Feedback and feedforward sympathetic haemodynamic control: chicken or egg?

Tan, Can Ozan; Taylor, J. Andrew

doi:10.1113/jphysiol.2011.208199

Cited by 9 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, previous studies have largely been based on spontaneous indices of BRS, whereas our study derived BRS from experimentally driven oscillations of SAP at specific frequencies. Spontaneous assessment of BRS at the breathing frequency is controversial (9,19,20), and it remains unclear whether BP and R-R interval fluctuations coincident with respiration are linked by the baroreflex or arise from a central neural mechanism (4,20,26). Second, when spontaneous methods are conducted at the breathing frequency, it is not possible to uncouple the effects of breathing rate on BRS from the effects of BP oscillation frequency.…”

Section: Discussionmentioning

confidence: 99%

Interactions between breathing rate and low-frequency fluctuations in blood pressure and cardiac intervals

Horsman

Peebles

Tzeng

2015

Journal of Applied Physiology

View full text Add to dashboard Cite

Evidence derived from spontaneous measures of cardiovagal baroreflex sensitivity (BRS) suggests that slow breathing at 6 breaths/min augments BRS. However, increases in BRS associated with slow breathing may simply reflect the frequency-dependent nature of the baroreflex rather than the modulation of baroreflex function by changes in breathing rate per se. To test this hypothesis we employed a crossover study design (n = 14) wherein breathing rate and systolic arterial blood pressure (SAP) oscillation induced via the application of oscillating lower body negative pressure (OLBNP) were independently varied at fixed frequencies. Breathing rate was controlled at 6 or 10 breaths/min with the aid of a metronome, and SAP oscillations were driven at 0.06 Hz and 0.1 Hz using OLBNP. The magnitudes of SAP and R-R interval (cardiac period) oscillations were quantified using power spectral analysis, and the transfer function gain between SAP and R-R interval was used to estimate BRS. Linear mixed-effects models were used to examine the main effects and interactions between breathing rate and OLBNP frequency. There was no statistical interaction between breathing and OLBNP frequency (P = 0.59), indicating that the effect of breathing rate on BRS did not differ according to OLBNP frequency (and vice versa). Additionally, there was no main effect for breathing rate (P = 0.28). However, we observed a significant main effect for OLBNP frequency (P = 0.01) consistent with the frequency-dependent nature of baroreflex. These findings suggest that increases in spectral indices of BRS reflect the frequency dependence of the baroreflex and are not due to slow breathing per se.

show abstract

Section: Discussionmentioning

confidence: 99%

Interactions between breathing rate and low-frequency fluctuations in blood pressure and cardiac intervals

Horsman

Peebles

Tzeng

2015

Journal of Applied Physiology

View full text Add to dashboard Cite

show abstract

“…Positional compensation is consequently best achieved by interplay between both mechanisms. Because feedback mechanisms are by nature reactive, feed‐forward mechanisms may take the lead in shaping HR and BP at rest (Silvani et al 2008; Kamiya et al 2011; Tan & Taylor, 2011). The vestibular system may be particularly well suited for such a role because its nuclei routinely receive input from so many sensors – motion, somatosensory, proprioceptive and graviceptive (Yates et al 2000).…”

Section: Discussionmentioning

confidence: 99%

Positional circulatory control in the sleeping infant and toddler: role of the inner ear and arterial pulse pressure

Cohen

Vella

Jeffery

et al. 2012

The Journal of Physiology

View full text Add to dashboard Cite

Key points• Fast-acting reflexes fine-tune heart rate and blood pressure as the push and pull of gravity changes from moment to moment.• Circulatory failure may occur if these mechanisms fail to develop normally.• Reactions to routine movements such as head-up and sideways tilt show how two key reflexes involved develop during sleep, in early infancy.• Sensors that detect motion and arterial pulsations, located in the inner ear and arteries, respectively, produce carefully coordinated changes in heart rate and blood pressure as body position and the force/direction of gravity alters.• Both mechanisms are intact in infants exposed to tobacco, but a mild pulse pressure anomaly reflexively slows their heart and lowers their blood pressure on tilt to upright.• Circulatory dysfunction need not necessarily reflect abnormal development of key reflexes per se, but other factors that inappropriately trigger or inhibit them.Abstract Heart rate (HR) and arterial blood pressure (BP) are rapidly and reflexively adjusted as body position and the force/direction of gravity alters. Anomalies in these mechanisms may predispose to circulatory failure during sleep. We analysed the development of two key reflexes involved by undertaking a longitudinal (birth-1 year) comparison of instantaneous HR and BP changes evoked by abrupt upright, sideways or horizontal repositioning. Each manoeuvre triggered an identical rise in HR (tachycardia) followed by a slower rise in diastolic blood pressure (DBP)/systolic blood pressure (SBP) and variable pulse pressure (PP) change. We show that tachycardia is triggered by acceleration (vestibular) sensors located in the inner ear and slight changes in the pulsatile component of BP then signal to the arterial baroreceptors to reinforce or oppose these actions as needed. We also identified a PP anomaly in sleeping 1-year-olds of smokers that prematurely slows HR and is associated with mild positional hypotension. We conclude that positional circulatory compensation is initiated pre-emptively in a feed-forward manner and that feedback changes in vago-sympathetic drive to the heart (and perhaps blood vessels) by PP exert a slower but powerful modulating effect. An anomaly in either or both mechanisms may weaken positional compensation in some sleeping infants. Abbreviations BP, blood pressure; BRS, baroreflex sensitivity; DBP, diastolic blood pressure; HR, heart rate; IBI, inter-beat interval; SBP, systolic blood pressure; PP, pulse pressure.

show abstract

“…Therefore, Seq and BER contained information on the influence of respiration on blood pressure, whilst the other methods were less sensitive. It remains unclear whether blood pressure and beat-to-beat interval fluctuations coinciding with respiration are of baroreflex origin or arise from another central neural mechanism (Diaz and Taylor, 2006;Tan and Taylor, 2011). Without controlled respiratory rate (with a metronome for example) disentangling the effects of respiratory rate on BRS from the effects of blood pressure oscillation frequency is very difficult if not impossible (Goldstein et al, 1982;Pagani et al, 1988;La Rovere et al, 2008;Bourdillon et al, 2018).…”

Section: Influence Of the Respiratory Rate On Brs Estimationmentioning

confidence: 99%

AltitudeOmics: Spontaneous Baroreflex Sensitivity During Acclimatization to 5,260 m: A Comparison of Methods

et al. 2019

View full text Add to dashboard Cite

Introduction: Baroreflex sensitivity (BRS) is essential to ensure rapid adjustment to variations in blood pressure (BP). Spontaneous baroreflex function can be assessed using continuous recordings of blood pressure. The goal of this study was to compare four methods for BRS quantification [the sequence, Bernardi's (BER), frequency and transfer function methods] to identify the most consistent method across an extreme range of conditions: rest and exercise, in normoxia, hypoxia, hypocapnia, and hypercapnia. Methods: Using intra-radial artery BP in young healthy participants, BRS was calculated and compared using the four methods in normoxia, acute and chronic hypoxia (terrestrial altitude of 5,260 m) in hypocapnia (hyperventilation), hypercapnia (rebreathing) and during ramp exercise to exhaustion. Results: The sequence and BER methods for BRS estimation showed good agreement during the resting and exercise protocols, whilst the ultra-and very-low frequency bands of the frequency and transfer function methods were more discrepant. Removing respiratory frequency from the blood pressure traces affected primarily the sequence and BER methods and occasionally the frequency and transfer function methods. Discussion/Conclusion: The sequence and BER methods contained more respiratory related information than the frequency and transfer function methods, indicating that the former two methods predominantly rely on respiratory effects of BRS. BER method is recommended because it is the easiest to compute and even though it tends to overestimate BRS compared to the sequence method, it is consistent with the other methods, whilst its interquartile range is the smallest.

show abstract

Feedback and feedforward sympathetic haemodynamic control: chicken or egg?

Cited by 9 publications

References 4 publications

Interactions between breathing rate and low-frequency fluctuations in blood pressure and cardiac intervals

Interactions between breathing rate and low-frequency fluctuations in blood pressure and cardiac intervals

Positional circulatory control in the sleeping infant and toddler: role of the inner ear and arterial pulse pressure

AltitudeOmics: Spontaneous Baroreflex Sensitivity During Acclimatization to 5,260 m: A Comparison of Methods

Contact Info

Product

Resources

About