scholarly journals Box-Jenkins Transfer Function Modelling for Reliable Determination of VO2 Kinetics in Patients with COPD

2019 ◽  
Vol 9 (9) ◽  
pp. 1822 ◽  
Author(s):  
Joren Buekers ◽  
Jan Theunis ◽  
Alberto Peña Fernández ◽  
Emiel F. M. Wouters ◽  
Martijn A. Spruit ◽  
...  
Keyword(s):  
Transfer Function ◽  
Mean Squared Error ◽  
Kinetic Feature ◽  
Reliable Determination ◽  
Exponential Models ◽  
Mean Response Time ◽  
Vo2 Kinetics ◽  
Constant Work Rate ◽  
Function Modelling ◽  
Feature Values

Oxygen uptake (VO2) kinetics provide information about the ability to respond to the increased physical load during a constant work rate test (CWRT). Box-Jenkins transfer function (BJ-TF) models can extract kinetic features from the phase II VO2 response during a CWRT, without being affected by unwanted noise contributions (e.g., phase I contribution or measurement noise). CWRT data of 18 COPD patients were used to compare model fits and kinetic feature values between BJ-TF models and three typically applied exponential modelling methods. Autocorrelation tests and normalised root-mean-squared error values (BJ-TF: 2.8 ± 1.3%; exponential methods A, B and C: 10.5 ± 5.8%, 11.3 ± 5.2% and 12.1 ± 7.0%; p < 0.05) showed that BJ-TF models, in contrast to exponential models, could account for the most important noise contributions. This led to more reliable kinetic feature values compared to methods A and B (e.g., mean response time (MRT), BJ-TF: 74 ± 20 s; methods A-B: 100 ± 56 s–88 ± 52 s; p < 0.05). Only exponential modelling method C provided kinetic feature values comparable to BJ-TF features values (e.g., MRT: 75 ± 20 s). Based on theoretical considerations, we recommend using BJ-TF models, rather than exponential models, for reliable determinations of VO2 kinetics.

Kinetic analyses as a tool to examine physiological exercise responses in a large sample of patients with COPD

2020 ◽  
Vol 128 (4) ◽  
pp. 813-821
Author(s):  
Joren Buekers ◽  
Jean-Marie Aerts ◽  
Jan Theunis ◽  
Sarah Houben-Wilke ◽  
Frits M. E. Franssen ◽  
...  
Keyword(s):  
Work Rate ◽  
Chronic Obstructive ◽  
Kinetic Feature ◽  
Obstructive Pulmonary Disease ◽  
Mean Response Time ◽  
Copd Patients ◽  
Constant Work Rate ◽  
Rate Test ◽  
Feature Values ◽  
Kinetic Features

Kinetic features such as oxygen uptake (V̇o2) mean response time (MRT), and gains of V̇o2, carbon dioxide output (V̇co2), and minute ventilation (V̇e) can describe physiological exercise responses during a constant work rate test of patients with chronic obstructive pulmonary disease (COPD). This study aimed to establish simple guidelines that can identify COPD patients for whom kinetic analyses are (un)likely to be reliable and examined whether slow V̇o2 responses and gains of V̇o2, V̇co2, and V̇e are associated with ventilatory, cardiovascular, and/or physical impairments. Kinetic features were examined for 265 COPD patients [forced expiratory volume in 1 s (FEV1): 54 ± 19%predicted] who performed a constant work rate test (duration > 180 s) with breath-by-breath measurements of V̇o2, V̇co2, and V̇e. Negative/positive predictive values were used to define cutoff values of relevant clinical variables below/above which kinetic analyses are (un)likely to be reliable. Kinetic feature values were unreliable for 21% (= 56/265) of the patients and for 79% (= 19/24) of the patients with a peak work rate (WRpeak)< 45 W. Kinetic feature values were considered reliable for 94% (= 133/142) of the patients with an FEV1 > 1.3 L. For patients exhibiting reliable kinetic feature values, V̇o2 MRT was associated with ventilatory (e.g., FEV1 %predicted: P < 0.001; r = −0.35) and physical (e.g., V̇o2peak %predicted: P = 0.009; r = −0.18) impairments. Gains were mainly associated with cardiac function and ventilatory constraints, representing both response efficiency and limitation. Kinetic analyses are likely to be unreliable for patients with a WRpeak < 45 W. Whereas gains enrich analyses of physiological exercise responses, V̇o2 MRT shows potential to serve as a motivation-independent, physiological indicator of physical performance. NEW & NOTEWORTHY A constant work rate test that is standardly performed during a prerehabilitation assessment is unable to provide reliable kinetic feature values for chronic obstructive pulmonary disease (COPD) patients with a peak work rate below 45 W. For patients suffering from less severe impairments, kinetic analyses are a powerful tool to examine physiological exercise responses. Especially oxygen uptake mean response time can serve as a motivation-independent, physiological indicator of physical performance in patients with COPD.

Box-Jenkins transfer function modelling for accurate determination of VO2 kinetics in COPD patients

2019 ◽  
Author(s):  
Joren Buekers ◽  
Patrick De Boever ◽  
Alberto Peña Fernández ◽  
Jan Theunis ◽  
Emiel Wouters ◽  
...  
Keyword(s):  
Transfer Function ◽  
Accurate Determination ◽  
Copd Patients ◽  
Vo2 Kinetics ◽  
Function Modelling ◽  
Transfer Function Modelling

scholarly journals Evaluation of Oxygen Uptake Kinetic Asymmetries in Patients with Multiple Sclerosis: A Pilot Study

2018 ◽  
Vol 6 (4) ◽  
pp. 21
Author(s):  
Rebecca D. Larson ◽  
Monica Barton ◽  
John W Farrell III ◽  
Gregory S. Cantrell ◽  
David J. Lantis ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Oxygen Uptake ◽  
Peak Oxygen Uptake ◽  
Mineral Density ◽  
Uptake Kinetic ◽  
Mean Response Time ◽  
Vo2 Kinetics ◽  
Constant Work Rate ◽  
Power Peak ◽  
Response To Exercise

Background of Study: Observations of limb to limb differences (bilateral asymmetry) in leg strength, power, peak oxygen uptake (VO2) and bone mineral density has been reported in individuals with Multiple Sclerosis (MS). Objetives: The purpose of this study was to quantify the magnitude of bilateral asymmetries in oxygen uptake (VO2) kinetics response to single leg cycling (SLC) in relapsing-remitting multiple sclerosis (MS) patients. Methods: Five MSpatients (2 men, 3 women; age 43±7 yrs) performed constant work rate SLC trials to determine VO2 kinetics in each leg. Asymmetry scores were used to quantify the magnitude of the bilateral asymmetries. Results: Significant asymmetries were seen in VO2 peak and parameters of VO2 kinetics. VO2peak asymmetry score was significantly different than 0% (p=0.015). Similarly,significant asymmetry for VO2 kinetic response to exercise as mean response time was observed (p=0.03). In addition the VO2 response to exercise resulted in a significant asymmetry in VO2 deficit between legs (p=0.03). No correlation between EDSS scores and any asymmetry scores existed. Conclusions: These findings provide insight into the potential differences in metabolic perturbation and limb specific symptomatic fatigue within the MS population.

The CRONE Suspension: Modelling and Stability Analysis

2003 ◽  
Author(s):  
Xavier Moreau ◽  
Olivier Altet ◽  
Alain Oustaloup
Keyword(s):  
Stability Analysis ◽  
Transfer Function ◽  
Design Methodology ◽  
Control Design ◽  
Internal Stability ◽  
Function Modelling ◽  
Robust Control Design ◽  
Force Displacement ◽  
Crone Suspension ◽  
Transfer Function Modelling

The CRONE suspension, French acronym of “suspension a` Comportement Robuste d’Ordre Non Entier”, results from a traditional suspension system whose spring and damper are replaced by a mechanical and hydropneumatic system defined by a fractional (so-called non-integer) order force-displacement transfer function. Modelling, frequency-domain robust control design methodology and internal stability analysis are presented in this paper.

scholarly journals Establishing the V̇o2 versus constant-work-rate relationship from ramp-incremental exercise: simple strategies for an unsolved problem

2019 ◽  
Vol 127 (6) ◽  
pp. 1519-1527 ◽  
Author(s):  
Danilo Iannetta ◽  
Rafael de Almeida Azevedo ◽  
Daniel A. Keir ◽  
Juan M. Murias
Keyword(s):  
Lactate Threshold ◽  
Unsolved Problem ◽  
Critical Power ◽  
Work Rate ◽  
Incremental Exercise ◽  
Mean Response Time ◽  
Constant Work Rate ◽  
Ramp Exercise ◽  
The Mean ◽  
Highly Correlated

The dissociation between constant work rate of O2 uptake (V̇o2) and ramp V̇o2 at a given work rate might be mitigated during slowly increasing ramp protocols. This study characterized the V̇o2 dynamics in response to five different ramp protocols and constant-work-rate trials at the maximal metabolic steady state (MMSS) to characterize 1) the V̇o2 gain (G) in the moderate, heavy, and severe domains, 2) the mean response time of V̇o2 (MRT), and 3) the work rates at lactate threshold (LT) and respiratory compensation point (RCP). Eleven young individuals performed five ramp tests (5, 10, 15, 25, and 30 W/min), four to five time-to-exhaustions for critical power estimation, and two to three constant-work-rate trials for confirmation of the work rate at MMSS. G was greatest during the slowest ramp and progressively decreased with increasing ramp slopes (from ~12 to ~8 ml·min−1·W−1, P < 0.05). The MRT was smallest during the slowest ramp slopes and progressively increased with faster ramp slopes (1 ± 1, 2 ± 1, 5 ± 3, and 10 ± 4, 15 ± 6 W, P < 0.05). After “left shifting” the ramp V̇o2 by the MRT, the work rate at LT was constant regardless of the ramp slope (~150 W, P > 0.05). The work rate at MMSS was 215 ± 55 W and was similar and highly correlated with the work rate at RCP during the 5 W/min ramp ( P > 0.05, r = 0.99; Lin’s concordance coefficient = 0.99; bias = −3 W; root mean square error = 6 W). Findings showed that the dynamics of V̇o2 (i.e., G) during ramp exercise explain the apparent dichotomy existing with constant-work-rate exercise. When these dynamics are appropriately “resolved”, LT is constant regardless of the ramp slope of choice, and RCP and MMSS display minimal variations between each other. NEW & NOTEWORTHY This study demonstrates that the dynamics of V̇o2 during ramp-incremental exercise are dependent on the characteristics of the increments in work rate, such that during slow-incrementing ramp protocols the magnitude of the dissociation between ramp V̇o2 and constant V̇o2 at a given work rate is reduced. Accurately accounting for these dynamics ensures correct characterizations of the V̇o2 kinetics at ramp onset and allows appropriate comparisons between ramp and constant-work-rate exercise-derived indexes of exercise intensity.

Transfer Function Modelling of Urban Drainage Systems, and Potential Uses in Real-Time Control Applications

1994 ◽  
Vol 29 (1-2) ◽  
pp. 409-417 ◽  
Author(s):  
Andrea G. Capodaglio
Keyword(s):  
Transfer Function ◽  
Real Time ◽  
Sewage Treatment ◽  
Operating Conditions ◽  
Urban Drainage ◽  
Real Time Control ◽  
Control Applications ◽  
Time Control ◽  
Function Modelling ◽  
Transfer Function Modelling

According to the present state-of-the-art, sewerage systems, sewage treatment plants and their subsequent improvements are often planned and designed as totally separate entities, each subject to a specific set of performance objectives. As a result, sewage treatment efficiency is subject to considerable variability, depending both on general hydrologic conditions in the urban watershed (wet versus dry periods), and on specific “instantaneous” operating conditions. It has been postulated that the integration of urban drainage and wastewater treatment design and operation could allow minimization of the harmful effects of discharges from treatment plants, overflows and surface water runoff. This “ideal condition” can be achieved through the introduction of so-called “real-time control” technology in sewerage collection and treatment operations. To be a feasible goal, this technology poses the demand for more powerful simulation models of either aspect of the system - or, ideally, of a unified sewer-and-treatment plant model - than most of those currently available. This paper examines the requirements of rainfall/runoff transformation and sewer flow models with respect to real-time control applications, and focuses on the methodology of stochastic, transfer function modelling, reporting application examples. Modalities and limitations of the extraction of information from the models thus derived are also analyzed.

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