Measuring postural-related changes of spontaneous baroreflex sensitivity after repeated long-duration diving: Frequency domain approaches

Faes, Luca; Masè, Michela; Nollo, Giandomenico; Chon, Ki H.; Florian, John P.

doi:10.1016/j.autneu.2013.03.006

Cited by 17 publications

(35 citation statements)

References 31 publications

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“…Results from this study and others (Faes et al. ; Florian et al. ) suggest that in addition to diminished blood volume, changes in cardiac function, reduced baroreflex sensitivity and coupling, and decreased vascular responsiveness, are responsible for the reduced orthostatic tolerance.…”

Section: Discussionsupporting

confidence: 63%

“…), and with postural stress, the resulting deterioration of baroreflex sensitivity/coupling (Faes et al. ) and an inability to augment systemic vascular resistance may contribute to post‐WI orthostatic intolerance (Iwase et al. ; Florian et al.…”

Section: Introductionmentioning

confidence: 99%

“…Physiological compensation to postural stress is altered after long-duration water immersion (WI), thus predisposing individuals to blood pressure instability and orthostatic intolerance (Stegemann et al 1975;Faes et al 2013;Florian et al 2013). During WI, central blood volume increases due to fluid shifts from the intracellular and interstitial fluid compartments to extracellular compartment (Epstein 1992) and redistribution of blood volume from the lower extremities to the thorax (Greenleaf et al orthostatic intolerance (Iwase et al 2000;Florian et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

et al. 2016

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Physiological compensation to postural stress is weakened after long‐duration water immersion (WI), thus predisposing individuals to orthostatic intolerance. This study was conducted to compare hemodynamic responses to postural stress following exposure to WI alone (Air WI), hyperbaric oxygen alone in a hyperbaric chamber (O2 HC), and WI combined with hyperbaric oxygen (O2 WI), all at a depth of 1.35 ATA, and to determine whether hyperbaric oxygen is protective of orthostatic tolerance. Thirty‐two healthy men underwent up to 15 min of 70° head‐up tilt (HUT) testing before and after a single 6‐h resting exposure to Air WI (N = 10), O2 HC (N = 12), or O2 WI (N = 10). Heart rate (HR), blood pressure (BP), cardiac output (Q), stroke volume (SV), forearm blood flow (FBF), and systemic and forearm vascular resistance (SVR and FVR) were measured. Although all subjects completed HUT before Air WI, three subjects reached presyncope after Air WI exposure at 10.4, 9.4, and 6.9 min. HUT time did not change after O2 WI or O2 HC exposures. Compared to preexposure responses, HR increased (+10 and +17%) and systolic BP (−13 and −8%), and SV (−16 and −23%) decreased during HUT after Air WI and O2 WI, respectively. In contrast, HR and SV did not change, and systolic (+5%) and diastolic BP (+10%) increased after O2 HC. Q decreased (−13 and −7%) and SVR increased (+12 and +20%) after O2 WI and O2 HC, respectively, whereas SVR decreased (−9%) after Air WI. Opposite patterns were evident following Air WI and O2 HC for FBF (−26 and +52%) and FVR (+28 and −30%). Therefore, breathing hyperbaric oxygen during WI may enhance post‐WI cardiovascular compensatory responses to orthostatic stress.

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Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

et al. 2016

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“…The simplest baroreflex spectral analysis is the α‐index, which only considers the single power spectrum of AP and the reflex response (in this case, RSNA) and, therefore, assumes that the whole variability of the reflex response is driven by the AP (Faes et al . ).…”

Section: Discussionmentioning

confidence: 97%

Baroreflex control of renal sympathetic nerve activity in early heart failure assessed by the sequence method

Lataro

Silva

et al. 2017

The Journal of Physiology

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In heart failure (HF), the reflex control of the heart rate is known to be markedly impaired; however, the baroreceptor control of the sympathetic drive remains under debate. Applying the sequence method to a series of arterial pressure (AP) and renal sympathetic nerve activity (RSNA), we demonstrated a clear dysfunction in the baroreflex control of sympathetic activity in rats with early HF. We analysed the baroreflex control of the sympathetic drive using three different approaches: AP vs. RSNA curve, cross-spectral analysis and sequence method between AP and RSNA. The sequence method also provides the baroreflex effectiveness index (BEI), which represents the percentage of AP ramps that actually produce a reflex response. The methods were applied to control rats and rats with HF induced by myocardial infarction. None of the methods employed to assess the sympathetic baroreflex gain were able to detect any differences between the control and the HF group. However, rats with HF exhibited a lower BEI compared to the controls. Moreover, an optimum delay of 1 beat was observed, i.e. 1 beat is required for the RSNA to respond after AP changing, which corroborates with the findings related to the timing between these two variables. For delay 1, the BEI of the controls was 0.45 ± 0.03, whereas the BEI of rats with HF was 0.29 ± 0.09 (P < 0.05). These data demonstrate that while the gain of the baroreflex is not affected in early HF, its effectiveness is markedly decreased. The analysis of the spontaneous changes in AP and RSNA using the sequence method provides novel insights into arterial baroreceptor reflex function.

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“…In [8] this result was interpreted as the consequence of the inability of spectral, cross-spectral and baroreflex sequence techniques to fully account for causality. Recently, others investigators reported the same conclusion in different experimental conditions such as prolonged diving [12]. Indeed, a model-based causal method capable to calculate the fraction of HP variability really driven by SAP changes detected a significant decrease of BRS [8].…”

Section: Empirical Mode Decomposition Approach To the Estimation Of Cmentioning

confidence: 55%

Empirical mode decomposition approach to the estimation of cardiac baroreflex sensitivity in patients undergoing coronary artery bypass graft surgery

Bari

Marchi

Bassani

et al. 2014

2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO)

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Cardiac baroreflex sensitivity (BRS) as assessed from spontaneous variability of heart period (HP) and systolic arterial pressure (SAP) is reduced during general anesthesia. Patients undergoing coronary artery bypass graft (CABG) surgery are characterized by a low BRS even before general anesthesia. These observations provide the basis of the difficulty in detecting the BRS reduction after the induction of general anesthesia in CABG patients. Empirical mode decomposition (EMD) is a technique decomposing the series into oscillatory modes at different time scales. We propose an EMD-based approach to the BRS estimate in 34 patients undergoing CABG. Results showed that the EMD-based method was not able to detect the BRS reduction in CABG patients after the induction of general anesthesia. The negative result was interpreted as a consequence of the inability of EMD-based method to account for HP-SAP causality.

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Measuring postural-related changes of spontaneous baroreflex sensitivity after repeated long-duration diving: Frequency domain approaches

Cited by 17 publications

References 31 publications

Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress

Baroreflex control of renal sympathetic nerve activity in early heart failure assessed by the sequence method

Empirical mode decomposition approach to the estimation of cardiac baroreflex sensitivity in patients undergoing coronary artery bypass graft surgery

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