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Dirk Beutner - One of the best experts on this subject based on the ideXlab platform.
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reliability of eustachian tube function measurements in a hypobaric and hyperbaric Pressure Chamber
Clinical Otolaryngology, 2017Co-Authors: Moritz F Meyer, Stefanie Jansen, Oxana Mordkovich, Karlbernd Huttenbrink, Dirk BeutnerAbstract:Objectives Measurement of the Eustachian tube (ET) function is a challenge. The demand for a precise and meaningful diagnostic tool increases – especially since more and more operative therapies are being offered without objective evidence. The measurement of the ET function by continuous impedance recording in a Pressure Chamber is an established method, although the reliability of the measurements is still unclear. Methods 25 participants (50 ears) were exposed to phases of compression and decompression in a hypo and hyperbaric Pressure Chamber. The ET function reflecting parameters – ET opening Pressure (ETOP), ET opening duration (ETOD), and ET opening frequency (ETOF) – were determined under exactly the same preconditions three times in a row. The intraclass correlation coefficient (ICC) and Bland and Altman plot were used to assess test-retest reliability. Results ICCs revealed a high correlation for ETOP and ETOF in phases of decompression (passive equalisation) as well as ETOD and ETOP in phases of compression (active induced equalisation). Very high correlation could be shown for ETOD in decompression and ETOF in compression phases. The Bland and Altmann graphs could show that measurements provide results within a 95 % confidence interval in compression and decompression phases. Conclusions We conclude that measurements in a Pressure Chamber are a very valuable tool in terms of estimating the ET opening and closing function. Measurements show some variance comparing participants, but provide reliable results within a 95 % confidence interval in retest. This study is the basis for enabling efficacy measurements of ET treatment modalities. This article is protected by copyright. All rights reserved.
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characterizing the active opening of the eustachian tube in a hypobaric hyperbaric Pressure Chamber
Otology & Neurotology, 2014Co-Authors: S Mikolajczak, Moritz F Meyer, Karlbernd Huttenbrink, Maria Grosheva, Moritz Hahn, Christine Korthauer, Masen Dirk Jumah, Jan Christoffer Luers, Dirk BeutnerAbstract:OBJECTIVE Active and passive opening of the Eustachian tube (ET) enables direct aeration of the middle ear and a Pressure balance between middle ear and the ambient Pressure. The aim of this study was to characterize standard values for the opening Pressure (ETOP), the opening frequency (ETOF), and the opening duration (ETOD) for active tubal openings (Valsalva maneuver, swallowing) in healthy participants. DESIGN/PARTICIPANTS In a hypobaric/hyperbaric Pressure Chamber, 30 healthy participants (19 women, 11 men; mean age, 25.57 ± 3.33 years) were exposed to a standardized profile of compression and decompression. The Pressure values were recorded via continuous impedance measurement during the Valsalva maneuver and swallowing. Based on the data, standard curves were identified and the ETOP, ETOD, and ETOF were determined. RESULTS Recurring patterns of the Pressure curve during active tube opening for the Valsalva maneuver and for active swallowing were characterized. The mean value for the Valsalva maneuver for ETOP was 41.21 ± 17.38 mbar; for the ETOD, it was 2.65 ± 1.87 seconds. In the active Pressure compensation by swallowing, the mean value for the ETOP was 29.91 ± 13.07 mbar; and for the ETOD, it was 0.82 ± 0.53 seconds. CONCLUSION Standard values for the opening Pressure of the tube and the tube opening duration for active tubal openings (Valsalva maneuver, swallowing) were described, and typical curve gradients for healthy subjects could be shown. This is another step toward analyzing the function of the tube in compression and decompression.
Moritz F Meyer - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the parameter mean impedance for representing eustachian tube functions during Pressure increase and decrease in Pressure Chamber measurements
Otology & Neurotology, 2019Co-Authors: David Schwarz, Stefanie Jansen, Susanne Steinhauser, Moritz F MeyerAbstract:HYPOTHESIS The hypothesis of the study is that the mean impedance (MI) during compression and decompression provides additional information of the Eustachian tube (ET) function. BACKGROUND The continuous impedance measurement in a Pressure Chamber can provide valuable information about the opening function of the ET. METHODS Around 55 ear-healthy volunteers were examined in a Pressure Chamber. These were subjected to a decompression phase and a compression phase. The Pressure change was constantly 20 kPa/min. Using evaluation software, the MI could be determined for both ears in each case for the phases of compression and decompression. RESULTS In 49 participants, we could interpret the data successfully. On average, an output value (without Pressure changes) of the impedance of 0.58 ±0.11 Pa on the right side and 0.43 ± 0.1 Pa on the left side were measured. During decompression, 0.098 ± 0.05 Pa (right) and 0.087 ± 0.043 Pa (left) could be determined. For compression, values of 0.086 ± 0.044 Pa on the right and 0.079 ± 0.045 Pa on the left were detected. The retest reliability was higher with an intraclass correlation coefficient for the decompression MI of 0.833 than the 0.772 compression MI. CONCLUSIONS It is possible to measure MI in healthy subjects during compression and decompression. This value represents a good average in terms of the Pressure tolerance of the middle ear. In future, studies will be required to determine whether MI will be a useful parameter in differentiating normal and abnormal ET function.
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evaluation of the parameter mean impedance for representing eustachian tube functions during Pressure increase and decrease in Pressure Chamber measurements
Otology & Neurotology, 2019Co-Authors: David Schwarz, Stefanie Jansen, Susanne Steinhauser, Moritz F MeyerAbstract:HYPOTHESIS The hypothesis of the study is that the mean impedance (MI) during compression and decompression provides additional information of the Eustachian tube (ET) function. BACKGROUND The continuous impedance measurement in a Pressure Chamber can provide valuable information about the opening function of the ET. METHODS Around 55 ear-healthy volunteers were examined in a Pressure Chamber. These were subjected to a decompression phase and a compression phase. The Pressure change was constantly 20 kPa/min. Using evaluation software, the MI could be determined for both ears in each case for the phases of compression and decompression. RESULTS In 49 participants, we could interpret the data successfully. On average, an output value (without Pressure changes) of the impedance of 0.58 ±0.11 Pa on the right side and 0.43 ± 0.1 Pa on the left side were measured. During decompression, 0.098 ± 0.05 Pa (right) and 0.087 ± 0.043 Pa (left) could be determined. For compression, values of 0.086 ± 0.044 Pa on the right and 0.079 ± 0.045 Pa on the left were detected. The retest reliability was higher with an intraclass correlation coefficient for the decompression MI of 0.833 than the 0.772 compression MI. CONCLUSIONS It is possible to measure MI in healthy subjects during compression and decompression. This value represents a good average in terms of the Pressure tolerance of the middle ear. In future, studies will be required to determine whether MI will be a useful parameter in differentiating normal and abnormal ET function.
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reliability of eustachian tube function measurements in a hypobaric and hyperbaric Pressure Chamber
Clinical Otolaryngology, 2017Co-Authors: Moritz F Meyer, Stefanie Jansen, Oxana Mordkovich, Karlbernd Huttenbrink, Dirk BeutnerAbstract:Objectives Measurement of the Eustachian tube (ET) function is a challenge. The demand for a precise and meaningful diagnostic tool increases – especially since more and more operative therapies are being offered without objective evidence. The measurement of the ET function by continuous impedance recording in a Pressure Chamber is an established method, although the reliability of the measurements is still unclear. Methods 25 participants (50 ears) were exposed to phases of compression and decompression in a hypo and hyperbaric Pressure Chamber. The ET function reflecting parameters – ET opening Pressure (ETOP), ET opening duration (ETOD), and ET opening frequency (ETOF) – were determined under exactly the same preconditions three times in a row. The intraclass correlation coefficient (ICC) and Bland and Altman plot were used to assess test-retest reliability. Results ICCs revealed a high correlation for ETOP and ETOF in phases of decompression (passive equalisation) as well as ETOD and ETOP in phases of compression (active induced equalisation). Very high correlation could be shown for ETOD in decompression and ETOF in compression phases. The Bland and Altmann graphs could show that measurements provide results within a 95 % confidence interval in compression and decompression phases. Conclusions We conclude that measurements in a Pressure Chamber are a very valuable tool in terms of estimating the ET opening and closing function. Measurements show some variance comparing participants, but provide reliable results within a 95 % confidence interval in retest. This study is the basis for enabling efficacy measurements of ET treatment modalities. This article is protected by copyright. All rights reserved.
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characterizing the active opening of the eustachian tube in a hypobaric hyperbaric Pressure Chamber
Otology & Neurotology, 2014Co-Authors: S Mikolajczak, Moritz F Meyer, Karlbernd Huttenbrink, Maria Grosheva, Moritz Hahn, Christine Korthauer, Masen Dirk Jumah, Jan Christoffer Luers, Dirk BeutnerAbstract:OBJECTIVE Active and passive opening of the Eustachian tube (ET) enables direct aeration of the middle ear and a Pressure balance between middle ear and the ambient Pressure. The aim of this study was to characterize standard values for the opening Pressure (ETOP), the opening frequency (ETOF), and the opening duration (ETOD) for active tubal openings (Valsalva maneuver, swallowing) in healthy participants. DESIGN/PARTICIPANTS In a hypobaric/hyperbaric Pressure Chamber, 30 healthy participants (19 women, 11 men; mean age, 25.57 ± 3.33 years) were exposed to a standardized profile of compression and decompression. The Pressure values were recorded via continuous impedance measurement during the Valsalva maneuver and swallowing. Based on the data, standard curves were identified and the ETOP, ETOD, and ETOF were determined. RESULTS Recurring patterns of the Pressure curve during active tube opening for the Valsalva maneuver and for active swallowing were characterized. The mean value for the Valsalva maneuver for ETOP was 41.21 ± 17.38 mbar; for the ETOD, it was 2.65 ± 1.87 seconds. In the active Pressure compensation by swallowing, the mean value for the ETOP was 29.91 ± 13.07 mbar; and for the ETOD, it was 0.82 ± 0.53 seconds. CONCLUSION Standard values for the opening Pressure of the tube and the tube opening duration for active tubal openings (Valsalva maneuver, swallowing) were described, and typical curve gradients for healthy subjects could be shown. This is another step toward analyzing the function of the tube in compression and decompression.
Tarantino Alessandro - One of the best experts on this subject based on the ideXlab platform.
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Measurement of plant xylem water Pressure using the high-capacity tensiometer and implications for the modelling of soil–atmosphere interaction
'Thomas Telford Ltd.', 2021Co-Authors: Dainese Roberta, Tarantino AlessandroAbstract:International audienceThe response of shallow geotechnical structures is affected by interaction with the atmosphere. Since the ground surface is very often vegetated, plant transpiration plays a major role in such an interaction. Transpiration in geotechnical applications is generally modelled by way of a transpiration reduction function (e.g. the Feddes function). However, its parameters are generally borrowed from the agricultural literature, where the focus is on crop species and often loosely compacted organic agricultural soils. For the non-crop species in denser soils typically encountered in geotechnical applications, monitoring of the flow taking place in the soil through the xylem up to the leaves can potentially be exploited to characterise the transpiration reduction function. The main challenge is the measurement of the water Pressure in the xylem. Techniques currently used include the Pressure Chamber and thermocouple psychrometer. The Pressure Chamber is destructive and thus not suitable for continuous monitoring and/or where a relatively small number of leaves is available (as often occurs in laboratory experiments). The thermocouple psychrometer is not accurate at low water tension, is affected by the presence of solutes in the xylem water and is significantly sensitive to temperature. This paper explores a novel application of the high-capacity tensiometer (HCT), initially developed for pore-water Pressure measurement in soils. The HCT was installed on the stem or branch of different trees and its measurement validated against Pressure Chamber measurements over a range of xylem water Pressure down to -1300 kPa. In addition, its measurement was used to investigate the response of the soil-plant continuum. Results show that the HCT is a viable and convenient instrument to use for xylem water Pressure measurement and can provide field-based data for the modelling of plant transpiration. Installing HCTs on stems and branches is quite straightforward and this will help achieve a step change in testing and modelling the effect of plant transpiration on the soil water regime in the vadose zone
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Measurement of xylem water Pressure using High-Capacity Tensiometer and benchmarking against Pressure Chamber and Thermocouple Psychrometer
'EDP Sciences', 2020Co-Authors: Dainese Roberta, Tedeschi Giuseppe, Fourcaud Thierry, Tarantino AlessandroAbstract:International audienceThe response of the shallow portion of the ground (vadose zone) and of earth structures is affected by the interaction with the atmosphere. Rainwater infiltration and evapotranspiration affect the stability of man-made and natural slopes and cause shallow foundations and embankments to settle and heave. Very frequently, the ground surface is covered by vegetation and, as a result, transpiration plays a major role in ground-atmosphere interaction. The soil, the plant, and the atmosphere form a continuous hydraulic system, which is referred to as Soil-Plant-Atmosphere Continuum (SPAC). The SPAC actually represents the ‘boundary condition’ of the geotechnical water flow problem. Water flow in soil and plant takes place because of gradients in hydraulic head triggered by the negative water Pressure (water tension) generated in the leaf stomata. To study the response of the SPAC, (negative) water Pressure needs to be measured not only in the soil but also in the plant. The paper presents a novel technique to measure the xylem water Pressure based on the use of the High-Capacity Tensiometer (HCT), which is benchmarked against conventional techniques for xylem water Pressure measurements, i.e. the Pressure Chamber (PC) and the Thermocouple Psychrometer (TP)
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Measurement of plant xylem water Pressure using the high-capacity tensiometer and implications on the modelling of soil-atmosphere interaction
'Thomas Telford Ltd.', 2020Co-Authors: Dainese Roberta, Tarantino AlessandroAbstract:The response of shallow geotechnical structures is affected by the interaction with the atmosphere. Since the ground surface is very often vegetated, plant transpiration plays a major role in such an interaction. Transpiration in geotechnical applications is generally modelled via a transpiration reduction function (e.g. the Feddes function). However, its parameters are generally borrowed from the agricultural literature, where the focus is on crop species and often loosely compacted organic agricultural soils. For non-crop species in denser soils typically encountered in geotechnical applications, monitoring of the flow taking place in the soil through the xylem up to the leaves can potentially be exploited to characterise the transpiration reduction function. The main challenge is the measurement of the water Pressure in the xylem. Techniques currently used include the Pressure Chamber and Thermocouple Psychrometer. The Pressure Chamber is destructive and thus not suitable for continuous monitoring and/or where a relatively small number of leaves is available (as often occurs in laboratory experiments). The Thermocouple Psychrometer is not accurate at low water tension, is affected by the presence of solutes in the xylem water, and is significantly sensitive to temperature. This paper explores a novel application of the High-Capacity Tensiometer (HCT), initially developed for pore-water Pressure-measurement in soils. The HCT was installed on the stem or branch of different trees and its measurement validated against Pressure Chamber measurements over a range of xylem water Pressure down to -1300 kPa. In addition, its measurement was used to investigate the response of the soil-plant continuum. Results show that the HCT is a viable and convenient instrument to use for xylem water Pressure measurement and can provide field-based data for the modelling of plant transpiration. Installing HCTs on stems and branches is quite straightforward and this will help achieve a step-change in testing and modelling the effect of plant transpiration on soil water regime in the vadose zone
J. A. C. Smith - One of the best experts on this subject based on the ideXlab platform.
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a critical comparison of the Pressure probe and Pressure Chamber techniques for estimating leaf ceil turgor Pressure in kalanchoe daigremontiana
Plant Cell and Environment, 1994Co-Authors: R. Murphy, J. A. C. SmithAbstract:The aim of the present study was to test the accuracy of the Pressure-Chamber technique as a method for estimating leaf-cell turgor Pressures. To this end, Pressure-probe measurements of cell turgor Pressure (Pcell) were made on mesophyll cells of intact, attached leaves of Kalanchoe daigremontiana. Immediately following these measurements, leaves were excised and placed in a Pressure Chamber for the determination of balance Pressure (Pbal). Cell-sap osmotic Pressure (?cell) and xylem-sap osmotic Pressure (?xyl) were also measured, and an average cell turgor Pressure calculated as Pcell=?cell–?xyl–Pbal. The apparent value of Pbal was positively correlated with the rate of increase of Chamber Pressure, and there was also a time-dependent increase associated with water loss. On expressing sap from the xylem, ?xyl fell to a plateau value that was positively correlated with ?cell. Correcting for these effects yielded estimates of Pbal and ?xyl at the time of leaf excision. On average, the values of Pcell obtained with the two techniques agreed to within ±002 MPa (errors are approximate 95% confidence limits). If ?xyl were ignored, however, the calculated turgor Pressures would exceed the measured values by an average of 0.074 ± 0.012MPa, or 48% at the mean measured Pressure of 0.155 MPa. We conclude that the Pressure-Chamber technique allows a good estimate to be made of turgor Pressure in mesophyll cells of K. daigremontiana, provided that ?xyl is included in the determination. The 1:1 relationship between the measured and calculated turgor Pressures also implies that the weighted-average reflection coefficient for the mesophyll cell membranes is close to unity.
James W Oleary - One of the best experts on this subject based on the ideXlab platform.
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sustained and significant negative water Pressure in xylem
Nature, 1995Co-Authors: William T Pockman, John S Sperry, James W OlearyAbstract:DESPITE two centuries of research, the mechanism of water transport in plants is still debated1–8.The prevailing cohesion–tension theory2,3, which states that water is pulled upwards by capillarity in cell-wall pores, remains vulnerable to challenge because its corollary is difficult to prove: that large negative Pressures exist in xylem conduits4–7. Recent xylem Pressure-probe and z-tube experiments suggest that cavitation limits xylem Pressures to above −0.5 MPa, despite the much more negative Pressures predicted by the cohesion–tension theory and measured with the standard Pressure-Chamber method4,5,9,10. Here we show, using centrifugal force to induce negative Pressure between −0.5 and −3.5 MPa in intact stems, that xylem conduits remained water-filled and conductive to species-specific Pressures ranging from −1.2 to below −3.5 MPa. Results were consistent when stems were air-dried or injected with air. Agreement among these techniques demonstrates that xylem can support large negative Pressures, that the Pressure Chamber reliably measures these Pressures, and that cavitation is nucleated by air entry through conduit wall pores.