Dysanapsis and the resistive work of breathing during exercise in healthy men and women

Dominelli, Paolo B.; Molgat‐Seon, Yannick; Bingham, Derek; Swartz, Philippa M.; Road, Jeremy; Foster, Glen E.; Sheel, A. William

doi:10.1152/japplphysiol.00409.2015

Cited by 68 publications

(96 citation statements)

References 31 publications

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“…While it is clear that the SR is not entirely predictive of flow-limitation, it can still be useful. Specifically, our finding that SR and EFL are related is of significance because SR is independent of magnitude, allowing for comparisons between groups known to differ in other predictor variables such as lung/airway size and aerobic fitness between men and women (Guenette et al, 2007; Mead, 1980; Sheel et al, 2009; Dominelli et al, 2015c) or older individuals (Johnson et al, 1991a; McClaran et al, 1995). For example, an average male would have greater lung volumes and expiratory flows compared to a height and age matched female.…”

Section: Discussionmentioning

confidence: 91%

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients

Dominelli

Molgat‐Seon

Foster

et al. 2016

Respiratory Physiology & Neurobiology

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Differences in the absolute flow and volume of maximal expiratory flow-volume (MEFV) curves have been studied extensively in health and disease. However, the shapes of MEFV curves have received less attention. We questioned if the MEFV curve shape was associated with (i) expiratory flow limitation (EFL) in health and (ii) changes in bronchial caliber in asthmatics. Using the slope-ratio (SR) index, we quantified MEFV curve shape in 84 healthy subjects and 8 matched asthmatics. Healthy subjects performed a maximal exercise test to assess EFL. Those with EFL during had a greater SR (1.15 ± 0.20 vs. 0.85 ± 0.20, p < 0.05) yet, there was no association between maximal oxygen consumption and SR (r = 0.14, p > 0.05). Asthmatics average SR was greater than the healthy subjects (1.35 ± 0.03 vs. 0.90 ± 0.11, p < 0.05), but there were no differences when bronchial caliber was manipulated. In conclusion, a greater SR is related to EFL and this metric could aid in discriminating between groups known to differ in the absolute size of MEFV curves.

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Section: Discussionmentioning

confidence: 91%

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients

Dominelli

Molgat‐Seon

Foster

et al. 2016

Respiratory Physiology & Neurobiology

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“…The DR calculated using predicted T‐Pst(l) 50 , via Eqn , has recently been shown not to differ from the DR calculated using Pst(l) 50 measured by oesophageal pressure in healthy adult males and females (Dominelli et al . ).

DR = FE {normalF}_{50} / false[FVC \times {Pst false(normall false)}_{50} false]

{T - Pst (l)}_{50} = - 0.056 \times age (years false) + 6.3038

{S - Pst (l)}_{50} = - 0.0466 \times age (years false) + 4.42292

{S - Pst (l)}_{50} = - 0.0492 \times age (years false) + 4.1788

…”

Section: Methodsmentioning

confidence: 97%

“…() and Mead () and used more recently (Dominelli et al . , ; Smith et al . ) as a ratio of measurements sensitive to lung size and airways size.…”

Section: Methodsmentioning

confidence: 99%

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Premature birth affects the degree of airway dysanapsis and mechanical ventilatory constraints

Duke

Gladstone

Sheel

et al. 2017

Experimental Physiology

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Edited by: Ken O'Halloran New Findings r What is the central question of this study?Adult survivors of preterm birth without (PRE) and with bronchopulmonary dysplasia (BPD) have airflow obstruction at rest and significant mechanical ventilatory constraints during exercise compared with those born at full term (CON). Do PRE/BPD have smaller airways, indexed via the dysanapsis ratio, than CON? r What is the main finding and its importance?The dysanapsis ratio was significantly smaller in BPD and PRE compared with CON, with BPD having the smallest dysanapsis ratio. These data suggest that airflow obstruction in PRE and BPD might be because of smaller airways than CON.Adult survivors of very preterm birth (ࣘ32 weeks gestational age) without (PRE) and with bronchopulmonary dysplasia (BPD) have obstructive lung disease as evidenced by reduced expiratory airflow at rest and have significant mechanical ventilatory constraints during exercise. Airflow obstruction, in any conditions, could be attributable to several factors, including small airways. PRE and/or BPD could have smaller airways than their counterparts born at full term (CON) owing to a greater degree of dysanaptic airway development during the pre-and/or postnatal period. Thus, the purpose of the present study was to compare the dysanapsis ratio (DR), as an index of airway size, between PRE, BPD and CON. To do so, we calculated DR in PRE (n = 21), BPD (n = 14) and CON (n = 34) individuals and examined flow-volume loops at rest and during submaximal exercise. The DR, using multiple estimates of static recoil pressure, was significantly smaller in PRE and BPD (0.16 ± 0.05 and 0.10 ± 0.03 a.u.) compared with CON (0.22 ± 0.04 a.u.; both P < 0.001) and smallest in BPD (P < 0.001). The DR was significantly correlated with peak expiratory airflow at rest (r = 0.42; P < 0.001) and the extent of expiratory flow limitation during exercise (r = 0.60; P < 0.001). Our findings suggest that PRE/BPD might have anatomically smaller airways than CON, which might help to explain their lower expiratory airflow rate at rest and during exercise and further our understanding of the consequences of preterm birth and neonatal O 2 therapy.

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“…It is important to note that the inflection will occur for different subjects at different absolute values ofV E . For example, a healthy woman will generally have a lower maximalV E than an age-and fitness-matched man (Sheel & Guenette, 2008;Dominelli et al 2015a). Therefore, the absoluteV E at which the PAV is not able to unload the WOB as much would occur considerably lower (ß80 l min −1 ) in women.…”

Section: Reduction In Work Of Breathingmentioning

confidence: 99%

A proportional assist ventilator to unload respiratory muscles experimentally during exercise in humans

Dominelli

Henderson

Sheel

2016

Experimental Physiology

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New Findings r What is the central question of this study?Can a modern proportional assist ventilator (PAV) function sufficiently well to unload the respiratory muscles during exercise? r What is the main finding and its importance?A PAV can be constructed with contemporary hardware and software and be used at all exercise intensities to unload the respiratory muscles by up to 70%. Previously, PAVs have allowed researchers to address many fundamental physiological problems in clinical and healthy populations, but those versions are no longer functional or available. We describe the creation of a PAV that permits researchers to use it as an experimental tool.Manipulation of the normally occurring work of breathing (WOB) during exercise can provide insights into whole-body regulatory mechanisms in clinical patients and healthy subjects. One method to reduce the WOB uses a proportional assist ventilator (PAV). Suitable commercially available units are not capable of being used during heavy exercise. This investigation was undertaken in order to create a PAV and assess the degree to which the WOB could be reduced during exercise. A PAV works by creating a positive mouth pressure (P m ) during inspiration, which consequently reduces the WOB. Spontaneous breathing patterns can be maintained, and the amplitude of P m is calculated using the equation of motion and predetermined proportionality constants. We generated positive P m using a breathing apparatus consisting of rigid tubing, solenoid valves to control the airflow direction and a proportional valve connected to compressed gas. Healthy male and female subjects were able to use the PAV successfully while performing cycling exercise over a range of intensities (50-100% of maximal workload) for different durations (from 30 s to 20 min) and different protocols (constant versus progressive workload). Inspiratory WOB was reduced up to 90%, while total WOB was reduced by 70%. The greatest reduction in WOB (50-75%) occurred during submaximal exercise, but at maximal ventilations (>180 l min −1 ) a 50% reduction was still possible. The calculated change in WOB and subsequent reduction in respiratory muscle oxygen consumption resulted in equivalent reductions in whole-body oxygen consumption. With adequate familiarization and practice, our PAV can consistently reduce the WOB across a range of exercise intensities.

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Dysanapsis and the resistive work of breathing during exercise in healthy men and women

Cited by 68 publications

References 31 publications

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients

Premature birth affects the degree of airway dysanapsis and mechanical ventilatory constraints

A proportional assist ventilator to unload respiratory muscles experimentally during exercise in humans

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