Noninvasive Monitoring of Dynamic Cerebrovascular Autoregulation and ‘Optimal Blood Pressure’ in Normal Adult Subjects

Pham, Paul; Bindra, Jessica; Åneman, Anders; Chuan, Alwin; Worthington, John; Jaeger, M.

doi:10.1007/s12028-018-0600-2

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…Patient‐specific CA monitoring tools have the potential to determine individualized optimal blood pressure treatment strategies to improve patient outcomes across many clinical fields. 40 , 41 …”

Section: Discussionmentioning

confidence: 99%

Differential Hemodynamic Response of Pial Arterioles Contributes to a Quadriphasic Cerebral Autoregulation Physiology

Klein

Sloovere

Meyfroidt³

et al. 2022

JAHA

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Background Cerebrovascular autoregulation (CA) regulates cerebral vascular tone to maintain near‐constant cerebral blood flow during fluctuations in cerebral perfusion pressure (CPP). Preclinical and clinical research has challenged the classic triphasic pressure‐flow relationship, leaving the normal pressure‐flow relationship unclear. Methods and Results We used in vivo imaging of the hemodynamic response in pial arterioles to study CA in a porcine closed cranial window model during nonpharmacological blood pressure manipulation. Red blood cell flux was determined in 52 pial arterioles during 10 hypotension and 10 hypertension experiments to describe the pressure‐flow relationship. We found a quadriphasic pressure‐flow relationship with 4 distinct physiological phases. Smaller arterioles demonstrated greater vasodilation during low CPP when compared with large arterioles ( P <0.01), whereas vasoconstrictive capacity during high CPP was not significantly different between arterioles ( P >0.9). The upper limit of CA was defined by 2 breakpoints. Increases in CPP lead to a point of maximal vasoconstriction of the smallest pial arterioles (upper limit of autoregulation [ULA] 1). Beyond ULA1, only larger arterioles maintain a limited additional vasoconstrictive capacity, extending the buffer for high CPP. Beyond ULA2, vasoconstrictive capacity is exhausted, and all pial arterioles passively dilate. There was substantial intersubject variability, with ranges of 29.2, 47.3, and 50.9 mm Hg for the lower limit, ULA1, and ULA2, respectively. Conclusions We provide new insights into the quadriphasic physiology of CA, differentiating between truly active CA and an extended capacity to buffer increased CPP with progressive failure of CA. In this experimental model, the limits of CA widely varied between subjects.

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Section: Discussionmentioning

confidence: 99%

Differential Hemodynamic Response of Pial Arterioles Contributes to a Quadriphasic Cerebral Autoregulation Physiology

Klein

Sloovere

Meyfroidt³

et al. 2022

JAHA

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“…It was found that the correlations between ABR sensitivity and BP estimation error at low frequency were higher than those at high frequency. This might be an important factor influencing the usability of PTT-based methods in cerebral autoregulation assessment, since the low-frequency changes are the ones of interest (Pham et al 2019).…”

Section: Importance Of Bp and Ptt Measurements In Brain Researchmentioning

confidence: 99%

“…Impairments in autoregulation are associated with worse functional outcomes in both of these patient groups (Freeman et al 2008, Reinhard et al 2012, Castro et al 2017, Rivera-Lara et al 2017. Thus, cerebral autoregulation assessment is important in patient care settings and is commonly done by monitoring slow fluctuations of arterial BP (ABP) (Pham et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Blood pressure wave propagation—a multisensor setup for cerebral autoregulation studies

et al. 2021

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Objective. Cerebral autoregulation is critically important to maintain proper brain perfusion and supply the brain with oxygenated blood. Non-invasive measures of blood pressure (BP) are critical in assessing cerebral autoregulation. Wave propagation velocity may be a useful technique to estimate BP but the effect of the location of the sensors on the readings has not been thoroughly examined. In this paper, we were interested in studying whether the propagation velocity of a pressure wave in the direction from the heart to the brain may differ compared with propagation from the heart to the periphery, as well as across different physiological tasks and/or health conditions. Using non-invasive sensors simultaneously placed at different locations of the human body allows for the study of how the propagation velocity of the pressure wave, based on pulse transit time (PTT), varies across different directions. Approach. We present a multi-sensor BP wave propagation measurement setup intended for cerebral autoregulation studies. The presented sensor setup consists of three sensors, one placed on each of the neck, chest and finger, allowing simultaneous measurement of changes in BP propagation velocity towards the brain and to the periphery. We show how commonly tested physiological tasks affect the relative changes of PTT and correlations with BP. Main results. We observed that during maximal blow, valsalva and breath hold breathing tasks, the relative changes of PTT were higher when PTT was measured in the direction from the heart to the brain than from the heart to the peripherals. In contrast, during a deep breathing task, the relative change in PTT from the heart to the brain was lower. In addition, we present a short literature review of the PTT methods used in brain research. Significance. These preliminary data suggest that the physiological task and direction of PTT measurement may affect relative PTT changes. The presented three-sensor setup provides an easy and neuroimaging compatible method for cerebral autoregulation studies by allowing measurement of BP wave propagation velocity towards the brain versus towards the periphery.

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“…The absolute regional cerebral oxygen saturation value (rSO 2 ) in itself does not appear to be associated with outcome in PCA patients [10]. Instead, observational studies have shown that NIRS enables identification of the limits of cerebral autoregulation and identification of an optimal MAP for each patient [11][12][13] using a cerebral oximetry index (COx). This optimal MAP may be different from the "one size fits all" haemodynamic targets recommended by guidelines and may be much higher in many patients [11,14,15].…”

Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 99%

Near-infrared spectroscopy “under pressure” as a post-cardiac arrest monitoring technique of cerebral autoregulation

Skrifvars

Åneman

2020

Resuscitation

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Noninvasive Monitoring of Dynamic Cerebrovascular Autoregulation and ‘Optimal Blood Pressure’ in Normal Adult Subjects

Abstract: TOx in healthy volunteers on average displays intact autoregulation and ABP close to ABP. However, some subjects have possible autoregulatory dysfunction or a significant deviation of ABP from ABP, which may confer a susceptibility to neurological injury.

Cited by 7 publications

References 19 publications

Differential Hemodynamic Response of Pial Arterioles Contributes to a Quadriphasic Cerebral Autoregulation Physiology

Differential Hemodynamic Response of Pial Arterioles Contributes to a Quadriphasic Cerebral Autoregulation Physiology

Blood pressure wave propagation—a multisensor setup for cerebral autoregulation studies

Near-infrared spectroscopy “under pressure” as a post-cardiac arrest monitoring technique of cerebral autoregulation

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