The effects of mitomycin C and 5-fluorouracil/triamcinolone on fibrosis/scar tissue formation secondary to subglottic trauma (experimental study)

Management and Discussion of COVID-19 Related Tracheal Stenosis: A Single Center Retrospective Review

SARS-CoV-2 virus has led to an unprecedented amount of tracheal stenosis. Rigid bronchoscopy can serve as a curative measure or bridge therapy to tracheal resection. We also briefly discuss the pathophysiology of tracheal stenosis from prolonged intubation and SARS-CoV-2 virus. This should be differentiated from other forms of airway obstruction such as tracheobronchomalacia which would be considered a pseudo-tracheal stenotic disease. The aim of this study is to evaluate stenosis that is unable to be improved with positive airway pressure or "PAP" therapies and required stenting and/or subsequent tracheal resection. By performing Rigid Bronchoscopy and subsequent stenting of airways, we demonstrated outcomes for long term airway patency regarding patients who were intubated secondary to the SARS-CoV-2 virus. We demonstrate superb outcomes in a consecutive case series of 6 patients managed with rigid bronchoscopy, airway stent and tracheal resection. The patients were all managed from a pulmonary perspective by the physicians mentioned in this study.

Topical 1% 5-fluorouracil eye drops as primary treatment for ocular surface squamous neoplasia: Long-term follow-up study

PURPOSE

To determine the efficacy and safety of topical 1% 5-fluorouracil (5FU) eye drops as primary treatment of ocular surface squamous neoplasia (OSSN).

METHODS

Patients were diagnosed with OSSN based on slit-lamp examination and anterior segment optical coherence tomography (AS-OCT). In ambiguous cases an incisional biopsy was performed. All were treated with 5FU eye drops as primary therapy and retrospectively reviewed. Data on demographics, tumor characteristics, treatment outcome, and side effects were collected. The primary outcome measures were resolution frequency and recurrence rate of OSSN. Secondary outcomes were risk factors for resolution and recurrence, and side effects of treatment.

RESULTS

The mean age of 251 subjects (258 eyes) was 67.5 ± 11.7 years, 182 were male. Patients were followed up on average for 752 ± 580 days. Overall, 87% of patients experienced complete tumor resolution. Multivariable analysis revealed that superior tumor location (HR: 0.62, 95% CI: 0.41-0.93, p = 0.02) and leukoplakia (HR: 0.65, 95% CI: 0.41-0.93, p = 0.02), decreased the likelihood of tumor resolution. The recurrence rate was 4% at six months, 8% at one year, and 19% at two years. Larger tumor area increased chances of tumor recurrence (HR: 1.01, 95% CI: 1.00-1.02 p = 0.03). The most common side effects of 5-FU were mild hyperemia and pain, which occurred in 26% and 23% of patients, respectively. Among the sight-threatening side effects, limbal stem cell deficiency occurred in only 3% of patients.

CONCLUSIONS

Topical 1% 5FU eye drops are a safe and effective medication for OSSN. Superior tumor location and leukoplakia decreased the chance of tumor resolution.

Use of MRI to Assess the Regenerative Effects of Adipose Tissue Derived Mesenchymal Stem Cells in a Rabbit Cartilaginous Laryngeal Defect Model

Background

Stenosis and scar formation after repair of laryngeal tissue defects are serious problems that can significantly influence a patient's quality of life.

Objective

In this study, we evaluated the use of magnetic resonance imaging to assess the efficacy of adipose tissue-derived mesenchymal stem cells (ASCs) on cartilaginous regeneration in an experimental rabbit model.

Methods

Ten male white Dutch rabbits each had a 5 mm cartilaginous defect created surgically in the right and left thyroid lamina. On the right side, ASCs labeled with iron oxide particles were infused. As a control, the left side was left untreated. Repair of the defects were then evaluated by direct observation, histological evaluation, and magnetic resonance imaging monitoring done on days 1, 7, 14, and 28.

Results

Histological examination revealed that compared with control, transplanted ASCs significantly increased cartilage regeneration (P ˂ 0.001), reduced inflammation (P ˂ 0.001), and fibrosis (P = 0.050). Magnetic resonance imaging tracking showed accurate placement and viability of the infused ASCs, as evidenced by low signal intensity onT2 weighted images at the level of the right thyroid cartilage.

Conclusions

Infusion of ASCs improved laryngeal regeneration of surgically induced cartilaginous defects while decreasing fibrous tissue formation in this in vivo rabbit model. Furthermore, magnetic resonance imaging was shown to be a useful, noninvasive method to track correct ASCs placement and viability in cartilage regeneration in this animal model.

Randomized Controlled Trial of Balloon Dilation in Treatment of Subglottic Stenosis With a Rabbit Model

OBJECTIVES

Identify the effects of balloon dilation duration and topical ciprofloxacin-dexamethasone application in treatment of subglottic stenosis.

STUDY DESIGN

Randomized controlled trial.

SETTING

Animal research facility.

SUBJECTS AND METHODS

Forty-four rabbits underwent subglottic injury in an Institutional Animal Care and Use Committee-approved study. One week after injury, the subglottis of each rabbit was measured and treated with endoscopic balloon dilation for 2 rounds of short duration (SBD; 3 seconds), long duration (LBD; 30 seconds), or LBD with topical ciprofloxacin-dexamethasone application (LBD+C). The subglottis of each rabbit was remeasured at the study endpoint: 1 month postdilation or following development of life-threatening respiratory distress.

RESULTS

Of 44 rabbits, 35 (80%) survived to endoscopic balloon dilation, with 21 rabbits developing a grade III Cotton-Myer stenosis. Prior to dilation, there was no difference in stenosis rates among groups (all subjects, P = .99; grade III stenosis only, P = .52). Among grade III subjects, improvement in stenosis after dilation was -1% (SD, 21%) for SBD, 27% (SD, 38%) for LBD, and 58% (SD, 29%) for LBD+C (P = .01). Early euthanasia/death rates among grade III subjects were 85% for SBD, 63% for LBD, and 17% for LBD+C (P = .03). Time to early euthanasia/death was 5.0 days for the SBD group and 8.4 days for the LBD group (P = .04).

CONCLUSION

SBD was inferior to LBD or LBD+C in multiple metrics. LBD+C offered significant improvements in stenosis size and mortality over the SBD group and had the lowest rate of early mortality. Further research is needed to identify optimal balloon dilation treatment duration.

The Healing Effect of Amniotic Membrane in Laryngeal Defects in Rabbit Model

OBJECTIVE

Fibrosis and scar formation following laryngeal repairing is a major concern. This study evaluated the efficacy of applying amniotic membrane (AM) as a biologic dressing to reduce fibrosis and inflammation and promote cartilage repair.

STUDY DESIGN

Experimental animal study.

METHODS

Nine male white Dutch rabbits were selected. A standard defect (5 mm) was created in right and left thyroid lamina. In the right side, two layers of AM were applied while the left side was kept intact for future comparison. Histologic examination with criteria of inflammation, fibrosis, and cartilage regeneration was performed 2, 4, and 6 weeks following AM application. All procedures were done according to animal ethics rules.

RESULTS

Histologic and gross examination showed that AM application was able to reduce inflammation and fibrosis and improve cartilage regeneration significantly.

CONCLUSION

As a useful intervention, AM application can reduce inflammation and fibrosis and enhance cartilage regeneration, following laryngeal defect repair.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E527-E533, 2021.

Effects of topical mitomycin-C on the tracheal epithelia of rabbits following tracheostomy

Background/aim

We aimed to investigate the topical application of mitomycin-C (MMC) after the conventional tracheostomy in a rabbit model.

Materials and methods

Twenty-four male New Zealand White rabbits were randomly divided among 3 equal groups (n: 8). Trache- ostomies were performed on 16 subjects. Group 1 which served as a control for all tracheal measurements. After tracheostomy, we applied sterile saline (group 2) or MMC at 0.8 mg/mL (group 3) around the tracheotomy site for 5 min. At the 3rd week after surgery, all tracheas were subjected to morphometric and histopathological examinations, including tracheal lumen diameter (LD), number of capillary vessels (CV), subepithelial tissue thickness (SETT), fibroblasts, and inflammatory cells (IC).

Results

There was a statistically significant difference between the two tracheostomy groups themselves and the control group for LD (p = 0.035), CV (p = 0.006), SETT, fibroblasts, and IC (p < 0.001). Histopathological analysis showed the decreased LD, CV, SETT, IC, and fibroblasts compared to MMC with tracheostomy groups. MMC was more effective than saline for LD, CV, SETT, IC, and fibroblasts.

Conclusion

Wound healing modulation may prevent scar formation. Fibrosis decreased following tracheostomy in the group treated with MMC. Fibroblasts appear to be key cells mediating these effects.

Profilactic role of simvastatin and mitomycin C in tracheal stenosis after tracheal damage: Study in rats

OBJECTIVES

We aimed to investigate the prophylactic effect simvastatin of and mitomycin C (MMC) on laryngeal and tracheal stenosis in tracheotomised rats by histopathological evaluation of laryngotracheal segment. Randomized prospective single-blind.

MATERIAL AND METHOD

Standard vertical tracheotomy was performed on 24 rats. Then the animals were randomly divided into three groups as A, B and C. In group A 0.4 mg/day once daily mitomycin C was injected to the paratracheal region for 14 days. In group B daily 30 mg/kg/day simvastatin was given via gavage to rats for 14 days. In group C 2 cc/day intraperitoneal saline given to rats and the created control group by 14 days follow up. After 10 days, tracheal cannulas were removed. Three weeks later, all animals were euthanized and trachea specimens were harvested. The present study investigates the effects of MMC and Simvastatin on fibrosis, inflammation, stenosis index and tracheal wall thickness in a tracheal injury model.

RESULTS

The difference between the groups in terms of degree of inflammation scores was statistically insignificant (P = 0,187). Differences between the groups were found to be insignificant in terms of the preventionof fibrosis (P = 0,993). There was no significant difference between groups in terms of stenosis index (P = 0.645). In terms of wall thickness, control, simvastatin and mitomycin C groups were statistically different (p = 0.038). The difference between post-hoc test results was between Mitomycin C and control groups (p = 0.036). Maximum wall thickness in the MMC group (0,299 mm) was significantly lower compared to the control group (0,382 mm)(P < 0,0001). Maximum wall thickness was statistically lower in the simvastatin (0.324 mm) group compared with the control group (0.382 mm) (P < 0.0001). There was no statistically significant difference between the simvastatin group (0,198 mm) and control group (0,200 mm) with respect to minimum wall thickness (P = 0.982). Minimum wall thickness was significantly lower in the mitomycin-C group (0,160 mm) comparison to the control group (0,200 mm) (P < 0.0001).

CONCLUSION

It was detected that the simvastatin and MMC is not effective in preventing the tracheal stenosis, inflammation and fibrosis formation.

Role of Topical Medication in Prevention of Post-extubation Subglottic Stenosis

Iatrogenic laryngotracheal injury is the most serious complication of endotracheal intubation since this method of establishing airway was first described by Eugene Bouchut in 1858. Even today, subglottic stenosis is the most dreaded complication of intubation. This animal study is focused on the host tissue response to intubation induced injury resulting in subglottic stenosis and methods to prevent this complication. To assess the role of topically applied Mitomycin-C and Triamcinolone Acetonide in wound healing process following post-extubation subglottic injury. Prospective Randomized block, single-blinded, experimental study. Forty New-Zealand white rabbits where block randomized and allocated into 4 groups based on the type of topical medication that was applied post-extubation. Further these groups where subdivided into 3 subgroups based on the time of sacrifice (4, 6 and 12 weeks) to study the histopathological changes that occurred in a temporal sequence at the subglottis. It was observed that the rabbits in the control group and those that received Mitomycin-C only had more respiratory distress compared to those treated with Triamcinolone Acetonide. Statistically significant histopathological changes were observed in all the 4 groups. Mitomycin-C applied topically did not alter the wound healing process following post-extubation injury in the subglottis. Triamcinolone Acetonide significantly altered wound healing in the subglottis and prevented occurrence of respiratory distress.

The therapy with ethosomes containing 5-fluorouracil for laryngotracheal stenosis in rabbit models

The aim of this study is to evaluate the efficacy of ethosomes encapsulated with 5-fluorouracil (5-FU) in treatment of laryngotracheal stenosis in rabbit models. The 5-FU ethosome was prepared by the thin film hydration method, and the amorphous, size distribution and the encapsulation efficiency was investigated. The tracheal mucosa were scraped about 0.5 cm with a nylon brush to induce the scar in airway grow, then models were divided into three groups: 5-FU ethosome group, 5-FU group and saline group, drug were injected into scar of every group by paracentesis guided under endoscope, respectively. The stenosis states were observed under laryngo fiberscope immediate, 7, 14 and 21 days after administrated. Airway stenosis of 5-FU ethosome group has no significant difference when compared with 5-FU group at 7 days after administration, but 5-FU ethosome significantly reduced the airway stenosis after 21-day administration when compared with 5-FU group again and has no restenosis during the period under observation. The fact that ethosomes encapsulated with 5-FU were effective for laryngotracheal stenosis suggests that it has potential as a new method for ameliorating airway stenosis originating from granulation tissue.

Diagnosis of subglottic stenosis in a rabbit model using long-range optical coherence tomography

OBJECTIVES/HYPOTHESIS

Current imaging modalities lack the necessary resolution to diagnose subglottic stenosis. The aim of this study was to use optical coherence tomography (OCT) to evaluate nascent subglottic mucosal injury and characterize mucosal thickness and structural changes using texture analysis in a simulated intubation rabbit model.

STUDY DESIGN

Prospective animal study in rabbits.

METHODS

Three-centimeter-long sections of endotracheal tubes (ETT) were endoscopically placed in the subglottis and proximal trachea of New Zealand White rabbits (n = 10) and secured via suture. OCT imaging and conventional endoscopic video was performed just prior to ETT segment placement (day 0), immediately after tube removal (day 7), and 1 week later (day 14). OCT images were analyzed for airway wall thickness and textural properties.

RESULTS

Endoscopy and histology of intubated rabbits showed a range of normal to edematous tissue, which correlated with OCT images. The mean airway mucosal wall thickness measured using OCT was 336.4 μm (day 0), 391.3 μm (day 7), and 420.4 μm (day 14), with significant differences between day 0 and day 14 (P = .002). Significance was found for correlation and homogeneity texture features across all time points (P < .05).

CONCLUSIONS

OCT is a minimally invasive endoscopic imaging modality capable of monitoring progression of subglottic mucosal injury. This study is the first to evaluate mucosal injury during simulated intubation using serial OCT imaging and texture analysis. OCT and texture analysis have the potential for early detection of subglottic mucosal injury, which could lead to better management of the neonatal airway and limit the progression to stenosis.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:64-69, 2017.

Safety and efficacy of Intraurethral Mitomycin C Hydrogel for prevention of post-traumatic anterior urethral stricture recurrence after internal urethrotomy

BACKGROUND

Evaluation of the safety and efficacy of intraurethral Mitomycin C (MMC) hydrogel for prevention of post-traumatic anterior urethral stricture recurrence after internal urethrotomy.

METHODS

A thermoresponsive hydrogel base consisting of 0.8 mg MMC with 1cc water and propylene glycol to PF-127 poloxamer was used in theater. 40 male patients with short, non-obliterated, urethral stricture were randomized into 2 groups: control and MMC. After internal urethrotomy, the MMC group patients received the MMC-Hydrogel while the others were just catheterized. Both groups had their catheters for at least 1 week. After surgery, they were followed up by means of medical history and physical examination, monitoring voiding patterns and retrograde urethrogram at 1 month, 6 months and 1 year after surgery.

RESULTS

40 male patients between 14 to 89 years old (Mean = 54.15) underwent internal urethrotomy. The average age for the control and MMC group was 54.55±21.25 and 53.75±24.75 respectively. In a comparison of age between the two groups, they were matched (P=0.574). Stricture length was 10.7±5.9 and 9.55±4.15 mm for the control and MMC group respectively. There were no statistically meaningful differences between the two groups (P=0.485). Fifteen patients had a history of one previous internal urethrotomy which in a comparison between the two groups meant there was no meaningful difference (P=0.327). During postoperative follow up, total urethral stricture recurrence happened in 12 patients: 10 patients (50%) in control group and 2 patients (10%) in MMC group. The difference was statistically significant (P=0.001). There were no significant complications associated with the MMC injection in our patients.

CONCLUSIONS

Based on our results, MMC Hydrogel may have an anti-fibrotic action preventing post-traumatic anterior urethral stricture recurrence with no side effects on pre-urethral tissue. Due to our study limitations, our follow up time and the small number of patients, our results were not conclusive and further studies will be needed with a longer follow up time.

A Novel Therapy for Laryngotracheal Stenosis: Treatment With Ethosomes Containing 5-Fluorouracil

PURPOSE

The purpose of our article was to explore the effect of ethosomes containing 5-fluorouracil (5-FU) with different sizes on laryngotracheal stenosis treatment.

METHODS

The physical characteristics of ethosomes containing 5-FU were investigated, including size, shape, and entrapment percentage. The effect of ethosomes containing 5-FU was evaluated on the airway stenosis rabbit model. The formation of fibrous/scar tissue was investigated by hematoxylin and eosin (HE) staining, and the permeation depth was observed under fluorescence microscope.

RESULTS

The mean sizes of 5-FU ethosomes extruded by D=50 nm and D=100 nm pore were 60±10 nm and 110±13 nm, respectively. The 5-FU entrapment percentage of ethosomes was determined to be 15% (D=60±10 nm) and 32% (D=110±13 nm). After being treated by ethosomes containing 5-FU (D=60±10 nm), the fibroblast and collagenous fiber distributed sparsely in the deep scar tissue. The permeation capability of ethosomes containing 5-FU (D=60 nm) was significantly better than ethosomes (D=110 nm). Besides, the 5-FU ethosomes resulted in less stenosis than 5-FU only.

CONCLUSIONS

Topical administration of 5-FU ethosomes may be a novel candidate therapy for laryngotracheal stenosis treatment.

Using Pulmonary Function Data to Assess Outcomes in the Endoscopic Management of Subglottic Stenosis

Objective:

This study aimed to examine the authors’ experience with endoscopic management of idiopathic subglottic stenosis (iSGS), and to identify pulmonary function test (PFT) values that can be used to quantify outcomes.

Methods:

Retrospective review.

Results:

Twenty-five patients with a new diagnosis of iSGS were seen between 2006 and 2012. Median age at surgery was 45.3 years (interquartile range [IQR], 38.5-67.0), and median body mass index was 28.7 kg/m2 (IQR, 23.5-32.1). Forty-five procedures were performed. Median preoperative stenosis was 56.8% (Cotton-Myer grade 2). The typical stenosis began 15 mm below the true vocal folds and was 12 mm long. Median follow-up was 21.4 months (IQR, 5.1-43.1). For patients receiving multiple dilations, median time between procedures was 23.7 months. Four PFT parameters demonstrated significant improvement after intervention: (1) PEF (absolute change = 2.54 L/s), (2) PIF (absolute change = 1.57 L/s), (3) FEV1/PEF (absolute change = 0.44), and (4) FIF50% (absolute change = 1.71 L/s). PIF was the only parameter affected by using a larger balloon ( P = .047).

Conclusion:

PEF, PIF, FEV1/PEF, and FIF50% improved significantly after endoscopic incision and dilation of iSGS, and this could potentially be used as a metric by which to evaluate outcomes in the endoscopic management of subglottic stenosis.

Subglottic injury: a clinically relevant animal model

OBJECTIVES/HYPOTHESIS

To develop a clinically aligned, reproducible model for subglottic injury.

STUDY DESIGN

Prospective randomized control pilot study.

METHODS

Juvenile (3-month-old) New Zealand White rabbits underwent intubation with a 3-cm length of an endotracheal tube that was chosen so that there would be no air leak below 20 cm of water. This tube was one or two sizes above the appropriate tube for the animal. It was held in situ with a suture placed at the trachea and secured over a button in the neck for a period of 1 week. Animals were sacrificed 1 week postextubation, and larynges were harvested. A range of histological techniques and gross morphology were utilized to examine the injury caused at the level of the subglottis. Unintubated animals constituted controlled specimens.

RESULTS

Intubated animals demonstrated considerable histopathology including evidence of ulceration, inflammation, granulation tissue, perichondritis, and chondritis when compared with control animals. Morphometric analysis demonstrated a significant increase in lamina propria thickness (P = .0013), mucosal thickness (P ≤ .0001), and in goblet cell areal density (P = .014). Analysis of mucin types found a significant decrease in acidic (P = .0001) mucin coinciding with a significant increase in mixed mucin types (P = .0013).

CONCLUSIONS

Our model provides a reliable and reproducible technique for acute/subacute injury to the subglottis secondary to intubation, which is consistent with previous histological findings of early changes associated with acquired subglottic stenosis (SGS). Future uses of this model could include the examination of current adjunctive therapies and their effects on limiting progression to SGS.

Effect of topical application of mitomycin-C on wound healing in a postlaminectomy rat model: an experimental study

The aim of this study was to investigate the effects of topical application mitomycin-C (MMC) on wound healing after laminectomy. 60 adult male SD rats were equally and randomly divided into five groups. Laminectomy was performed at the level of L1 in all rats. After hemostasis was achieved, cotton pads soaked with saline and MMC (0.1mg/ml, 0.3mg/ml, 0.5mg/ml and 0.7mg/ml) were directly subjected to the exposed dura for 5min in each group. Two weeks after laminectomy all the rats were killed. The vertebral column including the back scar tissue and muscles was obtained to make paraffin sections. The hematoxylin-eosin staining and Masson staining were performed with the obtained paraffin sections. The number of the fibroblast and the capillary density were counted by the hematoxylin-eosin staining slice. The extent of epidural fibrosis and the expression of vascular endothelial growth factor (VEGF) were evaluated by the immunohistochemical slice through a computer image analysis system. Our data showed that the number of fibroblast, capillary density and fibrotic tissue in the 0.5 and 0.7mg/ml MMC groups was significantly lower than the control, 0.1 and 0.3mg/ml MMC groups; while the expression of VEGF in control and 0.1mg/ml MMC groups was notably higher than 0.3, 0.5 and 0.7mg/ml MMC groups. Topical application of MMC above the concentration of 0.3mg/ml could affect all steps of the wound healing process via inhibiting the angiogenesis and fibroblast proliferation, thus delayed the wound healing after laminectomy.

Induction of tracheal stenosis in a rabbit model-endoscopic versus open technique

OBJECTIVE

To evaluate and compare open versus endoscopic methods of inducing tracheal stenosis in the New Zealand white rabbit model.

STUDY DESIGN

Prospective randomized control, pilot study.

SUBJECTS AND METHODS

Fifteen New Zealand white rabbits were used in the study. Induction of tracheal stenosis was performed through an open incision in 6 rabbits, an endoscopic approach was utilized in 8 rabbits, and 1 rabbit served as the control. The open approach was performed by brushing the tracheal mucosa 10 times through an anterior tracheotomy with a nylon brush. The endoscopic method was achieved using a rigid bronchoscope and at a measured distance below the cricoid cartilage, passing the same nylon brush four times in each of four quadrants. Repeat endoscopies for evaluation of stenosis progression were performed at 2 and 3 weeks on all rabbits.

RESULTS

In the open group, we observed no stenosis with one mortality as a result of gastroenteritis due to antibiotic use. In the endoscopic group, all animals achieved some degree of stenosis by 14 days, with a mean airway narrowing of 43%. The two deaths in the endoscopic group occurred in the immediate postoperative period secondary to laryngeal edema. The endoscopic procedure was 5 minutes in duration.

CONCLUSION

The endoscopic technique is an effective method of achieving circumferential tracheal stenosis in the rabbit model. Advantages include simple instrumentation, an endoscopic approach, potential for decreased costs, and more reliable results.

Esterified hyaluronic acid improves cartilage viability in experimental tracheal reconstruction with an auricular graft

OBJECTIVE: The aim of this study was to determine the efficacy of esterified hyaluronic acid (HYAFF) on the vitality of auricular cartilage grafts used for tracheoplasty, with respect to macroscopic and microscopic parameters.

STUDY DESIGN: Prospective, controlled.

SETTING: Academic research laboratory.

SUBJECTS AND METHODS: The study included 14 New Zealand rabbits acquired specifically for the study. The rabbits were divided into two groups: the control group, in which free cartilage grafts were not exposed to any materials or additional procedures (n = 7), and the hyaluronic acid (HA) treatment group, in which auricular grafts and anastomosis lines were covered with HYAFF (n = 7). Free auricular cartilage grafts used for the reconstruction of experimentally created tracheal defects were anastomosed extraluminally. All the rabbits were sacrificed two months post surgery. Samples were collected and examined histopathologically. The sections were stained with hematoxylineosin, Masson's trichrome, and inducible nitric oxide synthase (iNOS) and examined under a light microscope.

RESULTS: Fibrosis and cartilage mass significantly differed between the control and HYAFF group ( P < 0.05). Immunohistochemical examination showed that more chondrocytes stained with iNOS in the control group than in the HYAFF group, according to histologists' observations.

CONCLUSION: HYAFF catalyzed wound healing with less fibrous tissue formation, had chondroprotective and stimulatory effects on chondrocyte metabolism, and decreased nitric oxide production and apoptosis via improving the nourishment of free auricular cartilage grafts, subsequently preventing hypoxia and oxidative stress, particularly in the early postimplantation period.

Serial intralesional steroid injection combined with balloon dilation as an alternative to open repair of subglottic stenosis

This article will describe successful use of serial balloon dilations and steroid injections to help a child with acute SGS avoid tracheotomy or major reconstructive procedures. An 11-month infant presented with subglottic ulcerations that developed after intubation for acute laryngotracheitis. Over the next 4 months, the child developed SGS, requiring three balloon dilations consisting of triamcinalone injection into the scar tissue followed by outpatient balloon dilation without intraoperative intubation. Twelve months after initial presentation and 8 months follow-up from the third and final dilation, the patient is thriving. This report illustrates the potential safety and efficacy of serial intralesional steroids combined with balloon dilation as an alternative to more invasive treatments. The technique is novel in the number of attempts at balloon dilation, highlighting that serial dilations can succeed after initial failure. Issues for further investigation include optimal timing and number of dilations.

Effectiveness of topically applied halofuginone in management of subglottic stenosis in rats

OBJECTIVE

The aim of the study is to ascertain the antifibrotic effect of topically applied halofuginone after acute subglottic injury.

MATERIALS AND METHODS

After standardized trauma to subglottic area, rats were divided into two groups: the study group that received treatment and the control group that did not. The subjects were treated with topical application of cottonoid soaked in 30 mg/dL halofuginone solution for 5 minutes after subglottic trauma. The larynx specimens were examined histopathologically by light microscopy to assess fibrosis, epithelialization, inflammation, and necrosis.

RESULTS

The fibrosis indexes of the treated group were significantly less than those of the control group (P < 0.05).

CONCLUSIONS

Topically applied halofuginone hydrobromide decreases fibrosis/scar tissue formation secondary to experimentally induced acute subglottic trauma.

Mitomycin C and airway surgery: How well does it work?

Objective

Systematically review and critically evaluate all available published data on the use of topical mitomycin C (MMC) as an adjunctive in airway surgery.

Data Sources

Published studies indexed in MEDLINE, EMBASE, or Cochrane databases. Inclusion criteria were English language, sample size greater than five, and publication of data applicable to the analysis of topical MMC and airway surgery outcomes.

Review Methods

Evidence tables were compiled to include sample size, study design, and evidence level. Summary statistics, random-effects modeling, and subgroup analysis were performed.

Results

Twenty manuscripts (eight human, 12 animal) met the inclusion criteria. Seven of eight (87.5%) of the human studies and eight of 12 (66%) animal studies concluded topical MMC was beneficial to airway surgical outcomes. Eleven of twelve animal studies included randomization and a control group, compared with only two of eight human studies. Random-effects modeling of human studies (k=7) indicated that 81.4 percent (95% CI, 72.0%-90.9%; P < 0.001) of patients had improved outcomes attributable to MMC. Random-effects modeling of animal data included modeling of change in airway diameter (Hedge's G = −0.03; 95% CI, −0.66-0.60; P = 0.924) and the change in histologic measures (Hedge's G = 1.26; 95% CI, 0.596-1.92; P < 0.001) in MMC-treated animals vs controls.

Conclusion

The majority of the published literature individually suggests the use of topical MMC improves airway surgery outcomes. However, heterogeneity within the clinical studies, the lack of controlled data, and the lack of significance in the pooled animal data (other than histologic outcomes) suggest that the utility of MMC is still undetermined.

Effects of halofuginone on fibrosis formation secondary to experimentally induced subglottic trauma

OBJECTIVE

The aim of the study was to assess the antifibrotic effect of systemically applied halofuginone after subglottic injury.

MATERIALS AND METHODS

After standardized trauma to subglottic area, rats were divided into two groups: a study group that received treatment and a control group that did not. The rats were treated with 0.1 mg/kg/day intraperitoneal halofuginone injection for 30 days. The larynx specimens were examined histopathologically under light microscope for epithelization, inflammation, necrosis, and fibrosis.

RESULTS

The fibrosis indexes of the treated group were significantly less than those of the control group (P < .01).

CONCLUSIONS

Systemically applied halofuginone hydrobromide decreases fibrosis/scar tissue formation secondary to experimentally induced acute subglottic trauma.

Can Mitomycin C Really Prevent Airway Stenosis?

BACKGROUND/OBJECTIVES

Mitomycin C (MMC) is used in the prevention of upper airway stenosis. However, the efficacy of MMC is still debatable, and the potential complications of MMC use have been scarcely reported. We evaluated the efficacy and early complications of MMC in a wound model of the subglottis.

STUDY DESIGN

A randomized animal study.

METHODS

Sixty rabbits underwent a full-thickness injury to the posterior subglottis by diode laser. The animals were randomly assigned to three groups according to the different topical treatments of MMC 0.4 or 10 mg/mL or saline alone for 5 minutes. Animals were killed at 4 weeks, and gross and histologic findings were compared among different groups and 10 age-matched, non-wound, normal controls.

RESULTS

Thirty-two of the 60 (53%) animals died mainly of acute airway obstruction by necrotic debris, sloughs on, or cartilage collapse of the unhealed posterior subglottis during early weeks after wounding, higher in the MMC-treated animals (67%) than in the wound controls (25%) (P = .007). This resulted from the significant delay of wound healing in the MMC-treated groups compared with the wound controls (P = .012). The degree of subglottic stenosis was comparable among different groups (P > .8), although collagen deposition was significantly lower in the MMC-treated groups compared with the untreated controls (P = .036).

CONCLUSIONS

There was a significant risk of acute airway obstruction from delayed wound healing in rabbits that received subglottic laser wounding and MMC treatment. This risk should be considered in the use of MMC in clinical practice.