Respiratory Sinus Arrhythmia and Central Respiratory Drive in Humans

Al-Ani, Muzahim; Forkins, A. S.; Townend, Jonathan N.; Coote, John H.

doi:10.1042/cs0900235

Cited by 33 publications

(16 citation statements)

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“…During atrial pacing, it appears that respiratory-related oscillations in HR can contribute to respiratory oscillations in blood pressure (2,28). Furthermore, there is evidence that respiratory centers within the central nervous system can directly influence HR independently of changes in blood pressure (1). However, in the present study, we found that the changes in HR due to either vagal or sympathetic activity slightly reduced the gain of the transfer function between PRBS stimulus and arterial pressure but not the general shape of the profile.…”

Section: Identification Of Model Under Open-loop Conditionsmentioning

confidence: 99%

Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Liu

Guild

Ringwood

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

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. Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance. Am J Physiol Regulatory Integrative Comp Physiol 283: R533-R542, 2002; 10.1152/ajpregu.00489.2001The aim in the present experiments was to assess the dynamic baroreflex control of blood pressure, to develop an accurate mathematical model that represented this relationship, and to assess the role of dynamic changes in heart rate and stroke volume in giving rise to components of this response. Patterned electrical stimulation [pseudo-random binary sequence (PRBS)] was applied to the aortic depressor nerve (ADN) to produce changes in blood pressure under open-loop conditions in anesthetized rabbits. The stimulus provided constant power over the frequency range 0-0.5 Hz and revealed that the composite systems represented by the central nervous system, sympathetic activity, and vascular resistance responded as a second-order low-pass filter (corner frequency Ϸ0.047 Hz) with a time delay (1.01 s). The gain between ADN and mean arterial pressure was reasonably constant before the corner frequency and then decreased with increasing frequency of stimulus. Although the heart rate was altered in response to the PRBS stimuli, we found that removal of the heart's ability to contribute to blood pressure variability by vagotomy and ␤ 1-receptor blockade did not significantly alter the frequency response. We conclude that the contribution of the heart to the dynamic regulation of blood pressure is negligible in the rabbit. The consequences of this finding are examined with respect to low-frequency oscillations in blood pressure. sympathetic nerve activity; modeling; transfer function; vasculature; rabbit THE ABILITY OF THE ARTERIAL baroreflex pathway to regulate blood pressure under steady-state conditions is well understood (25). However, there is a paucity of information regarding its dynamic ability over the frequency range 0.001-0.5 Hz. This is particularly relevant when trying to understand the mechanisms that give rise to oscillations between 0.1 and 0.4 Hz. Although there is general acceptance that this oscillation seen in humans at 0.1 Hz involves an action of the sympathetic nervous system on the vasculature, it is a matter of debate as to the origin of the oscillation. It has been suggested that the oscillation results either as a by-product of the central generation of sympathetic nerve activity (SNA) (8,24) or from the time delay between the arterial baroreceptors sensing blood pressure and the subsequent reflex effect on the vasculature (3,6,9,22,29). Certainly the available evidence suggests that the oscillation requires the presence of each of the components of the baroreflex pathway, with baroreceptor denervation or sympathectomy abolishing the oscillation in blood pressure (7,16,19). Clearly, if measurement of the strength of such oscillations is to develop into a clinically useful tool, it is imperative to understand factors from which cardiovascular variability is derived (23).Although it is clear that SNA to t...

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Section: Identification Of Model Under Open-loop Conditionsmentioning

confidence: 99%

Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Liu

Guild

Ringwood

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Although the LF and HF components evaluate the influences of the autonomic system on the sinus node, their specificity as autonomic markers is incomplete because HRV also depends on other factors. Furthermore, the LF component is also influenced by the parasympathetic system (20,21). However, the passive postural change used in this study allows a better evaluation of sympathetic influence on HRV (9).…”

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confidence: 99%

Autonomic dysfunction and urinary albumin excretion rate are associated with an abnormal blood pressure pattern in normotensive normoalbuminuric type 1 diabetic patients.

et al. 2000

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Abbreviations: CV, coefficient of variation; dBP, diastolic blood pressure; ECG, electrocardiogram; ECV, extracellular volume; GFR, glomerular filtration rate; HF, high frequency; HRV, heart rate variability; LF, low frequency; LF/HF ratio, ratio of power in low-frequency and high-frequency bands; n.u., normalized units; PNN50, the percentage of differences between adjacent R-R intervals Ͼ50 ms; PSA, power spectral analysis; RMSSD, the root mean square of successive differences of adjacent R-R intervals; RRMED, the mean of all R-R intervals; sBP, systolic blood pressure; SDANNi, the SD of the averages of the R-R intervals calculated in 5-min segments; SDNN, the SD of the R-R intervals; SDNNi, the mean of the SD of R-R intervals calculated in 5-min segments; UAER, urinary albumin excretion rate.A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. RESEARCH DESIGN AND METHODS -A total of 39 normotensive normoalbuminuric type 1 diabetic patients were studied. Glomerular filtration rate ( 51 Cr-EDTA technique), extracellular volume ( 51 Cr-EDTA distribution volume), and urinary albumin excretion rate (UAER) (by radioimmunoassay) were measured. The subjects' 24-h ambulatory blood pressure and a 24-h electrocardiogram were recorded simultaneously. Heart rate variability was calculated in the time domain for 24 h, in the frequency domain at night, at rest in the supine position, and during tilt. Patients were classified according to diastolic blood pressure (dBP) night/day ratio as dipper patients (Յ0.9) and nondipper patients (Ͼ0.9). Autonomic Dysfunction and UrinaryRESULTS -Nondipper patients presented a higher low-frequency (LF) component (a sympathetic index) and higher LF/high-frequency (HF) ratio during sleep than dipper patients (0.29 ± 0.12 vs. 0.19 ± 0.10 normalized units [n.u.], P = 0.008; and 0.98 ± 0.53 vs. 0.55 ± 0.45 n.u., P = 0.007, respectively). At rest, the LF component in nondipper patients (0.38 ± 0.13 n.u.) was higher than in dipper patients (0.27 ± 0.12 n.u., P = 0.04). After the tilt, nondipper patients did not show an increase in the LF component (P = 0.32), but in dipper patients, the increase was significant (P = 0.001). In both groups, tilting promoted a decrease in the HF component (a parasympathetic index). In a stepwise multiple linear regression analysis, the LF component during sleep and the UAER accounted for 24% of the variability in the dBP night/day ratio.CONCLUSIONS -The predominance of sympathetic activity and increased levels of UAER, although within the normal range, are associated with a blunted fall in nocturnal dBP

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“…The characteristic CO 2 dependency of whatever causes the central respiratory rhythm (2,12,24,30) uniquely distinguishes it from other oscillators that may also exist in the central nervous system (CNS) (24) that may also oscillate at "respiratory frequencies" (without causing the central respiratory rhythm) and that influence autonomic activity during breath holding. We therefore tested whether any of the frequency components of sinus arrhythmia were reduced by a prior reduction in PCO 2 at the start of breath holding and were stimulated by the linear rise in PCO 2 throughout breath holding with preoxygenation (34).…”

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confidence: 99%

CO₂-dependent components of sinus arrhythmia from the start of breath holding in humans

Cooper

Parkes

Clutton-Brock

2003

American Journal of Physiology-Heart and Circulatory Physiology

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A substantial portion of sinus arrhythmia in conscious humans appears to be caused by the CO2-dependent central respiratory rhythm. Under some circumstances, therefore, sinus arrhythmia might indicate the presence of the central respiratory rhythm. Humans can voluntarily modify their central respiratory rhythm (e.g., by pacing breathing or by delaying or advancing breaths), but it is not clear what happens to it from the start of breath holding. In this study, we show that sinus arrhythmia persists from the start of breath holds prolonged by preoxygenation. We also show that some of the frequency components of sinus arrhythmia start within each subject's eupneic frequency range and change when end-tidal Pco2 is lowered or raised, as we would expect if the central respiratory rhythm continues from the start of breath holding. We discuss whether sinus arrhythmia can indicate if the central respiratory rhythm continues from the start of breath holding.

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Respiratory Sinus Arrhythmia and Central Respiratory Drive in Humans

Cited by 33 publications

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Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Autonomic dysfunction and urinary albumin excretion rate are associated with an abnormal blood pressure pattern in normotensive normoalbuminuric type 1 diabetic patients.

CO₂-dependent components of sinus arrhythmia from the start of breath holding in humans

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Respiratory Sinus Arrhythmia and Central Respiratory Drive in Humans

Cited by 33 publications

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Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance

Autonomic dysfunction and urinary albumin excretion rate are associated with an abnormal blood pressure pattern in normotensive normoalbuminuric type 1 diabetic patients.

CO2-dependent components of sinus arrhythmia from the start of breath holding in humans

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CO₂-dependent components of sinus arrhythmia from the start of breath holding in humans