Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow

Abeelen, Aisha S.S. Meel-van den; Beek, Arenda H.E.A. van; Slump, Cornelis H.; Panerai, Ronney B.; Claassen, Jurgen A.H.R.

doi:10.1016/j.medengphy.2014.02.001

Cited by 54 publications

(59 citation statements)

References 134 publications

(72 reference statements)

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“…Using standard procedures (Panerai et al 1998a, Zhang et al 1998, Panerai et al 1998b, Gommer et al 2010, Meel-van den Abeelen et al 2014b, Katsogridakis et al 2013, the coherence function, amplitude (gain) and phase frequency responses were calculated from the auto-and cross-spectra. The coherence function was visually inspected and TFA estimates were only accepted if the coherence was above 0.5 in the frequency range 0.15-0.25Hz where the BP-CBFV relationship can be assumed to be linear (Claassen et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Firstly, most studies have enrolled a relatively small number of subjects which sets limits on the statistical reliability of results. Secondly, it has been nearly impossible to pool together different studies to increase the statistical power of estimates due to the considerable diversity of methods used by different centres (Meel-van den Abeelen et al 2014b). The recent proposal to improve standardisation of these methods (Claassen et al 2016, Meel-van den Abeelen et al 2014a, should bear fruit in the near future, but in the meantime alternative approaches are needed.…”

Section: Introductionmentioning

confidence: 99%

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The Leicester cerebral haemodynamics database: normative values and the influence of age and sex

et al. 2016

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Normative values of physiological parameters hold significance in modern day clinical decision-making. Lack of such normative values has been a major hurdle in the translation of research into clinical practice. A large database containing uniform recordings was constructed to allow more robust estimates of normative ranges and also assess the influence of age and sex.Doppler recordings were performed on healthy volunteers in the same laboratory, using similar protocols and equipment. Beat-to-beat blood pressure, heart-rate, electrocardiogram, and end-tidal CO2 were measured continuously. Bilateral insonation of the middle cerebral arteries (MCAs) was performed using TCD following a 15-minute stabilisation, and a 5-minute baseline recording.Good quality Doppler recordings for both MCAs were obtained in 129 participants (57 female) with a median age of 57 years (range 20-82). Age was found to influence baseline haemodynamic and transfer function analysis parameters. Cerebral blood flow velocity and critical closing pressure were the only sex-related differences found, which was significantly higher in females than males.Normative values for cerebral haemodynamic parameters have been defined in a large, healthy population. Such age/sex-defined normal values can be used to reduce the burden of collecting additional control data in future studies, as well as to identify disease-associated changes. Key wordsCerebral haemodynamics, cerebral autoregulation, ageing, sex differences, cerebral blood

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Leicester cerebral haemodynamics database: normative values and the influence of age and sex

et al. 2016

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“…In the time domain, the cerebrovascular adjustments to a change in blood pressure is considered as a function of time, and may be quantitated by a moving correlation coefficient, which is continually calculated between a CBF estimate and MAP over specified time intervals [5][6][7][8]. In the frequency domain, the ability of the cerebrovasculature to respond to blood pressure fluctuations that occur at different frequencies is addressed by TFA [4], which is a classical and currently the most widely used approach for investigating dCA in humans [3,32]. Despite fundamentally different methodologies, these previous studies all report that higher PaCO 2 levels are associated with progressively prolonged response times of the cerebrovasculature [4,7,8].…”

Section: Discussionmentioning

confidence: 99%

“…We examined dCA by transfer function analysis (TFA) of spontaneous oscillations in MAP (as a surrogate for CPP) and MCAv (as a surrogate for CBF) [3,32]. Invasive arterial blood pressure and TCD-waveforms were recorded over a 20-min steady-state period and re-sampled at 10 Hz for spectral analysis.…”

Section: Dynamic Cerebral Autoregulationmentioning

confidence: 99%

“…MCAv that is linearly explained by the spectral power of MAP. We interpreted a decrease in gain and/or an increased phase as evidence for enhanced dCA, and vice versa [3,32]. To ensure valid gain and phase estimates, the contribution of an individual TFA estimate toward the band average was weighted according to the coherence function, so that the individual harmonics where the corresponding coherence was below 0.40 were excluded.…”

Section: Dynamic Cerebral Autoregulationmentioning

confidence: 99%

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Effects of short-term mechanical hyperventilation on cerebral blood flow and dynamic cerebral autoregulation in critically ill patients with sepsis

Berg

Plovsing

2016

Scandinavian Journal of Clinical and Laboratory Investigation

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In sepsis, higher PaCO2 levels are associated with impaired dynamic cerebral autoregulation (dCA), which may expose the brain to hypo- and hyperperfusion during acute fluctuations in blood pressure. We hypothesised that short-term mechanical hyperventilation would dCA in critically ill patients with sepsis. Seven mechanically ventilated septic patients were included. We assessed dCA before and after 30 min of mechanical hyperventilation. Transfer function analysis of spontaneous oscillations in transcranial Doppler-based middle cerebral artery blood flow velocity (MCAv) and invasive mean arterial blood pressure was used to assess dCA. Mechanical enhance hyperventilation reduced the median PaCO2 from 5.3 (IQR, 5.0-6.5) to 4.7 (IQR, 4.2-5.1) kPa (p < 0.05). This was associated with a reduction in the median MCAv from 57 (IQR, 33-68) to 32 (IQR, 21-40) cm sec(-1) (p < 0.05). Apart from a small increase in gain in the low frequency range (2.32 [IQR 1.80-2.41] vs. 2.59 (2.40-4.64) cm mmHg(-1) sec(-1); p < 0.05), this was not associated with any enhancement in dCA. In conclusion, cerebral CO2 vasoreactivity was found to be preserved in septic patients; nevertheless, and in contrast to our working hypothesis, short-term mechanical hyperventilation did not enhance dCA.

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Time‐evolving coupling functions for evaluating the interaction between cerebral oxyhemoglobin and arterial blood pressure with hypertension

Zhang

Huo

et al. 2021

Medical Physics

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Purposes This study aimed to investigate the network coupling between arterial blood pressure (ABP) and changes in cerebral oxyhemoglobin concentration (Δ [O2Hb]/Δ [HHb]) oscillations based on dynamical Bayesian inference in hypertensive subjects. Methods Two groups of subjects, consisting of 30 healthy (Group Control, 55.1 ± 10.6 y), and 32 hypertensive individuals (Group AH, 58.9 ± 8.7 y), participated in this study. A functional near‐infrared spectroscopy system was used to measure the Δ [O2Hb] and Δ [HHb] signals in the bilateral prefrontal cortex (LPFC/RPFC), motor cortex (LMC/RMC), and occipital lobe (LOL/ROL) during the resting state (12 min). Based on continuous wavelet analysis and coupling functions, the directed coupling strength (CS) between ABP and cerebral hemoglobin was identified and analyzed in three frequency intervals (I: 0.6–2 Hz, II: 0.145–0.6 Hz, III: 0.01–0.08 Hz). The Pearson correlations between the CS and blood pressure parameters were calculated in the hypertension group. Results In interval I, Group AH exhibited a significantly higher CS for the coupling from ABP to Δ [O2Hb] than Group Control in LMC, RMC, LOL, and ROL. In interval III, the CS from ABP to Δ [O2Hb] in LPFC, RPFC, LMC, RMC, LOL, and ROL was significantly higher in Group AH than in Group Control. For the patients with hypertension, diastolic blood pressure was negatively and pulse pressure was positively related to the CS from ABP to Δ [O2Hb] oscillations in interval III. Conclusions The higher CS from ABP to Δ [O2Hb] in interval I indicated that the components of cardiac activity in cerebral hemoglobin oscillations were more directly responsive to the changes in systematic ABP in patients with hypertension than in healthy subjects. Meanwhile, the higher CS from ABP to Δ [O2Hb] in interval III indicated that the cerebral hemoglobin oscillations were susceptible to changes in blood pressure in hypertensive subjects. The results may serve as evidence of impairment in cerebral autoregulation after hypertension. The Pearson correlation results showed that diastolic blood pressure and pulse pressure might be regarded as predictors of cerebral autoregulation function in patients with hypertension, and may be useful for hypertension stratification. This study provides novel insights into the interaction mechanism between ABP and cerebral hemodynamics and could help in the development of new assessment techniques for cerebral vascular disease.

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Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow

Cited by 54 publications

References 134 publications

The Leicester cerebral haemodynamics database: normative values and the influence of age and sex

The Leicester cerebral haemodynamics database: normative values and the influence of age and sex

Effects of short-term mechanical hyperventilation on cerebral blood flow and dynamic cerebral autoregulation in critically ill patients with sepsis

Time‐evolving coupling functions for evaluating the interaction between cerebral oxyhemoglobin and arterial blood pressure with hypertension

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