disorders seen in adolescents with menorrhagia are disorders of inherited platelet dysfunction, clotting factor deficiencies, thrombocytopenia, and disorders of the fibrinolytic pathway. Not only are women more likely to present early in their life with a bleeding disorder, they are also more likely to have other gynecologic manifestations as a result of these disorders. This article presents an overview of the problem and touches upon the different management strategies available.

Role of selective V2-receptor-antagonism in septic shock: a randomized, controlled, experimental study

Introduction

V₂-receptor (V₂R) stimulation potentially aggravates sepsis-induced vasodilation, fluid accumulation and microvascular thrombosis. Therefore, the present study was performed to determine the effects of a first-line therapy with the selective V₂R-antagonist (Propionyl₁-D-Tyr(Et)₂-Val₄-Abu₆-Arg_8,9)-Vasopressin on cardiopulmonary hemodynamics and organ function vs. the mixed V_1aR/V₂R-agonist arginine vasopressin (AVP) or placebo in an established ovine model of septic shock.

Methods

After the onset of septic shock, chronically instrumented sheep were randomly assigned to receive first-line treatment with the selective V₂R-antagonist (1 μg/kg per hour), AVP (0.05 μg/kg per hour), or normal saline (placebo, each n = 7). In all groups, open-label norepinephrine was additionally titrated up to 1 μg/kg per minute to maintain mean arterial pressure at 70 ± 5 mmHg, if necessary.

Results

Compared to AVP- and placebo-treated animals, the selective V₂R-antagonist stabilized cardiopulmonary hemodynamics (mean arterial and pulmonary artery pressure, cardiac index) as effectively and increased intravascular volume as suggested by higher cardiac filling pressures. Furthermore, left ventricular stroke work index was higher in the V₂R-antagonist group than in the AVP group. Notably, metabolic (pH, base excess, lactate concentrations), liver (transaminases, bilirubin) and renal (creatinine and blood urea nitrogen plasma levels, urinary output, creatinine clearance) dysfunctions were attenuated by the V₂R-antagonist when compared with AVP and placebo. The onset of septic shock was associated with an increase in AVP plasma levels as compared to baseline in all groups. Whereas AVP plasma levels remained constant in the placebo group, infusion of AVP increased AVP plasma levels up to 149 ± 21 pg/mL. Notably, treatment with the selective V₂R-antagonist led to a significant decrease of AVP plasma levels as compared to shock time (P < 0.001) and to both other groups (P < 0.05 vs. placebo; P < 0.001 vs. AVP). Immunohistochemical analyses of lung tissue revealed higher hemeoxygenase-1 (vs. placebo) and lower 3-nitrotyrosine concentrations (vs. AVP) in the V₂R-antagonist group. In addition, the selective V₂R-antagonist slightly prolonged survival (14 ± 1 hour) when compared to AVP (11 ± 1 hour, P = 0.007) and placebo (11 ± 1 hour, P = 0.025).

Conclusions

Selective V₂R-antagonism may represent an innovative therapeutic approach to attenuate multiple organ dysfunction in early septic shock.

Hemostatic and hemorrhagic problems in neurosurgical patients

BACKGROUND

Abnormalities of the hemostasis can lead to hemorrhage, and on the other hand to thrombosis. Intracranial neoplasms, complex surgical procedures, and head injury have a specific impact on coagulation and fibrinolysis. Moreover, the number of neurosurgical patients on medication (which interferes with platelet function and/or the coagulation systems) has increased over the past years.

METHOD

The objective of this review is to recall common hemostatic disorders in neurosurgical patients on the basis of the "new concept of hemostasis". Therefore the pertinent literature was searched to provide a structured and up to date manuscript about hemostasis in Neurosurgery.

FINDINGS

According to recent scientific publications abnormalities of the coagulation system are discussed. Pathophysiological background and the rational for specific (cost)-effective perioperative hemostatic therapy is provided.

CONCLUSIONS

Perturbations of hemostasis can be multifactorial and maybe encountered in the daily practice of neurosurgery. Early diagnosis and specific treatment is the prerequisite for successful treatment and good patients outcome.

von Willebrand factor to the rescue

von Willebrand factor (VWF) is a large multimeric adhesive glycoprotein with complex roles in thrombosis and hemostasis. Abnormalities in VWF give rise to a variety of bleeding complications, known as von Willebrand disease (VWD), the most common inherited bleeding disorder in humans. Current treatment of VWD is based on the replacement of the deficient or dysfunctional protein either by endogenous release from endothelial Weibel-Palade bodies or by administration of plasma-derived VWF concentrates. During the last years, several efforts have been made to optimize existing therapies for VWD, but also to devise new approaches, such as inducing endogenous expression with interleukin-11, administering exogenous recombinant VWF, or introducing the protein via gene delivery. Clearly, the efficacy of any strategy will depend on several factors, including, for example, the quantity, activity, and stability of the delivered VWF. The inherent complexity of VWF biosynthesis, which involves extensive posttranslational processing, may be limiting in terms of producing active VWF outside of its native cellular sources. This review summarizes recent progress in the development of different treatment strategies for VWD, including those that are established and those that are at the experimental stage. Potential pitfalls and benefits of each strategy are discussed.

Management of prehospital antiplatelet and anticoagulant therapy in traumatic head injury: a review

Trauma and emergency department clinicians encounter a growing number of patients admitted with traumatic head injury on prehospital antithrombotic therapies. These patients appear to be at increased risk of developing life-threatening intracranial hemorrhage. It is imperative that trauma clinicians understand the mechanism and duration of commonly prescribed outpatient antithrombotics in order to appropriately assess and treat patients who develop intracranial hemorrhage. This review summarizes current literature on the morbidity and mortality associated with premorbid non-steroidal anti-inflammatory drugs, aspirin, clopidogrel, warfarin, and heparinoids in the setting of traumatic head injury, and also examines the current strategies for reversal of these therapies.

Effect of desmopressin on erythrocyte aggregation

Experiments on rats showed that desmopressin in doses recommended for single injections to humans increased erythrocyte aggregation. A close correlation between erythrocyte aggregation index and blood viscosity, on the one hand, and plasma content of acid glycosaminoglycans on the other was detected.

Cushing's disease complicated with thrombosis in a dog

Thrombosis is a potential complication of hyperadrenocorticism (HAC) in dogs. An 8-year-old male Beagle diagnosed with pituitary-dependent HAC had complicated with thrombosis in the caudal vena cava and abdominal aorta, which was treated by hypophysectomy and antithrombotic therapy. After hypophysectomy, hypercortisolemia disappeared and the general condition was also significantly improved. Ultrasonography after hypophysectomy revealed that the thrombus remained in the abdominal aorta, but the thrombus in the caudal vena cava had disappeared. However 692 days after the hypophysectomy, the dog had an acute onset of dyspnea and died. Postmortem examination revealed the presence of thrombi in the abdominal aorta and the pulmonary artery. Observations from this case show that HAC dogs must be attention to thrombosis.

A phase II prospective open-label escalating dose trial of recombinant interleukin-11 in mild von Willebrand disease

von Willebrand factor (VWF) is a multimeric glycoprotein that mediates platelet adhesion and is decreased in von Willebrand disease (VWD). 1-8 deamino-d-arginine vasopressin (DDAVP), the most common treatment for VWD, is limited by tachyphylaxis and inconvenience, and in 20% of the patients, unresponsiveness. Recombinant human interleukin-11 (rhIL-11), a gp-130 signalling cytokine with haematopoietic and anti-inflammatory activity, increases VWF antigen and its activity in heterozygous VWF(+/-) mice and dogs. To determine the biological efficacy and safety of rhIL-11 in non-bleeding human subjects with mild VWD, we conducted a phase II prospective open-label trial of rhIL-11 at 10, 25 and 50 mug kg(-1) subcutaneously (s.c.), given daily for 7 days in nine subjects with mild VWD. VWF and factor VIII (FVIII) levels increased gradually and progressively after s.c. rhIL-11, which was sustained through 7 days of dosing to 1.5- to 3-fold over baseline. Following intravenous DDAVP, 0.3 mug kg(-1), on day 7 there was a further boost in VWF and FVIII levels, suggesting that the mechanism of rhIL-11 differs from that of DDAVP. Platelet VWF mRNA expression measured by quantitative PCR increased from two- to eightfold over baseline, suggesting that the mechanism of rhIL-11 effect may be upregulation of VWF mRNA. VWF and FVIII levels returned to baseline by day 14. rhIL-11 was well tolerated with less than grade-1 hypertension, hypokalaemia and fluid retention. Recombinant IL-11 increases VWF levels in humans with mild VWD, justifying future clinical trials to determine its potential in preventing or reducing bleeding in this patient population.

The use of desmopressin in von Willebrand disease: the experience of the first 30 years (1977-2007)

The aim of the treatment for von Willebrand disease (VWD) is to correct the dual defect of haemostasis, i.e. the abnormal platelet adhesion as a result of reduced and/or dysfunctional von Willebrand factor (VWF) and the abnormal coagulation expressed by low levels of factor VIII (FVIII). Correction of both deficiencies can be achieved by administering the synthetic peptide desmopressin (DDAVP) or, in cases unresponsive to this agent, the plasma concentrates containing VWF and FVIII (VWF/FVIII). DDAVP is the treatment of choice for type 1 VWD because it can induce release of normal VWF from cellular compartments, but the drug can be clinically useful also in other VWD types, including acquired von Willebrand syndrome (AVWS). A test dose of DDAVP at the time of diagnosis is recommended to establish the individual patterns of biological response and to predict clinical efficacy during bleeding and surgery. DDAVP is not effective in VWD type 3 and in severe forms of VWD 1 and 2. It can induce transient thrombocytopenia in patients with VWD type 2B. The results of several retrospective studies on the use of DDAVP in VWD management have been reported by many authors in different countries for the last 30 years. However, despite the widespread use of DDAVP in the treatment of VWD, there are only a few prospective clinical trials in a large number of cases on DDAVP efficacy and safety aimed at determining benefits and limits of this therapeutic approach. An investigator-driven observational prospective study on clinical efficacy of DDAVP in 200 patients with VWD types 1 and 2 has been recently organized: the effectiveness and safety of DDAVP will be evaluated prospectively for 24 months during bleeding episodes and minor or major surgeries in the VWD patients who were exposed to an infusion trial at enrollment.

Impact of intensive care on renal function before graft harvest: results of a monocentric study

Background

The aim of life-support measures in brain-dead donors is to preserve the functional value of their organs. In renal transplantation, serum creatinine level is one of the criteria for graft harvest. The aim of this study was to assess the impact of intensive care on donor renal function through two criteria: preharvesting serum creatinine level above 120 μmol/L and the elevation of serum creatinine level above 20% between intensive care unit (ICU) admission and graft harvest.

Methods

Between 1 January 1999 and 31 December 2005, we performed an observational study on 143 brain-dead donors. ICU chronology, hemodynamic, hematosis, and treatment data were collected for each patient from ICU admission to kidney removal.

Results

Twenty-two percent of the 143 patients had a serum creatinine level above 120 μmol/L before graft harvest. The independent factors revealed by multivariate analysis were the administration of epinephrine (odds ratio [OR]: 4.36, 95% confidence interval [CI]: 1.33 to 14.32; p = 0.015), oliguria (OR: 3.73, 95% CI: 1.22 to 11.36; p = 0.021), acidosis (OR: 3.26, 95% CI: 1.07 to 9.95; p = 0.038), the occurrence of disseminated intravascular coagulation (OR: 3.97, 95% CI: 1.05 to 15.02; p = 0.042), female gender (OR: 0.13, 95% CI: 0.03 to 0.50; p = 0.003), and the administration of desmopressin (OR: 0.12, 95% CI: 0.03 to 0.44; p = 0.002). The incidence of elevated serum creatinine level above 20% between admission and graft harvest was 41%. The independent risk factors were the duration of brain death greater than 24 hours (OR: 2.64, 95% CI: 1.25 to 5.59; p = 0.011) and the volume of mannitol (OR: 2.08, 95% CI: 1.03 to 4.21; p = 0.041).

Conclusion

This study shows that the resuscitation of brain-dead donors impacts on their renal function. The uses of epinephrine and mannitol are associated with impairment of kidney function. It seems that graft harvest should be performed less than 24 hours after brain death diagnosis.

Pharmacologic Interventions for the Management of Critical Bleeding

Hospital pharmacists are often consulted for their knowledge about coagulation and therapeutic interventions for the management of critical bleeding. Many pharmacotherapies are available for this purpose, both systemic and topical, and others are in development. These agents and their mechanisms of action are reviewed, and perspectives are provided regarding their use in various clinical settings. Also provided are associated precautions to promote safe use. Current controversies surrounding pharmacotherapeutic agents used to control serious bleeding (e.g., in various types of surgery, trauma, obstetrics, and intracranial hemorrhage) are also discussed.

Perioperative desmopressin prolongs survival in surgically treated bitches with mammary gland tumours: a pilot study

Desmopressin (1-deamino-8-d-arginine vasopressin, also known as DDAVP) is a safe haemostatic compound capable of inhibiting lymph node and lung metastasis in a mouse model of mammary tumour manipulation and surgical excision. The aim of this study was to test the efficacy and safety of perioperative DDAVP (1microg/kg) in surgically treated bitches with mammary gland tumours (MGT). Twenty-one, otherwise healthy, intact bitches, with malignant MGT stage III or IV were randomly allocated to DDAVP (n=11) or placebo (n=10) groups. En bloc mastectomy of the affected gland/s was performed. DDAVP had a significant beneficial effect on disease-free period (P<0.01) and overall survival time (P<0.05). No side effects were seen in any of the cases. Whatever the mechanism of action, it seems that DDAVP may have a novel use in cancer surgery to minimise spread or survival of residual malignant cells. Additional, large scale controlled trials are required to fully evaluate this adjuvant pharmacological protocol.