Revisiting the Sequence Method for Baroreflex Analysis

Silva, Luiz Eduardo Virgílio; Dias, Daniel Penteado Martins; Silva, Carlos Alberto Aguiar da; Salgado, Hélio César; Fazan, Rubens

doi:10.3389/fnins.2019.00017

Cited by 32 publications

(25 citation statements)

References 33 publications

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“…The following conventional validated BRS measures were assessed in rest: sequence method BRS and baroreflex effectiveness index (BEI) (Bertinieri et al, 1988;Di Rienzo et al, 2001;Laude et al, 2008;Silva et al, 2019). Sequence method BRS and BEI were computed based on the 5-min resting epochs preceding the sit to stand movements, using the criteria reported by Silva et al (2019).…”

Section: Baroreflex Sensitivity (Brs) and Cerebral Autoregulation (Car)mentioning

confidence: 99%

Multimodal Monitoring of Cardiovascular Responses to Postural Changes

et al. 2020

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Background: In the poorly understood relationship between orthostatic hypotension and falls, next to blood pressure (BP), baroreflex sensitivity (BRS) and cerebral autoregulation (CAR) may be key measures. The posture-and movement dependency of orthostatic hypotension requires continuous and unobtrusive monitoring. This may be possible using simultaneous photoplethysmography (PPG), electrocardiography (ECG), and near-infrared spectroscopy (NIRS) signal recordings, from which pulse wave velocity (PWV; potentially useful for BP estimation), BRS and CAR can be derived. The PPG, NIRS and PWV signal correlation with BP and BRS/CAR reliability and validity need to be addressed. Methods: In 34 healthy adults (mean age 25 years, inter quartile range 22-45; 10 female), wrist and finger PPG, ECG, bifrontal NIRS (oxygenated and deoxygenated hemoglobin) and continuous BP were recorded during sit to stand and supine to stand movements. Sixteen participants performed slow and rapid supine to stand movements; eighteen other participants performed a 1-min squat movement. Pulse wave velocity (PWV) was defined as the inverse of the ECG R-peak to PPG pulse delay; PPG, NIRS and PWV signal correlation with BP as their Pearson correlations with mean arterial pressure (MAP) within 30 s after the postural changes; BRS as inter beat interval drop divided by systolic BP (SBP) drop during the postural changes; CAR as oxygenated hemoglobin drop divided by MAP drop. BRS and CAR were separately computed using measured and estimated (linear regression) BP. BRS/CAR reliability was defined by the intra class correlation between repeats of the same postural change; validity as the Pearson correlation between BRS/CAR values based on measured and estimated BP. Results: The highest correlation with MAP was found for finger PPG and oxygenated hemoglobin, ranging from 0.75-0.79 (sit to stand), 0.66-0.88 (supine to stand), and 0.82-0.94 (1-min squat). BRS and CAR reliability was highest during the different supine

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Section: Baroreflex Sensitivity (Brs) and Cerebral Autoregulation (Car)mentioning

confidence: 99%

Multimodal Monitoring of Cardiovascular Responses to Postural Changes

et al. 2020

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“…Alternatively, the sequence method is a less invasive method for calculation of G and has long been available in the medical literature (Bertinieri et al, , ; Calvo et al, ; Laude et al, ; Silva, Dias, Silva, Salgado, & Fazan, ; Takahashi et al, ). This method analyzes the occurrence of spontaneous beat‐to‐beat variation of systolic pressures and the concomitant PI‐lengthening or ‐shortening events (Bertinieri et al, ; Di Rienzo, Castiglioni, et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the sequence method as a tool to assess spontaneous baroreflex in reptiles

et al. 2019

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The sequence method is an alternative to the traditional pharmacological approach (i.e., the Oxford technique) used to calculate baroreflex gain (G) in mammals. Although the sequence method assesses baroreflex by measuring spontaneous events of blood pressure regulation, the pharmacological method relies on the injection of vasoactive drugs that impact the baroreflex mechanism itself. The sequence method might be relevant for dynamic measurement of baroreflex modulation but it was never validated for vertebrates with low heart rate. Hence, we tested the sequence method in three species of reptiles and compared the results with those provided by the classic pharmacological method. G was similar between both methods and values correlated when parameters for the sequence method were set at delay 0 or 1 (i.e., the baroreflex system responds immediately to blood pressure changes or after 1 heartbeat). Calculation of the baroreflex effectiveness index was adequate at a minimum of 300 cycles and a delay of 1 for the three species. Therefore, the sequence method has been validated to investigate baroreflex regulation in reptiles, enabling studies during dynamic alterations in homeostasis.

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“…It has been shown that abnormalities in BEI are associated with cardiovascular disease ( 56 , 57 ). Yet because the sequence method to estimate BEI is influenced by breath state and is difficult to reproduce ( 58 ), and because it does not identify periods of disengagement lasting longer than 3 or 4 heartbeats, its application would not identify the relatively long periods of disengagement identified in this study.…”

Section: Discussionmentioning

confidence: 99%