scholarly journals Postinsertional Cable Movements of Cochlear Implant Electrodes and Their Effects on Intracochlear Pressure

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
I. Todt ◽  
D. Karimi ◽  
J. Luger ◽  
A. Ernst ◽  
P. Mittmann
Keyword(s):  
Cochlear Implantation ◽  
Maximum Amplitude ◽  
Storage Conditions ◽  
Mastoid Cavity ◽  
Maximum Pressure ◽  
Apical Region ◽  
Pressure Amplitude ◽  
Lower Maximum ◽  
Intracochlear Pressure ◽  
Pressure Changes

Introduction.To achieve a functional atraumatic cochlear implantation, intracochlear pressure changes during the procedure should be minimized. Postinsertional cable movements are assumed to induce intracochlear pressure changes. The aim of this study was to observe intracochlear pressure changes due to postinsertional cable movements.Materials and Methods.Intracochlear pressure changes were recorded in a cochlear model with a micro-pressure sensor positioned in the apical region of the cochlea model to follow the maximum amplitude and pressure gain velocity in intracochlear pressure. A temporal bone mastoid cavity was attached to the model to simulate cable positioning. The compared conditions were (1) touching the unsealed electrode, (2) touching the sealed electrode, (3) cable storage with an unfixed cable, and (4) cable storage with a fixed cable.Results.We found statistically significant differences in the occurrence of maximum amplitude and pressure gain velocity in intracochlear pressure changes under the compared conditions. Comparing the cable storage conditions, a cable fixed mode offers significantly lower maximum pressure amplitude and pressure gain velocity than the nonfixed mode.Conclusion.Postinsertional cable movement led to a significant pressure transfer into the cochlea. Before positioning the electrode cable in the mastoid cavity, fixation of the cable is recommended.

Effects of Different Insertion Techniques of a Cochlear Implant Electrode on the Intracochlear Pressure

2016 ◽  
Vol 21 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Ingo Todt ◽  
Arneborg Ernst ◽  
Philipp Mittmann
Keyword(s):  
Cochlear Implant ◽  
Maximum Amplitude ◽  
Cochlear Model ◽  
Pressure Peak ◽  
Insertion Techniques ◽  
Intracochlear Pressure ◽  
Pressure Changes

To achieve a functional atraumatic insertion, low intracochlear pressure changes during the procedure are assumed to be important. The aim of this study was to observe intracochlear pressure changes due to different insertion techniques in a cochlear model. Cochlear implant electrode insertions were performed in an artificial cochlear model to record intracochlear pressure changes with a micropressure sensor to evaluate the maximum amplitude and frequency of pressure changes under different insertional conditions. We found statistically significant differences in the occurrence of intracochlear pressure peak changes comparing different techniques. Based on our model results, an insertion should be maximally supported to minimize micromovement-related pressure changes.

Minimizing Intracochlear Pressure: Influence of the Insertion Sheath

2021 ◽  
pp. 1-6
Author(s):  
Ceyhun Ucta ◽  
Philipp Mittmann ◽  
Arneborg Ernst ◽  
Rainer Seidl ◽  
Gina Lauer
Keyword(s):  
Optical Sensor ◽  
Cochlear Implantation ◽  
Apical Part ◽  
Electrode Arrays ◽  
Insertion Technique ◽  
Cochlear Model ◽  
Electrode Insertion ◽  
Intracochlear Pressure ◽  
Pressure Changes

Objective: Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. Methods: In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. Results: Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. Conclusion: Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.

Insertional depth-dependent intracochlear pressure changes in a model of cochlear implantation

2016 ◽  
Vol 137 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Marlene Mittmann ◽  
Arneborg Ernst ◽  
Philipp Mittmann ◽  
Ingo Todt
Keyword(s):  
Cochlear Implantation ◽  
Intracochlear Pressure ◽  
Pressure Changes

Numerical simulation of unsteady cavitation flow in a centrifugal pump at off-design conditions

2013 ◽  
Vol 228 (11) ◽  
pp. 1994-2006 ◽  
Author(s):  
Tan Lei ◽  
Zhu Bao Shan ◽  
Cao Shu Liang ◽  
Wang Yu Chuan ◽  
Wang Bin Bin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Partial Discharge ◽  
Maximum Amplitude ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Cavitation Flow ◽  
Frequency Spectra ◽  
Large Discharge

Unsteady cavitation flows in a centrifugal pump operating under off-design conditions are investigated by using a numerical framework combining the re-normalization group k–ɛ turbulence model and the transport equation-based cavitation model. The reliability and accuracy of the numerical model are demonstrated by the satisfactory agreement between the experimental and numerical values of the pump performance. Under partial discharge, the frequency spectra of the pressure fluctuation at the impeller inlet become more complex as the pump inlet pressure decreases. The maximum amplitude of pressure fluctuation at the blade leading edge for cavitation flow is 2.54 times larger than that for non-cavitation flow because of the violent disturbances caused by cavitation shedding and explosion. Under large discharge, the magnification on the maximum pressure amplitude is 1.6. This finding indicates that cavitation has less influence on pressure fluctuations in the impeller under large discharge than under partial discharge. This numerical simulation demonstrates the evolution of cavitation structure inside the impeller.

The Effects of Gusher-Related Intracochlear Pressure Changes on Hearing Preservation in Cochlear Implantation: A Comparative Series

2018 ◽  
Vol 23 (3) ◽  
pp. 181-186 ◽  
Author(s):  
William Crohan ◽  
Jay Krishnaswamy ◽  
Gunesh Rajan
Keyword(s):  
Cochlear Implantation ◽  
Large Change ◽  
Lateral Wall ◽  
Hearing Preservation ◽  
Residual Hearing ◽  
Electrode Arrays ◽  
Significant Drop ◽  
Speech Performance ◽  
Intracochlear Pressure ◽  
Pressure Changes

Aim: To investigate and compare residual hearing preservation between patients based on the presence of intraoperative gusher. Methodology: We retrospectively compared 2 cohorts of cochlear implant recipients significantly distinguished by whether or not they experienced gusher intraoperatively. Patients underwent cochlear implantation using 24-mm lateral wall electrode arrays as well pharmacologic steroid protection. All patients were assessed by a hearing implant MDT. Hearing preservation rates and speech perception outcomes were assessed at 1, 6, 12, 24, 36, 48, and 60 months. Results: The patients with no gusher demonstrated complete hearing preservation. The patients with gusher demonstrated significant postoperative reduction of hearing thresholds, which declined at a significantly higher pace during follow-up. All patients demonstrated significantly better speech performance after cochlear implantation. Conclusion: The present study suggests that intraoperative gusher is associated with a significant drop in residual hearing, both immediately and over time, which may be related to the large change in intracochlear pressure intraoperatively.

Combined Effects of Steam Wetness and Pressure on Characteristics of Acoustic Resonance Amplitude in Closed Side Branch

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Yuta Uchiyama ◽  
Ryo Morita
Keyword(s):  
Density Ratio ◽  
Maximum Amplitude ◽  
Acoustic Resonance ◽  
Steam Pressure ◽  
Side Branch ◽  
Saturated Steam ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Wet Steam ◽  
Resonance Amplitude

Abstract Steam piping and components in many industrial applications such as power plants sometimes experience structural vibration and fatigue damage caused by flow-induced acoustic resonance in piping with closed side branches. The state of steam in the steam piping can be not only dry (superheated) steam but also wet steam (i.e., a two-phase flow comprising a mixture of saturated steam and saturated water). From our prior research on the general characteristics of acoustic resonance under wet steam flows, the maximum pressure amplitudes under low-pressure wet steam were significantly lower than those under dry steam, which is considered to be caused by the presence of a liquid phase. Here, we investigate how the steam wetness and steam pressure affect the maximum pressure amplitude since practical steam piping may be exposed to various conditions. Experiments on acoustic resonance in a single side branch were conducted under high-quality wet steam flows with a steam pressure of up to 0.8 MPa and a steam quality of 0.9 < x < 1.0 as parameters. For our experimental conditions, it was confirmed that the steam pressure and steam state had little impact on the critical Strouhal number, whereas the maximum amplitudes under wet steam were markedly lower than those under dry steam. Different dependences of the maximum amplitude on the Reynolds number were confirmed for dry steam and wet steam. Moreover, the reduction of the maximum pressure amplitude under wet steam was affected by both the void fraction and the density ratio.

Effects of Natural Gas Compositions on Engine In-Cylinder Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 498-503
Author(s):  
La Xiang ◽  
Yu Ding
Keyword(s):  
Natural Gas ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Test Bed ◽  
Promising Alternative ◽  
Natural Gas Engines ◽  
Lower Maximum

Natural gas (NG) is one of the most promising alternative fuels of diesel and petrol because of its economics and environmental protection. Generally the NG engine share the similar structure profile with diesel or petrol engine but the combustion characteristics of NG is varied from the fuels, so the investigation of NG engine combustion process receive more attentions from the researchers. In this paper, a zero-dimensional model on the basis of Vibe function is built in the MATLAB/SIMULINK environment. The model provides the prediction of combustion process in natural gas engines, which has been verified by the experimental data in the NG test bed. Furthermore, the influence of NG composition on engine performance is investigated, in which the in-cylinder maximum pressure and temperature and mean indicated pressure are compared using different type NG. It is shown in the results that NG with higher composition of methane results in lower maximum temperature and mean indicated pressure as well as higher maximum pressure.

scholarly journals Induction of Changes in Internal Gas Pressure of Bulky Plant Organs by Temperature Gradients

1990 ◽  
Vol 115 (2) ◽  
pp. 308-312 ◽  
Author(s):  
Kenneth A. Corey ◽  
Zhi-Yi Tan
Keyword(s):  
Bath Temperature ◽  
Ideal Gas ◽  
Gas Pressure ◽  
Temperature Gradients ◽  
Maximum Pressure ◽  
Plant Organs ◽  
Ideal Gas Law ◽  
Increasing Temperature ◽  
Pressure Changes

Water manometers were connected to fruits of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.), and then fruits were submerged in water baths providing initial temperature gradients between fruit and water of 0 to 19C. Apple (Malus domestics Borkh.) fruits, carrot (Daucus carota L.) roots, witloof chicory (Cichorium intybus L.) roots, rhubarb Rheum rhabarbarum L.) petioles, and pokeweed (Phytolacca americana L.) stems were subjected to water bath temperature gradients of 5C. Internal partial vacuums developed in all organs within minutes of imposing the gradients. The maximum partial vacuums in tomato and pepper fruits increased with increasing temperature gradients. Uptake of water accompanied changes in internal pressure reaching maxima of 17% (w/w) and 2% (w/w) of pepper and tomato fruits, respectively, after 22 hours. Maximum pressure changes achieved in bulky organs deviated from those predicted by the ideal gas law, possibly due to concomitant changes in gas pressure upon replacement of intercellular spaces with water and dissolution of CO2. Partial vacuums also developed in pepper fruits, rhubarb petioles, and pokeweed stems following exposure to air 15C cooler than initial organ temperatures. Results point to the role of temperature gradients in the transport of liquids and gases in plant organs.

Subcutaneous tissue gas space pressure during superficial isobaric counterdiffusion

1979 ◽  
Vol 47 (1) ◽  
pp. 224-227 ◽  
Author(s):  
J. R. Cowley ◽  
C. Allegra ◽  
C. J. Lambertsen
Keyword(s):  
Gas Phase ◽  
Subcutaneous Tissue ◽  
Inert Gas ◽  
Maximum Pressure ◽  
Tissue Pressure ◽  
Phase Development ◽  
New Zealand White Rabbits ◽  
Gas Space ◽  
Pressure Changes ◽  
Mean Time

Changes in subcutaneous tissue pressure caused by N2O-He, 1-ATA isobaric counterdiffusion gas phase development were measured. Only the ears of New Zealand White rabbits were subjected to counterdiffusion. The rabbits breathed a mixture of 80% N2O-20% O2 while their ears alone were surrounded by He and the rest of their bodies continued to be surrounded by air. Subcutaneous pressure changes were transmitted to the transducer-recorded system via a fluid-filled subcutaneous needle. When the gas phase developed in subcutaneous tissue, pressure rose and a maximum pressure (Pmax) was reached. Pmax in the counterdiffused ear was 48 +/- 10 (SD) Torr, and mean time to reach Pmax was 75 +/- 10 (SD) min. The findings are discussed in relation to the pathological processes of isobaric inert gas counterdiffusion.

scholarly journals Effect of distal esophageal irritation on the changes of cystometry parameters to esophagus and colon distentions in rats

2019 ◽  
Vol 97 (8) ◽  
pp. 766-772
Author(s):  
Ezidin G. Kaddumi
Keyword(s):  
Electrical Stimulation ◽  
Urinary Bladder ◽  
Vagus Nerve ◽  
Storage Time ◽  
Distal Colon ◽  
Bladder Function ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Chemical Irritation ◽  
Stimulation Of

The coexistence of different visceral pathologies in patients suffering from irritable bowel syndrome, interstitial cystitis, and other pathologies, necessitates the study of these pathologies under complicated conditions. In the present study, cystometry recordings were used to investigate the effect of distal esophageal chemical irritation on the urinary bladder interaction with distal colon distention, distal esophageal distention, and electrical stimulation of abdominal branches of vagus nerve. Distal esophageal chemical irritation significantly decreased the intercontraction time via decreasing the voiding time. Also, distal esophageal chemical irritation significantly decreased the pressure amplitude by decreasing the maximum pressure. Following distal esophageal chemical irritation, distal esophageal distention was able to significantly decrease the intercontraction time by decreasing the storage time. However, 3 mL distal colon distention significantly increased the intercontraction time by increasing the storage time. On the other hand, following distal esophageal chemical irritation, electrical stimulation of abdominal branches of vagus nerve did not have any significant effect on intercontraction time. However, electrical stimulation of abdominal branches of vagus nerve significantly increased the pressure amplitude by increasing the maximum pressure. The results of this study demonstrate that urinary bladder function and interaction of bladder with other viscera can be affected by chemical irritation of distal esophagus.

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