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Background: For most topical hemostatic agents the mechanism of hemostatic action is not fully understood., Objective: This work aimed to investigate the hemostatic mechanism of action and viscoelastic properties of polyurethane foam (PU) in comparison to the widely used collagen and gelatin., Methods: The hemostatic mechanism of action of the materials was tested using human whole blood and platelet-poor plasma (PPP). The ability of the hemostatic agent to exert pressure on the wound was quantified in terms of its viscoelastic properties both under dry and wet conditions using a low load compression tester (LLCT)., Results: It has been shown that collagen and PU initiate hemostasis through both thrombocyte aggregation and contact activation of the coagulation cascade. Gelatin did not show improved thrombocyte aggregation or initiation of the coagulation cascade compared to the negative control group. PU is more firm under wet conditions and shows more springback than collagen and gelatin., Conclusions: We conclude that PU is promising as a topical hemostatic agent because it initiates both the coagulation cascade and thrombocyte aggregation. Furthermore, it has favorable viscoelastic properties compared to collagen and gelatin which leads to increased pressure on a wound.

Most topical hemostatic agents are based on animal-derived products like collagen and gelatin. They carry the potential risk of pathogen transmission while adjustments in the production process of these materials are limited. A synthetic hemostatic agent based on polyurethane (PU) and polyethylene glycol (PEG) was developed to overcome these disadvantages. The goal of this study was to compare the degradation process of this biomaterial to collagen and gelatin hemostatic agents. Samples of the test materials were implanted subcutaneously in both rats and rabbits. The animals were sacrificed at certain time intervals up to three years and the explanted samples were microscopically assessed. The histological examination showed a comparable pattern of degradation for the different test materials. Remnants of gelatin and collagen were seen up to 26 and 39 weeks, respectively. For PU, it took up to three years before micro-particles of the material were no longer detected. All biomaterials showed a good biocompatibility and no severe foreign body reactions occurred. The good biocompatibility and predictable pattern of resorption indicate that PU can be used as a topical hemostatic agent. However, a degradation time comparable to collagen and gelatin would be favorable., (© 2015 Wiley Periodicals, Inc.)

To avoid increasing the risk of thromboembolic events, it is recommended that treatment with anticoagulants should be continued during dentoalveolar operations. We have evaluated the incidence of bleeding after dentoalveolar operations in a prospective study of 206 patients, 103 who were, and 103 who were not, taking anticoagulants. Seventy-one were taking thrombocyte aggregation inhibitors and 32 vitamin K antagonists. Patients were treated according to guidelines developed at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. The operations studied included surgical extraction (when the surgeon had to incise the gingiva before extraction), non-surgical extraction, apicectomy, and placement of implants. Patients were given standard postoperative care and those taking vitamin K antagonists used tranexamic acid mouthwash postoperatively. No patient developed a severe bleed that required intervention. Seven patients (7%) taking anticoagulants developed mild postoperative bleeds. Patients taking vitamin K antagonists reported 3 episodes (9%) compared with 4 (6%) in the group taking thrombocyte aggregation inhibitors. Among patients not taking anticoagulants, two (2%) developed mild bleeding. The differences between the groups were not significant. All bleeding was controlled by the patients themselves with compression with gauze. We conclude that dentoalveolar surgery is safe in patients being treated with anticoagulants provided that the conditions described in the ACTA guidelines are met., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

In this split mouth experiment, the feasibility ofpolyurethane foam as a local hemostatic agent after dental extractions was studied. Ten healthy patients underwent 2 extractions ofa dental element in 1 treatment session. The 10 patients were subsequently randomly divided in a gelatin group and a collagen group. In the gelatin group, a polyurethane foam (PU) was applied in 1 extraction socket, while in the other socket a commercially available gelatin foam was applied. In the collagen group, a PU was applied in 1 socket, and a collagen wadding in the other. All hemostats were removed after 2 minutes, after which the degree of coagulation was measured using a thrombin/antithrombin test and a fibrinogen test. This study suggests that polyurethane foam has hemostatic capacity. Large scale clinical research is needed to confirm this finding, and should indicate whether this hemostatic capacity is clinically relevant.

Objectives: Topical hemostatic agents are used in all surgical disciplines. Most of these hemostats are based on animal-derived products like collagen and gelatin. They carry the potential risk of pathogen transmission. A newly developed biodegradable, fully synthetic hemostatic agent based on polyurethane foam (PU) with 55 % polyethylene glycol (PEG) would prevent these potential risks., Materials and Methods: The hemostatic efficacy of this new agent was compared to gelatin and collagen in humans who underwent extraction of an upper and lower molar (split-mouth model). After extraction of a molar in the maxilla and mandible, a PU foam and collagen or gelatin were inserted in the extraction socket for 2 min. Hereafter, the agents were removed and stored in ethylenediaminetetraacetic acid to stop coagulation. Then, the concentration of coagulation parameters thrombin-antithrombin III (TAT) complexes, fibrinogen, and thromboxane B2 (TxB2) in blood extracts from the agents was measured. The concentrations were also determined in baseline blood samples which were collected from the extraction socket., Results: The concentrations of TAT and TxB2 were significantly increased, and fibrinogen concentration was significantly reduced compared to baseline wound blood concentrations indicating enhanced hemostasis. No significant differences were seen in the concentrations of these coagulation parameters in the three different hemostatic agents., Conclusions: These results show that PU combined with 55 % PEG is a promising alternative for the animal-derived hemostatic agents., Clinical Relevance: The synthetic hemostatic agent could replace the animal-derived products like collagen and gelatin and therewith prevent the potential risk of pathogen transmission.

Topical hemostatic agents can be used to treat problematic bleedings in patients who undergo surgery. Widely used are the collagen- and gelatin-based hemostats. This study aimed to develop a fully synthetic, biodegradable hemostatic agent to avoid exposure to animal antigens. In this in vitro study the suitability of different newly developed polyurethane-based foams as a hemostatic agent has been evaluated and compared to commonly used agents. An experimental in vitro test model was used in which human blood flowed through the test material. Different modified polyurethane foams were compared to collagen and gelatin. The best coagulation was achieved with collagen. The results of the polyurethane foam improved significantly by increasing the amount of polyethylene glycol. Therefore, the increase of the PEG concentration seems a promising approach. Additional in vivo studies will have to be implemented to assess the application of polyurethane foam as a topical hemostatic agent.

Recurrent respiratory papillomatosis (RRP) is a chronic and difficult to treat disease of the larynx. In 1998, the first article was published that described the use of the antiviral substance cidofovir to treat this disease. Although the results are promising, there remains some concern about the potential carcinogenicity of cidofovir. There is a demand for a qualitative review of the side-effects of this medicine. In this review, the side-effects of cidofovir are investigated. Special attention was given to the potential carcinogenicity of cidofovir. For this review a search is performed in PubMed and EMBASE for relevant articles in which the use of intralesional cidofovir for patients with RRP is described. Eventually, 31 articles could be included for this review. In these articles a total of 188 patients with RRP were described who underwent therapy with intralesional cidofovir. Five of these patients have developed dysplasia of the larynx during the treatment with cidofovir. This is a percentage of 2.7. This percentage is concurrent with the incidence of spontaneous malignant degeneration of RRP (2-3%). Based on this review, it can be concluded that the use of intralesional cidofovir does not increase the risk of laryngeal dysplasia. Apart from the articles that describe the intralesional administration of cidofovir, some articles have been published in which the use of intravenous cidofovir is described as a therapy for RRP. Therefore, a summary is given on the side-effects of intralesional cidofovir as well as a summary on the reported side-effects of the intravenous administration of cidofovir. Based on the outcomes of this review, recommendations are given for a safe use of cidofovir for treatment of recurrent respiratory papillomatosis in the future.