ORCID Profile
0000-0002-6458-0142
Current Organisation
Mayo Clinic Rochester
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Publisher: American Physiological Society
Date: 07-2016
Publisher: Springer Science and Business Media LLC
Date: 13-01-2021
DOI: 10.1038/S41598-020-79741-W
Abstract: We describe here a novel protocol that sequentially combines venous followed by arterial occlusions to determine muscle blood flow and O 2 uptake from a single measurement point using near-infrared spectroscopy (NIRS) during handgrip exercise. NIRS data were obtained from the flexor digitorum superficialis (FDS) muscle on the dominant arm of 15 young, healthy adults (3 women 26 ± 7 years 78.6 ± 9.1 kg). Participants completed a series of 15-s static handgrip contractions at 20, 40 and 60% of maximal voluntary contraction (MVC) immediately followed by either a: (i) venous occlusion (VO) (ii) arterial occlusion (AO) or venous then arterial occlusion (COMBO). Each condition was repeated 3 times for each exercise-intensity. The concordance correlation coefficient (CCC) and robust linear mixed effects modeling were used to determine measurement agreement between vascular occlusion conditions. FDS muscle blood flow ( $${\\dot{\\text{Q}}}_{{{\\text{FDS}}}}$$ Q ˙ FDS ) and conductance ( $${\\text{C}}_{{{\\text{FDS}}}}$$ C FDS ) demonstrated strong absolute agreement between VO and COMBO trials from rest up to 60%MVC, as evidenced by high values for CCC ( 0.82) and a linear relationship between conditions that closely approximated the line-of-identity (perfect agreement). Conversely, although FDS muscle O 2 uptake ( $${{\\dot {\\text{V}}}}{{\\text{O}}_{2{\\text{FDS}}}}$$ V ˙ O 2 FDS ) displayed “substantial” to “near perfect” agreement between methods across exercise intensities (i.e., CCC 0.80), there was a tendency for COMBO trials to underestimate $${{\\dot {\\text{V}}}}{{\\text{O}}_{2{\\text{FDS}}}}$$ V ˙ O 2 FDS by up to 7%. These findings indicate that the COMBO method provides valid estimates of $${\\dot {\\text{Q}}}_{{\\text{FDS}}}$$ Q ˙ FDS and, to a slightly lesser extent, $${{\\dot {\\text{V}}}}{{\\text{O}}_{2{\\text{FDS}}}}$$ V ˙ O 2 FDS at rest and during static handgrip exercise up to 60%MVC. Practical implications and suggested improvements of the method are discussed.
Publisher: American Physiological Society
Date: 09-2018
DOI: 10.1152/JAPPLPHYSIOL.00440.2018
Abstract: Airway luminal area is the major determinant of resistance to airflow in the tracheobronchial tree. Women may have smaller central conducting airways than men however, previous evidence is confounded by an indirect assessment of airway geometry and by subjects with prior smoking history. The purpose of this study was to examine the effect of sex on airway size in healthy nonsmokers. Using low-dose high-resolution computed tomography, we retrospectively assessed airway luminal area in healthy men ( n = 51) and women ( n = 73) of varying ages (19–86 yr). Subjects with a positive smoking history, cardiopulmonary disease, or a body mass index 40 kg/m 2 were excluded. Luminal areas of the trachea, right and left main bronchus, bronchus intermediate, left and right upper lobes, and the left lower lobe were analyzed at three discrete points. The luminal areas of the conducting airways were ~26%–35% smaller in women. The trachea had the largest differences in luminal area between men and women (298 ± 47 vs. 195 ± 28 mm 2 or 35% smaller for men and women, respectively), whereas the left lower lobe had the smallest differences (57 ± 15 vs. 42 ± 9 mm 2 or 26% smaller for men and women, respectively). When a subset of subjects was matched for height, the sex differences in airway luminal area persisted, with women being ~20%–30% smaller. With all subjects, there were modest relationships between height and airway luminal area ( r = 0.73–0.53, P 0.05). Although there was considerable overlap between sexes, the luminal areas of the large conducting airways were smaller in healthy women than in men. NEW & NOTEWORTHY Previous evidence for sex differences in airway size has been confounded by indirect measures and/or cohorts with significant smoking histories or pathologies. We found that central airways in healthy women were significantly smaller (~26%–35%) than men. The significant sex-difference in airway size was attenuated (20%–30% smaller) but preserved in a subset of subjects matched for height. Over a range of ages, healthy women have smaller central airways than men.
No related grants have been discovered for Chad Wiggins.