A new interpolation-free procedure for breath-by-breath analysis of oxygen uptake in exercise transients

Bringard, Aurélien; Adami, Alessandra; Moia, Christian; Ferretti, Guido

doi:10.1007/s00421-014-2920-z

Cited by 11 publications

(10 citation statements)

References 33 publications

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“…Invasive hemodynamic evaluation was carried out in PH patients in a recumbent position as previously described [11] and included measures of pulmonary artery mean pressure (mPAP), pulmonary artery wedge pressure (PAWP), right atrial pressure (RAP), CO by TD (CO TD ), PVR calculated as the transpulmonary gradient (mPAP − PAWP) divided by CO TD , and systemic vascular resistances (SVR) as mean systemic arterial pressure (MAP) divided by CO determined by MF (CO MF ), on the supposition that the RAP can be excluded from its calculation [13, 14]. …”

Section: Methodsmentioning

confidence: 99%

“…As proposed by Bringard and coworkers [13], no interpolation was performed and the analysis was performed on the beat-by-beat data. Based on previous published findings [2, 15], the kinetics of SV, CO, and HR were described with a monoexponential model firstly proposed by Barstow and Molé [16], whereby a flow increase with a time delay reflects the circulation time from active muscles to the lungs.…”

Section: Methodsmentioning

confidence: 99%

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Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

Lador

Bringard

Bengueddache

et al. 2016

BioMed Research International

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Purpose. Cardiac output (CO) is a cornerstone parameter in precapillary pulmonary hypertension (PH). The Modelflow (MF) method offers a reliable noninvasive determination of its beat-by-beat changes. So MF allows exploration of CO adjustment with the best temporal resolution. Methods. Fifteen subjects (5 PH patients, 10 healthy controls) performed a submaximal supine exercise on a cycle ergometer after 5 min of rest. CO was continuously determined by MF (COMF). Kinetics of heart rate (HR), stroke volume (SV), and CO were determined with 3 monoexponential models. Results. In PH patients, we observed a sudden and transitory drop of SV upon exercise onset. This implied a transitory drop of CO whose adjustment to a new steady state depended on HR increase. The kinetics of HR and CO for PH patients was slower than that of controls for all models and for SV in model 1. SV kinetics was faster for PH patients in models 2 and 3. Conclusion. This is the first description of beat-by-beat cardiovascular adjustments upon exercise onset in PH. The kinetics of HR and CO appeared slower than those of healthy controls and there was a transitory drop of CO upon exercise onset in PH due to a sudden drop of SV.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

Lador

Bringard

Bengueddache

et al. 2016

BioMed Research International

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show abstract

“…This approach increases the number of observations encompassed by a fitting procedure without artificial data manipulations, thus reinforcing the fitting by mere addition of data. A comparison of the results obtained by means of the stacking procedure with those obtained with the interpolation procedures (Bringard et al 2014), for the same _ V O 2 computational algorithm (Grønlund's), showed equivalent τ 2 values, but lower (faster) τ 1 values with stacking than with interpolation. It is not unlike that the _ V O 2 kinetics upon exercise onset be faster than usually reported as a consequence of insufficient or inadequate data treatment tools.…”

Section: The Problem Of Gas Flow Analysis On a Breath-by-breath Basismentioning

confidence: 84%

“…More recently, at least in the light exercise domain, mere stacking of multiple repetitions was proposed and treated as if the data were from the same rest-toexercise transient (Bringard et al 2014;Francescato et al 2014a, b). With this procedure, possible signal distortion was prevented by using superposition of raw data obtained during several identical _ V O 2 on transients, on the assumption that each repetition on a given subject is representative of the same physiological situation.…”

Section: The Problem Of Gas Flow Analysis On a Breath-by-breath Basismentioning

confidence: 98%

“…One may well obtain good, even better statistics with interpolation than with stacking, at least as far as the primary component is concerned. The problem here is that the conceptual error implicit in interpolation techniques, even if they provide accurate time constants for the primary component (Bringard et al 2014), should be avoided even at the price of somewhat weaker statistics. The study of gas exchange kinetics is less a matter of statistics than of ideas.…”

Section: The Problem Of Gas Flow Analysis On a Breath-by-breath Basismentioning

confidence: 99%

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Exercise Transients

Ferretti¹

2015

Energetics of Muscular Exercise

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The steady state of light constant-power submaximal exercise is attained after at least 3 min since the exercise start. Although the application of mechanical power is practically immediate, the rate of oxygen uptake _ V O 2 À Á increases at a remarkably slower rate: a metabolic transient phase occurs, during which _ V O 2 , despite increasing, is insufficient to provide all the metabolic power that is necessary to sustain ATP resynthesis, so that an oxygen deficit is incurred. The oxygen deficit consists of (i) an obligatory component, covered by phosphocreatine breakdown, reflecting the kinetics of glycolysis activation in the contracting muscles, and characterized by an invariant time constant independent of the exercise intensity and (ii) a facultative component, covered by anaerobic lactic metabolism (early lactate accumulation), due to the dissociation between cardiopulmonary response and muscular response at elevated powers, and characterized by a time constant depending on the exercise intensity. The kinetics of _ V O 2 upon exercise onset is described with exponential equations. The implications of single-and doubleexponential models are discussed. The former model carries along the assumption that the kinetics of _ V O 2 determined at the mouth reflects the kinetics of _ V O 2 in the contracting muscles. This correspondence, however, does not hold anymore when early lactate appears. The latter model, in particular, implies a rapid phase (phase I), which has been related to the fast cardiovascular responses at exercise start. A singleexponential model assumes also that the exercising muscles behave as dynamic linear first-order systems that, as such, admit only one transfer function. On this basis, ramp exercise and sinusoidal exercise, typically two unsteady-state conditions, are discussed. More recently, at powers higher than the critical power (see Chap. 5), the so-called slow component, or third phase of the _ V O 2 kinetics, has been also characterized. The energetic meaning of the slow component is also discussed. Finally, some methodological aspects of single-breath analysis of pulmonary gas exchange are discussed.

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Further Developments on Exercise Transients: Los Angeles Versus Milano

Ferretti

2023

Perspectives in Physiology

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A new interpolation-free procedure for breath-by-breath analysis of oxygen uptake in exercise transients

Cited by 11 publications

References 33 publications

Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

Exercise Transients

Further Developments on Exercise Transients: Los Angeles Versus Milano

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