Effects of a novel chitosan gel on mucosal wound healing following endoscopic sinus surgery in a sheep model of chronic rhinosinusitis

[Fundamentals and practice of the application of nasal packing in sinonasal surgery]

BACKGROUND AND OBJECTIVES

This paper presents an overview on nasal packing materials which are available in Germany. The current literature is analyzed whether there are robust criteria regarding use nasal packing after sinonasal surgery, whether there are fundamental and proven advantages or disadvantages of products, and what this means in clinical practice.

MATERIALS AND METHODS

Selective literature analysis using the PubMed database (key words "nasal packing", "nasal tamponade", "nasal surgery", "sinonasal surgery", or "sinus surgery"), corresponding text books and resulting secondary literature.

RESULTS AND CONCLUSIONS

Because of systematic methodological shortcomings, the literature does not help in the decision-making about which nasal packing should be used after which kind of sinonasal surgery. In fact, individual approaches for the many different clinical scenarios are recommended. In principle, nasal packing aims in hemostasis, should promote wound healing, and should not result in secondary morbidity. Nasal packing materials should be smooth (non-absorbable materials), inert (absorbable materials), and should not exert excessive pressure. Using non-absorbable packing entails the risk of potentially lethal aspiration and ingestion. For safety reasons inpatient control is recommended as long as this packing is in situ. With other, uncritical packing materials and in patients with special conditions, outpatient control could be justified.

Intranasal Synechiae as Complications of Rhinosurgical Treatment-A Review of Current Knowledge

Intranasal adhesions (synechiae) develop as a result of improper healing of the nasal mucosa. Their incidence ranges from 6.8% to 36% of rhinosurgical procedures. The aim of this study was to review the available publications and monographs dealing with intranasal adhesions-both in the context of formation and risk factors. The study used a review of the literature to determine the articles and studies available in the following medical databases: MEDLINE (National Library of Medicine's), PubMed, and Google Scholar. The following search terms were used: synechiae nasal + synechial nasal + intranasal adhesions + nasal adhesions. The time criterion of available materials was not applied. Available filters in the search engines were used to narrow down the search results. Artificial intelligence was not applied. The review indicated that the risk of intranasal adhesions correlates with the type of surgery, the surgical technique, the dressing materials, and wound care in the postoperative period. Every case requires an individualized approach. Nasal septum separators, (self-)dissolving dressings and (in selected cases) Mitomycin C were investigated thoroughly. Further studies are required which may result in a universal classification system for intranasal adhesions.

Self-assembling RADA16 peptide hydrogel supports hemostasis, synechiae reduction, and wound healing in a sheep model of endoscopic nasal surgery

OBJECTIVES

Complications of endoscopic sinus/nasal turbinate surgery include postoperative hemorrhage, synechiae formation, and poor wound healing. Our primary objectives were to evaluate whether a topical hydrogel based on self-assembling RADA16 peptides: i) reduces bleeding and synechiae formation, and ii) supports wound healing, using a sheep nasal surgery model.

METHODS

Thirty sheep received endoscopic surgery-created bilateral nasal mucosal injuries on the middle turbinate/opposing septum. Injuries were randomly assigned RADA16, Gelatin-thrombin, or no treatment. Outcomes included intra-operative hemostasis, scar tissue/synechiae formation and wound healing at 2 weeks and the 6-week study terminus, and histopathology.

RESULTS

Intra-operative hemostasis time improved with RADA16 and Gelatin-thrombin versus Control wounds (139.7±56.2 s, 145.4±58.1 s, and 224.0±69.9 s, respectively; p < 0.0001 for both comparisons). Two-week synechiae scores (maximum 4 points) were similar in Controls (2.9±1.8 points) and Gelatin-thrombin (3.1±1.6 points) wounds (p > 0.05), but were reduced in RADA16 sites by 91% versus Controls and 92% versus Gelatin-thrombin treatment (0.3±0.6 points; p < 0.0001 for both comparisons). Six-week synechiae scores were similar in Control (1.1±1.7 points) and Gelatin-thrombin (1.7±2.0 points) wounds (p > 0.05), but reduced 100% in RADA16-treated wounds. Synechiae occurred in fewer RADA16-treated sites at 2 weeks (20%) versus Gelatin-thrombin (80%) and Controls (75%; p < 0.01) and at 6 weeks (0%, 50% and 35%, respectively; p < 0.01). RADA16 was associated with significantly lower 6-week histopathology scores, driven by reduced submucosal fibrosis and angiogenesis.

CONCLUSION

Although RADA16 and Gelatin-thrombin similarly accelerated hemostasis in this sheep endoscopic sinus surgery model, only RADA16 reduced postoperative synechiae formation at 2 weeks with an absence of synechiae at 6 weeks. Histology suggested RADA16 enhanced mucosal regeneration.

Maximizing Postoperative Recovery: The Role of Functional Biomaterials as Nasal Packs-A Comprehensive Systematic Review without Meta-Analysis (SWiM)

Numerous biomaterials have been developed over the years to enhance the outcomes of endoscopic sinus surgery (ESS) for patients with chronic rhinosinusitis. These products are specifically designed to prevent postoperative bleeding, optimize wound healing, and reduce inflammation. However, there is no singular material on the market that can be deemed the optimal material for the nasal pack. We systematically reviewed the available evidence to assess the functional biomaterial efficacy after ESS in prospective studies. The search was performed using predetermined inclusion and exclusion criteria, and 31 articles were identified in PubMed, Scopus, and Web of Science. The Cochrane risk-of-bias tool for randomized trials (RoB 2) was used to assess each study's risk of bias. The studies were critically analyzed and categorized into types of biomaterial and functional properties, according to synthesis without meta-analysis (SWiM) guidelines. Despite the heterogeneity between studies, it was observed that chitosan, gelatin, hyaluronic acid, and starch-derived materials exhibit better endoscopic scores and significant potential for use in nasal packing. The published data support the idea that applying a nasal pack after ESS improves wound healing and patient-reported outcomes.

Wound healing in endoscopic sinus surgery: Phase 1 clinical trial evaluating the role of Chitogel with adjuvants

OBJECTIVES

This study aimed to determine the safety and efficacy of Chitogel, with and without Deferiprone (Def) and Gallium Protoporphyrin (GaPP), as a promoter of wound healing to improve surgical outcomes after endoscopic sinus susgery.

DESIGN

A double-blinded, randomised control human clinical trial was conducted in patients undergoing ESS as a treatment for chronic rhinosinusitis. Participants underwent functional ESS or FESS with drill out as required and were randomised to receive test product Chitogel, Chitogel in combination with Def or Def-GaPP versus no packing (control).

SETTING

Ostial stenosis and persistent inflammation are the main reasons for revision endoscopic sinus surgery (ESS). Post-operative (PO) dressings can improve PO wound healing and patient outcomes after ESS.

PARTICIPANTS

Eighty two patients were included in this study with 79 patients completing the study with 40 undergoing full house FESS and 39 FESS plus frontal drillout.

MAIN OUTCOME MEASURES

Patients were followed up at 2, 6 and 12 weeks PO, and outcome scores such as SNOT-22, VAS and LKS, pre and post-surgery (12 weeks) were compared.

RESULTS

Seventy nine patients completed the study, there was a significant reduction in SNOT-22 score and improvement of VAS at 12 weeks in patients treated with Chitogel compared to control (p < .05). In those patients, the mean ostium area for the Chitogel and the Chitogel + Def + GaPP groups was higher across all three sinuses compared to the no-treatment control group, without statistical significance. Sphenoid sinus ostium was significantly more patent in patients treated with Chitogel compared to the control at the 12-week time point (p < .05).

CONCLUSION

Chitogel as a PO dressing after ESS results in the best patient-reported symptom scores and objective measurements. The combination of Def and GaPP to Chitogel though proving safe, had no effect on the ostium patency or mucosal healing.

Composition, host responses and clinical applications of bioadhesives

Bioadhesives are medical devices used to join or seal tissues that have been injured or incised. They have been classified into tissue adhesives, sealants, and hemostatic agents. Bioadhesives such as FloSeal®, CoSeal®, BioGlue®, Evicel®, Tisseel®, Progel™ PALS, and TissuGlu® have been commercialized and used in clinical setting. They can be formulated with natural or synthetic components or a combination of both including albumin, glutaraldehyde, chitosan, cyanoacrylate, fibrin and thrombin, gelatin, polyethylene glycol (PEG), along with urethanes. Each formulation has intrinsic properties and has been developed and validated for a specific application. This review article briefs the mechanisms by which bioadhesives forms adhesion to tissues and highlights the correlation between bioadhesives composition and their potential host responses. Furthermore, clinical applications of bioadhesives and their application-driven requirements are outlined.

Effect of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps: A meta-analysis

A meta-analysis was performed to evaluate the effect of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps. A systematic literature search until March 2022 incorporated 386 subjects after endoscopic sinus surgery of nasal polyps at the beginning of the study; 187 were using chitosan-based gel dressing, and 199 were control. Statistical tools like the dichotomous method were used within a random or fixed-influence model to establish the odds ratio (OR) with 95% confidence intervals (CIs) to evaluate the influence of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps. Chitosan-based gel dressing had significantly lower wound infection (OR, 0.48; 95% CI, 0.25-0.92, P = 0.03), and synechia (OR, 0.25; 95% CI, 0.13-0.50, P < 0.001) compared with control in subjects with endoscopic sinus surgery of nasal polyps. However, no significant difference was found in granulations between chitosan-based gel dressing and control in subjects with endoscopic sinus surgery of nasal polyps. Chitosan-based gel dressing had significantly lower wound infection, synechia compared with control in subjects with endoscopic sinus surgery of nasal polyps, and no significant difference in granulations. Further studies are required to validate these findings.

Prevention of adhesions post-abdominal surgery: Assessing the safety and efficacy of Chitogel with Deferiprone in a rat model

Introduction

Adhesions are often considered to be an inevitable consequence of abdominal and pelvic surgery, jeopardizing the medium and long-term success of these procedures. Numerous strategies have been tested to reduce adhesion formation, however, to date, no surgical or medical therapeutic approaches have been successful in its prevention. This study demonstrates the safety and efficacy of Chitogel with Deferiprone and/or antibacterial Gallium Protoporphyrin in different concentrations in preventing adhesion formation after abdominal surgery.

Materials and methods

112 adult (8–10 week old) male Wistar albino rats were subjected to midline laparotomy and caecal abrasion, with 48 rats having an additional enterotomy and suturing. Kaolin (0.005g/ml) was applied to further accelerate adhesion formation. The abrasion model rats were randomized to receive saline, Chitogel, or Chitogel plus Deferiprone (5, 10 or 20 mM), together with Gallium Protoporphyrin (250μg/mL). The abrasion with enterotomy rats were randomised to receive saline, Chitogel or Chitogel with Deferiprone (1 or 5 mM). At day 21, rats were euthanised, and adhesions graded macroscopically and microscopically; the tensile strength of the repaired caecum was determined by an investigator blinded to the treatment groups.

Results

Chitogel with Deferiprone 5 mM significantly reduced adhesion formation (p<0.01) when pathologically assessed in a rat abrasion model. Chitogel with Deferiprone 5 mM and 1 mM also significantly reduced adhesions (p<0.05) after abrasion with enterotomy. Def-Chitogel 1mM treatment did not weaken the enterotomy site with treated sites having significantly better tensile strength compared to control saline treated enterotomy rats.

Conclusions

Chitogel with Deferiprone 1 mM constitutes an effective preventative anti-adhesion barrier after abdominal surgery in a rat model. Moreover, this therapeutic combination of agents is safe and does not weaken the healing of the sutured enterotomy site.

Injectable and Self-Healing Hydrogel with Anti-Bacterial and Anti-Inflammatory Properties for Acute Bacterial Rhinosinusitis with Micro Invasive Treatment

Systemic antibiotic therapy is the main treatment for acute bacterial rhinosinusitis (ABRS). However, this treatment often causes side effects of dizziness, diarrhea, and drug resistance. In this study, a new polyethylene glycol hydrogel (PEG-H) treatment model is developed to achieve sustained release of drugs at the locality while avoiding those adverse effects. The PEG-H is composed of 4-arm-PEG-SH and silver ions through a high affinity and dynamic reversible coordination bond between the thiol and silver ion. In the initial test, PEG-H is loaded with Clarithromycin (CAM-Lips@Hydrogel) or Clarithromycin and Budesonide liposomes (CAM+BUD-Lips@Hydrogel). The results show that PEG-H maintains the characteristics of self-healing, biodegradability, moderate swelling rate, injectibility and sustained drug release. In in vivo studies, the hydrogel is injected into the maxillary sinus of ABRS rabbit models. In both a single or combined load, the hydrogel not only plays an effective role as an anti-bacterial, but also inhibits inflammatory response of local sinus mucosa. In addition, no other side effects are observed in the ABRS rabbit model through behavioral observation and drug sensitivity tests. Therefore, the injectable self-healing hydrogel with anti-bacterial and anti-inflammatory properties provides a new micro invasive therapeutic method for the clinical treatment of ABRS.

Prevention of peridural adhesions in spinal surgery: Assessing safety and efficacy of Chitogel with Deferiprone in a sheep model

INTRODUCTION

Spinal laminectomy is a common procedure performed to relieve neural compression in patients suffering from myelopathy or radiculopathy. However, up to 40% of patients suffer from persistent post-operative pain and disability, a condition known as Failed Back Surgery Syndrome (FBSS). Excessive scarring in the surgical bed is implicated as a cause. Hydrogels have been proposed to prevent adhesion formation post-laminectomy; however, their efficacy has not been proven. This study uses Chitogel complexed with the iron chelator Deferiprone (Def) to prevent adhesion formation in a sheep laminectomy model.

MATERIAL & METHODS

Fifteen Adult Merino sheep (Ovis Aries, 1-5 yrs old) underwent laminectomy at lumbar levels 1-5 and had hydrated aluminum silicate (kaolin) applied to promote adhesion formation. Subjects were randomised to receive at each laminectomy level no-treatment control, Chitogel, Chitogel with Def at 20 mM or 40 mM or Carboxy-methyl-cellulose and Polyethylene oxide (CMC/PEO) gel. The animals were recovered for 3 months post-surgery, followed by assessment with Magnetic Resonance Imaging (MRI) and histopathology of the spinal tissues for evaluating the presence and extent of adhesions.

RESULTS

MRI and Histology assessment indicated that Kaolin induced severe inflammation with adhesion formation. Chitogel with and without 20 mM Def decreased inflammation (p < 0.01) and trended to reduce adhesions (p < 0.1). Chitogel with Def 40 mM was not significantly dis-similar to CMC/PEO and did not reduce inflammation or adhesions compared to no-treatment control.

CONCLUSION

Chitogel in combination with Def 20 mM is safe and effective in decreasing the inflammatory process and may possibly reduce post-operative adhesions following laminectomy.

Application of a Thermosensitive In Situ Gel of Chitosan-Based Nasal Spray Loaded with Tranexamic Acid for Localised Treatment of Nasal Wounds

The integrity of the nasal epithelium plays a crucial role in the airway defence mechanism. The nasal epithelium may be injured as a result of a large number of factors leading to nose bleeds, also known as epistaxis. However, local measures commonly used to treat epistaxis and improve wound healing present several side effects and patient discomfort. Hence, this study aims to address some of these drawbacks by developing a new formulation for nasal epithelial wound healing. Chitosan, a biodegradable and biocompatible polymer, was used to develop a thermosensitive nasal formulation for the delivery of tranexamic acid (TXA), one of the most effective pharmacological options to control bleeding with cost and tolerability advantages. The in situ gelation properties of the formulation upon administration in the nasal cavity were investigated in terms of gelation time and temperature. It was found that the developed formulation can undergo rapid liquid-to-gel phase change within approximately 5 min at 32°C, which is well within the human nasal cavity temperature range. The spray pattern, deposition and droplet size generated by the nasal spray was also characterised and were found to be suitable for nasal drug delivery. It was also observed that the in situ gelation of the formulation prevent nasal runoff, while the majority of drug deposited mainly in the anterior part of the nose with no lung deposition. The developed formulation was shown to be safe on human nasal epithelium and demonstrated six times faster wound closure compared to the control TXA solution.

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.

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.

Influence of chitosan-based dressing on prevention of synechia and wound healing after endoscopic sinus surgery: A meta-analysis

INTRODUCTION

Endoscopic sinus surgery (ESS) has had many complications, e.g., synechia formation. This meta-analysis investigated the effect of a novel chitosan-based dressing on prevention of synechia and wound healing after ESS.

METHODS

We systematically searched various medical literature data bases and included the randomized controlled trials (RCT) regarding the effect of novel chitosan-based dressing on ESS. The study outcomes included synechia, granulations, hemostasis, crusting scores, and infection.

RESULTS

Six RCTs, which involved 337 patients, were included in the meta-analysis. Compared with control intervention after ESS, chitosan-based gel dressing substantially inhibited synechia (risk ratio [RR] 0.28 [95% confidence interval {CI}, 0.15-0.54]; p = 0.0001), improved granulations (RR 1.47 [95% CI, 1.07-2.03]; p = 0.02), and hemostasis (RR 1.47 [95% CI, 1.07-2.03]; p = 0.02) but demonstrated no effect on crusting scores (standard mean difference -0.41 [95% CI, -1.06 to 0.23]; p = 0.21) and infection (RR 0.88 [95% CI, 0.51-1.52]; p = 0.64).

CONCLUSION

Compared with control intervention, chitosan-based dressing was associated with significantly reduced synechia and with increased granulations and hemostasis but showed no influence on crusting and infection after ESS.

Algorithm for Management of the Refractive Aerosinusitis Patient

Introduction

For some career military aviators, their ability to continue on flight status is limited by the pressure and pain of aerosinusitis, which is present only while in the flying environment. Failure to treat their disease process can mean the end of their flying careers and the loss of valuable assets trained with taxpayer dollars. Because some medications commonly used in treatment of sinus diseases are not allowed in aviation, this presents a unique problem for their medical management. Surgical treatment must be aimed at treating to symptom relief and not solely disease mitigation. One alternative is operating "beyond the scope of disease" present during a one-atmosphere clinic visit.

Materials and Methods

A case series of nine career aviators with aerosinusitis treated at one academic military Otolaryngology department in a tertiary care facility. Results from a treatment algorithm that balances symptomatology and staged surgical intervention are reviewed. The primary endpoint was return to flight duty.

Results

For patients treated according to this algorithm, the mean time to return to flight duty was 3.8 mo, requiring an average of 1.2 surgeries. To date, 100% of career aviators have returned to flight duty using this method.

Conclusion

Refractory aerosinusitis represents a potentially career-ending medical condition for the aviator and lost training costs to the taxpayers. Using the treatment algorithm presented, 100% of aviators were able to return to flight duty; a savings of millions of dollars for taxpayers. Future work will focus on modifications to the surgical techniques to reduce the extent of surgery while maintaining satisfactory results. Additional study should be undertaken to assess generalizability of these results in the broader aviation community.

Promotion of olfactory receptor neuron differentiation of olfactory neuroepithelial cells by using chitosan solution

BACKGROUND

Olfactory dysfunction significantly influences patients' quality of life. Chitosan has been reported to support neuron and Schwann cell growth and even leads to orient axonal growth. However, researchers have yet to explore whether chitosan solution can promote differentiation of olfactory receptor neurons of the olfactory neuroepithelium and be used for treating olfactory dysfunction.

OBJECTIVE

To evaluate the effect of chitosan solution on the differentiation of olfactory neuroepithelial cells.

METHOD

Olfactory neuroepithelial cells were isolated from embryonic day 17 of Wistar rats and then cultured with and without soluble chitosan for 9 days. The concentration of chitosan solution was set at 0.1 mg/mL. The effects of treatment were assessed by immunocytochemistry and Western blot after culturing.

RESULTS

The morphologic analysis indicated that olfactory neuroepithelial cells treated with chitosan exhibited bipolar shape with asymmetric processes. In addition, from days 3 to 9, the expression level of βIII tubulin gradually reduced, but the expression level of olfactory marker protein significantly rose at day 9 in the chitosan groups (p < 0.05). Importantly, chitosan-treated olfactory neuroepithelial cells expressed more signal transduction apparatuses, olfactory neuron specific-G protein and adenylate cyclase 3, than those without chitosan treatment at day 9. Western blot analysis also further confirmed the results (p < 0.05).

CONCLUSION

Experimental results revealed that soluble chitosan promoted differentiation of olfactory neuroepithelial cells based on its role in olfactory receptor neuron differentiation, neurite outgrowth, and signal transduction apparatus expressions.

Safety and Efficacy of Topical Chitogel- Deferiprone-Gallium Protoporphyrin in Sheep Model

Objectives: Increasing antimicrobial resistance has presented new challenges to the treatment of recalcitrant chronic rhinosinusitis fuelling a continuous search for novel antibiofilm agents. This study aimed to assess the safety and efficacy of Chitogel (Chitogel®, Wellington New Zealand) combined with novel antibiofilm agents Deferiprone and Gallium Protoporphyrin (CG-DG) as a topical treatment against S. aureus biofilms in vivo.

Methods: To assess safety, 8 sheep were divided into two groups of 7 day treatments (n = 8 sinuses per treatment); (1) Chitogel (CG) with twice daily saline flush, and (2) CG-DG gel with twice daily saline flush. Tissue morphology was analyzed using histology and scanning electron microscopy (SEM). To assess efficacy we used a S. aureus sheep sinusitis model. Fifteen sheep were divided into three groups of 7 day treatments (n = 10 sinuses per treatment); (1) twice daily saline flush (NT), (2) Chitogel (CG) with twice daily saline flush, and (3) CG-DG gel with twice daily saline flush. Biofilm biomass across all groups was compared using LIVE/DEAD BacLight stain and confocal scanning laser microscopy.

Results: Safety study showed no cilia denudation on scanning electron microscopy and no change in sinus mucosa histopathology when comparing CG-DG to CG treated sheep. COMSTAT2 assessment of biofilm biomass showed a significant reduction in CG-DG treated sheep compared to NT controls.

Conclusion: Results indicate that CG-DG is safe and effective against S. aureus biofilms in a sheep sinusitis model and could represent a viable treatment option in the clinical setting.

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.

Safety and Efficacy of Chitosan-Dextran Hydrogel in the Middle Ear in an Animal Model

OBJECTIVES

To investigate the efficacy of chitosan-dextran hydrogel (CDH) in preventing postoperative adhesions between the tympanic membrane (TM) and intratympanic structures, and to evaluate its ototoxicity in an animal study.

METHODS

In the first step, ototoxicity was evaluated with 7 male albino guinea pigs (GPs) via auditory brainstem responses (ABR) before and 4 weeks after unilateral intratympanic injection of CDH and saline solution contralaterally. In the second step, 12 GPs underwent bilateral ear surgery. The middle ear (ME) mucosa was abraded, and the cavity was filled with CDH on one side and packed with Gelfoam on the contralateral side. A control group of 6 GPs underwent the same procedure except that no material was applied in the ME. The animals were euthanized at the end of the 7th week, and otomicroscopic findings were noted and the temporal bones harvested for the histologic examination. The findings were scored and compared.

RESULTS

There was no statistically significant difference between the pre- and postoperative ABR thresholds. In the otomicroscopic findings, the most prominent difference between the two groups was the presence of retraction of the TM in the Gelfoam group. The histopathologic findings revealed a higher degree of inflammation in the Gelfoam group compared with the CDH group.

CONCLUSION

This study demonstrated that CDH has no ototoxic effects in GPs. Its use as an ME packing material revealed significantly less TM retraction and inflammatory reaction compared with Gelfoam.

Animal Models in CRS and Pathophysiologic Insights Gained: A Systematic Review

OBJECTIVE

Chronic rhinosinusitis (CRS) is a multifactorial inflammatory disease. In particular, CRS with eosinophilic features and/or nasal polyps (NPs) is often recalcitrant to current treatment; thus, appropriate animal models are mandatory to elucidate the pathogenesis of CRS and develop novel and efficient treatment modalities. The author reviewed the recently proposed animal models in CRS and discussed the pathophysiologic insights gained. Data Sources: Articles in the English language referenced in MEDLINE/PubMed from the year 2006 onward (for last 10 years). Review Methods: Review of the literature regarding animal models and related pathologic insights in CRS.

RESULTS

Mouse, rabbit, and sheep models of CRS have been used for studying the pathogenesis of CRS. Most of researchers adopted animal models of CRS to prove any molecular mechanisms or therapeutic efficacy. In vitro or human findings and related hypothesis were evaluated in vivo using these models. In addition, novel therapeutic candidates for CRS with or without NP have been applied to animal models.

CONCLUSION

Animal models have elicited insights into the pathogenesis of CRS and also have been useful in testing new treatment modalities. Although there are still clear limitations in the animal studies, newly proposed or revised animal models would be helpful to understand the exact pathophysiology of CRS.

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.

Efficacy of N-Acetylcysteine on Wound Healing of Nasal Mucosa

Postoperative nasal mucosa healing is a highly complex and organized process, and the success rates of endoscopic sinus surgery and septoplasty surgeries are closely associated with the postoperative wound healing processes. In this experimental study, the authors' aim was to use histopathologic examination to investigate the effects of N-Acetylcysteine (NAC) on the wound healing of rat nasal mucosa after mechanical trauma. Twenty-one Sprague-Dawley rats were randomly divided into 3 groups: the nontreated group (N = 7), the control saline group (N = 7), and the NAC group (N = 7). No treatment was given to the nontreated group for 15 days. The control saline group received intraperitoneal injection of saline (2.5  mL/kg, intraperitoneal) for 15 days and the NAC group was intraperitoneally injected with NAC at a dose of 300  mg/kg/day for 15 days. At the beginning of the study, unilateral mechanical nasal trauma was induced with an interdental brush inserted through the right nostril in all rats. Samples were stained using hematoxylin and eosin solution, and were examined by a pathologist using a light microscope. The severity of inflammation was milder in the NAC group compared with that in the nontreated and saline groups (P < 0.05). The subepithelial thickness index was lower in the experimental group (P < 0.05). Goblet cell loss was reduced in the experimental group compared with the nontreated and saline groups (P < 0.05). NAC decreases inflammation and goblet cell loss. Therefore, NAC has potential beneficial effects on the wound healing of nasal mucosa in rats.

Comprehensive review on endonasal endoscopic sinus surgery

Endonasal endoscopic sinus surgery is the standard procedure for surgery of most paranasal sinus diseases. Appropriate frame conditions provided, the respective procedures are safe and successful. These prerequisites encompass appropriate technical equipment, anatomical oriented surgical technique, proper patient selection, and individually adapted extent of surgery. The range of endonasal sinus operations has dramatically increased during the last 20 years and reaches from partial uncinectomy to pansinus surgery with extended surgery of the frontal (Draf type III), maxillary (grade 3-4, medial maxillectomy, prelacrimal approach) and sphenoid sinus. In addition there are operations outside and beyond the paranasal sinuses. The development of surgical technique is still constantly evolving. This article gives a comprehensive review on the most recent state of the art in endoscopic sinus surgery according to the literature with the following aspects: principles and fundamentals, surgical techniques, indications, outcome, postoperative care, nasal packing and stents, technical equipment.

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.

A golden experience: Fifty years of experience managing the frontal sinus

OBJECTIVES/HYPOTHESIS

The frontal sinus is one of the most anatomically complex and inaccessible of the paranasal sinuses. As a result, surgeons have continually tried to improve surgical management of the frontal sinus. The senior author (c.w.g.) shares 50 years of experience managing the frontal sinus.

DATA SOURCES

PubMed literature search.

REVIEW METHODS

Review of the literature regarding landmark innovations in frontal sinus surgery.

RESULTS

Open approaches established that the frontal sinus is accessible, and in certain circumstances, such as with large osteoma or papilloma, are still required. The endoscope changed the surgical landscape and allowed for greater finesse and decreased morbidity. Sinus balloon dilation is the newest change in frontal sinus management and shows promise in properly selected cases.

CONCLUSION

Surgery of the frontal sinus continues to evolve and improve. Although there are new techniques, the older techniques are still pertinent.

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.

Effect of aerosolized fibrin sealant on hemostasis and wound healing after endoscopic sinus surgery: a prospective randomized study

BACKGROUND

The purpose of this study was to investigate the effect of aerosolized fibrin sealant (FS) compared with that of polyvinyl acetal sponge packing on hemostasis and wound healing after functional endoscopic sinus surgery (FESS).

METHODS

We conducted a prospective randomized controlled trial of the use of aerosolized FS in 41 consecutive patients who underwent bilateral FESS between February 2011 and March 2012. The patients were randomized to receive FS applied via an aerosol spray in one nasal cavity and polyvinyl acetal sponge packing in the opposite cavity. The patients were followed up at 1, 2, 4, 8, and 12 weeks postoperatively. Crusting, adhesion, bleeding, granulation tissue formation, infection, and frontal sinus ostium stenosis after endoscopic surgery were assessed using a grading scale. Subjective symptoms related to nasal packing were evaluated using questionnaires quantified by visual analog scales.

RESULTS

The degree of granulation and crusting was significantly reduced in the side treated with FS compared with the polyvinyl acetal sponge side, as were bleeding and pain during nasal packing removal (p < 0.05). In addition, general satisfaction and willingness to reuse the material were significantly higher for the FS-treated side than for the polyvinyl acetal sponge-packed side (p < 0.001).

CONCLUSIONS

Compared with polyvinyl acetal sponge, aerosolized FS shows beneficial effects on hemostasis and wound healing after FESS. The application of FS resulted in a high degree of patient satisfaction without additional morbidity.

Synthesis, physiochemical characterization, and biocompatibility of a chitosan/dextran-based hydrogel for postsurgical adhesion prevention

An amine-functionalized succinyl chitosan and an oxidized dextran were synthesized and mixed in aqueous solution to form an in situ chitosan/dextran injectable, surgical hydrogel for adhesion prevention. Rheological characterization showed that the rate of gelation and moduli were tunable based on amine and aldehyde levels, as well as polymer concentrations. The CD hydrogels have been shown to be effective post-operative aids in prevention of adhesions in ear, nose, and throat surgeries and abdominal surgeries in vivo. In vitro biocompatibility testing was performed on CD hydrogels containing one of two oxidized dextrans, an 80 % oxidized (CD-100) or 25 % (CD-25) oxidized dextran. However, the CD-100 hydrogel showed moderate cytotoxicity in vitro to Vero cells. SC component of the CD hydrogel, however, showed no cytotoxic effect. In order to increase the biocompatibility of the hydrogel, a lower aldehyde level hydrogel was developed. CD-25 was found to be non-cytotoxic to L929 fibroblasts. The in vivo pro-inflammatory response of the CD-25 hydrogel, after intraperitoneal injection in BALB/c mice, was also determined by measuring serum TNF-α levels and by histological analysis of tissues. TNF-α levels were similar in mice injected with CD-25 hydrogel as compared to the negative saline injected control; and were significantly different (P < 0.05) as compared to the positive, lipopolysaccharide, injected control. Histological examination revealed no inflammation seen in CD hydrogel injected mice. The results of these in vitro and in vivo studies demonstrate the biocompatibility of the CD hydrogel as a post-operative aid for adhesion prevention.

Effects of caffeic acid phenethyl ester on wound healing of nasal mucosa in the rat: an experimental study

PURPOSE

Wound healing of the nasal mucosa is a highly complex process that restores the anatomical and functional integrity of tissue that has been exposed to trauma. In this experimental study, our aim was to use histopathological examination to investigate the effects of caffeic acid phenethyl ester on the wound healing of rat nasal mucosa after mechanical trauma.

MATERIALS AND METHODS

The rats were randomly divided into 3 experimental groups: a non-treated group (n=7), a control saline group (n=7) and a caffeic acid phenethyl ester group (n=7). The non-treated group received no treatment for 15 days. The second group was administered saline (2.5 mL/kg, intraperitoneal) once a day for 15 days. The third group received caffeic acid phenethyl ester intraperitoneally at a dose of 10 μmol/kg once a day for 15 days. At the beginning of the study, unilateral mechanical nasal trauma was induced on the right nasal mucosa of all rats in the three groups using a brushing technique. Samples were stained using hematoxylin and eosin solution and were examined by a pathologist using a light microscope.

RESULTS

The severity of inflammation was milder in the caffeic acid phenethyl ester group compared with that in the non-treated and saline groups (P<0.05). The subepithelial thickness index was lower in the experimental group (P<0.05). Goblet cell and ciliated cell loss was substantially reduced in the experimental group compared with the non-treated and saline groups (P<0.05).

CONCLUSIONS

Caffeic acid phenethyl ester decreases inflammation and the loss of goblet cells and ciliated cells. Therefore, caffeic acid phenethyl ester has potential beneficial effects on the wound healing of nasal mucosa in the rat.

Diode laser-induced tissue effects: in vitro tissue model study and in vivo evaluation of wound healing following non-contact application

INTRODUCTION

The basic difference between the various common medical laser systems is the wavelength of the emitted light, leading to altered light-tissue interactions due to the optical parameters of the tissue. This study examines laser induced tissue effects in an in vitro tissue model using 1,470 nm diode laser compared to our standard practice for endonasal applications (940 nm diode laser) under standardised and reproducible conditions. Additionally, in vivo induced tissue effects following non-contact application with focus on mucosal healing were investigated in a controlled intra-individual design in patients treated for hypertrophy of nasal turbinate.

METHODS

A certified diode laser system emitting the light of λ = 1470 nm was evaluated with regards to its tissue effects (ablation, coagulation) in an in vitro setup on porcine liver and turkey muscle tissue model. To achieve comparable macroscopic tissue effects the laser fibres (600 µm core diameter) were fixed to a computer controlled stepper motor and the laser light was applied in a reproducible procedure under constant conditions. For the in vivo evaluation, 20 patients with nasal obstruction due to hyperplasia of inferior nasal turbinates were included in this prospective randomised double-blinded comparative trial. The endoscopic controlled endonasal application of λ = 1470 nm on the one and λ = 940 nm on the other side, both in 'non-contact' mode, was carried out as an outpatient procedure under local anaesthesia. The postoperative wound healing process (mucosal swelling, scab formation, bleeding, infection) was endoscopically documented and assessed by an independent physician.

RESULTS

In the experimental setup, the 1,470 nm laser diode system proved to be efficient in inducing tissue effects in non-contact mode with a reduced energy factor of 5-10 for highly perfused liver tissue to 10-20 for muscle tissue as compared to the 940 nm diode laser system. In the in vivo evaluation scab formation following laser surgery as assessed clinically on endonasal endoscopy was significantly reduced on 1,470 nm treated site compared to 940 nm diode laser treated site.

CONCLUSIONS

Diode laser system (1,470 nm) induces efficient tissue effects compared to 940 nm diode laser system as shown in the tissue model experiment. From the clinical point of view, the healing process following non-contact diode laser application revealed to be improved using 1,470 nm diode laser compared to our standard diode laser practise with 940 nm.

Merocel versus Nasopore for nasal packing: a meta-analysis of randomized controlled trials

Objective

To compare the clinical outcomes, including efficacy and complications, of Merocel versus Nasopore as a nasal packing material after nasal surgery.

Methods

Relevant randomized controlled trials were identified from electronic databases (The Cochrane Library, PubMed, EMBASE, China National Knowledge Infrastructure and Chinese Biomedical Database). Conference proceedings and references from identified trials and review articles were also searched. Outcome measures were pain during nasal packing, pain and bleeding upon packing removal, pressure sensation, nasal blockage, formation of synechiae, mucosal healing, and patients' general satisfaction.

Results

Seven randomized controlled trials met criteria for analysis. Compared with Merocel, Nasopore significantly reduced patients' subjective symptoms including in situ pain (pain experienced while packing is in place), nasal pressure, pain and bleeding during packing removal, and increased patients' general satisfaction with nasal packing. There were no significant differences in nasal obstruction, adhesion and mucosal healing between the Merocel and Nasopore groups.

Conclusions

Preliminary evidence suggests that Nasopore may be superior to Merocel as a nasal packing material with regard to in situ pain, pain and bleeding upon removal, pressure, and general satisfaction and does not differ from Merocel in terms of nasal obstruction, tissue adhesion, and long-term mucosal healing.

Topical pluronic F-127 gel application enhances cutaneous wound healing in rats

Pluronic F-127 gel is used as vehicle for various topical applications. In the present study, effects of topical application of pluronic F-127 gel were evaluated in cutaneous wound healing in Wistar rats. Normal saline solution and pluronic F-127 gel (25%) were applied topically on open excision wounds for 14 days. Photography, determination of percentage wound contraction, and collection of granulation tissue were done on days 3, 7, 11 and 14 post-wounding. Topical application of gel (once daily) significantly increased the wound closure on days 11 and 14. The gel application increased the expressions of vascular endothelial growth factor (VEGF) and transforming growth factor-beta1 (TGF-β₁) on days 3 and 7. Histopathologically, more leukocyte infiltration followed by well formed granulation tissue with marked fibroblast proliferation was evident in the gel-treated group, as compared to the saline-treated control group. Immunohistochemistry of CD31 on day 7 revealed significant higher microvessel density in gel-treated wounds. Picrosirius staining demonstrated higher collagen fraction in gel-treated wounds. Thus, from the results, it could be concluded that pluronic F-127 gel has a mild inflammatory nature and enhanced the healing by stimulating expression of VEGF and TGF-β₁.

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

BACKGROUND

Achieving and maintaining haemostasis is of paramount importance in neurosurgery. Chitosan has been shown in both animal and human models to be significantly effective in haemostasis as well as in reducing adhesion formation.

OBJECTIVES

To evaluate the haemostatic potential and to study histopathological changes caused by novel chitosan dextran gel in a neurosurgical sheep model.

METHOD

Ten sheep underwent neurosurgical burr hole procedure. Bleeding control was tested at the level of bone, dura and brain separately with both chitosan gel and Gelfoam paste on separate burr holes. Baseline bleeding was measured at the time of injury using the Boezaart scale, and then every 2 min after the application of each agent until complete haemostasis or 10 min, whichever was earlier. Safety was assessed through MRI scans and histopathological analysis.

RESULTS

Mixed modeling showed no statistical difference in time to haemostasis between chitosan gel and Gelfoam paste (means of log-normalized areas under the curve were 1.3688 and 1.3196 respectively) for each burr hole (p = 0.7768). Logistic regression modeling showed that Chitosan significantly decreased the incidence of bleeding beyond the first time point measured after application of the treatment when compared to Gelfoam (OR = 2.7, p = 0.04). Average edema volume (cm(3)) on post-operative MRI was 0.97 for Gelfoam and 1.11 for (p = 0.49) while average histology scores were 2.5 for Gelfoam versus 3.3 for chitosan (p = 0.32).

CONCLUSION

Chitosan dextran gel is an effective haemostatic agent to control bleeding in brain tissue. It is safe and nontoxic to neural tissue.

A blinded randomized controlled trial evaluating the efficacy of chitosan gel on ostial stenosis following endoscopic sinus surgery

BACKGROUND

Stenosis of sinus ostia following endoscopic sinus surgery (ESS) is the most common reason for revision surgery. Chitosan-dextran (CD) gel has been shown to be an effective hemostatic agent; however, its effects on ostial stenosis are unknown. This study aims to quantify the effect of CD gel on circumferential scarring following ESS.

METHODS

A prospective, blinded, randomized, controlled trial was conducted in 26 patients undergoing ESS. Measurements of neo-ostia were taken using a standard-sized measuring probe. CD gel was applied unilaterally, while contralateral sides received no gel. Ostial diameters were measured by a blinded observer at 2, 8, and 12 weeks postoperation. Sinus ostial areas calculated as a proportion of the original were compared for each ostium at each time point.

RESULTS

Intraoperative ostial areas were comparable for CD gel and control sides (38 mm(2) vs 39 mm(2) , 131 mm(2) vs 120 mm(2) , and 203 mm(2) vs 193 mm(2) , in frontal, sphenoid, and maxillary ostia, respectively; p > 0.05). CD gel significantly improved sinus ostial patency. The largest difference was seen when ostial areas at 12 weeks were compared with their corresponding baseline areas (66% vs 31% frontal, p < 0.001; 85% vs 47% sphenoid, p < 0.001; and 74% vs 54% maxillary ostia, p = 0.002). The difference between raw ostial areas reached statistical significance in sphenoid (p < 0.001) and maxillary (p = 0.01), but not in frontal ostia (p > 0.05) at 12 weeks.

CONCLUSION

CD gel produced significantly less stenosis of all neo-ostia following ESS and may reduce the necessity for revision surgery in patients with chronic rhinosinusitis.

Sprayable chitosan/starch-based sealant reduces adhesion formation in a sheep model for chronic sinusitis

OBJECTIVES/HYPOTHESIS

Postoperative adhesion formation after endoscopic sinus surgery (ESS) remains a complication associated with high revision rates. This study determines the efficacy of a sprayable chitosan/starch-based sealant for reducing adhesions in an ESS sheep model for chronic sinusitis.

STUDY DESIGN

Prospective, blinded, randomized controlled trial.

METHODS

Sheep (n = 14) with eosinophilic rhinitis (determined by the presence of eosinophilia in nasal secretions) underwent ESS with middle turbinectomies, standardized mucosal injuries created on the lateral nasal wall, and partial thickness wounds created around the ethmoid cell region. Surgery was performed bilaterally (28 nasal cavities). Animals were randomized into treatment with sprayable chitosan/starch-based sealant (n = 7, 14 nasal cavities) or no treatment (n = 7, 14 nasal cavities). Two animals in the treatment group expired due to anesthetic complications associated with the turbinectomies, leaving five animals (10 sites) that completed the study. Presence of adhesions was assessed by endoscopic evaluation at days 14 and 28 after initial surgery. Adhesion formation was confirmed via necropsy of sinus cavities at day 28 after initial surgery.

RESULTS

Adhesions were observed in all seven control animals, resulting in an 86% (95% confidence interval [CI], 65-100) adhesion rate (12 of 14 sites). The five surviving treatment animals had a 10% (95% CI, 0-33) adhesion rate (one of 10 sites). Treatment with the sprayable chitosan/starch-based sealant resulted in a 76% reduction (95% CI, 32-100) of adhesions (P < .002).

CONCLUSIONS

In this sheep model for chronic sinusitis, treatment with sprayable chitosan/starch-based sealant reduced adhesion formation by 76% after ESS (P < .002).

Chitosan dressing promotes healing in third degree burns in mice: gene expression analysis shows biphasic effects for rapid tissue regeneration and decreased fibrotic signaling

Burns are a significant health challenge and healing can result in scar formation. Chitosan, a derivative of chitin, has been used to promote wound healing. In this study we used gene expression profiling in a mouse model of full thickness cutaneous burn to assess the benefits of treating with a chitosan lactate dressing. Three days after wounding mice treated with chitosan showed increased expression of genes associated with formation of granulation tissue. At a later time point, seven days after wounding, genes that initially showed increased expression were now down-regulated, and there was increased expression of genes involved in remodeling suggesting that the chitosan treatment results in accelerated healing. Quantitative RT-PCR showed modulated mRNA levels for TGFβ1 by the chitosan dressing. TGFβ1 initially promotes healing but extended activity can result in scarring. Importantly we found that expression was elevated at day three, but decreased at day seven suggesting that chitosan treatment will not result in scar formation, and may even be beneficial in preventing scar formation. Additionally, the biphasic regulation of expression of TGFβ1 could be a powerful biomarker for future studies of the wound-healing potential of chitosan based and other treatments for burn wounds.

A chitosan-based sinus sealant for reduction of adhesion formation in rabbit and sheep models

OBJECTIVE

Chronic sinusitis is the most prevalent chronic disease in the United States in adults aged 18 to 44 years, with approximately 250,000 operations performed annually. Although often successful, sinus surgery fails in greater than 15% of patients. Adhesion formation is a common complication and cause for subsequent revision surgery. Here, the authors evaluate a sprayable chitosan/starch-based sinus sealant and demonstrate its ability to reduce adhesion formation both in vitro and in 2 animal models.

STUDY DESIGN

Randomized, controlled, animal trials.

SETTING

Academic medical center (fibroblast experiments) and animal laboratories (sheep and rabbit studies).

SUBJECTS AND METHODS

This sinus sealant was applied to human cultured fibroblasts obtained from surgically removed polyps to examine its ability to inhibit fibroblast migration and proliferation. The sinus sealant was applied to New Zealand White rabbits (n = 20) in an established cecal-sidewall abrasion model and to sheep (n = 10) in a sinus surgical adhesion model to examine its ability to reduce adhesion formation.

RESULTS

This sinus sealant inhibited migration and proliferation of human cultured fibroblasts and reduced the total adhesion score from 4.9 to 0.3 for a total reduction of 94% (95th percentile confidence interval [CI], 78%, 100%; P < .001) in a well-established rabbit cecal-sidewall model commonly used for adhesion testing. Moreover, this sealant reduced adhesion formation from 80% to 10% for a total reduction of 70% (95th percentile CI, 57%, 93%; P = .003) in a sheep sinus adhesion surgical model.

CONCLUSION

This chitosan-based sealant demonstrates promise for reducing adhesion formation in sinus surgery.

Chitosan preparations for wounds and burns: antimicrobial and wound-healing effects

Since its discovery approximately 200 years ago, chitosan, as a cationic natural polymer, has been widely used as a topical dressing in wound management owing to its hemostatic, stimulation of healing, antimicrobial, nontoxic, biocompatible and biodegradable properties. This article covers the antimicrobial and wound-healing effects of chitosan, as well as its derivatives and complexes, and its use as a vehicle to deliver biopharmaceuticals, antimicrobials and growth factors into tissue. Studies covering applications of chitosan in wounds and burns can be classified into in vitro, animal and clinical studies. Chitosan preparations are classified into native chitosan, chitosan formulations, complexes and derivatives with other substances. Chitosan can be used to prevent or treat wound and burn infections not only because of its intrinsic antimicrobial properties, but also by virtue of its ability to deliver extrinsic antimicrobial agents to wounds and burns. It can also be used as a slow-release drug-delivery vehicle for growth factors to improve wound healing. The large number of publications in this area suggests that chitosan will continue to be an important agent in the management of wounds and burns.

Microporous polysaccharide hemospheres do not increase synechiae after sinus surgery: randomized controlled study

BACKGROUND

Many surgeons use absorbable packing materials after endoscopic sinus surgery (ESS). Despite their popularity, some of these agents have been shown to contribute to synechiae formation. Microporous polysaccharide hemospheres (MPH) is a plant-based hemostatic powder that does not interfere with regenerating sinus mucosa in the animal model. The goal of this study was to examine the impact of MPH on healing and synechiae formation after ESS in human subjects.

METHODS

A prospective, randomized, controlled, double-blind study was performed. Forty consenting adult patients with chronic sinusitis requiring symmetric ESS were randomized to receive MPH unilaterally at the conclusion of surgery. The opposite side was untreated. Standard postoperative care was performed bilaterally. Outcomes measured included blinded observer ratings for synechiae formation, edema, and infection. Each side was examined endoscopically and scored at postoperative days 7, 14, and 30.

RESULTS

Twenty men and 20 women with an average age of 48.2 years were included. There were no complications and all patients were discharged home the same day. There was no significant difference in synechiae formation at any point postoperatively. The rate of synechiae formation was determined to be 10% (4/40) on the MPH-treated side versus 7.5% (3/40) on the untreated side (p = 0.7639). In addition, there were no significant differences observed in edema (p = 0.7480) or infection (p = 0.5533).

CONCLUSION

The use of MPH after sinus surgery does not increase synechiae formation and does not appear to deleteriously affect the healing of postoperative sinus cavities.

Antimicrobial properties of a chitosan dextran-based hydrogel for surgical use

A chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activity in vitro against a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species. Scanning and transmission electron microscopy were carried out to elucidate the antimicrobial mechanism of this compound. CD hydrogel was found to be effective against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Clostridium perfringens at its surgical concentration of 50,000 mg/liter. Minimum bactericidal concentrations ranged from 2,000 to 50,000 mg/liter. Dextran aldehyde (DA) was found to be the antimicrobial component of the CD hydrogel with MBC ranging from 2,000 to 32,000 mg/liter. S. aureus appeared to be killed at a slightly faster rate than E. coli. Candida albicans and Pseudomonas aeruginosa were more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy of E. coli and S. aureus incubated with CD hydrogel and DA alone revealed morphological damage, disrupted cell walls, and loss of cytosolic contents, compatible with the proposed mode of action involving binding to cell wall proteins and disruption of peptide bonds. Motility and chemotaxis tests showed E. coli to be inhibited when incubated with DA. The antibacterial activity of CD hydrogel may make it a useful postsurgical aid at other body sites, especially where there is a risk of Gram-positive infections.