The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Diederik Gommers - One of the best experts on this subject based on the ideXlab platform.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Introduction Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients. Ventilation distribution was calculated on the basis of EIT results from 12 mechanically ventilated patients after cardiac surgery at a cardiothoracic ICU. Measurements were taken at four PEEP levels (15, 10, 5 and 0 cm H2O) at both the cranial and caudal Lung levels, which were divided into four ventral-to-dorsal regions. Regional compliance was calculated using impedance and driving Pressure data. We found that tidal impedance variation divided by tidal volume significantly decreased on caudal EIT slices, whereas this measurement increased on the cranial EIT slices. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, decreased during the decremental PEEP trial at both EIT levels. Optimal regional compliance differed at different PEEP levels: 10 and 5 cm H2O at the cranial level and 15 and 10 cm H2O at the caudal level for the dependent and nondependent Lung regions, respectively. At the bedside, EIT measured at two thoracic levels showed different behavior between the caudal and cranial Lung levels during a decremental PEEP trial. These results indicate that there is probably no single optimal PEEP level for all Lung regions.
Ido G Bikker - One of the best experts on this subject based on the ideXlab platform.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Introduction Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients. Ventilation distribution was calculated on the basis of EIT results from 12 mechanically ventilated patients after cardiac surgery at a cardiothoracic ICU. Measurements were taken at four PEEP levels (15, 10, 5 and 0 cm H2O) at both the cranial and caudal Lung levels, which were divided into four ventral-to-dorsal regions. Regional compliance was calculated using impedance and driving Pressure data. We found that tidal impedance variation divided by tidal volume significantly decreased on caudal EIT slices, whereas this measurement increased on the cranial EIT slices. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, decreased during the decremental PEEP trial at both EIT levels. Optimal regional compliance differed at different PEEP levels: 10 and 5 cm H2O at the cranial level and 15 and 10 cm H2O at the caudal level for the dependent and nondependent Lung regions, respectively. At the bedside, EIT measured at two thoracic levels showed different behavior between the caudal and cranial Lung levels during a decremental PEEP trial. These results indicate that there is probably no single optimal PEEP level for all Lung regions.
Ingo R. Titze - One of the best experts on this subject based on the ideXlab platform.
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A Cervid Vocal Fold Model Suggests Greater Glottal Efficiency in Calling at High Frequencies
2013Co-Authors: Ingo R. Titze, Tobias RiedeAbstract:Male Rocky Mountain elk (Cervus elaphus nelsoni) produce loud and high fundamental frequency bugles during the mating season, in contrast to the male European Red Deer (Cervus elaphus scoticus) who produces loud and low fundamental frequency roaring calls. A critical step in understanding vocal communication is to relate sound complexity to anatomy and physiology in a causal manner. Experimentation at the sound source, often difficult in vivo in mammals, is simulated here by a finite element model of the larynx and a wave propagation model of the vocal tract, both based on the morphology and biomechanics of the elk. The model can produce a wide range of fundamental frequencies. Low fundamental frequencies require low vocal fold strain, but large Lung Pressure and large glottal flow if sound intensity level is to exceed 70 dB at 10 m distance. A high-frequency bugle requires both large muscular effort (to strain the vocal ligament) and high Lung Pressure (to overcome phonation threshold Pressure), but at least 10 dB more intensity level can be achieved. Glottal efficiency, the ration of radiated sound power to aerodynamic power at the glottis, is higher in elk, suggesting an advantage of highpitched signaling. This advantage is based on two aspects; first, the lower airflow required for aerodynamic power and, second, an acoustic radiation advantage at higher frequencies. Both signal types are used by the respective males during the mating season and probably serve as honest signals. The two signal types relate differently to physical qualities of the sender. The low-frequency sound (Red Deer call) relates to overall body size via a strong relationship between acousti
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adapted to roar functional morphology of tiger and lion vocal folds
PLOS ONE, 2011Co-Authors: Sarah A Klemuk, Tobias Riede, Ingo R. Titze, Edward J WalshAbstract:Vocal production requires active control of the respiratory system, larynx and vocal tract. Vocal sounds in mammals are produced by flow-induced vocal fold oscillation, which requires vocal fold tissue that can sustain the mechanical stress during phonation. Our understanding of the relationship between morphology and vocal function of vocal folds is very limited. Here we tested the hypothesis that vocal fold morphology and viscoelastic properties allow a prediction of fundamental frequency range of sounds that can be produced, and minimal Lung Pressure necessary to initiate phonation. We tested the hypothesis in lions and tigers who are well-known for producing low frequency and very loud roaring sounds that expose vocal folds to large stresses. In histological sections, we found that the Panthera vocal fold lamina propria consists of a lateral region with adipocytes embedded in a network of collagen and elastin fibers and hyaluronan. There is also a medial region that contains only fibrous proteins and hyaluronan but no fat cells. Young's moduli range between 10 and 2000 kPa for strains up to 60%. Shear moduli ranged between 0.1 and 2 kPa and differed between layers. Biomechanical and morphological data were used to make predictions of fundamental frequency and subglottal Pressure ranges. Such predictions agreed well with measurements from natural phonation and phonation of excised larynges, respectively. We assume that fat shapes Panthera vocal folds into an advantageous geometry for phonation and it protects vocal folds. Its primary function is probably not to increase vocal fold mass as suggested previously. The large square-shaped Panthera vocal fold eases phonation onset and thereby extends the dynamic range of the voice.
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A cervid vocal fold model suggests greater glottal efficiency in calling at high frequencies.
Public Library of Science (PLoS), 2010Co-Authors: Ingo R. Titze, Tobias RiedeAbstract:Male Rocky Mountain elk (Cervus elaphus nelsoni) produce loud and high fundamental frequency bugles during the mating season, in contrast to the male European Red Deer (Cervus elaphus scoticus) who produces loud and low fundamental frequency roaring calls. A critical step in understanding vocal communication is to relate sound complexity to anatomy and physiology in a causal manner. Experimentation at the sound source, often difficult in vivo in mammals, is simulated here by a finite element model of the larynx and a wave propagation model of the vocal tract, both based on the morphology and biomechanics of the elk. The model can produce a wide range of fundamental frequencies. Low fundamental frequencies require low vocal fold strain, but large Lung Pressure and large glottal flow if sound intensity level is to exceed 70 dB at 10 m distance. A high-frequency bugle requires both large muscular effort (to strain the vocal ligament) and high Lung Pressure (to overcome phonation threshold Pressure), but at least 10 dB more intensity level can be achieved. Glottal efficiency, the ration of radiated sound power to aerodynamic power at the glottis, is higher in elk, suggesting an advantage of high-pitched signaling. This advantage is based on two aspects; first, the lower airflow required for aerodynamic power and, second, an acoustic radiation advantage at higher frequencies. Both signal types are used by the respective males during the mating season and probably serve as honest signals. The two signal types relate differently to physical qualities of the sender. The low-frequency sound (Red Deer call) relates to overall body size via a strong relationship between acoustic parameters and the size of vocal organs and body size. The high-frequency bugle may signal muscular strength and endurance, via a 'vocalizing at the edge' mechanism, for which efficiency is critical
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phonation threshold Pressure a missing link in glottal aerodynamics
Journal of the Acoustical Society of America, 1991Co-Authors: Ingo R. TitzeAbstract:Phonation threshold Pressure has previously been defined as the minimum Lung Pressure required to initiate phonation. By modeling the dependence of this Pressure on fundamental frequency, it is shown that relatively simple aerodynamic relations for time‐varying flow in the glottis are obtained. Lung Pressure and peak glottal flow are nearly linearly related, but not proportional. For this reason, typical power‐law relations that have previously been proposed do not hold. Glottal impedance for time‐varying flow must be defined differentially rather than as a simple ratio between Pressure and flow. It is shown that the peak flow, the peak flow derivative, the open quotient, and the speed quotient of inverse‐filtered glottal flow waveforms all depend explicitly on phonation threshold Pressure. Data from singers are compared with those from nonsingers. The primary difference is that singers obtain two to three times greater peak flow for a given Lung Pressure, suggesting that they adjust their glottal or voca...
Carsten Preis - One of the best experts on this subject based on the ideXlab platform.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Introduction Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients. Ventilation distribution was calculated on the basis of EIT results from 12 mechanically ventilated patients after cardiac surgery at a cardiothoracic ICU. Measurements were taken at four PEEP levels (15, 10, 5 and 0 cm H2O) at both the cranial and caudal Lung levels, which were divided into four ventral-to-dorsal regions. Regional compliance was calculated using impedance and driving Pressure data. We found that tidal impedance variation divided by tidal volume significantly decreased on caudal EIT slices, whereas this measurement increased on the cranial EIT slices. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, decreased during the decremental PEEP trial at both EIT levels. Optimal regional compliance differed at different PEEP levels: 10 and 5 cm H2O at the cranial level and 15 and 10 cm H2O at the caudal level for the dependent and nondependent Lung regions, respectively. At the bedside, EIT measured at two thoracic levels showed different behavior between the caudal and cranial Lung levels during a decremental PEEP trial. These results indicate that there is probably no single optimal PEEP level for all Lung regions.
Jan Bakker - One of the best experts on this subject based on the ideXlab platform.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Introduction Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients.
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electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end expiratory Lung Pressure trial
Critical Care, 2011Co-Authors: Ido G Bikker, Carsten Preis, Mahamud Egal, Jan Bakker, Diederik GommersAbstract:Computed tomography of the Lung has shown that ventilation shifts from dependent to nondependent Lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory Pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients. Ventilation distribution was calculated on the basis of EIT results from 12 mechanically ventilated patients after cardiac surgery at a cardiothoracic ICU. Measurements were taken at four PEEP levels (15, 10, 5 and 0 cm H2O) at both the cranial and caudal Lung levels, which were divided into four ventral-to-dorsal regions. Regional compliance was calculated using impedance and driving Pressure data. We found that tidal impedance variation divided by tidal volume significantly decreased on caudal EIT slices, whereas this measurement increased on the cranial EIT slices. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, decreased during the decremental PEEP trial at both EIT levels. Optimal regional compliance differed at different PEEP levels: 10 and 5 cm H2O at the cranial level and 15 and 10 cm H2O at the caudal level for the dependent and nondependent Lung regions, respectively. At the bedside, EIT measured at two thoracic levels showed different behavior between the caudal and cranial Lung levels during a decremental PEEP trial. These results indicate that there is probably no single optimal PEEP level for all Lung regions.
