Respiration‐synchronous fluctuations in stroke volume, heart rate and arterial pressure in humans.

Toska, Karin; Eriksen, Morten

doi:10.1113/jphysiol.1993.sp019958

Cited by 201 publications

(183 citation statements)

References 33 publications

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“…In adult rats, atropine increased HR and decreased the spectral HF peak (29,31). Similar results have been obtained in human adults, in which atropine increased HR and decreased HF spectral power (30,32,38). During sympathetic stimulation, variability of the R-R interval series showed virtually no spectral power in the HF band after atropine (30).…”

Section: Autonomic Function In Preterm Infantssupporting

confidence: 80%

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

et al. 2004

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To study cardiovascular autonomic control, we assessed the effect of atropine on heart rate (HR) and blood pressure (BP) variability in 12 preterm infants (range 26 -32 wk) before intubation for respiratory insufficiency. Spectral power analysis of R-R interval and systolic BP (SBP) series were estimated in a low-frequency (LF; 0.04 -0.15 Hz) and high-frequency (HF; 0.4 -1.5 Hz) band and evaluated for a 10-min period before and a 10-min period after atropine sulfate (0.01 mg/kg). Baroreceptor reflex (BR) functioning was estimated using transfer function analysis at LF (coherence, gain, and phase). Atropine resulted in a significant 12% increase in steady-state HR (p Ͻ 0.01) and unchanged SBP. For R-R interval series, the total spectral power decreased 6-fold (p Ͻ 0.01), which was predominantly due to a reduction in the LF band (16-fold; p Ͻ 0.01). In contrast, we observed a significant increase (25%; p Ͻ 0.05) in total spectral power of SBP series partly as a result of an increase in HF power. The LF power of SBP series was not altered. The median LF transfer gain (BR sensitivity) between SBP and R-R interval decreased from 4.2 to 1.4 ms/mm Hg (p Ͻ 0.01) after atropine. The LF phase relationship (BP leads R-R interval fluctuations bỹ 4 s) was not changed after atropine. In conclusion, even in preterm infants in distress, atropine modulates HR and BP variability, suggesting that BR-mediated parasympathetic control of heart rate is of significance for cardiovascular control at that age. The baroreceptor reflex (BR) is the most important regulatory mechanism in the short-term control of heart rate (HR) and blood pressure (BP). The BR buffers sudden changes in systemic BP by adapting HR and peripheral vascular resistance. These responses of HR and vascular resistance are mediated by the efferent parasympathetic and sympathetic limb of the BR. As both systems are involved, studies on the BR give information on autonomic cardiovascular regulation (1,2).Data about the ontogeny of the BR and functional maturation in the human infant are limited. This is partly caused by the limited experimental (pharmacologic or mechanical) possibilities to challenge the BR in neonates. Passive head-up tilt test has been applied to neonates to measure responses in BP, HR, and limb blood flow to body tilting. In preterm infants (26 -38 wk gestation), passive head-up tilt resulted in significant vasoconstriction of the lower limb with a slight fall in aortic BP and unchanged HR (3). The inadequate ability to maintain BP and the lack of tachycardia suggest that preterm infants lack the full integrated BR response as seen in adults. In term infants, however, a fall in systolic BP (SBP) was observed in conjunction with tachycardia and a fall in limb blood flow, suggesting the presence of active reflex vasoconstriction (4). In a recent study, BR maturation was studied longitudinally in preterm infants, using a beat-to-beat analysis of R-R interval series and noninvasively measured SBP (5). BR sensitivity (the R-R interval change in millisecon...

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Section: Autonomic Function In Preterm Infantssupporting

confidence: 80%

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

et al. 2004

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“…Data shown are from a male (28 years) and the mean heart rate was 53 beats min -1 with HF and LF components of 56.8 NU and 39.1 NU respectively, when supine. During HUT, the mean heart rate was 86 beats min -1 with HF and LF components of 28.6 NU and 63.4 NU respectively J Physiol Sci (2009) 59: 31-36 33 ventilation, as shown by others [23][24][25][26][27]. Also, in the current study, a decrease in HF cardiac variability was shown with HUT, again similar to the findings of others [14,[18][19][20]33].…”

Section: Discussionsupporting

confidence: 91%

“…However, directional changes in the LF component of HRV with tilting appear equivocal, with no change [14,18,21] or an increase [19,20,22] being reported for healthy subjects. Hypercapnia has consistently been shown to increase HF cardiac variability [7,[23][24][25], suggestive of an increase in respiratory sinus arrhythmia [24,[26][27][28] but shown to have variable effects on LF variability [29].…”

Section: Introductionmentioning

confidence: 99%

Indirect measures of human vagal withdrawal during head-up tilt with and without a respiratory acidosis

et al. 2008

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Human ECG records were analyzed during supine (SUP) rest and whole body 80°head-up tilt (HUT), with a respiratory acidosis (5%CO 2 ) and breathing room air (RA). HUT increased heart rate in both conditions (RA SUP 60 ± 13 vs. RA HUT 79 ± 16; 5%CO 2SUP 63 ± 12 vs. 5%CO 2HUT 79 ± 14 beats min -1 ) and decreased mean R-R interval, with no changes in the R-R interval standard deviation. When corrected for changes in frequency spectrum total power (NU), the high frequency (0.15-0. (D) in HF NU and R-R interval were recorded for RA (DHF NU = 0.0787(DR-R) -11.3, R 2 = 0.79, P \ 0.05), and for 5%CO 2 (DHF NU = 0.0334(DR-R) ? 1.1, R 2 = 0.82, P \ 0.05). The decreased HF component suggested withdrawal of vagal activity during HUT. For both RA and 5%CO 2 , the positive linear relations between DHF NU and DR-R suggested that the greater the increase in heart rate with HUT, the greater the vagal withdrawal. However, a reduced range of DHF during HUT with respiratory acidosis suggested vagal withdrawal was lower with a respiratory acidosis.

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“…Though not conclusive as they are drawn on a single subject, these results suggest a higher sensitivity of the cTE, compared with the traditional TE, in the detection of information transfers that can be associated to known cardiovascular and cardiorespiratory mechanisms. These mechanisms, also recently investigated using tools based on transfer entropy [7], are the baroreflex modulation of heart rate, manifested through coupling from systolic pressure to heart period variability [39], and the effects of respiration on heart period (describing the so-called respiratory sinus arrhythmia [40]) and on arterial pressure (describing the mechanical perturbations of arterial pressure originating from respiration-related movements [41]). In particular, the higher sensitivity of cTE to the information transferred from systolic pressure to heart period, denoted in this example by the significant values observed for cTE′ Y→Z but not for TE Y→Z in both conditions, could suggest a major role played by fast vagal effects −whereby the systolic pressure affects heart period within the same heartbeat-in the functioning of the baroreflex mechanism.…”

Section: Cardiovascular and Cardiorespiratory Variabilitymentioning

confidence: 99%

Compensated Transfer Entropy as a Tool for Reliably Estimating Information Transfer in Physiological Time Series

Faes

Nollo

Porta

2013

Entropy

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We present a framework for the estimation of transfer entropy (TE) under the conditions typical of physiological system analysis, featuring short multivariate time series and the presence of instantaneous causality (IC). The framework is based on recognizing that TE can be interpreted as the difference between two conditional entropy (CE) terms, and builds on an efficient CE estimator that compensates for the bias occurring for high dimensional conditioning vectors and follows a sequential embedding procedure whereby the conditioning vectors are formed progressively according to a criterion for CE minimization. The issue of IC is faced accounting for zero-lag interactions according to two alternative empirical strategies: if IC is deemed as physiologically meaningful, zero-lag effects are assimilated to lagged effects to make them causally relevant; if not, zero-lag effects are incorporated in both CE terms to obtain a compensation. The resulting compensated TE (cTE) estimator is tested on simulated time series, showing that its utilization improves sensitivity (from 61% to 96%) and specificity (from 5/6 to 0/6 false positives) in the detection of information transfer respectively when instantaneous effect are causally meaningful and non-meaningful. Then, it is evaluated on examples of cardiovascular and neurological time series, supporting the feasibility of the proposed framework for the investigation of physiological mechanisms.

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Respiration‐synchronous fluctuations in stroke volume, heart rate and arterial pressure in humans.

Cited by 201 publications

References 33 publications

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

Indirect measures of human vagal withdrawal during head-up tilt with and without a respiratory acidosis

Compensated Transfer Entropy as a Tool for Reliably Estimating Information Transfer in Physiological Time Series

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