Erstad What is the evidence for using hemostatic agents in surgery ?

Topical, local, regional, and systemic routes of medication administration have been employed for preventing or reducing blood loss and associated transfusion requirements in patients with bleeding diatheses. Examples would include topical fibrinor thrombin-based products for wound hemostasis, proton pump inhibitor therapy for preventing gastric rebleeding in patients with peptic ulceration, octreotide derivatives for reducing rebleeding in patients with variceal hemorrhage, and the antifibrinolytic agents and desmopressin for systemic hemostasis. The pharmacological methods used to achieve systemic hemostasis have generated much discussion due to concerns of serious adverse effects (e.g., thromboembolic complications) and costs of therapy in addition to efficacy considerations. The studies that have been conducted have focused on the operating room, where substantial blood loss can often be anticipated. This paper is intended to provide an overview of the consequences and costs of medications used for systemic hemostasis during spine surgery in light of currently available evidence. Ideally, the efficacy and adverse effects of these agents would be defined by large, well-controlled studies restricted to spine surgery rather than by extrapolation from other surgical procedures. Unfortunately, there are a limited number of such trials involving pharmacological hemostasis in association with Abstract The pharmacological methods used to achieve systemic hemostasis have generated much discussion due to concerns of serious adverse effects (e.g., thromboembolic complications) and costs of therapy in addition to efficacy considerations. There are a limited number of well-controlled trials involving pharmacological hemostasis for spine surgery. In the largest doubleblinded randomized controlled trial to date involving spine surgery, there was a trend toward reduced homologous transfusion in patients receiving aprotinin, but the only statistically significant result (p<0.001) was a reduction in autologous red cell donations. The findings of this trial are important, since the investigators used a number of restrictive transfusion strategies (e.g., autologous donation, low hematocrit trigger for transfusion, blood-salvaging procedures with the exception of no cell saver) that were not always employed in earlier trials involving hemostatic agents. Smaller studies involving antifibrinolytic agents other than aprotinin have demonstrated reductions in blood loss and transfusion requirements in patients undergoing spine surgery, although the results were not always statistically significant. A very large randomized trial would be required to address comparative medicationand transfusion-related adverse events; such a trial involving patients undergoing cardiac surgery is currently being performed. Additionally, cost-effectiveness analyses are needed to help define the role of these agents based on the data that is available.