Publications by authors named "T L Babb"

212 Publications

Dysanapsis in men and women with obesity.

J Appl Physiol (1985) 2021 06 24. Epub 2021 Jun 24.

Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Texas Health Dallas, Dallas, TX, United States.

Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in women than in men when matched for lung size. We examined whether differences in pulmonary mechanics with obesity and sex were associated with the dysanapsis ratio (DR), an estimate of airway size when expiratory flow is maximal, in men and women with and without obesity. Additionally, we examined the ability to estimate DR using predicted versus measured static recoil pressure at 50%FVC (Pst). Participants completed pulmonary function testing and measurements of pulmonary mechanics. Flow, volume, and transpulmonary pressure were recorded while completing forced vital capacity (FVC) maneuvers in a body plethysmograph. Static compliance curves were collected using the occlusion technique. DR was calculated using measured values of forced mid-expiratory flow and Pst. DR was also calculated using Pst predicted from previously reported data. There was no significant group (lean vs. obese) by sex interaction or main effect of group on DR. However, women displayed significantly larger DR compared with men. Predicted Pst was significantly greater than measured Pst. DR calculated from measured Pst was significantly greater than when using predicted Pst. In conclusion, while obesity does not appear to alter airway size, women may have larger airways compared with men when mid-expiratory flow is maximal. Additionally, DR estimated using predicted Pst should be used with caution.
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http://dx.doi.org/10.1152/japplphysiol.00133.2021DOI Listing
June 2021

Dyspnea during exercise and voluntary hyperpnea in women with obesity.

Respir Physiol Neurobiol 2021 05 11;287:103638. Epub 2021 Feb 11.

Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA. Electronic address:

Temporal responses of ratings of perceived breathlessness (RBP) during constant-load and incremental exercise, and during voluntary hyperpnea (EVH) were examined in women with obesity. Following 6 min of constant-load (60W) cycling, 34 women rated RPB≥4 (+DOE) and 22 women rated RPB≤2 (-DOE). Both groups completed an incremental cycling test and an EVH test at 40 and 60L/min; RPB was assessed each minute of incremental cycling and at the end of each EVH trial. RPB increased with ventilation during constant-load (+DOE: R=0.86; -DOE: R=0.82) and incremental (+DOE: R=0.91; -DOE: R=0.92) exercise, but + DOE had a greater y-intercept than -DOE (60W: -0.16±1.53 vs. -0.73±0.55; incremental: -0.50±1.40 vs. -1.71±0.84). Despite matching ventilation, RPB was greater in + DOE at baseline (0.97±1.14 vs. 0.14±0.28), 40L/min (2.50±1.43 vs. 0.98±0.91), and 60L/min (3.94±2.19 vs. 2.07±1.32) during EVH. These findings show that despite linear associations between RPB and ventilation during exercise and voluntary hyperpnea, breathlessness perception at a given ventilatory demand is heightened in +DOE compared with -DOE.
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http://dx.doi.org/10.1016/j.resp.2021.103638DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7983342PMC
May 2021

Obesity Blunts the Ventilatory Response to Exercise in Men and Women.

Ann Am Thorac Soc 2021 Jul;18(7):1167-1174

Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas.

Obesity presents a mechanical load to the thorax, which could perturb the generation of minute ventilation (V̇e) during exercise. Because the respiratory effects of obesity are not homogenous among all individuals with obesity and obesity-related effects could vary depending on the magnitude of obesity, we hypothesized that the exercise ventilatory response (slope of the V̇e and carbon dioxide elimination [V̇co] relationship) would manifest itself differently as the magnitude of obesity increases. To investigate the V̇e/V̇co slope in an obese population that spanned across a wide body mass index (BMI) range. A total of 533 patients who presented to a surgical weight loss center for pre-bariatric surgery testing performed an incremental maximal cycling test and were studied retrospectively. The V̇e/V̇co slope was calculated up to the ventilatory threshold. Patients were examined in groups based on BMI (category 1: 30-39.9 kg/m, category 2: 40-49.9 kg/m, and category 3: ≥50 kg/m). Because the respiratory effects of obesity could be sex and/or age specific, we further examined patients in groups by sex and age (younger: <50 yr and older: ≥50 yr). Differences in the V̇e/V̇co slope were then compared between BMI category, age, and sex using a three-way ANOVA. No significant BMI category by sex by age interactions was detected ( = 0.75). The V̇e/V̇co slope decreased with increases in BMI (category 1, 29.1 ± 4.0; category 2, 28.4 ± 4.1; and category 3, 27.1 ± 3.3) and was elevated in women (28.9 ± 4.1) compared with men (26.7 ± 3.2) (BMI category by sex interaction,  < 0.05). No age-related differences were observed (BMI category by age interaction,  = 0.55). The partial pressure for end-tidal CO was elevated at the ventilatory threshold in BMI category 3 compared with BMI categories 1 and 2 (both  < 0.01). These findings suggest that obesity presents a unique challenge to augmenting ventilatory output relative to CO elimination, such that the increase in the exercise ventilatory response becomes blunted as the magnitude of obesity increases. Further studies are required to investigate the clinical consequences and the mechanisms that may explain the attenuation of exercise ventilatory response with increasing BMI in men and women with obesity.
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http://dx.doi.org/10.1513/AnnalsATS.202006-746OCDOI Listing
July 2021

Inhaled albuterol increases estimated ventilatory capacity in nonasthmatic children without and with obesity.

Respir Physiol Neurobiol 2021 03 7;285:103597. Epub 2020 Dec 7.

Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX, United States. Electronic address:

Forced mid-expiratory flow (i.e., isoFEF) may increase with a short-acting β-agonist in nonasthmatic children without bronchodilator responsiveness. This could also increase estimated ventilatory capacity along mid-expiration (V̇Ecap), especially in vulnerable children with obesity who exhibit altered breathing mechanics. We estimated V̇Ecap pre- and post-albuterol treatment in 8-12yo children without (n = 28) and with (n = 46) obesity. A two-way ANOVA was performed to determine effects of an inhaled bronchodilator (pre-post) and obesity (group) on isoFEF and V̇Ecap. There was no group by bronchodilator interaction or main group effect on outcome variables. However, a significant main effect of the bronchodilator was detected in spirometry parameters, including a substantial increase in isoFEF (17.1 ± 18.0 %) and only a slight (non-clinical) but significant increase in FEV (2.4 ± 4.3 %). V̇Ecap significantly increased with albuterol (+11.7 ± 10.6 L/min; +15.8 ± 13.9 %). These findings imply potentially important increases in ventilatory reserve with a bronchodilator in nonasthmatic children without and with obesity, which could potentially influence respiratory function at rest and during exercise.
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http://dx.doi.org/10.1016/j.resp.2020.103597DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7854525PMC
March 2021

Effects of obesity on the oxygen cost of breathing in children.

Respir Physiol Neurobiol 2021 03 30;285:103591. Epub 2020 Nov 30.

Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas & UT Southwestern Medical Center, Dallas, TX, United States. Electronic address:

The objective of this study was to examine the effects of obesity on the oxygen (O) cost of breathing using the eucapnic voluntary hyperpnea (EVH) technique in 10- and 11-year-old children. Seventeen children (8 without and 9 with obesity) underwent EVH trials at two levels of ventilation for assessing the O cost of breathing (slope of oxygen uptake, V˙O vs. minute ventilation) and a dual energy x-ray absorptiometry scan. Resting and EVH V˙O was higher in children with obesity when compared with children without obesity (P = 0.0096). The O cost of breathing did not statistically differ between children without (2.09 ± 0.46 mL/L) and with obesity (2.08 ± 0.64 mL/L, P = 0.99), but the intercept was significantly greater in children with obesity. Chest mass explained 85 % of the variance in resting V˙O in children with obesity. Higher resting energy requirements, attributable to increased chest mass, can increase the absolute metabolic costs of exercise and hyperpnea in children with obesity.
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http://dx.doi.org/10.1016/j.resp.2020.103591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7854505PMC
March 2021