Hemostatic efficacy of a fibrin sealant dressing in an animal model of kidney injury

Morphological, cytotoxicity, and coagulation assessments of perlite as a new hemostatic biomaterial

Hemorrhage control is vital for clinical outcomes after surgical treatment and pre-hospital trauma injuries. Numerous biomaterials have been investigated to control surgical and traumatic bleeding. In this study, for the first time, perlite was introduced as an aluminosilicate biomaterial and compared with other ceramics such as kaolin and bentonite in terms of morphology, cytotoxicity, mutagenicity, and hemostatic evaluations. Cellular studies showed that perlite has excellent viability, good cell adhesion, and high anti-mutagenicity. Coagulation results demonstrated that the shortest clotting time (140 seconds with a concentration of 50 mg mL^-1) was obtained for perlite samples compared to other samples. Therefore, perlite seems most efficient as a biocompatible ceramic for hemorrhage control and other biomaterial designs.

Hemostatic agents for prehospital hemorrhage control: a narrative review

Hemorrhage is the leading cause of preventable death in combat trauma and the secondary cause of death in civilian trauma. A significant number of deaths due to hemorrhage occur before and in the first hour after hospital arrival. A literature search was performed through PubMed, Scopus, and Institute of Scientific Information databases for English language articles using terms relating to hemostatic agents, prehospital, battlefield or combat dressings, and prehospital hemostatic resuscitation, followed by cross-reference searching. Abstracts were screened to determine relevance and whether appropriate further review of the original articles was warranted. Based on these findings, this paper provides a review of a variety of hemostatic agents ranging from clinically approved products for human use to newly developed concepts with great potential for use in prehospital settings. These hemostatic agents can be administered either systemically or locally to stop bleeding through different mechanisms of action. Comparisons of current hemostatic products and further directions for prehospital hemorrhage control are also discussed.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Postoperative adhesions after application of topical hemostatic agents: outcomes in a rat partial nephrectomy model

OBJECTIVE

To compare 3 kinds of topical hemostatic agents in terms of adhesive strength, control of hemorrhage, and postoperative intra-abdominal adhesions in an experimental partial nephrectomy (PN) model.

METHODS

A total of 27 Wistar rats were divided into 5 groups. PN was performed in 6 rats (control group) with the conventional technique, in which the lower pole of the kidney was excised and sutured after hilar control. In 5 rats, oxidized cellulose was placed over the excised part of the kidney following conventional technique. In 6 rats, the hemostatic plant extract was used without hilar control. In 5 rats, the hemostatic agent chitosan was used without hilar control. As a sham group, 5 rats underwent a laparotomy and handling of the renal pedicle without the removal of renal pole. On the tenth day after the operation, the degree of adhesions to the operated kidney were evaluated. Histopathological evaluation was also performed by a blinded pathologist.

RESULTS

Mean warm ischemia times for control and oxidized cellulose groups were 4.85 ± 0.75 and 4.28 ± 1.28 minutes, respectively (P = .662). Wound healing was excellent in all groups except in 1 rat in the chitosan group. Chitosan was associated with significantly higher intestinal and peritoneal adhesion scores, although histopathologically comparable scores were revealed.

CONCLUSION

In our rat model, chitosan and the hemostatic plant extract were as effective as conventional suturing in achieving hemostasis even without hilar control. Warm ischemia was eliminated and PN time was significantly decreased. The use of oxidized cellulose was not associated with higher scores of adhesion, suppuration, or hematoma.

Wound healing and the immune response in swine treated with a hemostatic bandage composed of salmon thrombin and fibrinogen

We investigated the inflammatory response in pigs exposed to salmon fibrinogen/thrombin dressings. Animals were exposed to the material in 3 ways: (a) thrombin and fibrinogen were injected intravenously, (b) dual full-thickness skin lesions were surgically created on the dorsal aspect of the swine and treated with the fibrinogen/thrombin bandage and a commercial bandage or (c) a fibrinogen/thrombin bandage was inserted through an abdominal incision into the peritoneal cavity. Blood was collected twice weekly and animals were sacrificed at 7, 10 or 28 days. Animals in the 28-day dermal lesion group were given an injection of salmon fibrinogen/thrombin at the 10 day point to simulate a second bandage application. The immune response manifested itself as induction of germinal centers in mesenteric lymph nodes and in the white pulp of the spleen. Examination of the histology of the skin and organs showed a cellular inflammatory response with granulation tissue and signs of edema that resolved by the 28-day stage. Antibodies reactive to salmon and human thrombin and fibrinogen were detected, but fibrinogen levels and coagulation processes were not affected. In conclusion, animals treated with salmon fibrinogen/thrombin bandages demonstrated a smooth recovery course in terms of both tissue healing and the immune response without adverse effects from the exposure to the fish proteins.

Hemostatic properties of a venomic protein in rat organ trauma

Previous in vitro work characterized the protease Q8009 isolated from the venom of the Australian brown snake Pseudonaja textilis textilis with Factor Xa-like activity and hemostatic properties. The purpose of the work described here characterizes the in vivo hemostatic properties in a rat model of parenchymatous organ injury. The key parameters of activity included reduction in time-to-hemostasis and total volume of blood loss in spleen, liver and kidney wound models in rats. The surgical protocols involved exposure of the organs via a midline abdominal laparotomy. Using a clean metal template with 6, 6.5, 9 mm holes for spleen, liver and kidney, respectively, a predetermined volume of the organ was gently extruded through the template hole and excised with a razor blade. About 50 to 75 microL of collagen matrix with the different test solutions was applied to the wounds. Blood was collected and at the end of the procedure animals were humanely sacrificed with an anesthetic overdose. Determination of blood was performed using the hematin assay using a standard curve. Blood loss per minute and total blood loss were calculated. Results from the studies demonstrated that the application of Q8009 and collagen matrix to surgical wounds significantly reduced the total amount of blood loss and the time-to-hemostasis. In the spleen wound model, Q8009 at 100, 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis by 25-50%, as compared to 7% by thrombin. In the liver wound model, Q8009 at 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis from 10.5 min by thrombin to 5.6 min with Q8009. In the kidney wound model, Q8009 at 250 microg/ml significantly reduced (p<0.05) the total volume of blood lost and reduced the time-to-hemostasis by 25% when compared to thrombin. The hemostasis levels were consistent with previous findings in skin wound rat models where Q8009 consistently reduced the total volume of blood lost and shortened time-to-hemostasis. Application of Q8009 plus collagen matrix significantly reduced the volume of total blood loss and time-to-hemostasis in rat surgical organ wound models induced bleeding, as compared to a commercially available hemostat device. The protein Q8009 has greater capacity to reduce blood loss and shorten time-to-hemostasis; highly desirable properties where rapid hemostasis is needed in surgical wounds in parenchymatous organs.

Diffuse parenchymal urine leak after kidney transplantation following degloving injury during donor nephrectomy

Laparoscopic donor nephrectomy can result in trauma to the kidney which may affect recipient graft function. In this case, the kidney sustained a complete degloving of the capsule during extraction. The kidney was transplanted and had immediate, good renal function, but postoperative course was complicated by a large urinoma that drained through the wound. Exploration was negative for a defined urine leak, but the surface of the denuded kidney was leaking a significant amount of unconcentrated urine. The patient was successfully treated with tissue glue treatment to the kidney surface and peritoneal window.

In vivo bleeding time and in vitro thrombelastography measurements are better indicators of dilutional hypothermic coagulopathy than prothrombin time

BACKGROUND

The coagulopathy of trauma is generally confirmed by prothrombin time (PT) > or =16 seconds or an international normalized ratio > or =1.5. However, the utility of these values as a screening test is unknown. We examined different coagulation tests to determine the best predictor of coagulopathic bleeding and mortality in a small animal hemorrhage model.

METHODS

Coagulopathy was induced in male New Zealand White rabbits by warfarin (W; 2 mg/kg for 2 days; n = 7), or hemodilution and hypothermia (HH; 50% blood exchange with Hextend, 34.5 +/- 0.3 degrees C; n = 7). Normal (N) rabbits without pretreatment served as the control (n = 7). Blood samples collected after coagulopathy induction and analyzed by prothrombin time (PT), activated partial thromboplastin time (aPTT), and thromboelastography (TEG) tests. Liver bleeding time (BT) was also measured before injury. An uncontrolled hemorrhage was created by a longitudinal splenic incision and the abdomen was closed. Rabbits were resuscitated with Hextend solution (25 mL/kg) to return blood pressure to baseline and monitored for 2 hours or until death at which time blood loss was measured.

RESULTS

Warfarin-induced coagulopathy increased BT, PT, and aPTT. TEG showed increased reaction (R) and clot formation (K) times and marked decrease in clotting rate (alpha angle and Vmax). Hemodilution hypothermia coagulopathy increased only BT and aPTT, and decreased the clotting rate (alpha angle and Vmax) and strength of the clot. After injury, blood losses were higher in coagulopathic rabbits (W = 54.6 +/- 4.2 and HH = 51.1 +/- 8.9 mL/kg) than in normal rabbits (30.6 +/- 12.4 mL/kg) and resulted in 86%, 100%, and 0% death, respectively. BT and Vmax consistently predicted coagulopathic bleeding and death in all animals.

CONCLUSION

Although satisfactory in warfarin-induced coagulopathy, PT was not a valid screening test for dilutional and hypothermic coagulopathy. BT and TEG measurements of blood clotting rate are better indicators of coagulopathic bleeding and mortality in this lethal hemorrhage model.

Various Local Hemostatic Agents with Different Modes of Action; an in vivo Comparative Randomized Vascular Surgical Experimental Study

OBJECTIVES

To evaluate the effects of different local hemostatic agents in a new high flow vascular experimental bleeding model.

DESIGN

Bovine thrombin combined with collagen matrix (bTcM), microporous polysaccharide hemospheres (MPH), freeze-dried rFVIIa with and without the combination of MPH were compared to a control group (solely compression) in a randomized fashion (20 animals/group). Primary endpoint was hemostasis, and secondary endpoints were time to hemostasis, blood loss, and blood pressure at hemostasis.

METHODS

The common carotid artery of heparinized rats was ligated proximally and transected. Compression was applied for one minute followed by application of the topical hemostatic agent. Compression was maintained for another two minutes followed by re-evaluation of hemostasis: if bleeding continued additional compression was applied and thereafter bleeding was checked every minute until hemostasis.

RESULTS

All animals in the bTcM group obtained hemostasis compared to 20% in the control group (p<0.0001). The combination of MPH and rFVIIa (70% hemostasis) also showed a significant hemostatic capacity compared to control group (p<0.001). None of the other active treatment groups differed compared to control group. Animals treated with bTcM had a significantly shorter time to hemostasis compared to animals in the other active treatment groups. No significant difference in blood loss and blood pressure at hemostasis was detected.

CONCLUSIONS

The most effective hemostatic agent was bTcM, followed by the combination of rFVIIa and MPH, while neither MPH nor rFVIIa alone displayed any hemostatic capacity compared to compression only.

Use of Fibrin Glue and Gelfoam to Repair Collecting System Injuries in a Porcine Model: Implications for the Technique of Laparoscopic Partial Nephrectomy

BACKGROUND AND PURPOSE

One of the challenges of laparoscopic partial nephrectomies is the repair of a collecting system injury. We hypothesized that fibrin glue plus Gelfoam could be sufficient to repair such injuries.

MATERIALS AND METHODS

Four pigs (eight kidneys) underwent collecting system injuries of various lengths (3, 5, and 10 mm) (N = 8 each) during partial nephrectomy. Gelfoam soaked in the fibrin glue was applied to seal the collecting system and parenchymal defects. After 1 hour of passive filling, the renal pelvis was distended at supraphysiologic pressure to the point of leakage. Each repair site was examined for urinary extravasation during the physiologic and active phases of filling.

RESULTS

Hemostasis was achieved, and all collecting system injuries, regardless of size, were free of urinary leakage at physiologic pressures. Moreover, all defects maintained a seal at supraphysiologic pressures of at least 50 cm H(2)O.

CONCLUSION

The combined use of fibrin glue and Gelfoam is an effective means to obtain hemostasis and seal collecting system injuries up to 10 mm at physiologic pressures and up to 50 cm H(2)O in the acute setting. Our hope is that this technique can facilitate both laparoscopic and open partial nephrectomies. New technologies will be employed in an attempt to obtain better seating of the sealant plug in the future. Survival studies are in progress.

Advanced Hemostatic Dressing Development Program: Animal Model Selection Criteria and Results of a Study of Nine Hemostatic Dressings in a Model of Severe Large Venous Hemorrhage and Hepatic Injury in Swine

BACKGROUND

An advanced hemostatic dressing is needed to augment current methods for the control of life-threatening hemorrhage. A systematic approach to the study of dressings is described. We studied the effects of nine hemostatic dressings on blood loss using a model of severe venous hemorrhage and hepatic injury in swine.

METHODS

Swine were treated using one of nine hemostatic dressings. Dressings used the following primary active ingredients: microfibrillar collagen, oxidized cellulose, thrombin, fibrinogen, propyl gallate, aluminum sulfate, and fully acetylated poly-N-acetyl glucosamine. Standardized liver injuries were induced, dressings were applied, and resuscitation was initiated. Blood loss, hemostasis, and 60-minute survival were quantified.

RESULTS

The American Red Cross hemostatic dressing (fibrinogen and thrombin) reduced (p < 0.01) posttreatment blood loss (366 mL; 95% confidence interval, 175-762 mL) and increased (p < 0.05) the percentage of animals in which hemostasis was attained (73%), compared with gauze controls (2,973 mL; 95% confidence interval, 1,414-6,102 mL and 0%, respectively). No other dressing was effective. The number of vessels lacerated was positively related to pretreatment blood loss and negatively related to hemostasis.

CONCLUSION

The hemorrhage model allowed differentiation among topical hemostatic agents for severe hemorrhage. The American Red Cross hemostatic dressing was effective and warrants further development.

Addition of a propyl gallate-based procoagulant to a fibrin bandage improves hemostatic performance in a swine arterial bleeding model

Fibrin bandages manufactured by Nycomed Austria (TC-S) were modified by the addition of Hemostyptin (HS), a proprietary platelet-activating reagent containing propyl gallate. HS was added as an additional layer to TC-S fibrin bandages and the bandages were tested for hemostatic efficacy in a swine femoral artery bleeding model. Injuries were treated with a TC-S+HS bandage preparation using HS lyophilized onto a bandage surface that was then attached to the fibrin dressing. This preparation qualitatively and quantitatively exhibited more robust blood clotting at the surgical site than the control bandages. TC-S+HS bandages were more effective than control bandages with a difference in blood loss of 251.8+/-66.5 g for TC-S bandage alone, n=12 vs. 121+/-40.7 g, n=13 for the TC-S+HS bandage, P=0.05. Bleeding times were shortened for animals treated with the HS fortified bandages and residual platelets counts in these animals were higher.

Epsilon-amino caproic acid additive decreases fibrin bandage performance in a swine arterial bleeding model

epsilon -Amino caproic acid (EACA), a lysine analog that inhibits the activity of plasmin, was added to Nycomed (TC-S) fibrin bandages, and the bandages were tested for hemostatic efficacy in a swine femoral artery bleeding model. The blood loss using the bandage with EACA (TC-S+EACA; 728.8+/-132 g, n=5) was much greater as compared to the TC-S bandage alone (TC-S; 237.8+/-47.9 g, n=6, p=.02). The time to "cessation of bleeding" (T(b)) was also increased for animals treated with TC-S+EACA bandages compared to the TC-S controls (33.6+/-10.8 min vs. 9.2+/-2.2 min; p=.05). Although plasma fibrinogen concentration decreased in animals treated with the TC-S+EACA bandage, activated partial thromboplastin times (aPTT) and thrombin times (TT) were decreased. Animals treated with the TC-S control bandage exhibited no changes in fibrinogen, aPTT or TT. Prothrombin times (PT) were unchanged in either group. In conclusion, addition of EACA to the Nycomed product decreased fibrin bandage efficiency.

Effect of fibrin sealant composition on human neutrophil chemotaxis

The use of fibrin sealants offers one of the most physiologically compatible approaches to preventing postoperative adhesions. Although a number of fibrin sealant formulations have been developed, little is known about how the various components of these preparations affect the wound-healing process. Because one of the key steps in wound healing is the migration of phagocytic leukocytes, such as neutrophils, into the site of injury, we performed studies to characterize systematically the effects of various fibrin sealant components on neutrophil chemotaxis. Using a transwell chemotaxis assay, we found that increasing fibrin concentration resulted in an inhibition of the ability of the cells to migrate through the clots in a dose-dependent manner, and at fibrin clot concentrations >2.0 mg/mL chemotaxis was completely blocked. Factor XIII crosslinking of the clots also had a significant impact on neutrophil chemotaxis, and sealant preparations deficient in Factor XIII allowed neutrophil migration at much higher fibrin concentrations. The presence of various other fibrin sealant components such as plasminogen and fibrinolysis inhibitors (aprotinin and tranexamic acid) did not have any significant effects on the ability of neutrophils to migrate through fibrin clots as compared to control clots without these components. Overall, these studies show that the composition of fibrin sealant preparations can significantly affect neutrophil migration into the site of injury, which could possibly influence the wound healing process.

Development of an animal model for assessment of the hemostatic efficacy of fibrin sealant in vascular surgery

PURPOSE

Sustained hemostatic function of fibrin sealant (FS) is crucial when it is used in cardiovascular surgery. The purpose of this study was to develop a model that can determine the long-term hemostatic efficacy of tissue sealants in a vascular surgery.

METHODS

To determine the ability of the model to detect differences in FS performance, various concentrations of FS were prepared and tested. Tensile strength of FS clots was determined in vitro using a tensiometer. Laparotomy was performed on 49 anesthetized rabbits, and a segment of the aorta was occluded, transected, and then sutured in an end-to-end fashion with four or eight interrupted 9-O sutures. The four-suture repair was covered with FS or placebo, and blood flow restored. Spilled blood was absorbed with gauze and weighed to estimate blood loss. Four weeks after surgery the animals were euthanized and the vessels recovered for histology.

RESULTS

Average tensile strength of FS clots at 120, 90, and 60 mg/ml topical fibrinogen complex (TFC) concentration was 0.42 +/- 0.07 N, with no significant difference among them. The lowest TFC concentration, 30 mg/ml, produced weaker clots than either 120 or 90 mg/ml (P < 0.05). All rabbits with four-suture anastomoses that were treated with placebo bled to death after the vessel was unclamped (n = 6). Treatment of suture line with standard FS concentration (120 mg/ml TFC, n = 8) sealed the anastomosis and prevented blood loss. Hemostasis was sustained for 4 weeks, allowing vascular healing. All rabbits with the eight-suture anastomosis survived the operation but lost 42 +/- 9.2 ml blood (n = 5). Hemostatic efficacy of FS was unchanged when TFC was diluted to 90 mg/ml (n = 6) but further dilution to 60 mg/ml with water (n = 8) produced significantly less effective clots, with an average blood loss of 5.5 +/- 7.6 ml (P < 0.05) and two fatal clot failures postoperatively. When FS was diluted to 60 mg/ml TFC with a buffer, it maintained its hemostatic strength (n = 6). Further TFC dilution to 30 mg/ml led to consistent bleeding with an average blood loss of 35.3 +/- 10.3 ml (P < 0.001, n = 6).

CONCLUSIONS

The four-suture anastomosis of rabbit aorta offers a consistent and reliable method for evaluating the short- and long-term hemostatic efficacy of FS products. This model is not only able to determine the functional differences in various concentrations of FS, but it is also sensitive to detect the subtle changes in FS preparation (e.g., medium composition) that is not detected by in vitro testing.

New and potential uses of fibrin sealants as an adjunct to surgical hemostasis

Commercially prepared fibrin sealants have been available in Europe and Japan for many years. However, current formulations are exclusively two-component, liquid fibrin sealants, and delivery devices are rather rudimentary. To date, this has had the effect of limiting the number of clinical applications that make use of fibrin sealants. The recent licensing of fibrin sealants by the Food and Drug Administration in the United States has the potential to expand the use of these products in established procedures. As surgeons gain experience with fibrin sealants, it is likely that new clinical applications will be developed in a wider range of surgical specialties. The aim of this article is to explore the potential future formulations and uses of fibrin sealants and highlight a range of surgical procedures that may benefit from these products.

Assessment of topical hemostats in a renal hemorrhage model in heparinized rats

Various topical hemostatic agents or devices have been employed to address the challenges associated with hemorrhage from parenchymal organs during surgery or trauma. Their relative efficacy, however, has not been assessed in a single animal model. The objective of this study was to develop a small animal renal hemorrhage model for comparing hemostatic efficacy of various topical agents, and then to compare fibrin sealant (FS) to an existing standard of care for topical hemostasis. A left heminephrectomy was performed in anesthetized adult male Sprague-Dawley rats. Animals were anticoagulated with 2000 IU/kg heparin IV and various topical hemostatic agents were applied to the injury. Treatment groups included FS applied as a spray; FS applied through a cannula; gelatin sponge (GS) soaked in 1000 IU/mL thrombin solution; GS soaked in 300 IU/mL thrombin; dry GS; and fibrinogen without thrombin applied as a spray. The main endpoints of the study were incidence of hemostasis, blood loss, acute survival trends, and maintenance of mean arterial pressure (MAP). Three treatment groups, the two FS groups and the GS soaked in 1000 IU/mL thrombin, afforded significant hemostasis compared to the controls (P < 0.01). Both FS groups had significantly less blood loss, longer survival times, and maintained higher MAPs than the GS-treated groups. Quantitative dose effects and functional deficiencies in topical hemostatic products could be assessed using this animal model. The study demonstrated that liquid FS was significantly more efficacious than a GS soaked in thrombin for abating hemorrhage from a renal excision in a heparinized rat.

Fibrin glue applications in urology

Fibrin glue is used as a hemostatic and adhesive agent. Until recently, safety issues had delayed approval of the commercial preparation in the United States. Fibrin glue has found several urologic applications, especially as an adhesive agent. It has excellent potential in laparoscopic surgery, where conventional tissue approximation techniques are cumbersome and time-consuming. Fibrin glue has also been used as a delivery vehicle for autologous cell transplantation and may play a major role in tissue engineering techniques in the future.

Different hypotensive responses to intravenous bovine and human thrombin preparations in swine

BACKGROUND

Accidental intravenous introduction of commercial bovine thrombin (BT) during use of fibrin glue may result in profound hypotension. Commercial human thrombin (HT) is now available. This study compared the effects of intravenous BT versus HT in swine.

METHODS

Swine received 30 U/kg BT, 60 U/kg BT, 30 U/kg HT, or 60 U/kg HT intravenously. Mean arterial pressure (MAP) and survival were monitored for 30 minutes. Thrombin purities and in vitro activities were examined.

RESULTS

MAP nadir was lower (p < 0.05) after BT, 27.7 +/- 3.3% (mean +/- SEM) of pretreatment MAP, compared with 41.1 +/- 3.7% after HT. Five of six animals died after 60 U/kg BT, whereas all others survived (p < 0.05). Histology suggested more severe disseminated intravascular coagulation after BT. HT was purer than BT. In vitro activities were similar.

CONCLUSION

Both BT and HT produced hypotension. HT appeared safer, because of higher purity. Regardless of source and purity, thrombin must be used with caution.

Fibrin sealant in preclinical and clinical studies

Fibrin sealant, now commercially available in the United States, is a virally inactivated preparation of highly purified human fibrinogen and human thrombin that includes aprotinin to reduce fibrinolysis. Although the product is relatively expensive, cost can be justified when the sealant is used to produce localized hemostasis in surgery in which bleeding cannot be controlled by sutures. Fibrin sealant can also be justified as an alternative to factor concentrates in patients with coagulopathies who have a localized site of bleeding. Newer formulations of fibrinogen and thrombin in a freeze-dried form applied as a bandage may be useful in immediate, on-site treatment of trauma victims in either a civilian or military setting.

Hemostatic efficacy of fibrin sealant (human) on expanded poly-tetrafluoroethylene carotid patch angioplasty: a randomized clinical trial

PURPOSE

The efficacy of solvent-detergent-treated fibrin sealant (human [FSH]) for controlling anastomotic bleeding from expanded polytetrafluoroethylene (ePTFE) patch angioplasty during carotid endarterectomy was evaluated, and FSH was compared with thrombin-soaked gelatin sponge (Gelfoam; TSG).

METHODS

The study was of a randomized, open-label, single-site, single-treatment, parallel design that took place in a referral center with hospitalized patients. Forty-seven adult patients (33 men, 14 women) underwent elective carotid endarterectomy. Patients were randomized to receive either FSH (N = 24) or TSG (N = 23). FSH was obtained as an investigational new drug. FSH was applied as a liquid by means of a dual-syringe technique. Heparin anticoagulation, patch thickness, and suture type were standardized. Two different needle sizes were used (CV-6, PT-13: N = 21 [FSH: N = 10, TSG: N = 11]; CV-6, PT-9: N = 26 [FSH: N = 14, TSG: N = 13]). The FSH or TSG was applied to the ePTFE patch, and then blood flow was restored through the carotid artery. Degree of anticoagulation was assessed by anti-factor Xa activity. The time from restoration of carotid blood flow until achieving hemostasis was recorded. The blood loss from patch suture hole bleeding was measured. Completion intraoperative duplex ultrasound scanning was performed in all cases. Heparin was reversed with protamine sulfate. The primary end point was successful hemostasis within 15 minutes of restoration of carotid blood flow. The secondary end points were the amount of blood loss caused by suture line bleeding and the time to achieve hemostasis.

RESULTS

There was no difference in the number of patients with complete hemostasis at 15 minutes (TSG, 13 of 23; FSH, 12 of 24; P =.77). The measured blood loss was 99.0 +/- 119.9 (SD) mL for TSG, and 105.0 +/- 107.9 mL for FSH (P =.86). The time to hemostasis was the same for both groups (TSG, 16.5 +/- 16.5 minutes; FSH, 16.6 +/- 14.2 minutes; P =.97). Within both treatment groups, the use of larger needles (PT-13) was associated with greater blood loss (FSH, 169.7 +/- 124.2 mL; TSG, 172.7 +/- 151.5 mL) than was the use of smaller needles (PT-9; FSH, 58.8 +/- 66.3 mL; TSG, 34.1 +/- 25.6 mL; P =.036, P =.001, respectively). There were no postoperative strokes or bleeding complications in either group. No abnormalities were shown in either group by means of completion carotid duplex ultrasound scanning.

CONCLUSION

FSH was equivalent, but not superior to, TSG in achieving hemostasis during carotid endarterectomy performed with ePTFE patch angioplasty. Adhesion properties of FSH to ePTFE are possibly different than those to native tissue and warrant additional investigation.