The efficacy and safety of chitosan dextran gel in a burr hole neurosurgical sheep model

Functional Analysis of Injectable Substance Treatment on Surgically Injured Rabbit Vocal Folds

OBJECTIVES

The objective of this study was to evaluate the efficacy of immediate injection treatments of dexamethasone, hyaluronic acid (HA)/gelatin (Ge) hydrogel and glycol-chitosan solution on the phonatory function of rabbit larynges at 42 days after surgical injury of the vocal folds, piloting a novel ex vivo phonatory functional analysis protocol.

METHODS

A modified microflap procedure was performed on the left vocal fold of 12 rabbits to induce an acute injury. Animals were randomized into one of four treatment groups with 0.1 mL injections of dexamethasone, HA/Ge hydrogel, glycol-chitosan or saline as control. The left mid vocal fold lamina propria was injected immediately following injury. The right vocal fold served as an uninjured control. Larynges were harvested at Day 42 after injection, then were subjected to airflow-bench evaluation. Acoustic, aerodynamic and laryngeal high-speed videoendoscopy (HSV) analyses were performed. HSV segments of the vibrating vocal folds were rated by three expert laryngologists. Six parameters related to vocal fold vibratory characteristics were evaluated on a Likert scale.

RESULTS

The fundamental frequency, one possible surrogate of vocal fold stiffness and scarring, was lower in the dexamethasone and HA/Ge hydrogel treatment groups compared to that of the saline control (411.52±11.63 Hz). The lowest fundamental frequency value was observed in the dexamethasone group (348.79±14.99 Hz). Expert visual ratings of the HSV segments indicated an overall positive outcome in the dexamethasone treatment group, though the impacts were below statistical significance.

CONCLUSION

Dexamethasone injections might be used as an adjunctive option for iatrogenic vocal fold scarring. An increased sample size, histological correlate, and experimental method improvements will be needed to confirm this finding. Results suggested a promising use of HSV and acoustic analysis techniques to identify and monitor post-surgical vocal fold repair and scarring, providing a useful tool for future studies of vocal fold scar treatments.

A comparison of effectiveness between Posisep and Merocel nasal packing after endoscopic sinus surgery: Findings from a randomized, double-blinded, controlled trial

BACKGROUND

The effectiveness of nonabsorbable and biodegradable nasal packing is still controversial, and the choice of nasal packing type can alter the outcome of endoscopic sinus surgery. This study compared the effectiveness of Posisep and Merocel as nasal packing materials with regard to hemostasis, adhesion, wound healing, patient's satisfaction and health-related quality of life after endoscopic sinus surgery (ESS).

METHODS

A prospective, randomized, double-blinded, controlled trial was conducted in patients with chronic rhinosinusitis refractory undergoing symmetrical bilateral ESS. At the completion of surgery, a nasal packing (either Merocel or Posisep) was randomly chosen and placed into the middle meatus of each nasal cavity. All patients were scheduled for follow-up visits at 24 hours, 5 days, 3 weeks, and 5 weeks days after surgery. Health-related quality of life was measured using the Sino-Nasal Outcome Test (SNOT-22). The overall inflammatory burden of chronic rhinosinusitis was measured by the Lund-Mackay postoperative endoscopic score (LMES).

RESULTS

Among 62 patients included in data analysis (n = 31 for each group), the mean age was 42.4 years and 54.8% were females. Patients with Posisep after ESS had more improvement and better symptoms measured through SNOT-22 and LMES at 24 hours, 5 days, and 3 weeks than those with Merocel after ESS. While some aspects measured by LMES such as discharge and scarring were still better until 5 weeks after surgery, all symptoms measured by SNOT-22 were similar between the 2 groups 5 weeks after surgery.

CONCLUSION

Posisep containing chitosan provided patients with a better quality of life throughout the early recovery period compared with Merocel. Although more studies are needed, our findings support the use of Posisep after ESS.

Haemostatic efficacy and inflammatory response of a novel beta-chitin patch in a cerebral small vessel injury model - A pilot study

OBJECTIVE

Rapid and efficacious haemostasis is paramount in neurosurgery. Assessing the efficacy and short- and long-term safety of haemostatic agents utilised within cerebral tissue is essential. This pilot study investigates the haemostatic efficacy and long-term safety of a novel beta-chitin patch against traditionally used agents, bipolar and Floseal, within cerebral tissue.

METHODS

Eighteen Merino sheep underwent standardised distal cortical vessel injury via temporal craniotomy. Sheep were randomised to receive 2 mls Floseal, 2 cm novel beta-chitin patch, or bipolar cautery to manage bleeding. All sheep underwent cerebral magnetic resonance imaging (MRI) at three months, before euthanasia and brain harvesting for histological assessment.

RESULTS

Beta-chitin demonstrated a trend towards a faster mean time to haemostasis (TTH) compared to Floseal (223.3 ± 199 s v. 259.8 ± 186.4 s), albeit non-significant (p = 0.234). Radiologically, cerebrocortical necrosis (p = 0.842) and oedema (p = 0.368) were noted slightly more frequently in the beta-chitin group. Histologically, severe fibrotic (p = 0.017) and granulomatous changes at the craniotomy sites were only present in the beta-chitin group (p = 0.002). Neuronal degeneration was seen in all with Floseal, but beta-chitin showed a trend towards more severe reaction when present. Bipolar use predominantly showed an inflammatory cortical reaction with substantial microvascular proliferation, and Floseal showed worse severity and depth of subpial oedema, however no statistical significance was reached.

CONCLUSION

All haemostats controlled bleeding, with beta-chitin demonstrating a non-inferior TTH compared to Floseal. However, it resulted in intense granulomatous and fibrotic changes, including degenerative neuronal reactions. More extensive studies are needed to assess these trends, to make further clinical inferences.

Efficacy and Safety of Novel Beta-Chitin Patches as Haemostat in Rat Vascular and Neurosurgical Model

Background

Intraoperative hemorrhage is a major cause of poor post-operative outcome. Beta-chitin patch has previously been found to be an effective haemostat, but whether modifying the patch can improve its efficacy and safety, remains unknown. In this study, beta-chitin patches were modified using polyethylene oxide, Pluronic-F127 (Chi/F127), calcium (Chi/20%Ca), increased thickness (Chi/Thick) or polyphosphate (Chi/PP).

Objective

Using rat (Wistar Albino; 8–10 weeks old) vascular and neurosurgical models, this project investigated and compared the efficacy and safety of beta-chitin patches with gauze, Surgicel and FloSeal.

Methods

Ninety rats underwent a standardized femoral artery injury and were randomized to receive either beta-chitin patches, gauze, Surgicel or FloSeal. The bleeding time and total blood loss was measured. For the neurosurgical model, forty-four rats underwent a standardized cortical injury and randomization to a treatment group. Following a 48 h recovery period, their brains were collected for histopathological examination.

Results

The mean bleeding time with Chitin (120.8 s) and Chi/PP (117.3 s) was ~60 s lower than Chi/F127, Chi/20%Ca and Chi/Thick (p < 0.05). Chitin and Chi/PP had a significantly lower bleeding time than FloSeal (174.2 s) (p < 0.05), but not Surgicel (172.7 s). Gauze (400 s) had a significantly higher bleeding time compared to all other groups (p < 0.05). There were no significant differences in the total blood loss between the groups. Histopathological examination of brains found no adverse inflammatory reaction to any of the haemostatic compounds.

Conclusion

Chi/PP had superior haemostatic efficacy compared to Surgicel and FloSeal, but not compared to non-modified beta-chitin patch. All of the haemostats were equally safe.

Immunological Risk Assessment of Xenogeneic Dural Patch by Comparing with Raw Material via GTKO Mice

OBJECTIVE

In this study, α-Gal epitope-deficient (GGTA1 knockout (GTKO)) mice were used to assess the immunological risks of xenogeneic dural patch by comparing with raw material.

METHODS

The xenogeneic dural patch (T2) was prepared from bovine pericardium (T1, raw material) through decellularization and carboxymethyl chitosan (CMCS) coating. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the collagen fibers and surface microstructural changes in the T1 and T2 samples. The remnant α-Gal epitopes and DNA of implants were detected by standardized method. T1 and T2 were implanted subcutaneously into GTKO mice for 4 and 12 weeks, respectively, and the negative control group (Con) was only performed sham operation. The total serum antibody, anti-Gal antibody, and splenic lymphocyte subtypes were analyzed by ELISA or flow cytometry, and histological analysis of implant-tissue was performed by H&E and Masson stain.

RESULTS

TEM and Sirius red staining showed that the collagen fibers in the dural patch were closely arranged, and SEM showed that a loose three-dimensional structure was successfully constructed on the surface of the dural patch after CMCS coating. The remnant DNA in T2 was 24.64 ± 8.73 ng/mg (dry weight), and clearance of α-Gal epitope was up to 99.83% compared to T1. The significant increases in serum total IgM, anti-Gal IgG, and anti-Gal IgM at 4 weeks and the significant changes in anti-Gal IgG and spleen lymphocyte at 12 weeks were observed in the T1 group, but no significant change was observed in the T2 group, compared to the control group. Histological semiquantitative analysis showed severe cell and tissue responses at 4 weeks and a moderate response at 12 weeks in the T1 group, while a moderate response at 4 weeks and a slight response at 12 weeks in the T2 group.

CONCLUSIONS

The results demonstrated that the xenogeneic dural patch has a lower and acceptable immunological risk compared to the raw material and control, respectively. On the other hand, it was suggested that GTKO mice are useful experimental model for immunological risk assessment of animal tissue-derived biomaterials.

The potential of chitosan-based haemostats for use in neurosurgical setting - Literature review

Haemorrhage is a major nuance in neurosurgery since blood can distort the surgeon's field of view and increase the risk of post-operative complications. Currently a variety of commercially available haemostats have been approved for use in neurosurgery, but they have caveats to their use in the brain, including, localised tissue compression, neural toxicity, induce immune reaction or form thrombus within the vessel. Thus, there is a need for haemostats that are efficacious and safe for application on brain and spinal tissue. Chitosan is a naturally occurring bio-polymer that is found on the exoskeleton of arthropods and the cell wall of fungi. Chitosan has been shown to accelerate haemostasis through a myriad of physiological pathways. These findings have led to the development of multiple chitosan-based haemostats, for use in peripheral human tissue. Although, clinical data regarding the use of chitosan-based haemostats in the brain is lacking, a range on in vivo studies have proven chitosan to be efficacious and safe in managing neurosurgical bleeds. Similarly, literature comparing chitosan-based haemostats with commercial haemostats used commonly in neurosurgery, have all demonstrated chitosan to be the superior agent. Additionally, clinical trials of chitosan-based haemostat used in peripheral tissue have all demonstrated chitosan to be safe for human use. The marriage of these findings indicates that the safety and superior efficacy of chitosan-based haemostat, makes it a potentially suitable haemostat for use in neurosurgical setting. However, further research pertaining to the clinical use of chitosan-based haemostat within the central nervous system needs to be conducted.

Efficacy and histopathological effects of self-assembling peptides RADA16 and IEIK13 in neurosurgical hemostasis

There is a continued need for effective hemostatic agents that are safe for neurosurgical use. Self-assembling peptide hydrogels have been suggested as novel hemostatic agents. They offer some advantages for neurosurgical hemostasis (e.g., transparency), but their efficacy and safety for neurosurgery has not been established. In this paper, the efficacy and safety of two self-assembling peptides, RADA16 and IEIK13, are explored for hemostasis of oozing bleeding on the rat cerebral cortex (n=56). Chronic safety was evaluated by neuropathological evaluation at one, four, and twelve weeks after craniotomy (n=32). An inactive control and oxidized cellulose served as comparators. Mean time-to-hemostasis was significantly shorter for RADA16 and IEIK13 compared to controls, while safety evaluation yielded similar results. Histopathological response consisted primarily of macrophage infiltration at the lesion site in all groups. This study confirms the hemostatic potential and safety of RADA16 and IEIK13 for hemostasis in the rat brain.

The effect of chemical and structural modifiers on the haemostatic process and cytotoxicity of the beta-chitin patch

Beta-chitin patch has previously been proven to be an effective haemostat, but whether modifying the patch affects its efficacy and safety, remains unanswered. In this study, the patch was modified using polyethylene oxide, Pluronic-F127, calcium, increased thickness or polyphosphate, and their effect on the process of haemostasis and cytotoxicity was tested and compared with standard-of-care, Surgicel and FloSeal. Whole blood collected from volunteers was applied to the patches to test their whole blood clotting and thrombin generation capacities, whilst platelet isolates were used to test their platelet aggregation ability. The fluid absorption capacity of the patches was tested using simulated body fluid. Cytotoxicity of the patches was tested using AlamarBlue assays and PC12 cells and the results were compared with the standard-of-care. In this study, beta-chitin patch modifications failed to improve its whole blood clotting, platelet aggregation and thrombin generation capacity. Compared to non-modified patch, modifications with polyethylene oxide or calcium reduced platelet aggregation and thrombin generation capacity, while increasing the thickness or adding polyphosphate decreased platelet aggregation capacity. The cytotoxicity assays demonstrated that the beta-chitin patches were non-toxic to cells. In vivo research is required to evaluate the safety and efficacy of the beta-chitin patches in a clinical setting.

The role of hemostatic devices in neurosurgery. A systematic review

Hemostasis represents a fundamental step in every surgical procedure. During neurosurgical procedures, proper and robust hemostasis into confined spaces can significantly reduce the odds of perioperative complications. Over the decades, multiple methods have been applied, and several medical devices have been developed to promote and guarantee proper hemostasis. This study presents a systematic review of the most used intraoperative hemostatic methods and devices in neurosurgery. Insightful research was performed on the PubMed database according to the PRISMA guidelines. This comprehensive review of scientific literature represents a synoptic panel where the most used intraoperative hemostatic methods and devices available today in neurosurgery are classified and described.

In vivo systemic toxicity assessment of an oxidized dextrin-based hydrogel and its effectiveness as a carrier and stabilizer of granular synthetic bone substitutes

The worldwide incidence of bone disorders is raising, mainly due to aging population. The lack of effective treatments is pushing the development of synthetic bone substitutes (SBSs). Most ceramic-based SBSs commercially available display limited handling properties. Attempting to solve these issues and achieve wider acceptance by the clinicians, granular ceramics have been associated with hydrogels (HGs) to produce injectable/moldable SBSs. Dextrin, a low-molecular-weight carbohydrate, was used to develop a fully resorbable and injectable HG. It was first oxidized with sodium periodate and then cross-linked with adipic acid dihydrazide. The in vivo biocompatibility and safety of the dextrin-based HG was assessed by subacute systemic toxicity and skin sensitization tests, using rodent models. The results showed that the HG did not induce any systemic toxic effect, skin reaction, or genotoxicity, neither impaired the bone repair/regeneration process. Then, the HG was successfully combined with granular bone substitute, registered as Bonelike (250-500 μm) to obtain a moldable/injectable SBS, which was implanted in tibial fractures in goats for 3 and 6 weeks. The obtained results showed that HG allowed the stabilization of the granules into the defect, ensuring effective handling, and molding properties of the formulation, as well as an efficient cohesion of the granules. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1678-1689, 2019.

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility.

In vitro genotoxicity assessment of an oxidized dextrin-based hydrogel for biomedical applications

Hydrogels are three-dimensional, crosslinked networks of hydrophilic polymers swollen with a large amount of water or biological fluids, without dissolving. Dextrin, a low-molecular-weight carbohydrate composed by glucose residues, has been used to develop an injectable hydrogel for biomedical applications. Dextrin was first oxidized to introduce aldehyde groups, which then reticulate with adipic acid dihydrazide, forming the dextrin-based hydrogel (HG). The HG and its components were tested for cyto- and genotoxicity according to the International Standard ISO 10993-3 on the biological evaluation of medical devices. To assess genotoxicity, a battery of in vitro genotoxicity tests employing both eukaryotic and prokaryotic models was performed: comet assay, cytokinesis-block micronucleus assay and Ames test. Our data revealed that the HG (IC₅₀  = 2.8 mg/mL) and oxidized dextrin by itself (IC₅₀  = 1.2 mg/mL) caused a concentration-dependent decrease in cellular viability of human lymphoblastoid TK6 cells after 24 hours of exposure to the test agents. However, these concentrations are unlikely to be reached in vivo. In addition, no significant increase in the DNA and chromosomal damage of TK6 cells exposed to non-cytotoxic concentrations of the HG and its isolated components was detected. Furthermore, neither the HG nor its metabolites exerted a mutagenic effect in different of Salmonella typhimurium strains and in an Escherichia coli mix. Our data demonstrated the genocompatibility of the HG (up to 3.5 mg/mL) for biomedical applications. To our best acknowledge, this is the first report with a detailed genotoxicity assessment of an aldehyde-modified polysaccharide/adipic acid dihydrazide hydrogel.

Topical application of the hematostatic agent Surgiflo® could attenuate brain injury in experimental TBI mice

OBJECT

The pathologies resulting from traumatic brain injury (TBI) have been thoroughly studied, but rarely have the effects of bleeding and coagulation in the early stage of TBI been considered. In this study, we investigated the effects of topical Surgiflo^® application on brain injury in experimental TBI mice using S100β, MAP-2 and mNSS scores.

METHODS

TBI was induced by modified weight drop injury in male C57BL/6 mice. The mice were then randomly divided into (i) the sham group, (ii) TBI mice applied with saline (vehicle), and (iii) TBI mice applied with Surgiflo^® in the same volume. Modified neurological severity scores (mNSS) were measured on days 0 (before surgery), 1, 3, 7, and 28 to evaluate neurologic functional deficits. At day 28, the mice were sacrificed, and the forebrains were sliced. The effects of Surgiflo^® on microtubule-associated protein 2 and serum S100β protein were examined by immunohistochemistry and electro-chemiluminescence immunoassay.

RESULTS

Serum S100β protein levels were significantly elevated at different time points (24 h, 3 days, 7 days) in the TBI groups (p  <  0.01) compared to normal control groups. Surgiflo^® induced a lower concentration of serum S100β protein levels at day 3 (p < 0.05) and day 7 (p < 0.05) compared to the TBI group applied with saline. H&E staining showed that Surgiflo^® treatment led to a 45% decrease in cortical brain lesion volume and in subcortical white matter 28 days after TBI. Compared with the saline-treated group, the number of MAP2-positive cells was significantly increased in the perilesional area of the Surgiflo^®-treated group. The Surgiflo^®-treated group exhibited lower mNSS scores on days 7 and 28 than did the saline-treated group.

DISCUSSION

Surgiflo^® treatment produced a significant decrease in serum S100β protein levels in TBI mouse models, which may lead to an improvement in the recovery of TBI models.

Efficacy of chitosan dressing on endoscopic sinus surgery: a systematic review and meta-analysis

Chitosan dressing might be promising to promote the recovery following endoscopic sinus surgery (ESS). However, the results remain controversial. We conducted a systematic review and meta-analysis to explore the influence of chitosan dressing on ESS. PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases were systematically searched. Randomized controlled trials (RCTs) assessing the effect of chitosan dressing on endoscopic sinus surgery were included. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. The primary outcomes were synechia and hemostasis. Meta-analysis was performed using random-effect model. Four RCTs involving 268 patients were included in the meta-analysis. Overall following ESS, compared with control intervention, chitosan dressing significantly reduced synechia (RR = 0.25; 95% CI 0.13-0.49; P < 0.0001) and promoted hemostasis (RR = 1.70; 95% CI 1.37-2.11; P < 0.00001), but showed no impact on granulations (RR = 1.18; 95% CI 0.72-1.95; P = 0.52), mucosal edema (RR = 0.88; 95% CI 0.60-1.29; P = 0.51), crusting (RR = 0.85; 95% CI 0.48-1.53; P = 0.60), and infection (RR = 0.88; 95% CI 0.51-1.52; P = 0.64). Compared to control intervention, chitosan dressing could significantly decrease edema and improve hemostasis, but had no effect on granulations, mucosal edema, crusting and infection.

Effect of a Chitosan Gel on Hemostasis and Prevention of Adhesion After Endoscopic Sinus Surgery

OBJECTIVES

Postoperative bleeding and adhesion formation are the two most common complications after endoscopic sinus surgery (ESS). The former sometimes can be life threatening and the latter is the most common reason requiring revision surgery. This study was designed to evaluate the effect of newly developed chitosan gel (8% carboxymethyl chitosan, Surgi shield) on hemostasis and wound healing after ESS.

METHODS

A prospective, randomized, double-blind controlled trial was conducted in 33 patients undergoing symmetric ESS. At the conclusion of the operation, Surgi shield was randomly applied on one side of the nasal cavity, with the opposite side acting as control and the bleeding quantity of the surgical field was evaluated every 2 minutes. And then, Merocel was placed in the ethmoidectomized areas of the both sides. Five milliliters of Surgi shield was applied to the Merocel of intervention side and saline was applied to the other side. Merocel in both nasal cavities was removed and 5 mL of Surgi shield was applied again to the intervention side on the second day after surgery. The nasal cavity was examined using a nasal endoscope and the degree of adhesion, crusting, mucosal edema, infection, and granulations were graded at 1, 2, and 4 weeks after surgery.

RESULTS

Complete hemostasis was rapidly achieved in the Surgi shield applied side compared with the control side at 2, 4, 6, 8, and 10 minutes after application of Surgi shield (P=0.007, P=0.004, P<0.001, P=0.001, and P<0.001, respectively). There were significantly less adhesions on the Surgi shield applied side at postoperative 1, 2, and 4 weeks (P=0.001, P<0.001, and P<0.001, respectively). The degree of mucosal edema, infection, crusting, or granulation formation assessed by the endoscopic features in the Surgi shield applied side was not significantly different from that of the control side (P>0.05). No adverse effects were noted in the patient series.

CONCLUSION

Surgi shield containing chitosan can be used safely to achieve rapid hemostasis immediately after ESS and to prevent adhesion formation.

Effect of Plasma Sterilization on the Hemostatic Efficacy of a Chitosan Hemostatic Agent in a Rat Model

INTRODUCTION

The United States military has had success with chitosan (CS)-based hemostatic agents to control trauma-induced hemorrhages. Despite the positive reviews, additional physical forms of CS may enhance its hemostatic efficacy. Additionally, standard sterilization techniques may negatively affect the hemostatic efficacy of CS. We studied the effects of a CS-based hemostatic pad, the Clo-Sur P.A.D.™ (Scion Cardio-Vascular, Inc.), on severe femoral vessel bleeding in a rat model. The effects of different sterilization techniques on the bioadhesivity, surface atomic concentrations, and hemostatic efficacy of the P.A.D. were also evaluated.

METHODS

Hemostatic efficacy, bioadhesivity, and surface atomic concentrations of the P.A.D. were evaluated in its unsterilized form, after sterilization with standard e-beam treatment, and after sterilization with one of three types of non-thermal nitrogen plasma: nitrogen gas, air, or nitrous oxide plasma. After standardized puncture of the femoral artery or transection of the femoral vessels, rats were treated with either a CS P.A.D. or gauze pad.

RESULTS

The Clo-Sur P.A.D., regardless of sterilization technique, stopped arterial and mixed arterial/venous bleeding in all cases in <90 s with the time to hemostasis (TTH) significantly less for all P.A.D. treatment groups (P < 0.001; n = 4-5/group) compared to gauze-treated controls (n = 3). E-beam sterilized P.A.D.s consistently showed non-significant trends toward increased TTH and worse hemostasis scores compared to unsterilized and plasma sterilized P.A.D.s. Treating e-beam sterilized P.A.D.s with N2 plasma reverted the hemostatic efficacy to levels equivalent to native, unsterilized PADs.

CONCLUSION

A CS-based hemostatic pad successfully controlled severe bleeding in a rat model with combined e-beam and plasma sterilized P.A.D.s showing the most promising results. Further studies are warranted.

Product comparison model in otolaryngology: Equivalency analysis of absorbable hemostatic agents after endoscopic sinus surgery

OBJECTIVES/HYPOTHESIS

Evidence-based medicine in otolaryngology literature continues to be lacking, especially with regard to new products brought to market. The marketing of products often includes statements of benefit that have limited objective support in research or literature. To address this, and to adequately determine product equivalency/superiority, careful evaluation must be made. In order to establish standards for this process in rhinology products, we directly compare three different absorbable hemostatic agents in patients with chronic rhinosinusitis (CRS) after undergoing endoscopic sinus surgery (ESS), using both objective and subjective outcomes.

STUDY DESIGN

Double-blinded prospective (level 1) comparison and equivalency analysis of three plant-based absorbable hemostatic agents (carboxymethylcellulose [CMC] gel, mucopolysaccharide hemospheres (MPH), and potato starch wafer) in patients undergoing bilateral ESS.

METHODS

Patients with medically refractory CRS who underwent bilateral ESS were recruited and prospectively followed. At the conclusion of ESS, one of three different hemostatic agents was applied to each nasal passage. Subjective patient data was obtained using rated symptoms compared between the two sides (nasal obstruction, bleeding, pain, and nasal discharge) at baseline and on postoperative days 1, 7, and 14. Objective data was obtained by blinded endoscopic scoring to rate mucosal edema, inflammation, granulation, crusting, infection, and synechiae formation on postoperative weeks 1, 3, and 6.

RESULTS

Forty-eight patients who underwent ESS for CRS were included. There is no statistical difference in subjective scores for any of the variables measured, although (MPH) nearly reached statistical significance at postoperative day 7 for increased pain (P = 0.06) and obstruction (P = 0.22). Objective measures showed equivalency between all products, except the CMC gel approached significance at week 3 for increased crusting (P = 0.10), granulation (P = 0.24), and debridement (P = 0.07). At 6 weeks, increased debridement (P = 0.14) also approached significance.

CONCLUSION

Careful and deliberate consideration should be taken when choosing products to assist our surgical endeavors. Subjectively, patients treated with MPH showed near-significant increases in pain and obstruction. In objective measures, CMC gel nearly reaches significance for more postoperative debridement, with increased crusting and inflammation. Product choice could consider these factors, although it remains at the discretion of the surgeon. This model of comparison allows careful product comparison and should be applied to other hemostatics, as well as other materials in use in otolaryngology.

LEVEL OF EVIDENCE

1b. Laryngoscope, 126:S5-S13, 2016.

Reducing the Oxidation Level of Dextran Aldehyde in a Chitosan/Dextran-Based Surgical Hydrogel Increases Biocompatibility and Decreases Antimicrobial Efficacy

A highly oxidized form of a chitosan/dextran-based hydrogel (CD-100) containing 80% oxidized dextran aldehyde (DA-100) was developed as a post-operative aid, and found to significantly prevent adhesion formation in endoscopic sinus surgery (ESS). However, the CD-100 hydrogel showed moderate in vitro cytotoxicity to mammalian cell lines, with the DA-100 found to be the cytotoxic component. In order to extend the use of the hydrogel to abdominal surgeries, reformulation using a lower oxidized DA (DA-25) was pursued. The aim of the present study was to compare the antimicrobial efficacy, in vitro biocompatibility and wound healing capacity of the highly oxidized CD-100 hydrogel with the CD-25 hydrogel. Antimicrobial studies were performed against a range of clinically relevant abdominal microorganisms using the micro-broth dilution method. Biocompatibility testing using human dermal fibroblasts was assessed via a tetrazolium reduction assay (MTT) and a wound healing model. In contrast to the original DA-100 formulation, DA-25 was found to be non-cytotoxic, and showed no overall impairment of cell migration, with wound closure occurring at 72 h. However, the lower oxidation level negatively affected the antimicrobial efficacy of the hydrogel (CD-25). Although the CD-25 hydrogel's antimicrobial efficacy and anti-fibroblast activity is decreased when compared to the original CD-100 hydrogel formulation, previous in vivo studies show that the CD-25 hydrogel remains an effective, biocompatible barrier agent in the prevention of postoperative adhesions.