Inner ear decompression sickness after a routine dive and recompression chamber drill.

Inner ear decompression sickness (IEDCS) is an uncommon diving-related injury affecting the vestibulocochlear system, with symptoms typically including vertigo, tinnitus, and hearing loss, either in isolation or combination. Classically associated with deep, mixed-gas diving, more recent case series have shown that IEDCS is indeed possible after seemingly innocuous recreational dives, and there has been one previous report of IEDCS following routine hyperbaric chamber operations. The presence of right-to-left shunt (RLS), dehydration, and increases in intrathoracic pressure have been identified as risk factors for IEDCS, and previous studies have shown a predominance of vestibular rather than cochlear symptoms, with a preference for lateralization to the right side. Most importantly, rapid identification and initiation of recompression treatment are critical to preventing long-term or permanent inner ear deficits. This case of a U.S. Navy (USN) diver with previously unidentified RLS reemphasizes the potential for IEDCS following uncomplicated diving and recompression chamber operations - only the second reported instance of the latter.

Effects of Fractional CO2 Laser Treatment on Subglottic Scar in a Rabbit Model.

OBJECTIVE: The objective of this study was to investigate the effects of fractional CO2 laser on subglottic scar. STUDY DESIGN: Randomized controlled animal study. SETTING: Academic medical center. METHODS: Subglottic scar was induced in 12 New Zealand white rabbits via an endoscopic brush technique. This was followed by an open airway surgery that included vertical division of the cricoid and proximal trachea. Eight rabbits underwent fractional CO2 laser treatment of the scar via a Lumenis Ultrapulse Deep FX handpiece. Four rabbits underwent the open surgical approach without laser treatment. Bronchoscopy was performed at weeks 1, 2, 4, and 8. The animals were euthanized and laryngotracheal complexes harvested 12 weeks postsurgery. Immunohistochemistry was performed to determine the collagen composition of treated and untreated scars. RESULTS: All 12 subjects survived to the study endpoint with no significant respiratory complications, despite 10 of 12 developing some degree of lateral tracheal narrowing. The median ratio of type I collagen to type III collagen in the laser group (1.57) was significantly more favorable than that of the untreated group (2.84; P = .03). CONCLUSION: Treatment with fractional CO2 laser appears to have similar effects on subglottic scars as with cutaneous scars, improving the ratio of type I to type III collagen. Additionally, we developed an open airway approach in the rabbit model to deliver fractional CO2 laser treatment to the subglottis without introducing respiratory complications or compromising survival.

Rabbit model of consistently survivable subglottic stenosis using a modified brush technique.

INTRODUCTION: Several animal models of subglottic stenosis (SGS) have been described in the literature, however many result in severe stenosis that requires early intervention and carry a high mortality rate. This limits the application of the model and may require the use of additional animals to achieve desired results due to procedural complications. A novel endoscopic method of inducing SGS in a rabbit model was developed as part of a larger investigation on the treatment of this condition. The objective of this study was to develop an animal model for survivable subglottic stenosis. METHODS: 12 New Zealand white rabbits underwent 2 trials of prolonged intubation that were not successful in inducing SGS. A partially sheathed nylon brush injury technique was then designed and implemented. Airway assessment consisted of rigid bronchoscopy 6 weeks and 8 months after injury. RESULTS: 12 rabbits undergoing subglottic brush injury had focal posteriorly based subglottic stenosis on bronchoscopy at 6 weeks and 8 months post-injury. One rabbit was euthanized after the brush induced subglottic injury but prior to 6 week bronchoscopy due to an unrelated orthopedic injury. This animal was therefore excluded from analysis and replaced. No rabbits required early airway intervention or sacrifice. All survived a period of 8 months. CONCLUSION: Inducing subglottic injury with a partially-sheathed nylon brush safely and reliably creates a controlled SGS with zero procedure-related mortality over 8 months. This model could be the basis for a longer-term evaluation of subglottic scar evolution and intervention.

Balloon Dilation of the Eustachian Tube for Baro-Challenge-Induced Otologic Symptoms in Military Divers and Aviators: A Retrospective Analysis.

OBJECTIVE: To evaluate the effectiveness of balloon dilation (tuboplasty) of the Eustachian tube (BET) in active duty military personnel working in hyper- and hypobaric environments suffering from baro-challenge-induced ETD using functional outcomes. METHODS: Military divers and aviators diagnosed with persistent baro-challenge-induced ETD resulting in disqualification from performing flight and dive duties and who elected for treatment with BET were included for analysis. Posttreatment follow-up assessments were undertaken at 1, 6, and 12 months. Outcome measures included successful hyperbaric chamber testing or return to the hyper- or hypobaric environment without significant baro-challenge-induced ETD symptoms and pre- and postdilation Eustachian Tube Dysfunction Questionnaire (ETDQ-7) scores. RESULTS: Mean pretreatment duration of symptoms was 48 months (range: 3-120 months). Following treatment, 92% (12/13) of patients successfully returned to operational duties with resolution of limiting symptoms. Average return to duty time was 8.5 weeks (range: 6-24 weeks). The ETDQ-7 scores improved from a mean of 4.33 (2.57-6.57) predilation to 2.19 (1.00-4.43) postdilation (Z = 2.73, W = 70, P = .0063). Mean duration of follow-up was 38 weeks (range: 13-70 weeks). CONCLUSION: Eustachian tube balloon dilation appears to be a safe and highly effective treatment option for baro-challenge-induced ETD in affected military divers and aviators who work in hyper- and hypobaric environments. Further study is needed to determine whether similar results can be achieved in more diverse subject populations and to assess long-term effectiveness.

Navy diver with recurrent facial nerve baroparesis treated with eustachian tube balloon dilation.

Facial nerve baroparesis is a rare complication of middle ear barotrauma reported almost exclusively in overpressure events related to diving and flying. Until the development of Eustachian tube balloon dilation, no diving compatible options existed to effectively and safely prevent recurrence. We present a case of a U.S. Navy diver with a history of repeated ipsilateral facial nerve paresis that occurred during diving. The patient underwent Eustachian tube balloon dilation of the affected side. Following surgery, the patient completed a recompression chamber simulated dive that allowed the patient to return to diving. The patient has been symptom-free for 12 months following dilation. Laryngoscope, 129:E412-E414, 2019.

Congenital complete absence of tracheal rings with trifurcate carina: Case report of a rare clinical and endoscopic presentation.

We describe the case of a child with isolated absence of cartilaginous tracheal rings and a trifurcate carina. At 6 months of age, the patient presented to our multidisciplinary airway clinic with stridor and recurrent severe respiratory infections requiring hospitalization. Radiographs showed airway narrowing. Exam demonstrated biphasic stridor. Flexible fiberoptic laryngoscopy demonstrated only mild laryngomalacia. Operative bronchoscopy demonstrated severe tracheomalacia with absence of any visible tracheal rings and a trifurcate carina. Subsequent CT imaging corroborated these findings and did not demonstrate any other major abnormality. The patient did not require operative intervention and his subsequent course was uncomplicated.

Metalloproteinase expression is associated with traumatic wound failure.

BACKGROUND: Matrix metalloproteinases (MMPs) are crucial in the inflammatory and remodeling phases of wound healing. We previously reported the correlation between pro-inflammatory cytokines and timing of successful combat-wound closure. We now extend our studies to investigate the correlation between wound-remodeling MMP expression and wound healing. METHODS: Thirty-eight wounds in 25 patients with traumatic extremity combat wounds were prospectively studied. Surgical debridement with vacuum-assisted closure (VAC) device application was repeated every 48 to 72h until surgical wound closure. Wound effluent and patient serum were collected at each wound debridement and analyzed for five matrix metalloproteinases using the Luminex multiplex system; Millipore Corp, Billerica, MA. The primary outcome was wound healing within 30 d of definitive wound closure. Impairment was defined as delayed wound closure (>21 d from injury) or wound dehiscence. MMP expression was compared between impaired and normal healing wounds. RESULTS: Elevated levels of serum MMP-2 and MMP-7 and reduced levels of effluent MMP3 were seen in impaired wounds (n = 9) compared with wounds that healed (n = 29; P<0.001). Receiver operating characteristic (ROC) curve analysis yielded area-under-the-curve (AUC) of 0.744, 0.783, and 0.805, respectively. CONCLUSIONS: Impaired wound healing is characterized by pro-inflammatory MMP-2 and MMP-7. Serum and effluent concentrations of MMP-2, MMP-3, and MMP-7 can effectively predict the outcome of traumatic war wounds and can potentially provide decision-supportive, objective evidence for the timing of wound closure.