Agentes hemostáticos tópicos em cirurgia: revisão e perspectivas

The use of Arista AH as a local haemostatic agent in distal splenopancreatectomy: report of two cases

Bleeding is still one of the most feared intraoperative and postoperative complications that can lead to an increase in morbidity, mortality, length of hospital stay and costs. Nowadays, in addition to accurate surgical techniques, several local haemostatic agents are available and can be used in case of oozing bleeding. Herein, we report our experience with a ready-to-use polysaccharide powder in two patients undergoing distal splenopancreatectomy. Bleeding control was achieved in both cases. No patient showed postoperative bleeding, and no other complications were reported.

Protective Topical Dual-Sided Nanofibrous Hemostatic Dressing Using Mussel and Silk Proteins with Multifunctionality of Hemostasis and Anti-Bacterial Infiltration

Topical hemostatic agents are preferred for application to sensitive bleeding sites because of their immediate locoregional effects with less tissue damage. However, the majority of commercial hemostatic agents fail to provide stable tissue adhesion to bleeding wounds or act as physical barriers against contaminants. Hence, it has become necessary to investigate biologically favorable materials that can be applied and left within the body post-surgery. In this study, a dual-sided nanofibrous dressing for topical hemostasis is electrospun using a combination of two protein materials: bioengineered mussel adhesive protein (MAP) and silk fibroin (SF). The wound-adhesive inner layer is fabricated using dihydroxyphenylalanine (DOPA)-containing MAP, which promotes blood clotting by aggregation of hemocytes and activation of platelets. The anti-adhesive outer layer is composed of alcohol-treated hydrophobic SF, which has excellent spinnability and mechanical strength for fabrication. Because both proteins are fully biodegradable in vivo and biocompatible, the dressing would be suitable to be left in the body. Through in vivo evaluation using a rat liver damage model, significantly reduced clotting time and blood loss are confirmed, successfully demonstrating that the proposed dual-sided nanofibrous dressing has the right properties and characteristics as a topical hemostatic agent having dual functionality of hemostasis and physical protection.

Topical Hemostatic Agents and Risk of Postoperative Hemorrhage After Transoral Robotic Surgery

Objective: Postoperative hemorrhage is the most common complication of transoral robotic surgery (TORS). The available research literature on topical hemostatic agents is deficient, despite their wide use. This study aims to evaluate the frequency and severity of hemorrhagic events after TORS procedures, performed with various topical hemostatic agents. Methods: This study was planned as a retrospective review to identify postoperative hemorrhage events in a database of all consecutive adult patients who required TORS from January 1, 2015, to April 1, 2020. All procedures were performed in one single institution by the same surgeon. In 2017, bovine gelatin matrix with thrombin (BgMT) was replaced by the porcine gelatin matrix with thrombin (PgMT) for all procedures. Postoperative hemorrhage was identified, along with hemostatic agents employed and other variables. Results: A cohort of 80 TORS procedures was obtained from a population of 78 individuals (60 males:18 females). BgMT was used in 28 procedures (35%), and five cases of postoperative hemorrhage were identified (17.8%), two of them were severe. PgMT was used in 52 procedures (65%) just observing one minor hemorrhagic event (1.92%). Although a significant difference was observed for total events between groups (P = .0183), there was no difference between major or severe hemorrhagic events (P = .1196). The overall rate of major and severe postoperative hemorrhage in the study population was 2.5% (n = 80). Conclusions: This is the first study to evaluate topical hemostatic agents during TORS procedures. The PgMT group had a reduced incidence of total postoperative hemorrhages, although there was no difference in the number of severe hemorrhagic events. The overall simplicity and cost-effectiveness of these agents would support their use, particularly considering the potential risk associated with airway hemorrhage.

The importance of coordination in preventing overdiagnosis: a retrospective analysis of unabsorbed oxidized regenerated cellulose

BACKGROUND

Oxidized regenerated cellulose (ORC) is commonly used to control small intraoperative bleedings in lung cancer surgery. However, difficulties in its absorption may lead to complications that can mimic malignancy recurrence in the affected areas, and may require further examination.

METHODS

Between 2015 and 2022, patients who underwent malignant tumour resection and lymph node dissection and were subsequently evaluated for suspected lymph node recurrence and underwent EBUS-guided needle biopsy were included in the study. Pathology reports of these patients showed an ORC-related foreign body type granulomatous reaction. Such reactions, caused by delayed absorption of ORC, can mimic malignancy recurrence and result in unnecessary biopsies.

RESULTS

In a total of 13 patients (10 males), pathology was observed in 18 lymph node areas after malignant resection and lymph node dissection, and ORC was detected in subcarinal and inferior paratracheal lymph node areas in all patients. The average age of the patients was calculated as 63.1 years (range 51-74). The mean SUVmax value observed in these lymph node areas on PET/CT was 5.22 (range 0-14.36). Although the SUVmax value decreased as the time between surgery and EBUS increased, no statistically significant difference was observed (p = 0.100).

CONCLUSION

The study suggests that in cases of suspected unexpected lymph node recurrence in postoperative follow-up of lung cancer, it is important for clinicians to communicate with the surgeon and re-evaluate the use of ORC by reviewing the operative notes. This may help in determining an appropriate further investigation strategy.

Risk of bleeding in anticoagulated patients undergoing dental extraction treated with topical tranexamic acid compared to collagen-gelatin sponge: Randomized clinical trial

This two-arm, parallel-group, double-blind, randomized clinical trial design evaluated the risk of postoperative bleeding in anticoagulated patients undergoing dental extraction treated with topical TXA in comparison to collagen-gelatin sponge. Forty patients were randomly included in one of the study groups: (1) topical use of 4.8% TXA solution; and (2) resorbable hydrolyzed collagen-gelatin sponge applied to the surgical alveolus. Primary outcomes were postoperative bleeding episodes and secondary outcomes were thromboembolic events and postoperative INR values. The relative risk (RR), the absolute risk reduction (RAR) and the number needed to treat (NNT) were used as effect estimates and calculated from the counting of bleeding episodes observed during the first postoperative week. The bleeding rate under the TXA treatment was 22.2%, while in the collagen-gelatin sponge group it was 45.7%, resulting in a RR of 0.49 (95% CI 0.24-099; p = 0.046), RAR 23.5% and NNT 4.3. TXA was more effective in reducing bleeding in surgical sites located in the mandible (RR = 0.10; 95% CI 0.01-0.71; p = 0.021) and the posterior region (RR = 0.39; 95% CI 0.18-0.84; p = 0.016). Within the limitations of the study it seems that topical TXA is more effective in controlling bleeding after tooth extractions in anticoagulated patients than collagen-gelatin sponge. CLINICAL TRIAL REGISTRATION: RBR-83qw93.

Advances in the development and optimization strategies of the hemostatic biomaterials

Most injuries are accompanied by acute bleeding. Hemostasis is necessary to relieve pain and reduce mortality in these accidents. In recent years, the traditional hemostatic materials, including inorganic, protein-based, polysaccharide-based and synthetic materials have been widely used in the clinic. The most prominent of these are biodegradable collagen sponges (Helistat^®, United States), gelatin sponges (Ethicon^®, SURGIFOAM^®, United States), chitosan (AllaQuixTM, ChitoSAMTM, United States), cellulose (Tabotamp^®, SURGICEL^®, United States), and the newly investigated extracellular matrix gels, etc. Although these materials have excellent hemostatic properties, they also have their advantages and disadvantages. In this review, the performance characteristics, hemostatic effects, applications and hemostatic mechanisms of various biomaterials mentioned above are presented, followed by several strategies to improve hemostasis, including modification of single materials, blending of multiple materials, design of self-assembled peptides and their hybrid materials. Finally, the exploration of more novel hemostatic biomaterials and relative coagulation mechanisms will be essential for future research on hemostatic methods.

Validity of a novel ex vivo porcine liver perfusion model for studying haemostatic products

Introduction

We developed a novel normothermic ex vivo porcine liver perfusion model with whole blood in order to have alternatives for animal experiments in the research and development of new local haemostatic agents. This study aims to assess the construct and content validity of this model.

Methods

In this study we performed two ex vivo experiments using nine livers and one in vivo experiment using six female Norsvin Topigs pigs: (1) ex vivo liver perfusion for establishing physiological blood parameters of the perfused liver and controlled heparinization, (2) ex vivo liver perfusion with a surgical injury and (3) a surgical liver injury in anaesthetized pigs with and without heparin.

Results

Ex vivo coagulation parameters were comparable to in vivo with heparin. Blood gas values and metabolic parameters were comparable between ex vivo and in vivo with heparin, but significantly different compared with in vivo baseline, with the exception of (partial pressure of oxygen (PO2). Activated clotting time (ACT) values significantly differed depending on the heparin doses. The coagulation parameters fibrinogen, activated partial thromboplastin time, prothrombin time and ACT were rather constant during the 4 h ex vivo perfusion. Haemostatic efficacy of commercially available products was comparable between in vivo with heparin and the ex vivo liver perfusion experiment.

Conclusion

This novel ex vivo liver perfusion model demonstrates good construct and content validity for at least 4 h of perfusion. The model is an easily accessible, table-top, tunable and effective alternative for the in vivo testing of (new) haemostatic products on their haemostatic properties. Validité d'un nouveau modèle de perfusion hépatique porcin ex-vivo pour l'étude des produits hémostatiques Résumé

Evaluating the risk of post-operative abscess formation following use of hemostatic agents at time of hysterectomy

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Use of hemostatic agent at time of hysterectomy is not associated with post-operative abscess formation in this small study.

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Hemostatic agent use is associated with increased post-operative emergency room visits and readmissions.

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Overuse of hemostatic agents at time of hysterectomy may contribute to post-operative adverse events.

Objective

At an academic institution in rural Virginia, we noticed a trend of increased re-admissions for postoperative pelvic abscesses. The primary study objective was to determine if intraoperative use of hemostatic agents (HA) was associated with postoperative abscess formation in patients undergoing hysterectomy.

Methods

Retrospective chart review identified women who underwent hysterectomy by a Gynecologic Oncologist for any indication at a single institution from January 1, 2019 through December 31, 2019. Patient and surgical characteristics were abstracted and comparisons were made among those who received any HA and those that did not. The relationship between intraoperative HA use and postoperative pelvic abscess formation was determined using multivariate logistic regression. Secondary outcomes evaluated included the presence of other major post-operative adverse events.

Results

428 hysterectomies were identified with a postoperative pelvic abscess rate of 3.7 %. Abscesses were identified in 4 (2.2 %) of cases without vs 12 (4.9 %) of cases with HA use with a logistic regression model demonstrating no significant difference in the groups (OR = 2.10, p = 0.22). Data showed an increase in presentation to the Emergency Department (ED) (OR = 3.43, p = 0.002 adjusted) and higher odds of readmission within 30 days of surgery (OR = 3.19, p = 0.03) with HA use.

Conclusions

No association was found between HA use and abscess formation; however, data showed HA use was associated with increased odds of presentation to the ED and readmission to the hospital within 30 days of surgery. Given the potential negative impact on patient outcomes, use of these products at time of hysterectomy should be made with careful consideration.

Design of nanoconstructs that exhibit enhanced hemostatic efficiency and bioabsorbability

Hemorrhage is a prime cause of death in civilian and military traumatic injuries, whereby a significant proportion of death and complications occur prior to paramedic arrival and hospital resuscitation. Hence, it is crucial to develop hemostatic materials that are able to be applied by simple processes and allow control over bleeding by inducing rapid hemostasis, non-invasively, until subjects receive necessary medical care. This tutorial review discusses recent advances in synthesis and fabrication of degradable hemostatic nanomaterials and nanocomposites. Control of assembly and fine-tuning of composition of absorbable (i.e., degradable) hemostatic supramolecular structures and nanoconstructs have afforded the development of smart devices and scaffolds capable of efficiently controlling bleeding while degrading over time, thereby reducing surgical operation times and hospitalization duration. The nanoconstructs that are highlighted have demonstrated hemostatic efficiency pre-clinically in animal models, while also sharing characteristics of degradability, bioabsorbability and presence of nano-assemblies within their compositions.

Exploring Adverse Events and Utilization of Topical Hemostatic Agents in Surgery

Background and Objectives:

This retrospective study provides preliminary qualitative assessment of the adverse events (AEs), focusing on pelvic and abdominal AEs and patient outcomes reported for three hemostatic agents used in gynecologic surgery.

Methods:

Utilization rates for oxidized regenerated cellulose powder (ORC), polysaccharide powder (PSP), and fibrin sealant solution (FSS) were obtained from hospitals via the Premier Healthcare databases for all surgical procedures from January 1, 2018 to September 30, 2020. All reported cases were extracted from the Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database for ORC and PSP and from the FDA Adverse Event Reporting System (FAERS) database for FSS. Distributions of AEs by anatomical site (MAUDE/FAERS) and surgical procedures by specialty (Premier) were evaluated for each product. Number of cases and number and types of AEs were compared to the total utilization for each product.

Results:

PSP was the most used product during the period analyzed (n = 126,509 uses), followed by FSS (n = 80,628 uses), and ORC (n = 41,583 uses). Distribution of surgical procedures by anatomical site varied significantly between hemostatic agents (p < 0.001). ORC was associated with more patient cases with AEs and numbers of reported AEs compared with PSP and FSS (p < 0.001). ORC was associated with higher number of infections than PSP (p < 0.001) and FSS (p < 0.001).

Conclusion:

These findings suggest that ORC use in abdominal and pelvic surgery may result in more postoperative complications compared with non-ORC hemostatic agents. Further prospective randomized studies are needed to compare efficacy and safety of these products.

Silk Fibroin Based Formulations as Potential Hemostatic Agents

Effective hemorrhage control is indispensable for life-threatening emergencies in defense fields and civilian trauma. During major injuries, hemostatic agents are applied externally to mimic and accelerate the natural hemostasis process. Commercially available topical hemostatic agents are associated with several limitations, e.g., burning sensation, necrosis, futile in severe injuries, and high costs of the products. In the present study, we developed silk fibroin fiber-based formulations and evaluated their use as a cost-effective potential hemostatic agent with shortened clotting time. Silk fiber-based powder was produced following the alkaline hydrolysis process, wherein Bombyx mori silk fibroin fibers were treated with sodium hydroxide (NaOH) solution that randomly chopped the silk microfibers. Physicochemical reaction parameters, e.g., reaction temperature, molarity of NaOH solution, and incubation time, were optimized to achieve the maximum yield of microfibers. The surface properties of alkaline hydrolyzed silk microfibers (AHSMf) were analyzed by field emission scanning electron microscopy and energy dispersive X-ray studies. The water uptake capacity of AHSMf and the change in pH and temperature (∼30 °C) during blood clotting were analyzed. Further, the hemostatic potential of AHSMf was evaluated by an in vitro whole blood clotting assay using both goat and human blood. The in vitro studies demonstrated a reduced blood clotting time (CT = 20-30 s), prothrombin time (PT = ∼27%), and activated partial thromboplastin time (APTT = ∼14%) in the presence of AHSMf when compared to silk hydrogel powder (devoid of NaOH). Thus, the developed AHSMf could be a promising material to serve as a potential hemostatic agent.

In Vitro Evaluation of Real-Time Viscoelastic and Coagulation Properties of Various Classes of Topical Hemostatic Agents Using a Novel Contactless Nondestructive Technology

Hemorrhaging is the main cause of death among combat and civilian injuries and has significant clinical and economic consequences. Despite their vital roles in bleeding management, an optimal topical hemostatic agent (HA) has yet to be developed for a particular scenario. This is partly due to a lack of an overarching quantitative testing technology to characterize the various classes of HAs in vitro. Herein, the feasibility of a novel, contactless, and nondestructive technique to quantitatively measure the shear storage modulus (G') and clotting properties of whole blood in contact with different dosages of eight topical HAs, including particulates and gauze-like and sponge-like systems, was assessed. The real-time G'-time profiles of these blood/HA systems revealed their distinct biomechanical behavior to induce and impact coagulation. These were analyzed to characterize the clot initiation time, clotting rate, clotting time, and apparent stiffness of the formed clots (both immediately and temporally), which were correlated with their reported hemostatic mechanisms of action. Moreover, the HAs that worked independently from the natural blood clotting cascade were identified and quantified through this technology. In sum, this study indicated that the nondestructive nature of the technology may offer a promising tool for accurate, quantitative in vitro measurements of the clotting properties of various classes of HAs, which may be used to better predict their in vivo outcomes.

Polymeric Materials for Hemostatic Wound Healing

Hemorrhage is one of the greatest threats to life on the battlefield, accounting for 50% of total deaths. Nearly 86% of combat deaths occur within the first 30 min after wounding. While external wound injuries can be treated mostly using visual inspection, abdominal or internal hemorrhages are more challenging to treat with regular hemostatic dressings because of deep wounds and points of injury that cannot be located properly. The need to treat trauma wounds from limbs, abdomen, liver, stomach, colon, spleen, arterial, venous, and/or parenchymal hemorrhage accompanied by severe bleeding requires an immediate solution that the first responders can apply to reduce rapid exsanguinations from external wounds, including in military operations. This necessitates the development of a unique, easy-to-use, FDA-approved hemostatic treatment that can deliver the agent in less than 30 s and stop bleeding within the first 1 to 2 min at the point of injury without application of manual pressure on the wounded area.

Topical hemostatic agents in neurosurgery, a comprehensive review: 15 years update

Hemostasis in neurosurgery is of utmost importance. Bleeding management is one of the crucial steps of each neurosurgical procedure. Several strategies, namely thermal, mechanical, electric, and chemical, have been advocated to face blood loss within the surgical field. Over time, countless hemostatic agents and devices have been proposed. Furthermore, the ever-growing recent technological innovation has made available several novel and interesting tools. Pursuant to their impact on surgical practice, we perceived the imperative to update our previous disclosure paper. Therefore, we reviewed the literature and analyzed technical data sheets of each product in order to provide an updated and comprehensive overview in regard to chemical properties, mechanisms of action, use, complications, tricks, and pitfalls of topical hemostatic agents.

Tranexamic acid in head and neck procedures: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

We conducted a meta-analysis of all randomized controlled trials (RCTs) that examined the benefits of tranexamic acid (TXA) among cancer patients undergoing head and neck (H&N) procedures.

METHODS

We screened five databases from inception until 20 June 2021 and evaluated the risk of bias of the eligible studies. We pooled continuous outcomes using the weighted mean difference (WMD) with 95% confidence interval (CI).

RESULTS

Five studies, comprising seven RCTs, met the inclusion criteria. This meta-analysis included a total of 540 patients; 265 and 275 patients were assigned to the TXA and control group, respectively. Overall, the included RCTs revealed a low risk of bias. The volume of postoperative bleeding was significantly lower in favor of the TXA group compared with the control group (n = 7 RCTs, WMD = - 51.33 ml, 95% CI [- 101.47 to - 1.2], p = 0.04). However, no significant difference was found between both groups regarding the volume of intraoperative bleeding (n = 6 RCTs, WMD = - 3.48 ml, 95% CI [- 17.11 to 10.15], p = 0.62), postoperative hemoglobin (n = 3 RCTs, WMD = 0.42 mg/dl, 95% CI [- 0.27 to 1.11], p = 0.23), duration of drainage tube removal (n = 4 RCTs, MD = - 0.41 days, 95% CI [- 1.14 to 0.32], p = 0.27), and operation time (n = 6 RCTs, WMD = 1.59 min, 95% CI [- 10.09 to 13.27], p = 0.79). TXA was safe and did not culminate in thromboembolic events or major coagulation derangements.

CONCLUSION

TXA administration is safe and significantly reduces the volume of postoperative bleeding. However, no difference is identified between TXA and control groups regarding the volume of intraoperative bleeding, postoperative hemoglobin level, duration of drainage tube removal, and operation time.

Hemostatic materials in wound care

Blood plays an essential role in the human body. Hemorrhage is a critical cause of both military and civilian casualties. The human body has its own hemostatic mechanism that involves complex processes and has limited capacity. However, in emergency situations such as battlefields and hospitals, when the hemostatic mechanism of the human body itself cannot stop bleeding effectively, hemostatic materials are needed for saving lives. In this review, the hemostatic mechanisms and performance of the most commonly used hemostatic materials, (including fibrin, collagen, zeolite, gelatin, alginate, chitosan, cellulose and cyanoacrylate) and the commercial wound dressings based on these materials, will be discussed. These materials may have limitations, such as poor tissue adhesion, risk of infection and exothermic reactions, that may lessen their hemostatic efficacy and cause secondary injuries. High-performance hemostatic materials, therefore, have been designed and developed to improve hemostatic efficiency in clinical use. In this review, hemostatic materials with advanced performances, such as antibacterial capacity, superhydrophobicity/superhydrophilicity, superelasticity, high porosity and/or biomimicry, will be introduced. Future prospects of hemostatic materials will also be discussed in this review.

An Injectable Hybrid Gelatin Methacryloyl (GelMA)/Phenyl Isothiocyanate-Modified Gelatin (Gel-Phe) Bioadhesive for Oral/Dental Hemostasis Applications

Biomaterials are widely used for effectively controlling bleeding in oral/dental surgical procedures. Here, gelatin methacryloyl (GelMA) was synthesized by grafting methacrylic anhydride on gelatin backbone, and phenyl isothiocyanate-modified gelatin (Gel-Phe) was synthesized by conjugating different gelatin/phenyl isothiocyanate molar ratios (G/P ratios) (i.e., 1:1, 1:5, 1:10, 1:15, 1:25, 1:50, 1:100, and 1:150) with gelatin polymer chains. Afterward, we combined GelMA and Gel-Phe as an injectable and photo-crosslinkable bioadhesive. This hybrid material system combines photo-crosslinking chemistry and supramolecular interactions for the design of bioadhesives exhibiting a highly porous structure, injectability, and regulable mechanical properties. By simply regulating the G/P ratio (1:1-1:15) and UV exposure times (15-60 s), it was possible to modulate the injectability and mechanical properties of the GelMA/Gel-Phe bioadhesive. Moreover, we demonstrated that the GelMA/Gel-Phe bioadhesive showed low cytotoxicity, a highly porous network, and the phenyl-isothiourea and amine residues on Gel-Phe and GelMA polymers with synergized hemostatic properties towards fast blood absorption and rapid clotting effect. An in vitro porcine skin bleeding and an in vitro dental bleeding model confirmed that the bioadhesive could be directly extruded into the bleeding site, rapidly photo-crosslinked, and reduced blood clotting time by 45%. Moreover, the in situ crosslinked bioadhesive could be easily removed from the bleeding site after clotting, avoiding secondary wound injury. Overall, this injectable GelMA/Gel-Phe bioadhesive stands as a promising hemostatic material in oral/dental surgical procedures.

Evaluation of the hemostatic effect of a combination of hemostatic agents and fibrin glue in a rabbit venous hemorrhage model

BACKGROUND

In neurosurgery, it is important to use local hemostatic agents. We have explored a more powerful method of hemostasis by the combination of commercially available hemostatic agents with fibrin glue in the hopes of synergistic effects.

METHOD

A bleeding model was constructed by puncturing the rabbit posterior vena cava with a needle. After applying the sample to the bleeding point, compression was performed for 10 s. If temporary hemostasis was achieved after pressure release, a 30 s wash was performed to confirm that ultimate hemostasis was achieved. Up to three hemostasis attempts were performed on the same bleeding point until hemostasis was achieved, and the number of attempts required for hemostasis was counted. If hemostasis was not achieved after three attempts, it was counted as four times. Four groups were evaluated: (1) gelatin sponge alone, (2) gelatin sponge + fibrin glue, (3) oxidized cellulose alone, and (4) oxidized cellulose + fibrin glue; each group was tested 16 times.

RESULTS

The median value (range minimum value-maximum value) of the number of hemostatic attempts in Group 1 to Group 4 was 3 (1-4), 1 (1-1), 4 (4-4), and 4 (2-4). In Group 2, there were two test exclusions owing to deviations of the test procedure.

CONCLUSIONS

The compatibility of gelatin sponge and fibrin glue was very good, with a very strong and rapid hemostatic effect compared to other methods, showed its usefulness. This combination method may be effective for a variety of venous hemorrhages in neurosurgery.

[Local application of recombinant activated factor VII for massive surgical bleeding]

The authors report resection of anaplastic convexital meningioma in a middle-aged woman complicated by expected massive blood loss. The most intense bleeding occurred at the final stage of resection and it was impossible to stop it with traditional approaches. The surgeon pressed a standard tachocomb plate moistened with a diluted solution of recombinant activated factor VII (coagil, Russia) to the most bleeding area for 5 minutes. Subsequently, surgeon replaced finger pressure with a permanent napkin. Hemostatic effect of recombinant activated factor VII following its systemic administration is well known and convincingly proven in many surgical areas including neurosurgery. However, we do not know any descriptions of its local application in neurosurgical patients.

Fast acting hemostatic agent based on self-assembled hybrid nanofibers from chitosan and casein

Hemorrhage is a leading cause of preventable death in both military combat and civilian accidents. To overcome these challenges, an affordable and effective bandage is must required substance. A novel strategy is reported for developing chitosan-casein (CC) based self-assembled nanofibrous polyelectrolyte complex (PEC) for rapid blood clotting. The amide group (1630 cm^-1) and phosphate group (910 cm^-1) of chitosan-casein can form PEC at pH 8.2 ± 0.2. The PECs contain intertwined nanofibers (≤100 nm diameter) with a high surface area. Increasing chitosan percentage from 30% (CC30) to 50% (CC50) or 70% (CC70) results, increase in zeta potential of PEC from -9.14 ± 3.3 to 7.46 ± 3.7 and 14.8 ± 3.3 mV, respectively. Under in vitro conditions, the CC30, CC50, and CC70 PECs allow platelet adhesion and rapidly absorbs blood fluid to form mechanically stable blood clots within 9 ± 3, 16 ± 3, and 30 ± 4 s, respectively, which are better than Celox™ (90 ± 3 s). In vivo application of PEC (CC50) causes clotting within 37 ± 6 s of large (1 cm) arterial incision in rabbit models. The PEC is biocompatible with promising hemostatic efficiency. This is the first report of nanofibrous PEC from chitosan and casein for rapid clotting, to the best of our knowledge.

Clinical Use of the Self-Assembling Peptide RADA16: A Review of Current and Future Trends in Biomedicine

RADA16 is a synthetic peptide that exists as a viscous solution in an acidic formulation. In an acidic aqueous environment, the peptides spontaneously self-assemble into β-sheet nanofibers. Upon exposure and buffering of RADA16 solution to the physiological pH of biological fluids such as blood, interstitial fluid and lymph, the nanofibers begin physically crosslinking within seconds into a stable interwoven transparent hydrogel 3-D matrix. The RADA16 nanofiber hydrogel structure closely resembles the 3-dimensional architecture of native extracellular matrices. These properties make RADA16 formulations ideal topical hemostatic agents for controlling bleeding during surgery and to prevent post-operative rebleeding. A commercial RADA16 formulation is currently used for hemostasis in cardiovascular, gastrointestinal, and otorhinolaryngological surgical procedures, and studies are underway to investigate its use in wound healing and adhesion reduction. Straightforward application of viscous RADA16 into areas that are not easily accessible circumvents technical challenges in difficult-to-reach bleeding sites. The transparent hydrogel allows clear visualization of the surgical field and facilitates suture line assessment and revision. The shear-thinning and thixotropic properties of RADA16 allow its easy application through a narrow nozzle such as an endoscopic catheter. RADA16 hydrogels can fill tissue voids and do not swell so can be safely used in close proximity to pressure-sensitive tissues and in enclosed non-expandable regions. By definition, the synthetic peptide avoids potential microbiological contamination and immune responses that may occur with animal-, plant-, or mineral-derived topical hemostats. In vitro experiments, animal studies, and recent clinical experiences suggest that RADA16 nanofibrous hydrogels can act as surrogate extracellular matrices that support cellular behavior and interactions essential for wound healing and for tissue regenerative applications. In the future, the unique nature of RADA16 may also allow us to use it as a depot for precisely regulated drug and biopharmaceutical delivery.