The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
A. William Sheel - One of the best experts on this subject based on the ideXlab platform.
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The Mechanics of Breathing during Swimming.
Medicine and science in sports and exercise, 2019Co-Authors: Michael G. Leahy, Mckenzie N. Summers, Carli M. Peters, Yannick Molgat-seon, Caitlin M. Geary, A. William SheelAbstract:The thorax undergoes unique conditions while swimming. Hydrostatic pressure from water immersion places an external load on the thorax and increases airway resistance, and the horizontal body position results in central venous engorgement and an associated reduction in lung compliance. The aforementioned factors likely increase the work of Breathing (Wb); however, this hypothesis remains untested. PURPOSE This study aimed to compare Wb during freestyle swimming relative to cycling and to characterize the differences in the cardiorespiratory responses to swimming relative to cycling in the same individuals. METHODS Eight collegiate swimmers (four men and four women, age = 22 ± 2 yr) performed an incremental swim test while tethered to a resistance apparatus. On a separate day, subjects performed an incremental cycle test. During swimming and cycling, metabolic and ventilatory parameters were measured using a customized metabolic cart, and inspired Wb was quantified using an esophageal balloon catheter. RESULTS Swimming and cycling elicited statistically similar levels of peak oxygen uptake (3.87 ± 0.92 vs 4.20 ± 0.83 L·min, P = 0.143). However, peak minute ventilation (V˙E) (118 ± 3 vs 154 ± 25 L·min) and heart rate (164 ± 19 vs 183 ± 8 bpm) were significantly lower during swimming relative to cycling (both P < 0.05). Inspired Wb was higher at a V˙E of 50 L·min (+27 ± 16 J·min), 75 L·min (+56 ± 23 J·min), and 100 L·min (+53 ± 22 J·min) during swimming compared with cycling (all P < 0.05). Periods of interbreath apnea were observed while swimming (duration = 0.13-2.07 s). CONCLUSION We interpret our findings to mean that the horizontal body position and hydrostatic pressure on the chest wall requires swimmers to generate greater inspiratory pressures to sustain adequate V˙E during exercise.
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Revisiting dysanapsis: sex-based differences in airways and the Mechanics of Breathing during exercise.
Experimental physiology, 2015Co-Authors: A. William Sheel, Paolo B Dominelli, Yannick Molgat-seonAbstract:New Findings What is the topic of this review? This review focuses on sex-based differences in the anatomy of the respiratory system, which manifest in mechanical ventilatory contraints and potentially alter the integrative response to exercise. What advances does it highlight? Recent evidence indicates that women have smaller conducting airways than men, even when matched for lung size. Consequently, women are more likely to experience mechanical ventilatory constraints to exercise hyperpnoea. Furthermore, at a given ventilation, women have a higher work and oxygen cost of Breathing, both of which may lead to differences in the whole-body integrative response to dynamic exercise. Our understanding of the human ventilatory response to exercise is largely based on a historical body of literature focused primarily on male rather than female research subjects. In recent years, important sex-based differences in the anatomy of the human respiratory system have been identified; for a given lung size, women appear to have smaller-diameter conducting airways than men. The presence of such inherent differences in the tracheobronchial tree greatly affects the Mechanics of airflow generation, especially during conditions of high ventilation rates, such as exercise. Data from a growing number of studies suggest that women may be more susceptible to respiratory system limitations during exercise than their male counterparts. Specifically, women are more likely to experience expiratory flow limitation and exercise-induced arterial hypoxaemia and have a higher metabolic cost of Breathing for a given ventilation. Collectively, the available evidence suggests that sex differences in the ventilatory response to exercise are present and may have important ramifications for the integrated response to exercise; however, several fundamental questions remain unanswered.
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Exercise‐induced arterial hypoxaemia and the Mechanics of Breathing in healthy young women
The Journal of physiology, 2013Co-Authors: Paolo B Dominelli, Glen E. Foster, Giulio S. Dominelli, William R. Henderson, Michael S. Koehle, Donald C. Mckenzie, A. William SheelAbstract:The purpose of this study was to characterize exercise-induced arterial hypoxaemia (EIAH), pulmonary gas exchange and respiratory Mechanics during exercise, in young healthy women. We defined EIAH as a >10 mmHg decrease in arterial oxygen tension ( ) during exercise compared to rest. We used a heliox inspirate to test the hypothesis that mechanical constraints contribute to EIAH. Subjects with a spectrum of aerobic capacities (n = 30; maximal oxygen consumption ( ) = 49 ± 1, range 28-62 ml kg(-1) min(-1)) completed a stepwise treadmill test and a subset (n = 18 with EIAH) completed a constant load test (~85% ) with heliox gas. Throughout exercise arterial blood gases, oxyhaemoglobin saturation ( ), the work of Breathing (WOB) and expiratory flow limitation (EFL) were assessed. Twenty of the 30 women developed EIAH with a nadir and ranging from 58 to 88 mmHg and 87 to 96%, respectively. At maximal exercise, was inversely related to (r = -0.57, P < 0.05) with notable exceptions where some subjects with low aerobic fitness levels demonstrated EIAH. Subjects with EIAH had a greater (51 ± 1 vs. 43 ± 2 ml kg(-1) min(-1)), lower end-exercise (93.2 ± 0.5 vs. 96.1 ± 0.3%) and a greater maximal energetic WOB (324 ± 19 vs. 247 ± 23 J min(-1)), but had similar resting pulmonary function compared to those without EIAH. Most subjects developed EIAH at submaximal exercise intensities, with distinct patterns of hypoxaemia. In some subjects with varying aerobic fitness levels, mechanical ventilatory constraints (i.e. EFL) were the primary mechanism associated with the hypoxaemia during the maximal test. Mechanical ventilatory constraints also prevented adequate compensatory alveolar hyperventilation in most EIAH subjects. Minimizing mechanical ventilatory constraints with heliox inspiration partially reversed EIAH in subjects who developed EFL. In conclusion, healthy women of all aerobic fitness levels can develop EIAH and begin to do so at submaximal intensities. Mechanical ventilatory constraints are a primary mechanism for EIAH in some healthy women and prevent reversal of hypoxaemia in women for whom it is not the primary mechanism.
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Experimental approaches to the study of the Mechanics of Breathing during exercise.
Respiratory physiology & neurobiology, 2011Co-Authors: Paolo B Dominelli, A. William SheelAbstract:This review describes the methodology and analysis of respiratory Mechanics as it pertains to dynamic exercise. Underlying physical principles governing respiratory Mechanics and commonly used measuring instruments will be discussed. We explain the physiological basis behind respiration, along with the dynamics of pulmonary ventilation. This review will outline the theoretical framework behind several forms of analysis along with their specific pitfalls, advantages and assumptions. Particular attention will be given to the techniques used to estimate the mechanical work of Breathing. Specifically, we detail the different styles of work of Breathing analysis and their inherent limitations as well as common sources of error often encountered. Finally, recent technological advancements that contribute to the understanding of respiratory Mechanics are explained.
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Mechanics of Breathing during Exercise in Men and Women: Sex versus Body Size Differences?
Exercise and sport sciences reviews, 2008Co-Authors: A. William Sheel, Jordan A. GuenetteAbstract:Women have smaller airways and lung volumes and lower resting maximal expiratory flow rates relative to men. Female athletes develop expiratory flow limitation more frequently than male athletes, and they have greater increases in end-expiratory and end-inspiratory lung volume at maximal exercise. Women use a greater fraction of their ventilatory reserve and have a higher metabolic cost of Breathing.
Max Klein - One of the best experts on this subject based on the ideXlab platform.
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the Mechanics of Breathing in children with acute severe croup
Intensive Care Medicine, 2008Co-Authors: Andrew C. Argent, Christopher J. L. Newth, Max KleinAbstract:The assessment of the severity of croup and response to therapy has remained a clinical one. Despite recognition of the importance of a reproducible and easily applicable method for objectively measuring severity, currently, no such technique exists. We postulated that measurements of air flow and intrathoracic pressure changes in patients with severe croup would provide detailed information about the Mechanics of Breathing and the potential for the development of continuous bedside methods for objective monitoring of upper airway obstruction. Twenty out of 21 eligible infants and children with severe upper airway obstruction from croup, and 5 control participants, were studied under light sedation utilizing face masks and nasogastric feeding tubes for flow and esophageal pressure measurements. Children with croup had lower tidal volumes, but breathed faster, thus maintaining similar minute volumes to the controls. During inspiration, all but 2 croup patients (but no controls) displayed flow limitation. Area within the flow–volume curve was significantly decreased and minute ventilation for effort expended was nearly 4.5 times higher in croup patients than in controls. Peak-to-trough pleural pressure swings, pressure–rate product and pressure–time integral were also significantly higher than in controls (p < 0.001) and returned to the normal range in the 9 patients who were subsequently intubated (p < 0.001). Patients with severe croup maintain minute ventilation by means of huge increases in intrathoracic pressure changes. Inspiratory flow limitation is present. In future outcome studies, measurements of respiratory function that do not include intrathoracic pressure changes are unlikely to be effective measures of the severity of croup.
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The Mechanics of Breathing in children with acute severe croup.
Intensive care medicine, 2007Co-Authors: Andrew C. Argent, Christopher J. L. Newth, Max KleinAbstract:The assessment of the severity of croup and response to therapy has remained a clinical one. Despite recognition of the importance of a reproducible and easily applicable method for objectively measuring severity, currently, no such technique exists. We postulated that measurements of air flow and intrathoracic pressure changes in patients with severe croup would provide detailed information about the Mechanics of Breathing and the potential for the development of continuous bedside methods for objective monitoring of upper airway obstruction. Twenty out of 21 eligible infants and children with severe upper airway obstruction from croup, and 5 control participants, were studied under light sedation utilizing face masks and nasogastric feeding tubes for flow and esophageal pressure measurements. Children with croup had lower tidal volumes, but breathed faster, thus maintaining similar minute volumes to the controls. During inspiration, all but 2 croup patients (but no controls) displayed flow limitation. Area within the flow–volume curve was significantly decreased and minute ventilation for effort expended was nearly 4.5 times higher in croup patients than in controls. Peak-to-trough pleural pressure swings, pressure–rate product and pressure–time integral were also significantly higher than in controls (p
Paolo B Dominelli - One of the best experts on this subject based on the ideXlab platform.
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Revisiting dysanapsis: sex-based differences in airways and the Mechanics of Breathing during exercise.
Experimental physiology, 2015Co-Authors: A. William Sheel, Paolo B Dominelli, Yannick Molgat-seonAbstract:New Findings What is the topic of this review? This review focuses on sex-based differences in the anatomy of the respiratory system, which manifest in mechanical ventilatory contraints and potentially alter the integrative response to exercise. What advances does it highlight? Recent evidence indicates that women have smaller conducting airways than men, even when matched for lung size. Consequently, women are more likely to experience mechanical ventilatory constraints to exercise hyperpnoea. Furthermore, at a given ventilation, women have a higher work and oxygen cost of Breathing, both of which may lead to differences in the whole-body integrative response to dynamic exercise. Our understanding of the human ventilatory response to exercise is largely based on a historical body of literature focused primarily on male rather than female research subjects. In recent years, important sex-based differences in the anatomy of the human respiratory system have been identified; for a given lung size, women appear to have smaller-diameter conducting airways than men. The presence of such inherent differences in the tracheobronchial tree greatly affects the Mechanics of airflow generation, especially during conditions of high ventilation rates, such as exercise. Data from a growing number of studies suggest that women may be more susceptible to respiratory system limitations during exercise than their male counterparts. Specifically, women are more likely to experience expiratory flow limitation and exercise-induced arterial hypoxaemia and have a higher metabolic cost of Breathing for a given ventilation. Collectively, the available evidence suggests that sex differences in the ventilatory response to exercise are present and may have important ramifications for the integrated response to exercise; however, several fundamental questions remain unanswered.
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exercise induced arterial hypoxaemia and the Mechanics of Breathing in healthy young women
The Journal of Physiology, 2013Co-Authors: Paolo B Dominelli, Glen E. Foster, Giulio S. Dominelli, William R. Henderson, Michael S. Koehle, Donald C. Mckenzie, William A SheelAbstract:The purpose of this study was to characterize exercise-induced arterial hypoxaemia (EIAH), pulmonary gas exchange and respiratory Mechanics during exercise, in young healthy women. We defined EIAH as a >10 mmHg decrease in arterial oxygen tension ( ) during exercise compared to rest. We used a heliox inspirate to test the hypothesis that mechanical constraints contribute to EIAH. Subjects with a spectrum of aerobic capacities (n = 30; maximal oxygen consumption ( ) = 49 ± 1, range 28-62 ml kg(-1) min(-1)) completed a stepwise treadmill test and a subset (n = 18 with EIAH) completed a constant load test (~85% ) with heliox gas. Throughout exercise arterial blood gases, oxyhaemoglobin saturation ( ), the work of Breathing (WOB) and expiratory flow limitation (EFL) were assessed. Twenty of the 30 women developed EIAH with a nadir and ranging from 58 to 88 mmHg and 87 to 96%, respectively. At maximal exercise, was inversely related to (r = -0.57, P < 0.05) with notable exceptions where some subjects with low aerobic fitness levels demonstrated EIAH. Subjects with EIAH had a greater (51 ± 1 vs. 43 ± 2 ml kg(-1) min(-1)), lower end-exercise (93.2 ± 0.5 vs. 96.1 ± 0.3%) and a greater maximal energetic WOB (324 ± 19 vs. 247 ± 23 J min(-1)), but had similar resting pulmonary function compared to those without EIAH. Most subjects developed EIAH at submaximal exercise intensities, with distinct patterns of hypoxaemia. In some subjects with varying aerobic fitness levels, mechanical ventilatory constraints (i.e. EFL) were the primary mechanism associated with the hypoxaemia during the maximal test. Mechanical ventilatory constraints also prevented adequate compensatory alveolar hyperventilation in most EIAH subjects. Minimizing mechanical ventilatory constraints with heliox inspiration partially reversed EIAH in subjects who developed EFL. In conclusion, healthy women of all aerobic fitness levels can develop EIAH and begin to do so at submaximal intensities. Mechanical ventilatory constraints are a primary mechanism for EIAH in some healthy women and prevent reversal of hypoxaemia in women for whom it is not the primary mechanism.
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Exercise‐induced arterial hypoxaemia and the Mechanics of Breathing in healthy young women
The Journal of physiology, 2013Co-Authors: Paolo B Dominelli, Glen E. Foster, Giulio S. Dominelli, William R. Henderson, Michael S. Koehle, Donald C. Mckenzie, A. William SheelAbstract:The purpose of this study was to characterize exercise-induced arterial hypoxaemia (EIAH), pulmonary gas exchange and respiratory Mechanics during exercise, in young healthy women. We defined EIAH as a >10 mmHg decrease in arterial oxygen tension ( ) during exercise compared to rest. We used a heliox inspirate to test the hypothesis that mechanical constraints contribute to EIAH. Subjects with a spectrum of aerobic capacities (n = 30; maximal oxygen consumption ( ) = 49 ± 1, range 28-62 ml kg(-1) min(-1)) completed a stepwise treadmill test and a subset (n = 18 with EIAH) completed a constant load test (~85% ) with heliox gas. Throughout exercise arterial blood gases, oxyhaemoglobin saturation ( ), the work of Breathing (WOB) and expiratory flow limitation (EFL) were assessed. Twenty of the 30 women developed EIAH with a nadir and ranging from 58 to 88 mmHg and 87 to 96%, respectively. At maximal exercise, was inversely related to (r = -0.57, P < 0.05) with notable exceptions where some subjects with low aerobic fitness levels demonstrated EIAH. Subjects with EIAH had a greater (51 ± 1 vs. 43 ± 2 ml kg(-1) min(-1)), lower end-exercise (93.2 ± 0.5 vs. 96.1 ± 0.3%) and a greater maximal energetic WOB (324 ± 19 vs. 247 ± 23 J min(-1)), but had similar resting pulmonary function compared to those without EIAH. Most subjects developed EIAH at submaximal exercise intensities, with distinct patterns of hypoxaemia. In some subjects with varying aerobic fitness levels, mechanical ventilatory constraints (i.e. EFL) were the primary mechanism associated with the hypoxaemia during the maximal test. Mechanical ventilatory constraints also prevented adequate compensatory alveolar hyperventilation in most EIAH subjects. Minimizing mechanical ventilatory constraints with heliox inspiration partially reversed EIAH in subjects who developed EFL. In conclusion, healthy women of all aerobic fitness levels can develop EIAH and begin to do so at submaximal intensities. Mechanical ventilatory constraints are a primary mechanism for EIAH in some healthy women and prevent reversal of hypoxaemia in women for whom it is not the primary mechanism.
-
Experimental approaches to the study of the Mechanics of Breathing during exercise.
Respiratory physiology & neurobiology, 2011Co-Authors: Paolo B Dominelli, A. William SheelAbstract:This review describes the methodology and analysis of respiratory Mechanics as it pertains to dynamic exercise. Underlying physical principles governing respiratory Mechanics and commonly used measuring instruments will be discussed. We explain the physiological basis behind respiration, along with the dynamics of pulmonary ventilation. This review will outline the theoretical framework behind several forms of analysis along with their specific pitfalls, advantages and assumptions. Particular attention will be given to the techniques used to estimate the mechanical work of Breathing. Specifically, we detail the different styles of work of Breathing analysis and their inherent limitations as well as common sources of error often encountered. Finally, recent technological advancements that contribute to the understanding of respiratory Mechanics are explained.
Andrew C. Argent - One of the best experts on this subject based on the ideXlab platform.
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the Mechanics of Breathing in children with acute severe croup
Intensive Care Medicine, 2008Co-Authors: Andrew C. Argent, Christopher J. L. Newth, Max KleinAbstract:The assessment of the severity of croup and response to therapy has remained a clinical one. Despite recognition of the importance of a reproducible and easily applicable method for objectively measuring severity, currently, no such technique exists. We postulated that measurements of air flow and intrathoracic pressure changes in patients with severe croup would provide detailed information about the Mechanics of Breathing and the potential for the development of continuous bedside methods for objective monitoring of upper airway obstruction. Twenty out of 21 eligible infants and children with severe upper airway obstruction from croup, and 5 control participants, were studied under light sedation utilizing face masks and nasogastric feeding tubes for flow and esophageal pressure measurements. Children with croup had lower tidal volumes, but breathed faster, thus maintaining similar minute volumes to the controls. During inspiration, all but 2 croup patients (but no controls) displayed flow limitation. Area within the flow–volume curve was significantly decreased and minute ventilation for effort expended was nearly 4.5 times higher in croup patients than in controls. Peak-to-trough pleural pressure swings, pressure–rate product and pressure–time integral were also significantly higher than in controls (p < 0.001) and returned to the normal range in the 9 patients who were subsequently intubated (p < 0.001). Patients with severe croup maintain minute ventilation by means of huge increases in intrathoracic pressure changes. Inspiratory flow limitation is present. In future outcome studies, measurements of respiratory function that do not include intrathoracic pressure changes are unlikely to be effective measures of the severity of croup.
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The Mechanics of Breathing in children with acute severe croup.
Intensive care medicine, 2007Co-Authors: Andrew C. Argent, Christopher J. L. Newth, Max KleinAbstract:The assessment of the severity of croup and response to therapy has remained a clinical one. Despite recognition of the importance of a reproducible and easily applicable method for objectively measuring severity, currently, no such technique exists. We postulated that measurements of air flow and intrathoracic pressure changes in patients with severe croup would provide detailed information about the Mechanics of Breathing and the potential for the development of continuous bedside methods for objective monitoring of upper airway obstruction. Twenty out of 21 eligible infants and children with severe upper airway obstruction from croup, and 5 control participants, were studied under light sedation utilizing face masks and nasogastric feeding tubes for flow and esophageal pressure measurements. Children with croup had lower tidal volumes, but breathed faster, thus maintaining similar minute volumes to the controls. During inspiration, all but 2 croup patients (but no controls) displayed flow limitation. Area within the flow–volume curve was significantly decreased and minute ventilation for effort expended was nearly 4.5 times higher in croup patients than in controls. Peak-to-trough pleural pressure swings, pressure–rate product and pressure–time integral were also significantly higher than in controls (p
Franco Saibene - One of the best experts on this subject based on the ideXlab platform.
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Mechanics of Breathing in Horses at Rest and During Exercise
The Journal of Experimental Biology, 1991Co-Authors: Claudio L. Lafortuna, Franco SaibeneAbstract:The respiratory Mechanics together with the rate of work of Breathing were studied in five healthy adult Standardbred horses at rest and during different levels of exercise on a treadmill (0.8-2.3 ms−1, 7% slope). In three of the horses the stride frequency was also determined. The ventilatory response to exercise increased linearly with treadmill speed up to 9.6 times the resting values and was sustained more by an increase in respiratory frequency than by an increase in tidal volume. At the most elevated work load, respiratory frequency and tidal volume averaged 5.2 and 1.4 times the resting values, respectively. Lung resistance decreased during the most intense level of exercise to about 30% of the average value observed at rest, while lung dynamic compliance remained unchanged. The rate of work of Breathing (Wresp, in W) increased exponentially with ventilation (Ve, in 1 min−1) according to the equation: Wresp=5.263Ve1.5897 × 10−4. In the three animals investigated a definite locomotor-respiratory coupling was observed at a trot and in two animals also during walking. This observation, together with other considerations based on available data on the energetics of respiration, suggests that the efficiency of the equine respiratory system is relatively high. In addition, when compared with other smaller mammals (man and dog), horses are, in mechanical terms, more economical breathers.