Protein composition of clots detected in pooled cryoprecipitate units.

BACKGROUND: On rare occasions, upon thawing of stored cryoprecipitate components, clots are observed on visual inspection. Although it has been assumed that the clot reflects fibrinogen to fibrin conversion, there are few published studies that document that this assumption is correct. Our studies were conducted to further identify the protein characteristics of the clotted material. STUDY DESIGN AND METHODS: Clotted material isolated from four thawed cryoprecipitate pools was examined by solubilization procedures and electrophoresis analysis. RESULTS: Solubilization of much of the clotted material in phosphate-buffered saline warmed to 37°C suggested the presence of soluble fibrin. Gel electrophoresis under reducing conditions showed that the most prevalent bands exhibited molecular weights corresponding to the α, ß, and γ subunits of fibrinogen with a much lighter band exhibiting the molecular weight of fibrinogen γ-γ dimer, consistent with the presence of partially crosslinked fibrin. The presence of the dimer indicated that the clotted material was caused by the action of thrombin, but also reflected the action of Factor XIIIa. No ongoing clot formation was observed. CONCLUSION: Our studies indicate that, on rare occasions, fibrinogen conversion to fibrin is responsible for observable clots in thawed cryoprecipitate pools. These clots are structurally heterogeneous, including both noncrosslinked (soluble) and crosslinked (insoluble) fibrin. This diversity in the fibrin structure may account for some of the diversity in the limited literature regarding their presence in cryoprecipitate pools.

New hemostatic dressing (FAST Dressing) reduces blood loss and improves survival in a grade V liver injury model in noncoagulopathic swine.

BACKGROUND: We performed this study to evaluate the hemostatic efficacy of the FAST Dressing in treating a grade V liver injury in noncoagulopathic swine. METHODS: Sixteen female splenectomized, noncoagulopathic swine underwent reproducible grade V liver injuries. The animals were blindly randomized to two treatment groups: (1) FAST Dressing (n = 8) or (2) IgG placebo dressing (n = 8). After 30 seconds of uncontrolled hemorrhage, dressings and manual compression were applied at 4-minute intervals. The number of dressings used, time to hemostasis, total blood loss, mean arterial pressure, blood chemistry, and total resuscitation fluid volume were monitored for 2 hours after injury. RESULTS: The mean total blood loss was 412.5 mL (SD 201.3) for the FAST Dressing group compared with 2296.6 mL (SD 1076.0) in the placebo group (p < 0.001). All animals in the FAST Dressing group achieved hemostasis and survived for the duration of the experiment (2 hours) after injury, whereas none of the animals in the placebo group attained hemostasis or survived to 2 hours after injury (p < 0.001). The mean time to hemostasis was 6.6 minutes (SD 2.5). A median of five dressings (mean absolute deviation 1.0, p = 0.007) was sufficient to control hemorrhage in the FAST Dressing group. CONCLUSION: The FAST Dressing reduced blood loss and improved survival compared with placebo in a noncoagulopathic, grade V liver injury swine model.

Clot-inducing minerals versus plasma protein dressing for topical treatment of external bleeding in the presence of coagulopathy.

BACKGROUND: Previous studies identified WoundStat (WS, smectite) and Combat Gauze (CG, kaolin-coated gauze) as the most effective available agents for controlling arterial bleeding with potential utility in casualty care. Tissue sealant properties of WS suggested its potential advantage over clot-promoting CG for treating coagulopathic bleeding. This study compared the efficacy of CG and WS with a fibrinogen-based (FAST) dressing to control bleeding in coagulopathic animals. METHODS: Coagulopathy was induced in pigs (n = 55, 35 kg) by ∼50% isovolemic hemodilution and hypothermia (core temperature, 33°C ± 0.5°C). A 6-mm arteriotomy was made in the femoral artery and free bleeding allowed for 30 seconds. A test agent (n = 13-15 per group) or control product (gauze, GZ, n = 12) was applied to the wounds and compressed with a Kerlix gauze for 2 minutes. Fluid resuscitation was given, titrated to a mean arterial pressure of 65 mm Hg. Animals were observed for 180 minutes or until death. Angiography using the computed tomography method was performed on survivors, and local tissues were collected for histology. RESULTS: No differences were seen in baseline measures. Coagulopathy, confirmed by a 31% increase in prothrombin time and a 28% reduction in clotting strength (maximum amplitude, thrombelastography assay), was similar in all groups before injury. The average pretreatment blood loss was 11.9 mL/kg ± 0.4 mL/kg with no difference among groups. Posttreatment blood loss, however, was significantly different (p = 0.015) ranging from 18.2 mL/kg ± 8.8 mL/kg (FAST) to 63.3 mL/kg ± 10.2 mL/kg (GZ controls). Stable hemostasis was achieved in 10 of 13 (FAST), 5 of 15 (CG), 2 of 15 (WS), and 1 of 12 (GZ) animals in each group, resulting in significantly different survival rates (8-77%; p = 0.001). The average survival times were 145 (FAST), 119 (CG), 75 (WS), and 74 (GZ) minutes for different groups (p < 0.002). The outcomes with the FAST dressing were significantly better than with WS or GZ in this coagulopathic bleeding model. Essentially, no difference was found between WS and GZ control. Computed tomography images showed limited blood flow only through the vessels treated with FAST dressings. Histologic observations of the vessels indicated minimal damage with FAST and CG and greater injury with WS with some residues present on the tissues. CONCLUSION: The tissue sealant property of WS is apparently mediated by clot formation in the wound; therefore, it was ineffective under coagulopathic conditions. CG was partially effective in maintaining blood pressure up to 1 hour after application. FAST dressing showed the highest efficacy because of the exogenous delivery of concentrated fibrinogen and thrombin to the wound, which bypasses coagulopathy and secures hemostasis.