Development of an In Vivo Model for Eustachian Tube Dysfunction.

Otitis media is often connected to Eustachian tube dysfunction (ETD). Until now, there was no large animal model available for the examination of new treatment methods such as stents for the Eustachian tube (ET). Thus, the aim of the study was to develop a method to reproducibly induce ETD by injection of fillers and without permanent closure of the ET. Tools for safe injection of hyaluronic acid (HA) in the surrounding of the ET were developed. In ex vivo experiments, HA mixed with Imeron® was injected close to the nasopharyngeal orifice of the ET of blackface sheep. The established depot was visualized using cone beam computer tomography and magnetic resonance imaging, and stents could be placed into the ET. A reliable position of the HA depot was achieved. This method was transferred to in vivo, and middle ear ventilation was investigated by tympanometry. ETD was achieved with amounts of 2.5 mL HA or higher. None of the animals showed any sign of discomfort or complications. The induced ETD lasted for 3 to 13 (maximum observation period) weeks and was also combined with middle ear effusion. A model of ETD based on injection of HA next to the ET was successfully established and is now available to test novel treatment options for ET functionality.

Stenting the Eustachian tube to treat chronic otitis media - a feasibility study in sheep.

BACKGROUND: Untreated chronic otitis media severely impairs quality of life in affected individuals. Local destruction of the middle ear and subsequent loss of hearing are common sequelae, and currently available treatments provide limited relief. Therefore, the objectives of this study were to evaluate the feasibility of the insertion of a coronary stent from the nasopharynx into the Eustachian tube in-vivo in sheep and to make an initial assessment of its positional stability, tolerance by the animal, and possible tissue reactions. METHODS: Bilateral implantation of bare metal cobalt-chrome coronary stents of two sizes was performed endoscopically in three healthy blackface sheep using a nasopharyngeal approach. The postoperative observation period was three months. RESULTS: Stent implantation into the Eustachian tube was feasible with no intra- or post-operative complications. Health status of the sheep was unaffected. All stents preserved their cylindrical shape. All shorter stents remained in position and ventilated the middle ear even when partially filled with secretion or tissue. One of the long stents became dislocated toward the nasopharynx. Both of the others remained fixed at the isthmus but appeared to be blocked by tissue or secretion. Tissue overgrowth on top of the struts of all stents resulted in closure of the tissue-lumen interface. CONCLUSION: Stenting of the Eustachian tube was successfully transferred from cadaver studies to an in-vivo application without complications. The stent was well tolerated, the middle ears were ventilated, and clearance of the auditory tube appeared possible. For fixation, it seems to be sufficient to place it only in the cartilaginous part of the Eustachian tube.

Tympanometric measurements in conscious sheep - a diagnostic tool for pre-clinical middle ear implant studies.

OBJECTIVE: To investigate and establish the use of tympanometry in conscious sheep to provide a means of objective assessment of tympanic membrane integrity, middle ear ventilation and functioning of the Eustachian tube (ET). DESIGN: After conditioning the sheep for four weeks, tympanometric measurements at 226 Hz were carried out weekly for 13 weeks. Before measurements, the external ear canal had been cleaned. Resultant curves were classified according to human reference values. STUDY SAMPLE: Tests were performed on 12 female blackface sheep. RESULTS: After cleaning of the external ear canal under otoscopic control, tympanic membranes were intact with no evidence of acute or chronic middle ear inflammation, middle ear effusion or retraction. Cleaning ensured valid, objective and reproducible measurements. As the majority of normal tympanograms were notched without the appearance of any malformation, an additional tympanogram type (AN) was introduced. The notched appearance can most likely be explained by the anatomy of the middle ear of the sheep and the test frequency that was used. CONCLUSION: The current study demonstrated how tympanometry can be used to evaluate treatment modalities for middle ear and ET function in conscious sheep. This provided a large animal model for further human research in otology.

Screening for Gram-negative bacteria: Impact of preanalytical parameters.

Screening recommendations for multidrug-resistant Gram-negative bacteria comprise microbiological analyses from rectal swabs. However, essential specifications of the preanalytic steps of such screenings, i.e. the sampling technique, sampling devices and sampling site, are lacking. For standardized and optimum screening conditions these parameters are indispensable. Here, the optimum parameters were examined irrespective of the antibiotic resistance patterns of the target bacteria in order to establish a general basis for this type of screening. Swabs with rayon, polyurethane-cellular-foam and nylon-flocked tips were tested. Different sampling locations were evaluated, i.e. perianal, intraanal and deep intraanal. Subjects were swabbed and quantities of E. coli, K. pneumoniae, P. aeruginosa and A. baumannii were assessed. Overall prevalences of E. coli, K. pneumoniae, P. aeruginosa, and A. baumannii were 94%, 16%, 12%, and 2%, respectively. Bacterial recovery rates were independent from the sampling-timepoint during hospital stay. Polyurethane-cellular-foam or nylon-flocked swabs recovered significantly more bacteria as compared to rayon swabs. Intraanal swabbing resulted in significantly higher bacterial quantities as compared to perianal swabbing. In contrast, for the detection of A. baumannii, perianal swabbing seems more suitable than intraanal swabbing. Gender-related differences in bacterial recovery could be detected from perianal but not from intraanal swabs.

Concurrent hyperbaric oxygen therapy and intratympanic steroid application as salvage therapy after severe sudden sensorineural hearing loss.

Concurrent hyperbaric oxygen therapy (HBOT) and intratympanic steroid application (ITS) are beneficial as salvage therapy for therapy-refractory sudden sensorineural hearing loss (SSNHL). The findings encourage further research on the treatment of noise-induced and idiopathic SSNHL with concurrent use of HBOT and ITS respecting also patients with long-term or therapy-refractory SSNHL.