On Pressure Regulation of the Middle Ear

The middle ear (ME) pressure is regulated by gas diffusion over the ME mucosa and pressure equalizations via the Eustachian tube (ET). Disturbance in the regulation of ME pressure is believed to contribute to the development of chronic ear diseases. In this work subjects with chronic central perforation (CCP), healthy ears with ventilation tubes (VTs), attic cholesteatoma (AC) and Meniere’s disease (MD) were investigated by measuring the ME pressure directly, continuously and long-term, in combination with ET provocation tests. Pathological conditions were characterised by a negative ME pressure during the daytime measurements, indicating an abnormality in the diffusion of gas from the ME and insufficient ET equalizations. The MEs of subjects with CCP and healthy ears with VTs were open to the atmosphere before the investigations, which influenced the results, resulting in negative ME pressure during the daytime. These results support the theory that the opening per se, impaired or contributed to the impairment in the ME pressure regulation. Subjects with AC showed negative ME pressure and/or episodes of sniff-induced rapid negative pressure changes during the continuous pressure measurements. These findings indicate a clear relation between the disease and impaired ME pressure regulation. Subjects with MD showed an increased incidence of reduced opening capacity of the ET in provocation tests. This indicates that ME of patients with MD are exposed to pressure situations in daily life exceeding the equilibration capacity of the ET, leading to a possible influence of pressure on the inner ear. The results of these physiological studies have enhanced our understanding of the regulation of ME pressure in diseased ears. Future studies may elucidate the possibility to complement clinical investigations in chronic ear diseases with the method of continuous, long-term measurement of ME pressure

Inadequate opening capacity of the eustachian tube in Meniere's disease.

Abstract Conclusion: In this physiological study subjects with Meniere's disease (MD) had high resistance to opening of the eustachian tube (ET) in three of four provocation tests. These subjects can be exposed to pressure deviations in the middle ear (ME) above their equalizing capacity. Transmission of the pressure deviations to the inner ear fluids and influence of the symptoms of MD are feasible. Objective: The aim of the study was to reveal potential inadequacy in the ET equilibration capacity and deviations in ME pressure in patients with MD. Methods: Direct ME pressure measurements were made during provocation tests of the ET, and continuously during the daytime and night-time in 21 patients with unilateral, definite and active MD. Twenty subjects with healthy ears (HEs) were used for comparison. Results: In all, 15/21 subjects could not equilibrate an induced positive and/or negative pressure in the ME by deglutition; 9/21 subjects were not able to perform Valsalva's manoeuvre. All the controls could effectively perform these manoeuvres. However, the continuous measurements showed a similar pressure pattern in patients with MD and the controls, i.e. a slightly negative mean ME pressure during the daytime and positive pressure during sleep

Wear protection of deep drawing tools by systematic optimization of highly stressed surfaces

The automotive sector is one of the largest energy consumers in Germany. Requests from politics and industry to significantly reduce emissions require new developments during utilization as well as during production phase. In line with the framework concept "InnoCaT", where more than 60 companies and research facilities from Germany take part, possibilities for producing companies are developed and analyzed to reduce the resource and energy consumption and by this reducing costs along the entire process chain of car body manufacturing. One approach to design car bodies lighter and more efficiently is to use aluminium and high strength steels. By this means weight and sheet thickness are reduced. However higher strengths of the steels and the adhesion affinity of aluminium significantly increase the requirements regarding the used tool steel. Thus grooves or galling appear more frequent at highly stressed surfaces. To assure high lifetimes and by this increase especially the resource efficiency concerning use of material and setting-up times within the press plant, a local optimization at the highly stressed surfaces is necessary. For this a FEM/BEM-tool for a time efficient and exact calculation of the occurring tool loads for complex die profiles is developed. Based on this development of load calculation a shape-optimization is performed at the corresponding areas. After the geometric optimization of the tool a local laser surface treatment for further wear protection is carried out using laser cladding or laser alloying/ -dispersing. By combining the technologies a highly wear resistant surface is achievable, which increases the tool's lifetime as well as the reproducibility within production