Clinical relevance of the effects of plasma expanders on coagulation

Patients with severe bleeding are often treated with colloids as plasma replacement fluids, including dextrans, gelatin-based solutions, or starches. Many of these agents will affect the hemostatic system beyond their effect on hemodilution. Obviously, the ensuing impairment of coagulation is not desirable in patients with major blood loss. However, there is considerable controversy whether the anticoagulant effects of the various compounds will truly translate into clinically relevant effects, such as increased blood loss or, even more importantly, transfusion requirements, the need for surgical (re) exploration, organ dysfunction, or mortality. In this overview, we discuss the effects of various plasma replacement solutions on the coagulation system and review the controlled clinical studies with different plasma expanders on clinically significant end points. We conclude that most plasma expanders have indeed marked effects at various points in the hemostatic system and that there are significant differences between various plasma replacement fluids but that clinically relevant effects on bleeding are mostly present if large volumes (i.e., > 1.5 L) are infused or if the patient has a concomitant or preexistent hemostatic impairment.