Modern aspects of prophylaxis and therapy for venous thrombo-embolic disease

Effects of different plasma substitutes on blood coagulation: a comparative review

OBJECTIVE

To compare the effects of different colloid plasma substitutes on blood coagulation and postoperative blood loss.

DATA SOURCES

Relevant studies were obtained from the medical literature.

STUDY SELECTION

Articles were selected that provided data on the effects of colloids on hemostasis and postoperative blood loss in humans. Studies comparing different colloids were looked for using MEDLINE and by searching through the references of studies as they were collected.

DATA SYNTHESIS

Articles were reviewed and relevant data were extracted and partly presented in comparative tables.

CONCLUSIONS

Dextran, gelatin, and hydroxyethyl starch (HES) all can induce a specific decrease of von Willebrand factor and factor VIII:c. Blood coagulation is most impaired by dextran and high molecular weight HES, both associated with increased postoperative blood loss. The effects of HES on blood coagulation have been shown to depend on its molecular weight and rate of elimination. Detrimental effects have been shown for high molecular weight HES. Medium molecular weight (MMW)-HES with a high degree of substitution (HES 200/0.62) and MMW-HES with high C2/C6 hydroxyethylation ratio (HES 200/0.5/13) are slowly degradable and have been shown to impair blood coagulation after repeated administration. Rapidly degradable HES 200/0.5/6 and gelatin-based plasma expanders appear not to impair hemostasis. However, based on the reviewed literature, all artificial colloids could potentially induce increased bleeding tendency after infusion of very large volumes and especially when given to patients with even mild forms of von Willebrand disease. In those circumstances, crystalloid solutions or alternatives such as plasma or albumin, although associated with other serious complications, could be considered.

Dalteparin: an update of its pharmacological properties and clinical efficacy in the prophylaxis and treatment of thromboembolic disease

Dalteparin is a low molecular weight heparin (LMWH) with a mean molecular weight of 5000. Compared with unfractionated heparin (UFH), the drug has markedly improved bioavailability and increased plasma elimination half-life, and exerts a greater inhibitory effect on plasma activity of coagulation factor Xa relative to its effects on other coagulation parameters. Dalteparin also has less lipolytic activity than UFH. Dalteparin 2500U once daily subcutaneously is of similar antithrombotic efficacy to UFH 5000IU twice daily, and 2 studies have shown superiority over UFH 2 or 3 times daily of dalteparin 5000U once daily in patients requiring surgical thromboprophylaxis. After total hip arthroplasty, dalteparin was superior to adjusted-dosage warfarin and was of greater thromboprophylactic efficacy when given for 35 than for 7 days. Intravenous or subcutaneous dalteparin is as effective as intravenous UFH when given once or twice daily in the initial management of established deep vein thrombosis (DVT). The drug is also effective in long term home treatment. Dalteparin has been shown to be effective in combination with aspirin in the management of unstable coronary artery disease (CAD), with composite end-point data from 1 study suggesting benefit for up to 3 months. Current data indicate potential of the drug in the management of acute myocardial infarction (MI). Dalteparin is also of similar efficacy to UFH, with a single bolus dose being sufficient in some patients, in the prevention of clotting in haemodialysis and haemofiltration circuits. Pharmacoeconomic data indicate that overall costs relative to UFH from a hospital perspective can be reduced through the use of dalteparin in patients receiving treatment for venous thromboembolism. Dalteparin has also been shown to be cost effective when used for surgical thromboprophylaxis. Overall, rates of haemorrhagic complications in patients receiving dalteparin are low and are similar to those seen with UFH.

CONCLUSIONS

Dalteparin is effective and well tolerated when given subcutaneously once daily in the prophylaxis and treatment of thromboembolic disease. The simplicity of the administration regimens used and the lack of necessity for laboratory monitoring facilitate home or outpatient treatment and appear to translate into cost advantages from a hospital perspective over UFH or warfarin. Dalteparin also maintains the patency of haemodialysis and haemofiltration circuits, with beneficial effects on blood lipid profiles and the potential for prophylaxis with a single bolus injection in some patients. Data are also accumulating to show dalteparin to be an effective and easily administered alternative to UFH in patients with CAD.