Clinical Physiology and Functional Imaging最新文献

Ultrasound imaging is extensively used by both practitioners and researchers in assessing muscle thickness (MT); however, its use in the field is constrained by the transportability of stationary devices. New portable ultrasound probes pose as a cost-effective and transportable alternative for field-based assessments. This study evaluated the concurrent validity of a portable probe (Lumify) against a laboratory-based device (Vivid S5) in measuring MT. Eighteen participants (nine males and nine females) visited the laboratory and their MT measurements were collected using each device at five different sites (anterior and posterior arm, anterior and posterior thigh, and posterior lower leg). Bland-Altman plots (systematic and proportional bias, random error, and 95% limits of agreement), Pearson's product–moment correlation coefficient (r), and paired samples t-tests with Cohen's d effect sizes (ES) were used to assess the concurrent validity of the Lumify device. Systematic bias was low at all sites ( ≤ 0.11 cm) while proportional bias was detected only at the posterior lower leg (r² = 0.217 [r = 0.466]). The difference in MT between devices was significant only at the anterior thigh (p < 0.05); however, ES for all sites were considered trivial (ES ≤ 0.131). Linear associations were found between the devices at each site of measurement (r ≥ 0.95). These results highlight that the Lumify probe can be used interchangeably with the Vivid S5 for MT measurements, providing practitioners and researchers with a more cost-effective and portable alternative for field-based assessments.

There is no study that has investigated the impact of exercise in a combined hypoxic and hot environment on endothelial function. Therefore, we tested whether aerobic exercise in a combined hypoxic and hot conditions induces further enhancement of endothelial function. Twelve healthy males cycled at a constant workload (50% of their maximal oxygen uptake under normoxic/thermoneutral conditions) for 30 min in four different environments: exercise under normoxic condition (NOR: fraction of inspiratory oxygen or FiO₂ = 20.9%, 20°C), exercise under hypoxic condition (HYP: FiO₂ = 14.5%, 20°C), exercise under hot condition (HOT: FiO₂ = 20.9%, 30°C), and exercise under combined hypoxia and hot conditions (HH: FiO₂ = 14.5%, 30°C). Before, during, and after exercise, cardiovascular variables (e.g., heart rate, blood flow, and shear rate), blood variables, and endothelial function evaluated by flow-mediated dilation (FMD) were assessed. Heart rates were significantly higher throughout the HH trial's experimental period than the other trials (p < 0.05). However, in the HH trial, brachial artery blood flow and shear rate did not differ from those in other trials after exercise. Plasma catecholamines (epinephrine, norepinephrine, and dopamine) elevations in response to exercise were significantly higher in the HH trial than in the other three trials (p < 0.05). No considerable differences were observed in FMD responses among trials before and after the exercise. In conclusion, aerobic exercise in a combined hot and hypoxic environment further activated sympathetic nervous activity but did not considerably enhance blood flow, shear rate, or endothelial function.

Diagnosis of asthma can be confirmed based on variability in peak expiratory flow (PEF) or changes in forced expiratory volume in 1 s (FEV₁) measured with spirometry. Our aim was to use methacholine challenge as a model of induced airway obstruction to assess how well relative changes in PEF reflect airway obstruction in comparison to relative changes in FEV₁. We retrospectively studied 878 patients who completed a methacholine challenge test. To assess congruency along with differences between relative changes in FEV₁ and PEF during airway obstruction, a regression analysis was performed, and a Bland & Altman plot was constructed. ROC analysis, sensitivity, specificity, positive and negative predictive values and κ-coefficient were used to analyze how decrease in PEF predicts decrease of 10% or 15% in FEV₁. The relative change in PEF was on average less than the relative change in FEV₁. In the ROC analysis areas under the curve were 0.844 and 0.893 for PEF decrease to predict a 10% and 15% decrease in FEV₁, respectively. The agreement between changes in PEF and FEV₁ varied from fair to moderate. Airway obstruction detected by change in PEF was false in about 40% of cases when compared to change in FEV₁. Change in PEF is not a very accurate measure of airway obstruction when compared to change in FEV₁. Replacing peak flow metre with a handheld spirometer might improve diagnostic accuracy of home monitoring in asthma.