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Roy S, Lam MY, Panerai RB, Robinson TG, Minhas JS. Blood pressure variability at rest and during pressor challenges in patients with acute ischemic stroke. Blood Press Monit 2024:00126097-990000000-00111. [PMID: 38841869 DOI: 10.1097/mbp.0000000000000710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
INTRODUCTION Patients with acute ischemic stroke (AIS) have elevated blood pressure (BP) variability (BPV) and reduced baroreflex sensitivity (BRS) at rest for several days after initial stroke symptoms. We aimed to assess BPV and BRS in AIS patients during pressor challenge maneuvers in the acute and subacute phases of stroke. Pressor challenge maneuvers simulate day-to-day activities and can predict the quality of life. METHODS Continuous beat-to-beat BP and ECG in 15 AIS patients (mean age 69 ± 7.5 years) and 15 healthy controls (57 ± 16 years) were recorded at rest and during a 5-min rapid head positioning (RHP) paradigm. Patients were assessed within 24 h (acute phase) and 7 days (subacute phase) of stroke onset. Low frequency (LF) SBP power (measure of BPV), LF-α, and combined α-index (measure of BRS) were calculated from the recordings. RESULTS In the acute phase, at rest, LF-SBP power was higher (P = 0.024) and α-index was lower (P = 0.006) in AIS patients than in healthy controls. There was no change in LF-SBP during RHP in the patients but in healthy controls, it increased significantly (P = 0.018). In the subacute phase, at rest, the alpha-index increased (P = 0.037) and LF-SBP decreased (P = 0.029) significantly in the AIS patients, however, there was still no rise in the LF-SBP power during RHP (P = 0.240). CONCLUSION AIS patients have a high resting BPV. High resting BPV may be responsible for blunted BPV responses during pressor challenge maneuvers such as RHP, suggesting ongoing autonomic dysfunction and compromised quality of life.
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Affiliation(s)
- Sankanika Roy
- Department of Cardiovascular Sciences, University of Leicester
| | - Man Y Lam
- Department of Cardiovascular Sciences, University of Leicester
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
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Burma JS, Roy MA, Kennedy CM, Labrecque L, Brassard P, Smirl JD. A systematic review, meta-analysis, and meta-regression amalgamating the driven approaches used to quantify dynamic cerebral autoregulation. J Cereb Blood Flow Metab 2024:271678X241235878. [PMID: 38635887 DOI: 10.1177/0271678x241235878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Numerous driven techniques have been utilized to assess dynamic cerebral autoregulation (dCA) in healthy and clinical populations. The current review aimed to amalgamate this literature and provide recommendations to create greater standardization for future research. The PubMed database was searched with inclusion criteria consisting of original research articles using driven dCA assessments in humans. Risk of bias were completed using Scottish Intercollegiate Guidelines Network and Methodological Index for Non-Randomized Studies. Meta-analyses were conducted for coherence, phase, and gain metrics at 0.05 and 0.10 Hz using deep-breathing, oscillatory lower body negative pressure (OLBNP), sit-to-stand maneuvers, and squat-stand maneuvers. A total of 113 studies were included, with 40 of these incorporating clinical populations. A total of 4126 participants were identified, with younger adults (18-40 years) being the most studied population. The most common techniques were squat-stands (n = 43), deep-breathing (n = 25), OLBNP (n = 20), and sit-to-stands (n = 16). Pooled coherence point estimates were: OLBNP 0.70 (95%CI:0.59-0.82), sit-to-stands 0.87 (95%CI:0.79-0.95), and squat-stands 0.98 (95%CI:0.98-0.99) at 0.05 Hz; and deep-breathing 0.90 (95%CI:0.81-0.99); OLBNP 0.67 (95%CI:0.44-0.90); and squat-stands 0.99 (95%CI:0.99-0.99) at 0.10 Hz. This review summarizes clinical findings, discusses the pros/cons of the 11 unique driven techniques included, and provides recommendations for future investigations into the unique physiological intricacies of dCA.
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Affiliation(s)
- Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Canada
| | - Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Courtney M Kennedy
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Canada
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Brassard P, Roy MA, Burma JS, Labrecque L, Smirl JD. Quantification of dynamic cerebral autoregulation: welcome to the jungle! Clin Auton Res 2023; 33:791-810. [PMID: 37758907 DOI: 10.1007/s10286-023-00986-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023]
Abstract
PURPOSE Patients with dysautonomia often experience symptoms such as dizziness, syncope, blurred vision and brain fog. Dynamic cerebral autoregulation, or the ability of the cerebrovasculature to react to transient changes in arterial blood pressure, could be associated with these symptoms. METHODS In this narrative review, we go beyond the classical view of cerebral autoregulation to discuss dynamic cerebral autoregulation, focusing on recent advances pitfalls and future directions. RESULTS Following some historical background, this narrative review provides a brief overview of the concept of cerebral autoregulation, with a focus on the quantification of dynamic cerebral autoregulation. We then discuss the main protocols and analytical approaches to assess dynamic cerebral autoregulation, including recent advances and important issues which need to be tackled. CONCLUSION The researcher or clinician new to this field needs an adequate comprehension of the toolbox they have to adequately assess, and interpret, the complex relationship between arterial blood pressure and cerebral blood flow in healthy individuals and clinical populations, including patients with autonomic disorders.
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Affiliation(s)
- Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada.
| | - Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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Zhou R, Li J, Wang R, Chen Z, Zhou F. The neurovascular unit in healthy and injured spinal cord. J Cereb Blood Flow Metab 2023; 43:1437-1455. [PMID: 37190756 PMCID: PMC10414016 DOI: 10.1177/0271678x231172008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 02/09/2023] [Accepted: 03/24/2023] [Indexed: 05/17/2023]
Abstract
The neurovascular unit (NVU) reflects the close temporal and spatial link between neurons and blood vessels. However, the understanding of the NVU in the spinal cord is far from clear and largely based on generalized knowledge obtained from the brain. Herein, we review the present knowledge of the NVU and highlight candidate approaches to investigate the NVU, particularly focusing on the spinal cord. Several unique features maintain the highly regulated microenvironment in the NVU. Autoregulation and neurovascular coupling ensure regional blood flow meets the metabolic demand according to the blood supply or local neural activation. The blood-central nervous system barrier partitions the circulating blood from neural parenchyma and facilitates the selective exchange of substances. Furthermore, we discuss spinal cord injury (SCI) as a common injury from the perspective of NVU dysfunction. Hopefully, this review will help expand the understanding of the NVU in the spinal cord and inspire new insights into SCI.
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Affiliation(s)
- Rubing Zhou
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Junzhao Li
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Ruideng Wang
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
| | - Zhengyang Chen
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
| | - Fang Zhou
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
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Urner TM, Cowdrick KR, Brothers RO, Boodooram T, Zhao H, Goyal V, Sathialingam E, Quadri A, Turrentine K, Akbar MM, Triplett SE, Bai S, Buckley EM. Normative cerebral microvascular blood flow waveform morphology assessed with diffuse correlation spectroscopy. BIOMEDICAL OPTICS EXPRESS 2023; 14:3635-3653. [PMID: 37497521 PMCID: PMC10368026 DOI: 10.1364/boe.489760] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/05/2023] [Accepted: 05/20/2023] [Indexed: 07/28/2023]
Abstract
Microvascular cerebral blood flow exhibits pulsatility at the cardiac frequency that carries valuable information about cerebrovascular health. This study used diffuse correlation spectroscopy to quantify normative features of these waveforms in a cohort of thirty healthy adults. We demonstrate they are sensitive to changes in vascular tone, as indicated by pronounced morphological changes with hypercapnia. Further, we observe significant sex-based differences in waveform morphology, with females exhibiting higher flow, greater area-under-the-curve, and lower pulsatility. Finally, we quantify normative values for cerebral critical closing pressure, i.e., the minimum pressure required to maintain flow in a given vascular region.
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Affiliation(s)
- Tara M Urner
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Kyle R Cowdrick
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Rowan O Brothers
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Tisha Boodooram
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Hongting Zhao
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Vidisha Goyal
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Eashani Sathialingam
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Ayesha Quadri
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Katherine Turrentine
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Mariam M Akbar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Sydney E Triplett
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Shasha Bai
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
| | - Erin M Buckley
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
- Children's Research Scholar, Children's Healthcare of Atlanta, 2015 Uppergate Dr., Atlanta, GA 30322, USA
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6
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Hagan B, Mujumdar R, Sahoo JP, Das A, Dutta A. Technical feasibility of multimodal imaging in neonatal hypoxic-ischemic encephalopathy from an ovine model to a human case series. Front Pediatr 2023; 11:1072663. [PMID: 37425273 PMCID: PMC10323750 DOI: 10.3389/fped.2023.1072663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 06/02/2023] [Indexed: 07/11/2023] Open
Abstract
Hypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia occurs when the brain does not receive enough oxygen and blood. A surrogate marker for "intact survival" is necessary for the successful management of HIE. The severity of HIE can be classified based on clinical presentation, including the presence of seizures, using a clinical classification scale called Sarnat staging; however, Sarnat staging is subjective, and the score changes over time. Furthermore, seizures are difficult to detect clinically and are associated with a poor prognosis. Therefore, a tool for continuous monitoring on the cot side is necessary, for example, an electroencephalogram (EEG) that noninvasively measures the electrical activity of the brain from the scalp. Then, multimodal brain imaging, when combined with functional near-infrared spectroscopy (fNIRS), can capture the neurovascular coupling (NVC) status. In this study, we first tested the feasibility of a low-cost EEG-fNIRS imaging system to differentiate between normal, hypoxic, and ictal states in a perinatal ovine hypoxia model. Here, the objective was to evaluate a portable cot-side device and perform autoregressive with extra input (ARX) modeling to capture the perinatal ovine brain states during a simulated HIE injury. So, ARX parameters were tested with a linear classifier using a single differential channel EEG, with varying states of tissue oxygenation detected using fNIRS, to label simulated HIE states in the ovine model. Then, we showed the technical feasibility of the low-cost EEG-fNIRS device and ARX modeling with support vector machine classification for a human HIE case series with and without sepsis. The classifier trained with the ovine hypoxia data labeled ten severe HIE human cases (with and without sepsis) as the "hypoxia" group and the four moderate HIE human cases as the "control" group. Furthermore, we showed the feasibility of experimental modal analysis (EMA) based on the ARX model to investigate the NVC dynamics using EEG-fNIRS joint-imaging data that differentiated six severe HIE human cases without sepsis from four severe HIE human cases with sepsis. In conclusion, our study showed the technical feasibility of EEG-fNIRS imaging, ARX modeling of NVC for HIE classification, and EMA that may provide a biomarker of sepsis effects on the NVC in HIE.
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Affiliation(s)
- Brian Hagan
- School of Engineering, University of Lincoln, Lincoln, United Kingdom
| | - Radhika Mujumdar
- School of Engineering, University of Lincoln, Lincoln, United Kingdom
| | - Jagdish P. Sahoo
- Department of Neonatology, IMS & SUM Hospital, Bhubaneswar, India
| | - Abhijit Das
- Department of Neurology, The Lancashire Teaching Hospitals NHS Foundation Trust, Preston, United Kingdom
| | - Anirban Dutta
- School of Engineering, University of Lincoln, Lincoln, United Kingdom
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Whitaker AA, Vidoni ED, Montgomery RN, Carter K, Struckle K, Billinger SA. Force sensor reduced measurement error compared with verbal command during sit-to-stand assessment of cerebral autoregulation. Physiol Rep 2023; 11:e15750. [PMID: 37308311 PMCID: PMC10260377 DOI: 10.14814/phy2.15750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/12/2023] [Accepted: 05/28/2023] [Indexed: 06/14/2023] Open
Abstract
Current methods estimate the time delay (TD) before the onset of dynamic cerebral autoregulation (dCA) from verbal command to stand. A force sensor used during a sit-to-stand dCA measure provides an objective moment an individual stands (arise-and-off, AO). We hypothesized that the detection of AO would improve the accuracy of TD compared with estimation. We measured middle cerebral artery blood velocity (MCAv) and mean arterial pressure (MAP) for 60 s sitting followed by 2-min standing, three times separated by 20 min. TD was calculated as the time from: (1) verbal command and (2) AO, until an increase in cerebrovascular conductance index (CVCi = MCAv/MAP). Sixty-five participants were enrolled: young adults (n = 25), older adults (n = 20), and individuals post-stroke (n = 20). The TD calculated from AO (x ¯ $$ \overline{x} $$ = 2.98 ± 1.64 s) was shorter than TD estimated from verbal command (x ¯ $$ \overline{x} $$ = 3.35 ± 1.72 s, η2 = 0.49, p < 0.001), improving measurement error by ~17%. TD measurement error was not related to age or stroke. Therefore, the force sensor provided an objective method to improve the calculation of TD compared with current methods. Our data support using a force sensor during sit-to-stand dCA measures in adults across the lifespan and post-stroke.
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Affiliation(s)
- Alicen A. Whitaker
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Physical Medicine and RehabilitationMedical College of WisconsinMilwaukeeWisconsinUSA
- Cardiovascular CenterMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Eric D. Vidoni
- University of Kansas Alzheimer's Disease Research CenterFairwayKansasUSA
- Department of NeurologyUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Robert N. Montgomery
- Department of Biostatistics & Data ScienceUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Kailee Carter
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Katelyn Struckle
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Sandra A. Billinger
- University of Kansas Alzheimer's Disease Research CenterFairwayKansasUSA
- Department of NeurologyUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Physical Medicine and RehabilitationUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Cell Biology and PhysiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
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Dynamic cerebral autoregulation during step-wise increases in blood pressure during anaesthesia: A nonrandomised interventional trial. Eur J Anaesthesiol 2023; 40:407-417. [PMID: 36655712 PMCID: PMC10155696 DOI: 10.1097/eja.0000000000001798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Classically, cerebral autoregulation (CA) entails cerebral blood flow (CBF) remaining constant by cerebrovascular tone adapting to fluctuations in mean arterial pressure (MAP) between ∼60 and ∼150 mmHg. However, this is not an on-off mechanism; previous work has suggested that vasomotor tone is proportionally related to CA function. During propofol-based anaesthesia, there is cerebrovascular vasoconstriction, and static CA remains intact. Sevoflurane-based anaesthesia induces cerebral vasodilation and attenuates CA dose-dependently. It is unclear how this translates to dynamic CA across a range of blood pressures in the autoregulatory range. OBJECTIVE The aim of this study was to quantify the effect of step-wise increases in MAP between 60 and 100 mmHg, using phenylephrine, on dynamic CA during propofol- and sevoflurane-based anaesthesia. DESIGN A nonrandomised interventional trial. SETTING Single centre enrolment started on 11 January 2019 and ended on 23 September 2019. PATIENTS We studied American Society of Anesthesiologists (ASA) I/II patients undergoing noncardiothoracic, nonneurosurgical and nonlaparoscopic surgery under general anaesthesia. INTERVENTION In this study, cerebrovascular tone was manipulated in the autoregulatory range by increasing MAP step-wise using phenylephrine in patients receiving either propofol- or sevoflurane-based anaesthesia. MAP and mean middle cerebral artery blood velocity (MCA Vmean ) were measured in ASA I and II patients, anaesthetised with either propofol ( n = 26) or sevoflurane ( n = 28), during 10 mmHg step-wise increments of MAP between 60 and 100 mmHg. Static CA was determined by plotting 2-min averaged MCA Vmean versus MAP. Dynamic CA was determined using transfer function analysis and expressed as the phase lead (°) between MAP and MCA Vmean oscillations, created with positive pressure ventilation with a frequency of 6 min -1 . MAIN OUTCOMES The primary outcome of this study was the response of dynamic CA during step-wise increases in MAP during propofol- and sevoflurane-based anaesthesia. RESULTS MAP levels achieved per step-wise increments were comparable between anaesthesia regiment (63 ± 3, 72 ± 2, 80 ± 2, 90 ± 2, 100 ± 3 mmHg, and 61 ± 4, 71 ± 2, 80 ± 2, 89 ± 2, 98 ± 4 mmHg for propofol and sevoflurane, respectively). MCA Vmean increased more during step-wise MAP increments for sevoflurane compared to propofol ( P ≤0.001). Dynamic CA improved during propofol (0.73° mmHg -1 , 95% CI 0.51 to 0.95; P ≤ 0.001)) and less pronounced during sevoflurane-based anaesthesia (0.21° mmHg -1 (95% CI 0.01 to 0.42, P = 0.04). CONCLUSIONS During general anaesthesia, dynamic CA is dependent on MAP, also within the autoregulatory range. This phenomenon was more pronounced during propofol anaesthesia than during sevoflurane. TRIAL REGISTRATION NCT03816072 ( https://clinicaltrials.gov/ct2/show/NCT03816072 ).
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Rodrigues GD, Nobrega ACLD, Soares PPDS. Respiratory training in older women: Unravelling central and peripheral hemodynamic slow oscillatory patterns. Exp Gerontol 2023; 172:112058. [PMID: 36529363 DOI: 10.1016/j.exger.2022.112058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 11/28/2022] [Accepted: 12/09/2022] [Indexed: 12/16/2022]
Abstract
We hypothesized that inspiratory muscle training (IMT) increases the respiratory-induced low-frequency oscillations of mean blood pressure (MBP) and middle cerebral artery blood velocity (MCAv), upregulating cerebrovascular function in older women. Firstly, participants were recorded with free-breathing (FB) and then breathed at a slow-paced frequency (0.1 Hz; DB test) supported by sonorous metronome feedback. Blood pressure was recorded using finger photoplethysmography method, ECG, and respiration using a thoracic belt. To obtain the MCAv a transcranial ultrasound Doppler device was used. Spectral analysis of MBP, R-R intervals, and mean MCAv time series was obtained by an autoregressive model. The transfer function analysis (TFA) was employed to calculate the coherence, gain, and phase. After that, older women were enrolled in a randomized controlled protocol, the IMT-group (n = 8; 64 ± 3 years-old) performed IMT at 50 % of maximal inspiratory pressure (MIP), and Sham-group, a placebo training at 5 % MIP (Sham-group; n = 6; 66 ± 3 years-old). Participants breathed against an inspiratory resistance twice a day for 4-weeks. DB test is repeated post IMT and Sham interventions. IMT-group, compared to Sham-group, augmented tidal volume responses to DB (Sham-group 1.03 ± 0.41 vs. IMT-group 1.61 ± 0.56 L; p = 0.04), increased respiratory-induced MBP (Sham-group 26.37 ± 4.46 vs. IMT-group 48.21 ± 3.15 mmHg2; p = 0.04) and MCAv (Sham-group 14.16 ± 31.26 vs. IMT-group 79.90 ± 21.76 cm2s-2; p = 0.03) slow oscillations, and reduced TFA gain (Sham-group 2.46 ± 1.32 vs. IMT-group 1.78 ± 1.30 cm·s-1.mmHg-1; p = 0.01). Our findings suggest that IMT increases the respiratory-induced oscillations in MBP and MCAv signals and reduces TFA gain. It seems compatible with an improved dynamic cerebrovascular regulation following IMT in older women.
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Affiliation(s)
- Gabriel Dias Rodrigues
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, RJ, Brazil; INCT (In)Activity and Exercise, CNPq, National Institute for Science and Technology, Niterói, RJ, Brazil; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.
| | - Antonio Claudio Lucas da Nobrega
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, RJ, Brazil; INCT (In)Activity and Exercise, CNPq, National Institute for Science and Technology, Niterói, RJ, Brazil
| | - Pedro Paulo da Silva Soares
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, RJ, Brazil; INCT (In)Activity and Exercise, CNPq, National Institute for Science and Technology, Niterói, RJ, Brazil
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10
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Panerai RB, Brassard P, Burma JS, Castro P, Claassen JA, van Lieshout JJ, Liu J, Lucas SJ, Minhas JS, Mitsis GD, Nogueira RC, Ogoh S, Payne SJ, Rickards CA, Robertson AD, Rodrigues GD, Smirl JD, Simpson DM. Transfer function analysis of dynamic cerebral autoregulation: A CARNet white paper 2022 update. J Cereb Blood Flow Metab 2023; 43:3-25. [PMID: 35962478 PMCID: PMC9875346 DOI: 10.1177/0271678x221119760] [Citation(s) in RCA: 42] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response to changes in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is often described as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) can be assessed using multiple techniques, with transfer function analysis (TFA) being the most common. A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet) that is focused on CA strove to improve TFA standardization by way of introducing data acquisition, analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvement and refinement of the original recommendations, as well as for the inclusion of new guidelines to reflect recent advances in the field. This second edition of the white paper contains more robust, evidence-based recommendations, which have been expanded to address current streams of inquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods, estimating alternative dCA metrics, and incorporating dCA quantification into clinical trials. Implementation of these new and revised recommendations is important to improve the reliability and reproducibility of dCA studies, and to facilitate inter-institutional collaboration and the comparison of results between studies.
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Affiliation(s)
- Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, and Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Joel S Burma
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Pedro Castro
- Department of Neurology, Centro Hospitalar Universitário de São João, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Jurgen Ahr Claassen
- Department of Geriatric Medicine and Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Johannes J van Lieshout
- Department of Internal Medicine, Amsterdam, UMC, The Netherlands and Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, UK
| | - Jia Liu
- Institute of Advanced Computing and Digital Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen University Town, Shenzhen, China
| | - Samuel Je Lucas
- School of Sport, Exercise and Rehabilitation Sciences and Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Georgios D Mitsis
- Department of Bioengineering, McGill University, Montreal, Québec, QC, Canada
| | - Ricardo C Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Stephen J Payne
- Institute of Applied Mechanics, National Taiwan University, Taipei
| | - Caroline A Rickards
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Andrew D Robertson
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel D Rodrigues
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Jonathan D Smirl
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - David M Simpson
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
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11
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Quispe-Cornejo AA, Crippa IA, Bakos P, Dominguez-Faure A, Creteur J, Taccone FS. Correlation between heart rate variability and cerebral autoregulation in septic patients. Auton Neurosci 2023; 244:103051. [PMID: 36493585 DOI: 10.1016/j.autneu.2022.103051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 10/20/2022] [Accepted: 11/09/2022] [Indexed: 11/19/2022]
Abstract
BACKGROUND Heart rate variability (HRV) may provide an estimation of the autonomous nervous system (ANS) integrity in critically ill patients. Disturbances of cerebral autoregulation (CAR) may share common pathways of ANS dysfunction. AIM To explore whether changes in HRV and CAR index correlate in critically ill septic patients. METHODS Prospectively collected data on septic adult (> 18 years) patients admitted into a mixed Intensive Care between February 2016 and August 2019 with a recorded transcranial doppler CAR assessment. CAR was assessed calculating the Pearson's correlation coefficient (i.e. mean flow index, Mxa) between the left middle cerebral artery flow velocity (FV), insonated with a 2-MHz probe, and invasive blood pressure (BP) signal, both recorded simultaneously through a Doppler Box (DWL, Germany). MATLAB software was used for CAR assessment using a validated script; a Mxa >0.3 was considered as impaired CAR. HRV was assessed during the same time period using a specific software (Kubios HRV 3.2.0) and analyzed in both time-domain and frequency domain methods. Correlation between HRV-derived variables and Mxa were assessed using the Spearman's coefficient. RESULTS A total of 141 septic patients was studied; median Mxa was 0.35 [0.13-0.60], with 77 (54.6 %) patients having an impaired CAR. Mxa had a significant although weak correlation with HRV time domain (SDNN, r = 0.17, p = 0.04; RMSSD, r = 0.18, p = 0.03; NN50, r = 0.23, p = 0.006; pNN50, r = 0.23, p = 0.007), frequency domain (FFT-HF, r = 0.21; p = 0.01; AR-HF, r = 0.19; p = 0.02), and non-linear domain (SD1, r = 0.18, p = 0.03) parameters. Impaired CAR patients had also all of these HRV-derived parameters higher than those with intact CAR. CONCLUSIONS In this exploratory study, a potential association of ANS dysfunction and impaired CAR during sepsis was observed.
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Affiliation(s)
- Armin Alvaro Quispe-Cornejo
- Department of Intensive Care, Erasme University Hospital, Brussels, Belgium; Instituto Académico Científico Quispe-Cornejo, INAAQC, La Paz, Bolivia.
| | | | - Péter Bakos
- Department of Intensive Care, Erasme University Hospital, Brussels, Belgium; Instituto Académico Científico Quispe-Cornejo, INAAQC, La Paz, Bolivia
| | | | - Jacques Creteur
- Department of Intensive Care, Erasme University Hospital, Brussels, Belgium
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12
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Laganà MM, Di Tella S, Ferrari F, Pelizzari L, Cazzoli M, Alperin N, Jin N, Zacà D, Baselli G, Baglio F. Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters. Fluids Barriers CNS 2022; 19:100. [PMID: 36517859 PMCID: PMC9749305 DOI: 10.1186/s12987-022-00394-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/12/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Cervical blood and cerebrospinal fluid (CSF) flow rates can be quantified with Phase-contrast (PC) MRI, which is routinely used for clinical studies. Previous MRI studies showed that venous and CSF flow alterations are linked to various pathological conditions. Since it is well known that, besides the heart beating, the thoracic pump influences the blood and CSF dynamics, we studied the effect of different respiration modes on blood and CSF flow rates using a real-time (RT)-PC prototype. METHODS Thirty healthy volunteers were examined with a 3 T scanner. A RT-PC sequence was acquired at the first cervical level to quantify the flow rates of internal carotid arteries, internal jugular veins (IJVs) and CSF. Each RT-PC acquisition was repeated three times, while the subjects were asked to breathe in three different ways for 60 s each: freely (F), with a constant rate (PN) and with deep and constant respiration rate (PD). The average flow rates were computed, they were removed from the respective signals and integrated in the inspiratory and expiratory phases (differential volumes). Finally, the power spectral density was computed for each detrended flow rate. High- and very-high frequency peaks were identified on the spectra while their frequencies were compared to the respiratory and cardiac frequencies estimated using a thoracic belt and a pulse oximeter. The area under the spectra was computed in four 0.5 Hz-wide ranges, centered on the high-frequency peak, on very-high frequency peak and its 2nd and 3rd harmonics, and then they were normalized by the flow rate variance. The effect of breathing patterns on average flow rates, on systolic and diastolic peaks, and on the normalized power was tested. Finally, the differential volumes of inspiration were compared to those of expiration. RESULTS The frequencies of the high- and very-high spectral peaks corresponded to the respiratory and cardiac frequencies. The average flow rate progressively decreased from F to PN to PD breathing, and the cardiac modulations were less predominant especially for the IJVs. The respiratory modulation increased with PD breathing. The average volumes displaced in the inspiratory phases were not significantly different from those of the expiratory one. CONCLUSIONS The spectral analyses demonstrated higher respiratory modulations in PD compared to free breathing, even prevailing the cardiac modulation in the IJVs, showing an increment of the thoracic pump affecting the flow rate shape.
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Affiliation(s)
- Maria Marcella Laganà
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Sonia Di Tella
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy ,grid.8142.f0000 0001 0941 3192Department of Psychology, Università Cattolica del Sacro Cuore, Milan, Italy
| | - Francesca Ferrari
- grid.4643.50000 0004 1937 0327Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Laura Pelizzari
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Marta Cazzoli
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Noam Alperin
- grid.26790.3a0000 0004 1936 8606University of Miami, Miami, USA
| | - Ning Jin
- MR R&D Collaborations, Siemens Medical Solutions USA, Inc, Cleveland, OH USA
| | | | - Giuseppe Baselli
- grid.4643.50000 0004 1937 0327Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Francesca Baglio
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
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13
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Validity of transcranial Doppler ultrasonography-determined dynamic cerebral autoregulation estimated using transfer function analysis. J Clin Monit Comput 2022; 36:1711-1721. [PMID: 35075510 DOI: 10.1007/s10877-022-00817-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
Transcranial Doppler ultrasonography (TCD) is used widely to evaluate dynamic cerebral autoregulation (dCA). However, the validity of TCD-determined dCA remains unknown because TCD is only capable of measuring blood velocity and thus only provides an index as opposed to true blood flow. To test the validity of TCD-determined dCA, in nine healthy subjects, dCA was evaluated by transfer function analysis (TFA) using cerebral blood flow (CBF) or TCD-measured cerebral blood velocity during a perturbation that induces reductions in TCD-determined dCA, lower body negative pressure (LBNP) at two different stages: LBNP - 15 mmHg and - 50 mmHg. Internal carotid artery blood flow (ICA Q) was assessed as an index of CBF using duplex Doppler ultrasound. The TFA low frequency (LF) normalized gain (ngain) calculated using ICA Q increased during LBNP at - 50 mmHg (LBNP50) from rest (P = 0.005) and LBNP at - 15 mmHg (LBNP15) (P = 0.015), indicating an impaired dCA. These responses were the same as those obtained using TCD-measured cerebral blood velocity (from rest and LBNP15; P = 0.001 and P = 0.015). In addition, the ICA Q-determined TFA LF ngain from rest to LBNP50 was significantly correlated with TCD-determined TFA LF ngain (r = 0.460, P = 0.016) despite a low intraclass correlation coefficient. Moreover, in the Bland-Altman analysis, the difference in the TFA LF ngains determined by blood flow and velocity was within the margin of error, indicating that the two measurement methods can be interpreted as equivalent. These findings suggest that TCD-determined dCA can be representative of actual dCA evaluated with CBF.
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14
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Arora Y, Dutta A. Human-in-the-Loop Optimization of Transcranial Electrical Stimulation at the Point of Care: A Computational Perspective. Brain Sci 2022; 12:brainsci12101294. [PMID: 36291228 PMCID: PMC9599464 DOI: 10.3390/brainsci12101294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/05/2022] [Accepted: 09/18/2022] [Indexed: 11/17/2022] Open
Abstract
Individual differences in the responsiveness of the brain to transcranial electrical stimulation (tES) are increasingly demonstrated by the large variability in the effects of tES. Anatomically detailed computational brain models have been developed to address this variability; however, static brain models are not “realistic” in accounting for the dynamic state of the brain. Therefore, human-in-the-loop optimization at the point of care is proposed in this perspective article based on systems analysis of the neurovascular effects of tES. First, modal analysis was conducted using a physiologically detailed neurovascular model that found stable modes in the 0 Hz to 0.05 Hz range for the pathway for vessel response through the smooth muscle cells, measured with functional near-infrared spectroscopy (fNIRS). During tES, the transient sensations can have arousal effects on the hemodynamics, so we present a healthy case series for black-box modeling of fNIRS−pupillometry of short-duration tDCS effects. The block exogeneity test rejected the claim that tDCS is not a one-step Granger cause of the fNIRS total hemoglobin changes (HbT) and pupil dilation changes (p < 0.05). Moreover, grey-box modeling using fNIRS of the tDCS effects in chronic stroke showed the HbT response to be significantly different (paired-samples t-test, p < 0.05) between the ipsilesional and contralesional hemispheres for primary motor cortex tDCS and cerebellar tDCS, which was subserved by the smooth muscle cells. Here, our opinion is that various physiological pathways subserving the effects of tES can lead to state−trait variability, which can be challenging for clinical translation. Therefore, we conducted a case study on human-in-the-loop optimization using our reduced-dimensions model and a stochastic, derivative-free covariance matrix adaptation evolution strategy. We conclude from our computational analysis that human-in-the-loop optimization of the effects of tES at the point of care merits investigation in future studies for reducing inter-subject and intra-subject variability in neuromodulation.
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Affiliation(s)
- Yashika Arora
- Neuroimaging and Neurospectroscopy Lab, National Brain Research Centre, Gurgaon 122052, India
| | - Anirban Dutta
- Neuroengineering and Informatics for Rehabilitation and Simulation-Based Learning (NIRSlearn), University of Lincoln, Lincoln LN6 7TS, UK
- Correspondence:
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15
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Giannokostas K, Dimakopoulos Y, Tsamopoulos J. Shear stress and intravascular pressure effects on vascular dynamics: two-phase blood flow in elastic microvessels accounting for the passive stresses. Biomech Model Mechanobiol 2022; 21:1659-1684. [PMID: 35962247 DOI: 10.1007/s10237-022-01612-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/07/2022] [Indexed: 11/02/2022]
Abstract
We study the steady hemodynamics in physiological elastic microvessels proposing an advanced fluid-structure interaction model. The arteriolar tissue is modeled as a two-layer fiber-reinforced hyperelastic material representing its Media and Adventitia layers. The constitutive model employed (Holzapfel et al. in J Elast 61:1-48, 2000) is parametrized via available data on stress-strain experiments for arterioles. The model is completed by simulating the blood/plasma flow in the lumen, using the thixotropic elasto-viscoplastic model in its core, and the linear Phan-Thien and Tanner viscoelastic model in its annular part. The Cell-Free Layer (CFL) and the Fåhraeus and Fåhraeus-Lindqvist effects are considered via analytical expressions based on experimental data (Giannokostas et al. in Materials (Basel) 14:367, 2021b). The coupling between tissue deformation and blood flow is achieved through the experimentally verified pressure-shear hypothesis (Pries et al. Circ Res 77:1017-1023, 1995). Our calculations confirm that the increase in the reference inner radius produces larger expansion. Also, by increasing the intraluminal pressure, the thinning of the walls is more pronounced and it may reach 40% of the initial thickness. Comparing our predictions with those in rigid-wall microtubes, we conclude that apart from the vital importance of vasodilation, there is an up to 25% reduction in wall shear stress. The passive vasodilation contributes to the decrease in the tissue stress fields and affects the hemodynamic features such as the CFL thickness, reducing the plasma layer when blood flows in vessels with elastic walls, in quantitative agreement with previous experiments. Our calculations verify the correctness of the pressure-shear hypothesis but not that of the Laplace law.
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Affiliation(s)
- K Giannokostas
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Y Dimakopoulos
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - J Tsamopoulos
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, Patras, Greece
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16
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Valkov S, Nilsen JH, Mohyuddin R, Schanche T, Kondratiev T, Sieck GC, Tveita T. Autoregulation of Cerebral Blood Flow During 3-h Continuous Cardiopulmonary Resuscitation at 27°C. Front Physiol 2022; 13:925292. [PMID: 35755426 PMCID: PMC9218627 DOI: 10.3389/fphys.2022.925292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
Introduction: Victims of accidental hypothermia in hypothermic cardiac arrest (HCA) may survive with favorable neurologic outcome if early and continuous prehospital cardiopulmonary resuscitation (CPR) is started and continued during evacuation and transport. The efficacy of cerebral autoregulation during hypothermic CPR is largely unknown and is aim of the present experiment. Methods: Anesthetized pigs (n = 8) were surface cooled to HCA at 27°C before 3 h continuous CPR. Central hemodynamics, cerebral O2 delivery (DO2) and uptake (VO2), cerebral blood flow (CBF), and cerebral perfusion pressure (CPP) were determined before cooling, at 32°C and at 27°C, then at 15 min after the start of CPR, and hourly thereafter. To estimate cerebral autoregulation, the static autoregulatory index (sARI), and the CBF/VO2 ratio were determined. Results: After the initial 15-min period of CPR at 27°C, cardiac output (CO) and mean arterial pressure (MAP) were reduced significantly when compared to corresponding values during spontaneous circulation at 27°C (-66.7% and -44.4%, respectively), and remained reduced during the subsequent 3-h period of CPR. During the first 2-h period of CPR at 27°C, blood flow in five different brain areas remained unchanged when compared to the level during spontaneous circulation at 27°C, but after 3 h of CPR blood flow in 2 of the 5 areas was significantly reduced. Cooling to 27°C reduced cerebral DO2 by 67.3% and VO2 by 84.4%. Cerebral VO2 was significantly reduced first after 3 h of CPR. Cerebral DO2 remained unaltered compared to corresponding levels measured during spontaneous circulation at 27°C. Cerebral autoregulation was preserved (sARI > 0.4), at least during the first 2 h of CPR. Interestingly, the CBF/VO2 ratio during spontaneous circulation at 27°C indicated the presence of an affluent cerebral DO2, whereas after CPR, the CBF/VO2 ratio returned to the level of spontaneous circulation at 38°C. Conclusion: Despite a reduced CO, continuous CPR for 3 h at 27°C provided sufficient cerebral DO2 to maintain aerobic metabolism and to preserve cerebral autoregulation during the first 2-h period of CPR. This new information supports early start and continued CPR in accidental hypothermia patients during rescue and transportation for in hospital rewarming.
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Affiliation(s)
- Sergei Valkov
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Jan Harald Nilsen
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway
| | - Rizwan Mohyuddin
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Torstein Schanche
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
| | - Timofei Kondratiev
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
| | - Torkjel Tveita
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
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17
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The Cerebral Arterial Wall in the Development and Growth of Intracranial Aneurysms. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12125964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A considerable number of people harbor intracranial aneurysms (IA), which is a focal or segmental disease of the arterial wall. The pathophysiologic mechanisms of IAs formation, growth, and rupture are complex. The mechanism also differs with respect to the type of aneurysm. In broad aspects, aneurysms may be considered a disease of the vessel wall. In addition to the classic risk factors and the genetic/environmental conditions, altered structural and pathologic events along with the interaction of the surrounding environment and luminal flow dynamics contribute to the aneurysm’s development and growth. In this review, we have tried to simplify the complex interaction of a multitude of events in relation to vessel wall in the formation and growth of IAs.
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18
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Pham T, Fernandez C, Blaney G, Tgavalekos K, Sassaroli A, Cai X, Bibu S, Kornbluth J, Fantini S. Noninvasive Optical Measurements of Dynamic Cerebral Autoregulation by Inducing Oscillatory Cerebral Hemodynamics. Front Neurol 2021; 12:745987. [PMID: 34867729 PMCID: PMC8637213 DOI: 10.3389/fneur.2021.745987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: Cerebral autoregulation limits the variability of cerebral blood flow (CBF) in the presence of systemic arterial blood pressure (ABP) changes. Monitoring cerebral autoregulation is important in the Neurocritical Care Unit (NCCU) to assess cerebral health. Here, our goal is to identify optimal frequency-domain near-infrared spectroscopy (FD-NIRS) parameters and apply a hemodynamic model of coherent hemodynamics spectroscopy (CHS) to assess cerebral autoregulation in healthy adult subjects and NCCU patients. Methods: In five healthy subjects and three NCCU patients, ABP oscillations at a frequency around 0.065 Hz were induced by cyclic inflation-deflation of pneumatic thigh cuffs. Transfer function analysis based on wavelet transform was performed to measure dynamic relationships between ABP and oscillations in oxy- (O), deoxy- (D), and total- (T) hemoglobin concentrations measured with different FD-NIRS methods. In healthy subjects, we also obtained the dynamic CBF-ABP relationship by using FD-NIRS measurements and the CHS model. In healthy subjects, an interval of hypercapnia was performed to induce cerebral autoregulation impairment. In NCCU patients, the optical measurements of autoregulation were linked to individual clinical diagnoses. Results: In healthy subjects, hypercapnia leads to a more negative phase difference of both O and D oscillations vs. ABP oscillations, which are consistent across different FD-NIRS methods and are highly correlated with a more negative phase difference CBF vs. ABP. In the NCCU, a less negative phase difference of D vs. ABP was observed in one patient as compared to two others, indicating a better autoregulation in that patient. Conclusions: Non-invasive optical measurements of induced phase difference between D and ABP show the strongest sensitivity to cerebral autoregulation. The results from healthy subjects also show that the CHS model, in combination with FD-NIRS, can be applied to measure the CBF-ABP dynamics for a better direct measurement of cerebral autoregulation.
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Affiliation(s)
- Thao Pham
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
| | - Cristianne Fernandez
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
| | - Giles Blaney
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
| | - Kristen Tgavalekos
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
| | - Angelo Sassaroli
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
| | - Xuemei Cai
- Department of Neurology, Tufts University School of Medicine, Boston, MA, United States
| | - Steve Bibu
- Department of Neurology, Tufts University School of Medicine, Boston, MA, United States
| | - Joshua Kornbluth
- Department of Neurology, Tufts University School of Medicine, Boston, MA, United States
| | - Sergio Fantini
- Department of Biomedical Engineering, Tufts University, Medford, MA, United States
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19
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Martinez-Tejada I, Czosnyka M, Czosnyka Z, Juhler M, Smielewski P. Causal relationship between slow waves of arterial, intracranial pressures and blood velocity in brain. Comput Biol Med 2021; 139:104970. [PMID: 34735948 DOI: 10.1016/j.compbiomed.2021.104970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/12/2021] [Accepted: 10/20/2021] [Indexed: 11/20/2022]
Abstract
PURPOSE Slow vasogenic waves in arterial blood pressure (ABP), intracranial pressure (ICP) and cerebral blood flow velocity (FV) carry information on multiple brain homeostatic control mechanisms. This work presents an approach to evaluate causal relation between oscillatory modes of these signals as an alternative to time or frequency domain Granger analysis. METHODS Forty-five patients with simultaneous recordings of ICP, ABP and FV during CSF infusion studies were examined retrospectively. Each time series was decomposed into ten intrinsic mode functions (IMFs) via Ensemble Empirical Mode Decomposition (EEMD) and, afterwards, Granger causality (GC) was computed. RESULTS Slow waves of ICP, ABP and FV were reconstructed from mode functions IMF6-9 of each time series, covering a frequency range between 0.013 and 0.155 Hz. Most significant connections were from FV to ICP, being stronger during elevation of mean ICP during infusion study. No G-causality was found between any of the IMFs during the baseline phase. CONCLUSION Nonlinearity and nonstationarity of the cerebral and systemic signals can be addressed using EEMD decomposition There is a causal influence of slow waves of FV on slow waves on ICP during the plateau phase of the infusion study for a frequency band between 0.095 and 0.155 Hz. This relationship is magnified during mild intracranial hypertension.
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Affiliation(s)
- Isabel Martinez-Tejada
- Rigshospitalet, Clinic of Neurosurgery, Blegdamsvej 9, Copenhagen, 2100, Denmark; Technical University of Denmark, Department of Health Technology, Orsteds Pl. 345C, Kongens Lyngby, 2800, Denmark.
| | - Marek Czosnyka
- University of Cambridge, Brain Physics Laboratory, Division of Neurosurgery, Box 167, Addenbrooke's Hospital, Cambridge, CB2 0QQ, United Kingdom
| | - Zofia Czosnyka
- University of Cambridge, Brain Physics Laboratory, Division of Neurosurgery, Box 167, Addenbrooke's Hospital, Cambridge, CB2 0QQ, United Kingdom
| | - Marianne Juhler
- Rigshospitalet, Clinic of Neurosurgery, Blegdamsvej 9, Copenhagen, 2100, Denmark
| | - Peter Smielewski
- University of Cambridge, Brain Physics Laboratory, Division of Neurosurgery, Box 167, Addenbrooke's Hospital, Cambridge, CB2 0QQ, United Kingdom
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Bryant JED, Birch AA, Panerai RB, Nikolic D, Bulters D, Simpson DM. Estimating confidence intervals for cerebral autoregulation: a parametric bootstrap approach. Physiol Meas 2021; 42. [PMID: 34534969 DOI: 10.1088/1361-6579/ac27b8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/17/2021] [Indexed: 11/12/2022]
Abstract
Cerebral autoregulation (CA) refers to the ability of the brain vasculature to control blood flow in the face of changing blood pressure. One of the methods commonly used to assess cerebral autoregulation, especially in participants at rest, is the analysis of phase derived from transfer function analysis (TFA), relating arterial blood pressure (ABP) to cerebral blood flow (CBF). This and other indexes of CA can provide consistent results when comparing groups of subjects (e.g. patients and healthy controls or normocapnia and hypercapnia) but can be quite variable within and between individuals. The objective of this paper is to present a novel parametric bootstrap method, used to estimate the sampling distribution and hence confidence intervals (CIs) of the mean phase estimate in the low-frequency band, in order to optimise estimation of measures of CA function and allow more robust inferences on the status of CA from individual recordings. A set of simulations was used to verify the proposed method under controlled conditions. In 20 healthy adult volunteers (age 25.53.5 years), ABP and CBF velocity (CBFV) were measured at rest, using a Finometer device and Transcranial Doppler (applied to the middle cerebral artery), respectively. For each volunteer, five individual recordings were taken on different days, each approximately 18 min long. Phase was estimated using TFA. Analysis of recorded data showed widely changing CIs over the duration of recordings, which could be reduced when noisy data and frequencies with low coherence were excluded from the analysis (Wilcoxon signed rank testp= 0.0065). The TFA window-lengths of 50s gave smaller CIs than lengths of 100s (p< 0.001) or 20s (p< 0.001), challenging the usual recommendation of 100s. The method adds a much needed flexible statistical tool for CA analysis in individual recordings.
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Affiliation(s)
- Jack E D Bryant
- Faculty of Engineering, University of Southampton, Highfield, Southampton, United Kingdom
| | - Anthony A Birch
- Department of Medical Physics, University Hospital Southampton NHS Foundation Trust, Southampton, Hampshire, United Kingdom
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, United Kingdom
| | - Dragana Nikolic
- Faculty of Engineering, University of Southampton, Highfield, Southampton, United Kingdom
| | - Diederik Bulters
- Wessex Neurological Centre, University Hospital Southampton NHS Foundation Trust, Southampton, Hampshire, United Kingdom
| | - David M Simpson
- Faculty of Engineering, University of Southampton, Highfield, Southampton, United Kingdom
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21
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Geometry and Flow Properties Affect the Phase Shift between Pressure and Shear Stress Waves in Blood Vessels. FLUIDS 2021. [DOI: 10.3390/fluids6110378] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The phase shift between pressure and wall shear stress (WSS) has been associated with vascular diseases such as atherosclerosis and aneurysms. The present study aims to understand the effects of geometry and flow properties on the phase shift under the stiff wall assumption, using an immersed-boundary-lattice-Boltzmann method. For pulsatile flow in a straight pipe, the phase shift is known to increase with the Womersley number, but is independent of the flow speed (or the Reynolds number). For a complex geometry, such as a curved pipe, however, we find that the phase shift develops a strong dependence on the geometry and Reynolds number. We observed that the phase shift at the inner bend of the curved vessel and in the aneurysm dome is larger than that in a straight pipe. Moreover, the geometry affects the connection between the phase shift and other WSS-related metrics, such as time-averaged WSS (TAWSS). For straight and curved blood vessels, the phase shift behaves qualitatively similarly to and can thus be represented by the TAWSS, which is a widely used hemodynamic index. However, these observables significantly differ in other geometries, such as in aneurysms. In such cases, one needs to consider the phase shift as an independent quantity that may carry additional valuable information compared to well-established metrics.
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A Method for More Accurate Determination of Resonance Frequency of the Cardiovascular System, and Evaluation of a Program to Perform It. Appl Psychophysiol Biofeedback 2021; 47:17-26. [PMID: 34655366 DOI: 10.1007/s10484-021-09524-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2021] [Indexed: 12/17/2022]
Abstract
This study validated a more exact automated method of determining cardiovascular resonance frequency (RF) against the "stepped" protocol described by Lehrer et al. (Appl Psychophysiol Biofeedback 25(3):177-191, https://doi.org/10.1023/a:1009554825745 , 2000; in Foundations of heart rate variability biofeedback: A book of readings, The Association for Applied Psychophysiology and Biofeedback, pp 9-19, 2016). Thirteen participants completed a 15-min RF determination session by each method. The "stepped" protocol assesses HRV in five 3-min stationary windows from 4.5 to 6.5 breaths per minute (bpm), decreasing in 0.5 bpm steps. Multiple criteria, subjectively weighted by the clinician, determines RF. For this study, the proposed method used a sliding window with a fixed rate of change (67.04 ms per breath) at each of 78 breath cycles ranging from 4.25 to 6.75 bpm. Its algorithm analyzes IBI to locate the midpoint of the 1-min region of stable maximum peak-trough variability. RF is quantified from breath duration at that point. The software generates a visual display of superimposed HR and breathing data. Thus, the new method fully automates RF determination. Eleven of the 13 matched pairs fell within the 0.5 bpm resolution of the stepped method. Comparisons of LF power generated by the autoregressive (AR) spectral method showed a strong correlation in LF power production by the stepped and sliding methods (R = 0.751, p = 0.000). The "sliding" pacing protocol was favored by 69% of participants (p < 0.02). The new, fully-automated, method may facilitate both in-person and remote HRV biofeedback training. Software is available open-source.
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23
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Claassen JAHR, Thijssen DHJ, Panerai RB, Faraci FM. Regulation of cerebral blood flow in humans: physiology and clinical implications of autoregulation. Physiol Rev 2021; 101:1487-1559. [PMID: 33769101 PMCID: PMC8576366 DOI: 10.1152/physrev.00022.2020] [Citation(s) in RCA: 289] [Impact Index Per Article: 96.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Brain function critically depends on a close matching between metabolic demands, appropriate delivery of oxygen and nutrients, and removal of cellular waste. This matching requires continuous regulation of cerebral blood flow (CBF), which can be categorized into four broad topics: 1) autoregulation, which describes the response of the cerebrovasculature to changes in perfusion pressure; 2) vascular reactivity to vasoactive stimuli [including carbon dioxide (CO2)]; 3) neurovascular coupling (NVC), i.e., the CBF response to local changes in neural activity (often standardized cognitive stimuli in humans); and 4) endothelium-dependent responses. This review focuses primarily on autoregulation and its clinical implications. To place autoregulation in a more precise context, and to better understand integrated approaches in the cerebral circulation, we also briefly address reactivity to CO2 and NVC. In addition to our focus on effects of perfusion pressure (or blood pressure), we describe the impact of select stimuli on regulation of CBF (i.e., arterial blood gases, cerebral metabolism, neural mechanisms, and specific vascular cells), the interrelationships between these stimuli, and implications for regulation of CBF at the level of large arteries and the microcirculation. We review clinical implications of autoregulation in aging, hypertension, stroke, mild cognitive impairment, anesthesia, and dementias. Finally, we discuss autoregulation in the context of common daily physiological challenges, including changes in posture (e.g., orthostatic hypotension, syncope) and physical activity.
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Affiliation(s)
- Jurgen A H R Claassen
- Department of Geriatrics, Radboud University Medical Center, Donders Institute for Brain, Cognition, and Behaviour, Nijmegen, The Netherlands
| | - Dick H J Thijssen
- Department of Physiology, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- >National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Frank M Faraci
- Departments of Internal Medicine, Neuroscience, and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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24
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Zhang W, Fu W, Yan L, Wang M, Ning B, Mo X, Xiong L, Liu J, Zhang P, Zhong J, Sun L, Fu W. Impaired dynamic cerebral autoregulation in young adults with mild depression. Psychophysiology 2021; 59:e13949. [PMID: 34587299 DOI: 10.1111/psyp.13949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/02/2021] [Accepted: 09/20/2021] [Indexed: 01/02/2023]
Abstract
The incidence of depression is increasing, especially in the young adult population. Impaired cognitive function is one of the characteristics of depression, which may be related to impaired cerebral autoregulation (CA). We investigated the characteristics of CA in young adults with mild depression, as well as its validity for identifying patients with depression. Patients (aged 18-35 years) with Hamilton Depression Rating Scale (HAMD) scores ranging from 8 to 17 and a first episode of mild depression were enrolled in this study. Healthy volunteers were recruited as controls. Noninvasive continuous arterial blood pressure and bilateral middle cerebral artery blood flow velocity were simultaneously recorded from each subject. Transfer function analysis was applied to derive phase difference, gain, coherence and rate of recovery for the assessment of CA. Forty-three patients and 43 healthy controls were enrolled. Phase difference values were significantly compromised in young adults with mild depression and were negatively correlated with HAMD scores. Rate of recovery values estimated from depressed patients was significantly lower. The validity in identifying patients with depression was favorable for the phase difference. The cutoff phase difference value was 29.66. Our findings suggest that dynamic CA was impaired in young patients with mild depression and negatively correlated with HAMD scores. CA represented by phase difference can be used as an objective auxiliary examination of depression, and has clinical diagnostic value for the early identification of patients with depression.
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Affiliation(s)
- Weijun Zhang
- Department of Cerebral Function, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wen Fu
- Department of Rheumatology, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Luda Yan
- Shenzhen Bao'an Research Center for Acupuncture and Moxibustion, Shenzhen, China
| | - Mengyu Wang
- School of Rehabilitation Medicine, Henan University of Chinese Medicine, Zhengzhou, China
| | - Baile Ning
- Department of Acupuncture and Moxibustion, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiuyun Mo
- Department of Cerebral Function, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Li Xiong
- Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Jia Liu
- Institute of Advanced Computing and Digital Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Pandeng Zhang
- Institute of Advanced Computing and Digital Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jingxin Zhong
- Department of Cerebral Function, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lu Sun
- Department of Psychosomatics, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenbin Fu
- Department of Acupuncture and Moxibustion, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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25
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Castro P, Serrador J, Rocha I, Chaves PC, Sorond F, Azevedo E. Heart failure patients have enhanced cerebral autoregulation response in acute ischemic stroke. J Thromb Thrombolysis 2021; 50:753-761. [PMID: 32488831 DOI: 10.1007/s11239-020-02166-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The cerebrovascular effects of a failing heart-pump are largely unknown. Chronic heart failure (HF) might cause pre-conditioning effect on cerebral hemodynamics but not study so far in acute stroke. We aimed to investigate if HF induces effects in dynamic cerebral autoregulation (CA), within 6 h of symptom-onset through chronic stage of ischemic stroke. We enrolled 50 patients with acute ischemic stroke. Groups with (N = 8) and without HF and 20 heathy controls were compared. Arterial blood pressure (Finometer) and cerebral blood flow velocity (transcranial Doppler) were monitored within 6 and at 24 h from symptom-onset and at 3 months. We assessed dynamic CA by transfer function analysis and cardiac disease markers. HF associated with higher phase (better dynamic CA) at ischemic hemisphere within 6 (p = 0.042) and at 24 h (p = 0.006) but this effect was not evident at 3 months (p > 0.05). Gain and coherence trends were similar between groups. We found a positive correlation between phase and admission troponin I levels (Spearman's r = 0.348, p = 0.044). Our findings advances on the knowledge of how brain and heart interact in acute ischemic stroke by showing a sustained dynamic cerebral autoregulation response in HF patients mainly with severe aortic valve disease. Understanding the physiological mechanisms that govern this complex interplay can be useful to find novel therapeutic targets which can improve outcome in ischemic stroke.
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Affiliation(s)
- Pedro Castro
- Cardiovascular Research and Development Center, Faculty of Medicine, University of Porto, Alameda Professor Hernani Monteiro, 4200-319, Porto, Portugal. .,Department of Neurology, Centro Hospitalar Universitário de São João, Porto, Portugal.
| | - Jorge Serrador
- Veterans Biomedical Institute and War Related Illness and Injury Study Center, Department of Veterans Affairs, New Jersey Healthcare System, East Orange, USA.,New Jersey Medical School, Newark, NJ, USA
| | - Isabel Rocha
- Cardiovascular Autonomic Function Lab, Institute of Physiology, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
| | - Paulo Castro Chaves
- Cardiovascular Research and Development Center, Faculty of Medicine, University of Porto, Alameda Professor Hernani Monteiro, 4200-319, Porto, Portugal
| | - Farzaneh Sorond
- Division of Stroke and Neurocritical, Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Elsa Azevedo
- Cardiovascular Research and Development Center, Faculty of Medicine, University of Porto, Alameda Professor Hernani Monteiro, 4200-319, Porto, Portugal.,Department of Neurology, Centro Hospitalar Universitário de São João, Porto, Portugal
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26
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Pfurtscheller G, Schwerdtfeger AR, Rassler B, Andrade A, Schwarz G. MRI-related anxiety can induce slow BOLD oscillations coupled with cardiac oscillations. Clin Neurophysiol 2021; 132:2083-2090. [PMID: 34284243 DOI: 10.1016/j.clinph.2021.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Although about 1-2% of MRI examinations must be aborted due to anxiety, there is little research on how MRI-related anxiety affects BOLD signals in resting states. METHODS We re-analyzed cardiac beat-to beat interval (RRI) and BOLD signals of 23 healthy fMRI participants in four resting states by calculation of phase-coupling in the 0.07-0.13 Hz band and determination of positive time delays (pTDs; RRI leading neural BOLD oscillations) and negative time delays (nTDs; RRI lagging behind vascular BOLD oscillations). State anxiety of each subject was assigned to either a low anxiety (LA) or a high anxiety (HA, with most participants exhibiting moderate anxiety symptoms) category based on the inside scanner assessed anxiety score. RESULTS Although anxiety strongly differed between HA and LA categories, no significant difference was found for nTDs. In contrast, pTDs indicating neural BOLD oscillations exhibited a significant cumulation in the high anxiety category. CONCLUSIONS Findings may suggest that vascular BOLD oscillations related to slow cerebral blood circulation are of about similar intensity during low/no and elevated anxiety. In contrast, neural BOLD oscillations, which might be associated with a central rhythm generating mechanism (pacemaker-like activity), appear to be significantly intensified during elevated anxiety. SIGNIFICANCE The study provides evidence that fMRI-related anxiety can activate a central rhythm generating mechanism very likely located in the brain stem, associated with slow neural BOLD oscillation.
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Affiliation(s)
- G Pfurtscheller
- Institute of Neural Engineering, Graz University of Technology, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - A R Schwerdtfeger
- Institute of Psychology, University of Graz, Graz, Austria; BioTechMed Graz, Graz, Austria.
| | - B Rassler
- Carl-Ludwig-Institute of Physiology, University of Leipzig, Leipzig, Germany
| | - A Andrade
- Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal
| | - G Schwarz
- Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria
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27
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Srinivas S, Retson T, Simon A, Hattangadi-Gluth J, Hsiao A, Farid N. Quantification of hemodynamics of cerebral arteriovenous malformations after stereotactic radiosurgery using 4D flow magnetic resonance imaging. J Magn Reson Imaging 2020; 53:1841-1850. [PMID: 33354852 DOI: 10.1002/jmri.27490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 12/26/2022] Open
Abstract
Stereotactic radiosurgery (SRS) is used to treat cerebral arteriovenous malformations (AVMs). However, early evaluation of efficacy is difficult as structural magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) often does not demonstrate appreciable changes within the first 6 months. The aim of this study was to evaluate the use of four-dimensional (4D) flow MRI to quantify hemodynamic changes after SRS as early as 2 months. This was a retrospective observational study, which included 14 patients with both pre-SRS and post-SRS imaging obtained at multiple time points from 1 to 27 months after SRS. A 3T MRI Scanner was used to obtain T2 single-shot fast spin echo, time-of-flight MRA, and postcontrast 4D flow with three-dimensional velocity encoding between 150 and 200 cm/s. Post-hoc two-dimensional cross-sectional flow was measured for the dominant feeding artery, the draining vein, and the corresponding contralateral artery as a control. Measurements were performed by two independent observers, and reproducibility was assessed. Wilcoxon signed-rank tests were used to compare differences in flow, circumference, and pulsatility between the feeding artery and the contralateral artery both before and after SRS; and differences in nidus size and flow and circumference of the feeding artery and draining vein before and after SRS. Arterial flow (L/min) decreased in the primary feeding artery (mean: 0.1 ± 0.07 vs. 0.3 ± 0.2; p < 0.05) and normalized in comparison to the contralateral artery (mean: 0.1 ± 0.07 vs. 0.1 ± 0.07; p = 0.068). Flow decreased in the draining vein (mean: 0.1 ± 0.2 vs. 0.2 ± 0.2; p < 0.05), and the circumference of the draining vein also decreased (mean: 16.1 ± 8.3 vs. 15.7 ± 6.7; p < 0.05). AVM volume decreased after SRS (mean: 45.3 ± 84.8 vs. 38.1 ± 78.7; p < 0.05). However, circumference (mm) of the primary feeding artery remained similar after SRS (mean: 15.7 ± 2.7 vs. 16.1 ± 3.1; p = 0.600). 4D flow may be able to demonstrate early hemodynamic changes in AVMs treated with radiosurgery, and these changes appear to be more pronounced and occur earlier than the structural changes on standard MRI/MRA. Level of Evidence: 4 Technical Efficacy Stage: 1.
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Affiliation(s)
- Shanmukha Srinivas
- Department of Radiology, University of California-San Diego, San Diego, California, USA
| | - Tara Retson
- Department of Radiology, University of California-San Diego, San Diego, California, USA
| | - Aaron Simon
- Department of Radiation Medicine and Applied Sciences, University of California-San Diego, San Diego, California, USA
| | - Jona Hattangadi-Gluth
- Department of Radiation Medicine and Applied Sciences, University of California-San Diego, San Diego, California, USA
| | - Albert Hsiao
- Department of Radiology, University of California-San Diego, San Diego, California, USA
| | - Nikdokht Farid
- Department of Radiology, University of California-San Diego, San Diego, California, USA
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28
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Noninvasive Cerebral Perfusion and Oxygenation Monitoring Augment Prolonged Field Care in a Non-Human Primate Model of Decompensated Hemorrhage and Resuscitation. Shock 2020; 55:371-378. [PMID: 32925606 DOI: 10.1097/shk.0000000000001631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Decompensated hemorrhagic shock (DHS) is the leading cause of preventable death in combat casualties. "Golden hour" resuscitation effects on cerebral blood flow and perfusion following DHS in prolonged field care (PFC) are not well investigated. Using an established non-human primate model of DHS, we hypothesized noninvasive regional tissue oxygenation (rSO2) and Transcranial Doppler (TCD) would correlate to the invasive measurement of partial pressure of oxygen (PtO2) and mean arterial pressure (MAP) in guiding hypotensive resuscitation in a PFC setting. METHODS Ten rhesus macaques underwent DHS followed by a 2 h PFC phase (T0-T120), and subsequent 4 h hospital resuscitation phase (T120-T360). Invasive monitoring (PtO2, MAP) was compared against noninvasive monitoring systems (rSO2, TCD). Results were analyzed using t tests and one-way repeated measures ANOVA. Linear correlation was determined via Pearson r. Significance = P < 0.05. RESULTS MAP, PtO2, rSO2, and mean flow velocity (MFV) significantly decreased from baseline at T0. MAP and PtO2 were restored to baseline by T15, while rSO2 was delayed through T30. At T120, MFV returned to baseline, while the Pulsatility Index significantly elevated by T120 (1.50 ± 0.31). PtO2 versus rSO2 (R2 = 0.2099) and MAP versus MFV (R2 = 0.2891) shared very weak effect sizes, MAP versus rSO2 (R2 = 0.4636) displayed a low effect size, and PtO2 versus MFV displayed a moderate effect size (R2 = 0.5540). CONCLUSIONS Though noninvasive monitoring methods assessed here did not correlate strongly enough against invasive methods to warrant a surrogate in the field, they do effectively augment and direct resuscitation, while potentially serving as a substitute in the absence of invasive capabilities.
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29
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Kermorgant M, Nasr N, Czosnyka M, Arvanitis DN, Hélissen O, Senard JM, Pavy-Le Traon A. Impacts of Microgravity Analogs to Spaceflight on Cerebral Autoregulation. Front Physiol 2020; 11:778. [PMID: 32719617 PMCID: PMC7350784 DOI: 10.3389/fphys.2020.00778] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
It is well known that exposure to microgravity in astronauts leads to a plethora physiological responses such as headward fluid shift, body unloading, and cardiovascular deconditioning. When astronauts return to Earth, some encounter problems related to orthostatic intolerance. An impaired cerebral autoregulation (CA), which could be compromised by the effects of microgravity, has been proposed as one of the mechanisms responsible for orthostatic intolerance. CA is a homeostatic mechanism that maintains cerebral blood flow for any variations in cerebral perfusion pressure by adapting the vascular tone and cerebral vessel diameter. The ground-based models of microgravity are useful tools for determining the gravitational impact of spaceflight on human body. The head-down tilt bed rest (HDTBR), where the subject remains in supine position at −6 degrees for periods ranging from few days to several weeks is the most commonly used ground-based model of microgravity for cardiovascular deconditioning. head-down bed rest (HDBR) is able to replicate cephalic fluid shift, immobilization, confinement, and inactivity. Dry immersion (DI) model is another approach where the subject remains immersed in thermoneutral water covered with an elastic waterproof fabric separating the subject from the water. Regarding DI, this analog imitates absence of any supporting structure for the body, centralization of body fluids, immobilization and hypokinesia observed during spaceflight. However, little is known about the impact of microgravity on CA. Here, we review the fundamental principles and the different mechanisms involved in CA. We also consider the different approaches in order to assess CA. Finally, we focus on the effects of short- and long-term spaceflight on CA and compare these findings with two specific analogs to microgravity: HDBR and DI.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospital, Cambridge, United Kingdom.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Dina N Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Ophélie Hélissen
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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30
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Liu X, Czosnyka M, Donnelly J, Cardim D, Cabeleira M, Lalou DA, Hu X, Hutchinson PJ, Smielewski P. Assessment of cerebral autoregulation indices - a modelling perspective. Sci Rep 2020; 10:9600. [PMID: 32541858 PMCID: PMC7295753 DOI: 10.1038/s41598-020-66346-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 05/13/2020] [Indexed: 11/09/2022] Open
Abstract
Various methodologies to assess cerebral autoregulation (CA) have been developed, including model - based methods (e.g. autoregulation index, ARI), correlation coefficient - based methods (e.g. mean flow index, Mx), and frequency domain - based methods (e.g. transfer function analysis, TF). Our understanding of relationships among CA indices remains limited, partly due to disagreement of different studies by using real physiological signals, which introduce confounding factors. The influence of exogenous noise on CA parameters needs further investigation. Using a set of artificial cerebral blood flow velocities (CBFV) generated from a well-known CA model, this study aims to cross-validate the relationship among CA indices in a more controlled environment. Real arterial blood pressure (ABP) measurements from 34 traumatic brain injury patients were applied to create artificial CBFVs. Each ABP recording was used to create 10 CBFVs corresponding to 10 CA levels (ARI from 0 to 9). Mx, TF phase, gain and coherence in low frequency (LF) and very low frequency (VLF) were calculated. The influence of exogenous noise was investigated by adding three levels of colored noise to the artificial CBFVs. The result showed a significant negative relationship between Mx and ARI (r = −0.95, p < 0.001), and it became almost purely linear when ARI is between 3 to 6. For transfer function parameters, ARI positively related with phase (r = 0.99 at VLF and 0.93 at LF, p < 0.001) and negatively related with gain_VLF(r = −0.98, p < 0.001). Exogenous noise changed the actual values of the CA parameters and increased the standard deviation. Our results show that different methods can lead to poor correlation between some of the autoregulation parameters even under well controlled situations, undisturbed by unknown confounding factors. They also highlighted the importance of exogenous noise, showing that even the same CA value might correspond to different CA levels under different ‘noise’ conditions.
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Affiliation(s)
- Xiuyun Liu
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK. .,Department of Anesthesiology & Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.,Institute of Electronic Systems, Warsaw University of Technology, Warszawa, Poland
| | - Joseph Donnelly
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.,Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
| | - Danilo Cardim
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, USA
| | - Manuel Cabeleira
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Despina Aphroditi Lalou
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Xiao Hu
- School of Nursing, Duke University, Durham, NC, USA
| | - Peter J Hutchinson
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Peter Smielewski
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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Saqr KM, Rashad S, Tupin S, Niizuma K, Hassan T, Tominaga T, Ohta M. What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review. J Cereb Blood Flow Metab 2020; 40:1021-1039. [PMID: 31213162 PMCID: PMC7181089 DOI: 10.1177/0271678x19854640] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.
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Affiliation(s)
- Khalid M Saqr
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan.,Department of Mechanical Engineering, College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport, Alexandria, Egypt
| | - Sherif Rashad
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Simon Tupin
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
| | - Kuniyasu Niizuma
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.,Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
| | - Tamer Hassan
- Department of Neurosurgery, Alexandria University School of Medicine, Azarita Medical Campus, Alexandria, Egypt
| | - Teiji Tominaga
- Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan
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Othman MH, Bhattacharya M, Møller K, Kjeldsen S, Grand J, Kjaergaard J, Dutta A, Kondziella D. Resting-State NIRS-EEG in Unresponsive Patients with Acute Brain Injury: A Proof-of-Concept Study. Neurocrit Care 2020; 34:31-44. [PMID: 32333214 DOI: 10.1007/s12028-020-00971-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND Neurovascular-based imaging techniques such as functional MRI (fMRI) may reveal signs of consciousness in clinically unresponsive patients but are often subject to logistical challenges in the intensive care unit (ICU). Near-infrared spectroscopy (NIRS) is another neurovascular imaging technique but low cost, can be performed serially at the bedside, and may be combined with electroencephalography (EEG), which are important advantages compared to fMRI. Combined NIRS-EEG, however, has never been evaluated for the assessment of neurovascular coupling and consciousness in acute brain injury. METHODS We explored resting-state oscillations in eight-channel NIRS oxyhemoglobin and eight-channel EEG band-power signals to assess neurovascular coupling, the prerequisite for neurovascular-based imaging detection of consciousness, in patients with acute brain injury in the ICU (n = 9). Conscious neurological patients from step-down units and wards served as controls (n = 14). Unsupervised adaptive mixture-independent component analysis (AMICA) was used to correlate NIRS-EEG data with levels of consciousness and clinical outcome. RESULTS Neurovascular coupling between NIRS oxyhemoglobin (0.07-0.13 Hz) and EEG band-power (1-12 Hz) signals at frontal areas was sensitive and prognostic to changing consciousness levels. AMICA revealed a mixture of five models from EEG data, with the relative probabilities of these models reflecting levels of consciousness over multiple days, although the accuracy was less than 85%. However, when combined with two channels of bilateral frontal neurovascular coupling, weighted k-nearest neighbor classification of AMICA probabilities distinguished unresponsive patients from conscious controls with > 90% accuracy (positive predictive value 93%, false discovery rate 7%) and, additionally, identified patients who subsequently failed to recover consciousness with > 99% accuracy. DISCUSSION We suggest that NIRS-EEG for monitoring of acute brain injury in the ICU is worthy of further exploration. Normalization of neurovascular coupling may herald recovery of consciousness after acute brain injury.
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Affiliation(s)
- Marwan H Othman
- Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Mahasweta Bhattacharya
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Kirsten Møller
- Department of Neuroanesthesiology, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Kjeldsen
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Johannes Grand
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jesper Kjaergaard
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Anirban Dutta
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Daniel Kondziella
- Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark. .,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Rosenberg AJ, Schroeder EC, Grigoriadis G, Wee SO, Bunsawat K, Heffernan KS, Fernhall B, Baynard T. Aging reduces cerebral blood flow regulation following an acute hypertensive stimulus. J Appl Physiol (1985) 2020; 128:1186-1195. [PMID: 32240012 DOI: 10.1152/japplphysiol.00137.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Aging increases arterial stiffness, which has a negative impact on cerebral blood flow (CBF) regulation (decreases CBF and increases CBF pulsatility). The association between arterial stiffness and CBF pulsatility may, in part, explain the relationship between elevated blood pressure (BP) fluctuations and end-organ disease with aging. To understand the mechanisms by which large BP alterations influence cerebral blood flow regulation in both young and old, we examined the effects of age on central and cerebral blood flow regulation following an acute hypertensive stimulus [resistance-exercise (RE)]. Measurements were obtained pre and immediately, 5, and 30 min post-RE in young (n = 35) and older (n = 26) adults. Measurements included cerebral blood velocity (CBv), CBv pulsatility, central pulse-wave velocity (PWV), beta-stiffness index (β), and carotid blood flow pulsatility. Central hemodynamics and BP were continuously recorded. Mean CBv increased immediately post-RE only in the young and decreased below baseline at 5 min post-RE in both groups (interaction, P < 0.05). Older adults had a greater increase in CBv pulsatility immediately post-RE compared with the young (interaction, P < 0.05). Mean BP was higher and carotid pulsatility was lower in the older group and increased immediately post-RE in both groups (P < 0.05). PWV increased immediately post-RE (P < 0.05). There were no changes in β. In conclusion, with aging, greater central arterial stiffness leads to a greater transmission of pulsatile blood velocity from the systemic circulation to the cerebral circulation following an acute hypertensive stress.NEW & NOTEWORTHY Reductions in cerebral blood flow and increases in flow pulsatility with aging are associated to cerebrovascular disease; however, little is known about how an acute hypertensive stimulus effects cerebral blood flow regulation in an aged population. Following the hypertensive stimulus, older adults elicit an attenuated increase in cerebral blood velocity and greater transmission of pulsatile velocity to the brain compared with young adults, demonstrating reduced cerebral blood flow regulation to elevated blood pressure responses with aging.
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Affiliation(s)
- Alexander J Rosenberg
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois
| | - Elizabeth C Schroeder
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois
| | - Georgios Grigoriadis
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois
| | - Sang Ouk Wee
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois.,Department of Kinesiology, California State University, San Bernardino, California
| | - Kanokwan Bunsawat
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois.,Department of Internal Medicine, Division of Geriatrics, University of Utah; Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Kevin S Heffernan
- Department of Exercise Science, Human Performance Laboratory, Syracuse University, Syracuse, New York
| | - Bo Fernhall
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois
| | - Tracy Baynard
- Department of Kinesiology and Nutrition, Integrative Physiology Laboratory, University of Illinois, Chicago, Illinois
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35
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Intharakham K, Beishon L, Panerai RB, Haunton VJ, Robinson TG. Assessment of cerebral autoregulation in stroke: A systematic review and meta-analysis of studies at rest. J Cereb Blood Flow Metab 2019; 39:2105-2116. [PMID: 31433714 PMCID: PMC6827119 DOI: 10.1177/0271678x19871013] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dynamic cerebral autoregulation (dCA) has been shown to be impaired in cerebrovascular diseases, but there is a lack of consistency across different studies and the different metrics that have been proposed for assessment. We performed a systematic review and meta-analyses involving assessment of dCA in ischemic and hemorrhagic stroke. Thirty-three articles describing assessment of dCA with transfer function analysis (TFA) were included, with meta-analyses performed for derived parameters of gain, phase and autoregulation index (ARI). A total of 1233 patients were pooled from 12 studies on acute ischemic stroke (AIS) and two studies on intracerebral hemorrhage (ICH). In comparison with controls, TFA phase of AIS was significantly reduced (nine studies), in both hemispheres (P < 0.0001). TFA gain provided inconsistent results, with reduced values in relation to controls, for both hemispheres. The ARI (six studies) was reduced compared to controls, in both hemispheres (P < 0.005). In ICH, gain showed higher values compared to controls for the unaffected (P = 0.01), but not for the affected hemisphere. Meta-analyses in AIS have demonstrated that phase and the ARI index can show highly significant differences in comparison with healthy controls, while ICH have been limited by the scarcity of studies and the diversity of units adopted for gain.
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Affiliation(s)
| | - Lucy Beishon
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Victoria J Haunton
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
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36
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Perry BG, Cotter JD, Korad S, Lark S, Labrecque L, Brassard P, Paquette M, Le Blanc O, Lucas SJE. Implications of habitual endurance and resistance exercise for dynamic cerebral autoregulation. Exp Physiol 2019; 104:1780-1789. [DOI: 10.1113/ep087675] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 09/23/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Blake G. Perry
- School of Health SciencesMassey University Wellington New Zealand
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - James D. Cotter
- School of Physical EducationSport and Exercise SciencesUniversity of Otago Dunedin New Zealand
| | - Stephanie Korad
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - Sally Lark
- School of Sport, Exercise and NutritionMassey University Wellington New Zealand
| | - Lawrence Labrecque
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Patrice Brassard
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Myriam Paquette
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Olivier Le Blanc
- Department of KinesiologyFaculty of MedicineLaval University Quebec Canada
- Research center of the Institut universitaire de cardiologie et de pneumologie de Québec Quebec Canada
| | - Samuel J. E. Lucas
- Department of PhysiologyUniversity of Otago Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences & Centre for Human Brain HealthUniversity of Birmingham Birmingham UK
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Kermorgant M, Nasr N, Custaud MA, Navasiolava N, Arbeille P, Guinet P, Labrunée M, Besnier F, Arvanitis DN, Czosnyka M, Senard JM, Pavy-Le Traon A. Effects of Resistance Exercise and Nutritional Supplementation on Dynamic Cerebral Autoregulation in Head-Down Bed Rest. Front Physiol 2019; 10:1114. [PMID: 31507460 PMCID: PMC6718616 DOI: 10.3389/fphys.2019.01114] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/12/2019] [Indexed: 11/13/2022] Open
Abstract
Head-down bed rest (HDBR) is commonly considered as ground-based analog to spaceflight and simulates the headward fluid shift and cardiovascular deconditioning associated with spaceflight. We investigated in healthy volunteers whether HDBR, with or without countermeasures, affect cerebral autoregulation (CA). Twelve men (at selection: 34 ± 7 years; 176 ± 7 cm; 70 ± 7 kg) underwent three interventions of a 21-day HDBR: a control condition without countermeasure (CON), a condition with resistance vibration exercise (RVE) comprising of squats, single leg heel, and bilateral heel raises and a condition using also RVE associated with nutritional supplementation (NeX). Cerebral blood flow velocity was assessed using transcranial Doppler ultrasonography. CA was evaluated by transfer function analysis and by the autoregulatory index (Mxa) in order to determine the relationship between mean cerebral blood flow velocity and mean arterial blood pressure. In RVE condition, coherence was increased after HDBR. In CON condition, Mxa index was significantly reduced after HDBR. In contrast, in RVE and NeX conditions, Mxa were increased after HBDR. Our results indicate that HDBR without countermeasures may improve dynamic CA, but this adaptation may be dampened with RVE. Furthermore, nutritional supplementation did not enhance or worsen the negative effects of RVE. These findings should be carefully considered and could not be applied in spaceflight. Indeed, the subjects spent their time in supine position during bed rest, unlike the astronauts who perform normal daily activities.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marc-Antoine Custaud
- MITOVASC Institute, UMR CNRS 6015, UMR INSERM 1083, Clinical Research Centre, University Hospital of Angers, Angers, France
| | - Nastassia Navasiolava
- MITOVASC Institute, UMR CNRS 6015, UMR INSERM 1083, Clinical Research Centre, University Hospital of Angers, Angers, France
| | | | - Patrick Guinet
- Department of Anesthesiology, Thoracic and Cardiovascular Surgery, Rennes University Hospital, Rennes, France
| | - Marc Labrunée
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Rehabilitation, Toulouse University Hospital, Toulouse, France
| | - Florent Besnier
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Dina N Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospitals, Cambridge, United Kingdom.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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Janzarik WG, Jacob J, Katagis E, Markfeld-Erol F, Sommerlade L, Wuttke M, Reinhard M. Preeclampsia postpartum: Impairment of cerebral autoregulation and reversible cerebral hyperperfusion. Pregnancy Hypertens 2019; 17:121-126. [DOI: 10.1016/j.preghy.2019.05.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/26/2019] [Accepted: 05/29/2019] [Indexed: 11/28/2022]
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Armstead WM, Vavilala MS. Translational approach towards determining the role of cerebral autoregulation in outcome after traumatic brain injury. Exp Neurol 2019; 317:291-297. [PMID: 30928388 PMCID: PMC6544502 DOI: 10.1016/j.expneurol.2019.03.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 03/22/2019] [Accepted: 03/26/2019] [Indexed: 12/18/2022]
Abstract
Cerebral autoregulation is impaired after traumatic brain injury (TBI), contributing to poor outcome. In the context of the neurovascular unit, cerebral autoregulation contributes to neuronal cell integrity and clinically Glasgow Coma Scale is correlated to intactness of autoregulation after TBI. Cerebral Perfusion Pressure (CPP) is often normalized by use of vasoactive agents to increase mean arterial pressure (MAP) and thereby limit impairment of cerebral autoregulation and neurological deficits. However, current vasoactive agent choice used to elevate MAP to increase CPP after TBI is variable. Vasoactive agents, such as phenylephrine, dopamine, norepinephrine, and epinephrine, clinically have not sufficiently been compared regarding effect on CPP, autoregulation, and survival after TBI. The cerebral effects of these clinically commonly used vasoactive agents are incompletely understood. This review will describe translational studies using a more human like animal model (the pig) of TBI to identify better therapeutic strategies to improve outcome post injury. These studies also investigated the role of age and sex in outcome and mechanism(s) involved in improvement of outcome in the setting of TBI. Additionally, this review considers use of inhaled nitric oxide as a novel neuroprotective strategy in treatment of TBI.
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Affiliation(s)
- William M Armstead
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA l9l04, United States of America; Pharmacology, University of Pennsylvania, Philadelphia, PA l9l04, United States of America.
| | - Monica S Vavilala
- Department of Anesthesiology, Pediatrics, and Neurological Surgery, Harborview Injury Prevention and Research Center, University of Washington, Seattle, WA, United States of America
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Armstead WM, Vavilala MS. Improving Understanding and Outcomes of Traumatic Brain Injury Using Bidirectional Translational Research. J Neurotrauma 2019; 37:2372-2380. [PMID: 30834818 DOI: 10.1089/neu.2018.6119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent clinical trials in traumatic brain injury (TBI) have failed to demonstrate therapeutic effects even when there appears to be good evidence for efficacy in one or more appropriate pre-clinical models. While existing animal models mimic the injury, difficulties in translating promising therapeutics are exacerbated by the lack of alignment of discrete measures of the underlying injury pathology between the animal models and human subjects. To address this mismatch, we have incorporated reverse translation of bedside experience to inform pre-clinical studies in a large animal (pig) model of TBI that mirror practical clinical assessments. Cerebral autoregulation is impaired after TBI, contributing to poor outcome. Cerebral perfusion pressure (CPP) is often normalized by use of vasoactive agents to increase mean arterial pressure (MAP) and thereby limit impairment of cerebral autoregulation and neurological deficits. Vasoactive agents clinically used to elevate MAP to increase CPP after TBI, such as phenylephrine (Phe), dopamine (DA), norepinephrine (NE), and epinephrine (EPI), however, have not been compared sufficiently regarding effect on CPP, autoregulation, and survival after TBI, and clinically, current vasoactive agent use is variable. The cerebral effects of these clinically commonly used vasoactive agents are not known. This review will emphasize pediatric work and will describe bidirectional translational studies using a more human-like animal model of TBI to identify better therapeutic strategies to improve outcome post-injury. These studies in addition investigated the mechanism(s) involved in improvement of outcome in the setting of TBI.
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Affiliation(s)
- William M Armstead
- Department of Anesthesiology and Critical Care and University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Monica S Vavilala
- Department of Anesthesiology, Pediatrics, and Neurological Surgery, and Harborview Injury Prevention and Research Center, University of Washington, Seattle, Washington, USA
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Kacprzak M, Sawosz P, Weigl W, Milej D, Gerega A, Liebert A. Frequency analysis of oscillations in cerebral hemodynamics measured by time domain near infrared spectroscopy. BIOMEDICAL OPTICS EXPRESS 2019; 10:761-771. [PMID: 30800513 PMCID: PMC6377883 DOI: 10.1364/boe.10.000761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/23/2018] [Accepted: 12/23/2018] [Indexed: 05/21/2023]
Abstract
In this paper, we propose the application of time-domain near-infrared spectroscopy to the assessment of oscillations in cerebral hemodynamics. These oscillations were observed in the statistical moments of the distributions of time of flight of photons (DTOFs) measured on the head. We analyzed the zeroth and second centralized moments of DTOFs (total number of photons and variance) to obtain their spectra to provide parameters for the frequency components of microcirculation, which differ between the extracerebral and intracerebral layers of the head. Analysis of these moments revealed statistically significant differences between a control group of healthy subjects and a group of patients with severe neurovascular disorders, which is a promising result for the assessment of cerebral microcirculation and cerebral autoregulation mechanisms.
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Affiliation(s)
- Michal Kacprzak
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences Trojdena 4, 02-109 Warsaw, Poland
| | - Piotr Sawosz
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences Trojdena 4, 02-109 Warsaw, Poland
| | - Wojciech Weigl
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska Hospital, 751 85 Uppsala, Sweden
| | - Daniel Milej
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences Trojdena 4, 02-109 Warsaw, Poland
- Department of Medical Biophysics, Western University, London, Ontario N6A 5C1, Canada
- Imaging Division, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada
| | - Anna Gerega
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences Trojdena 4, 02-109 Warsaw, Poland
| | - Adam Liebert
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences Trojdena 4, 02-109 Warsaw, Poland
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Stok WJ, Karemaker JM, Berecki‐Gisolf J, Immink RV, van Lieshout JJ. Slow sinusoidal tilt movements demonstrate the contribution to orthostatic tolerance of cerebrospinal fluid movement to and from the spinal dural space. Physiol Rep 2019; 7:e14001. [PMID: 30810293 PMCID: PMC6391715 DOI: 10.14814/phy2.14001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 01/11/2019] [Indexed: 11/24/2022] Open
Abstract
Standing up elicits a host of cardiovascular changes which all affect the cerebral circulation. Lowered mean arterial blood pressure (ABP) at brain level, change in the cerebral venous outflow path, lowered end-tidal PCO2 (PET CO2 ), and intracranial pressure (ICP) modify cerebral blood flow (CBF). The question we undertook to answer is whether gravity-induced blood pressure (BP) changes are compensated in CBF with the same dynamics as are spontaneous or induced ABP changes in a stable position. Twenty-two healthy subjects (18/4 m/f, 40 ± 8 years) were subjected to 30° and 70° head-up tilt (HUT) and sinusoidal tilts (SinTilt, 0°↨60° around 30° at 2.5-10 tilts/min). Additionally, at those three tilt levels, they performed paced breathing at 6-15 breaths/min to induce larger than spontaneous cardiovascular oscillations. We measured continuous finger BP and cerebral blood flow velocity (CBFv) in the middle cerebral artery by transcranial Doppler to compute transfer functions (TFs) from ABP- to CBFv oscillations. SinTilt induces the largest ABP oscillations at brain level with CBFv gains strikingly lower than for paced breathing or spontaneous variations. This would imply better autoregulation for dynamic gravitational changes. We demonstrate in a mathematical model that this difference is explained by ICP changes due to movement of cerebrospinal fluid (CSF) into and out of the spinal dural sack. Dynamic cerebrovascular autoregulation seems insensitive to how BP oscillations originate if the effect of ICP is factored in. CSF-movement in-and-out of the spinal dural space contributes importantly to orthostatic tolerance by its effect on cerebral perfusion pressure.
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Affiliation(s)
- Wim J. Stok
- Department of Medical BiologySection Systems PhysiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
- Department of Medical BiologyLaboratory for Clinical Cardiovascular PhysiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
| | - John M. Karemaker
- Department of Medical BiologySection Systems PhysiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
| | - Janneke Berecki‐Gisolf
- Department of Medical BiologySection Systems PhysiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
- Present address:
Monash University Accident Research Centre (Vic Injury Surveillance Unit)Monash University Clayton CampusClaytonVictoriaAustralia
| | - Rogier V. Immink
- Department of AnesthesiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
| | - Johannes J. van Lieshout
- Department of Medical BiologyLaboratory for Clinical Cardiovascular PhysiologyAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
- Department of Internal MedicineAmsterdam UMCLocation AMCUniversity of AmsterdamAmsterdamThe Netherlands
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Hamner JW, Ishibashi K, Tan CO. Revisiting human cerebral blood flow responses to augmented blood pressure oscillations. J Physiol 2019; 597:1553-1564. [PMID: 30633356 DOI: 10.1113/jp277321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 01/10/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cerebral autoregulation is most effective in buffering against pressure fluctuations slower than 0.03 Hz (∼30 s). This suggests that frequency bands for characterizing cerebral autoregulation should be redefined Low cross-spectral coherence below 0.03 Hz highlights the limitations of transfer function approaches Haemodynamic changes induced by lower body pressure could not fully explain the differences in autoregulation estimated from spontaneous vs. augmented fluctuations, and thus, observations of spontaneous fluctuations should not be relied on whenever possible. ABSTRACT There is currently little empirical basis for time scales that are considered to be most significant in cerebrovascular counter-regulation of changes in arterial pressure. Although it is well established that cerebral autoregulation behaves as a 'high-pass' filter, recommended frequency bands have been largely arbitrarily determined. To test effectiveness of cerebral autoregulation, we refined oscillatory lower body pressure (LBP) to augment resting pressure fluctuations below 0.1 Hz by a factor of two in 13 young male volunteers, and thoroughly characterized the time and frequency responses of cerebral autoregulation. We observed that despite a threefold increase in arterial pressure power <0.03 Hz with oscillatory LBP, there was no change in cerebral blood flow power, indicating near perfect counter-regulation. By contrast, in the range 0.03-0.10 Hz, both cerebral blood flow and arterial pressure power more than doubled. Our data demonstrate that cerebral autoregulation is most effective in buffering against pressure fluctuations slower than 0.03 Hz (∼30 s). This suggests that frequency bands of interest should be redefined and recording length should be increased considerably to account for this. Furthermore, low cross-spectral coherence below 0.03 Hz, even when pressure fluctuations were augmented, highlights the uncertainty in transfer function approaches and the need to either report precision or use non-linear approaches. Finally, haemodynamic changes induced by LBP could not fully explain the differences in autoregulation estimated from spontaneous vs. augmented fluctuations, and thus, observations of spontaneous fluctuations should not be relied on whenever possible.
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Affiliation(s)
- J W Hamner
- Cerebrovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, MA, USA
| | - Keita Ishibashi
- Graduate School of Engineering, Chiba University, Chiba, Japan
| | - Can Ozan Tan
- Cerebrovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, MA, USA.,Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA
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Panerai RB, Haunton VJ, Minhas JS, Robinson TG. Inter-subject analysis of transfer function coherence in studies of dynamic cerebral autoregulation. Physiol Meas 2018; 39:125006. [DOI: 10.1088/1361-6579/aaf160] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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MRI-related anxiety in healthy individuals, intrinsic BOLD oscillations at 0.1 Hz in precentral gyrus and insula, and heart rate variability in low frequency bands. PLoS One 2018; 13:e0206675. [PMID: 30475859 PMCID: PMC6261029 DOI: 10.1371/journal.pone.0206675] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 10/17/2018] [Indexed: 12/20/2022] Open
Abstract
Participation in magnetic resonance imaging (MRI) scanning is associated with increased anxiety, thus possibly impacting baseline recording for functional MRI studies. The goal of the paper is to elucidate the significant hemispheric asymmetry between blood-oxygenation-level-dependent (BOLD) signals from precentral gyrus (PCG) and insula in 23 healthy individuals without any former MRI experience recently published in a PLOSONE paper. In addition to BOLD signals state anxiety and heart rate variability (HRV) were analyzed in two resting state sessions (R1, R2). Phase-locking and time delays from BOLD signals were computed in the frequency band 0.07-0.13 Hz. Positive (pTD) and negative time delays (nTD) were found. The pTD characterize descending neural BOLD oscillations spreading from PCG to insula and nTD characterize ascending vascular BOLD oscillations related to blood flow in the middle cerebral artery. HRV power in two low frequency bands 0.06-0.1 Hz and 0.1-0.14 Hz was computed. Based on the anxiety change from R1 to R2, two groups were separated: one with a strong anxiety decline (large change group) and one with a moderate decline or even anxiety increase (small change group). A significant correlation was found only between the left-hemispheric time delay (pTD, nTD) and anxiety change, with a dominance of nTD in the large change group. The analysis of within-scanner HRV revealed a pronounced increase of low frequency power between both resting states, dominant in the band 0.06-0.1 Hz in the large change group and in the band 0.1-0.14 Hz in the small change group. These results suggest different mechanisms related to anxiety processing in healthy individuals. One mechanism (large anxiety change) could embrace an increase of blood circulation in the territory of the left middle cerebral artery (vascular BOLD) and another (small anxiety change) translates to rhythmic central commands (neural BOLD) in the frequency band 0.1-0.14 Hz.
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Pais-Roldán P, Biswal B, Scheffler K, Yu X. Identifying Respiration-Related Aliasing Artifacts in the Rodent Resting-State fMRI. Front Neurosci 2018; 12:788. [PMID: 30455623 PMCID: PMC6230988 DOI: 10.3389/fnins.2018.00788] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/12/2018] [Indexed: 12/31/2022] Open
Abstract
Resting-state functional magnetic resonance imaging (rs-fMRI) combined with optogenetics and electrophysiological/calcium recordings in animal models is becoming a popular platform to investigate brain dynamics under specific neurological states. Physiological noise originating from the cardiac and respiration signal is the dominant interference in human rs-fMRI and extensive efforts have been made to reduce these artifacts from the human data. In animal fMRI studies, physiological noise sources including the respiratory and cardiorespiratory artifacts to the rs-fMRI signal fluctuation have typically been less investigated. In this article, we demonstrate evidence of aliasing effects into the low-frequency rs-fMRI signal fluctuation mainly due to respiration-induced B0 offsets in anesthetized rats. This aliased signal was examined by systematically altering the fMRI sampling rate, i.e., the time of repetition (TR), in free-breathing conditions and by adjusting the rate of ventilation. Anesthetized rats under ventilation showed a significantly narrower frequency bandwidth of the aliasing effect than free-breathing animals. It was found that the aliasing effect could be further reduced in ventilated animals with a muscle relaxant. This work elucidates the respiration-related aliasing effects on the rs-fMRI signal fluctuation from anesthetized rats, indicating non-negligible physiological noise needed to be taken care of in both awake and anesthetized animal rs-fMRI studies.
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Affiliation(s)
- Patricia Pais-Roldán
- High-Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tuebingen, Tuebingen, Germany
| | - Bharat Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
| | - Klaus Scheffler
- High-Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Department for Biomedical Magnetic Resonance, University of Tuebingen, Tuebingen, Germany
| | - Xin Yu
- High-Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States
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Ogoh S, Yoo JK, Badrov MB, Parker RS, Anderson EH, Wiblin JL, North CS, Suris A, Fu Q. Cerebral blood flow regulation and cognitive function in women with posttraumatic stress disorder. J Appl Physiol (1985) 2018; 125:1627-1635. [DOI: 10.1152/japplphysiol.00502.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Posttraumatic stress disorder (PTSD) is associated with structural and functional alterations in a number of interacting brain regions, but the physiological mechanism for the high risk of cerebrovascular disease or impairment in brain function remains unknown. Women are more likely to develop PTSD after a trauma than men. We hypothesized that cerebral blood flow (CBF) regulation is impaired in women with PTSD, and it is associated with impairment in cognitive function. To test our hypothesis, we examined dynamic cerebral autoregulation (CA) and cognitive function by using a transfer function analysis between arterial pressure and middle cerebral artery blood velocity and the Stroop Color and Word test (SCWT), respectively. We did not observe any different responses in these hemodynamic variables between women with PTSD ( n = 15) and healthy counterparts (all women; n = 8). Cognitive function was impaired in women with PTSD; specifically, reaction time for the neutral task of SCWT was longer in women with PTSD compared with healthy counterparts ( P = 0.011), but this cognitive dysfunction was not affected by orthostatic stress. On the other hand, transfer function phase, gain, and coherence were not different between groups in either the supine or head-up tilt (60°) position, or even during the cognitive challenge, indicating that dynamic CA was well maintained in women with PTSD. In addition, there was no relationship between cognitive function and dynamic CA. These findings suggest that PTSD-related cognitive dysfunction may not be due to compromised CBF regulation. NEW & NOTEWORTHY Cognitive function was impaired; however, dynamic cerebral autoregulation (CA) as an index of cerebral blood flow regulation was not impaired during supine and 60° head-up tilt in women with PTSD compared with healthy females. In addition, there was no relationship between cognitive function and dynamic CA. These findings suggest that the mechanism of PTSD-related cognitive dysfunction may not be due to CBF regulation.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Jeung-Ki Yoo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mark B. Badrov
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Rosemary S. Parker
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas
| | - Elizabeth H. Anderson
- University of Texas Southwestern Medical Center, Dallas, Texas
- Veterans Affairs North Texas Health Care System, Dallas, Texas
| | - Jessica L. Wiblin
- University of Texas Southwestern Medical Center, Dallas, Texas
- Veterans Affairs North Texas Health Care System, Dallas, Texas
| | - Carol S. North
- Metrocare Services and the University of Texas Southwestern Medical Center, Dallas, Texas
| | - Alina Suris
- University of Texas Southwestern Medical Center, Dallas, Texas
- Veterans Affairs North Texas Health Care System, Dallas, Texas
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
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Truijen J, Rasmussen LS, Kim YS, Stam J, Stok WJ, Pott FC, van Lieshout JJ. Cerebral autoregulatory performance and the cerebrovascular response to head-of-bed positioning in acute ischaemic stroke. Eur J Neurol 2018; 25:1365-e117. [PMID: 29935041 PMCID: PMC6220945 DOI: 10.1111/ene.13737] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 06/19/2018] [Indexed: 11/28/2022]
Abstract
Background and purpose Cerebrovascular responses to head‐of‐bed positioning in patients with acute ischaemic stroke are heterogeneous, questioning the applicability of general recommendations on head positioning. Cerebral autoregulation is impaired to various extents after acute stroke, although it is unknown whether this affects cerebral perfusion during posture change. We aimed to elucidate whether the cerebrovascular response to head position manipulation depends on autoregulatory performance in patients with ischaemic stroke. Methods The responses of bilateral transcranial Doppler ultrasound‐determined cerebral blood flow velocity (CBFV) and local cerebral blood volume (CBV), assessed by near‐infrared spectroscopy of total hemoglobin tissue concentration ([total Hb]), to head‐of‐bed lowering from 30° to 0° were determined in 39 patients with acute ischaemic stroke and 17 reference subjects from two centers. Cerebrovascular autoregulatory performance was expressed as the phase difference of the arterial pressure‐to‐CBFV transfer function. Results Following head‐of‐bed lowering, CBV increased in the reference subjects only ([total Hb]: + 2.1 ± 2.0 vs. + 0.4 ± 2.6 μM; P < 0.05), whereas CBFV did not change in either group. CBV increased upon head‐of‐bed lowering in the hemispheres of patients with autoregulatory performance <50th percentile compared with a decrease in the hemispheres of patients with better autoregulatory performance ([total Hb]: +1.0 ± 1.3 vs. −0.5 ± 1.0 μM; P < 0.05). The CBV response was inversely related to autoregulatory performance (r = −0.68; P < 0.001) in the patients, whereas no such relation was observed for CBFV. Conclusion This study is the first to provide evidence that cerebral autoregulatory performance in patients with acute ischaemic stroke affects the cerebrovascular response to changes in the position of the head.
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Affiliation(s)
- J Truijen
- Department of Internal Medicine, Waterlandziekenhuis, Purmerend.,Medical Biology, Laboratory for Cardiovascular Physiology, AMC Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - L S Rasmussen
- Bispebjerg Hospital Research Unit for Anesthesia and Intensive Care, University of Copenhagen, Copenhagen, Denmark
| | - Y S Kim
- Medical Biology, Laboratory for Cardiovascular Physiology, AMC Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Nephrology, VU University Medical Center, Amsterdam
| | - J Stam
- Stroke Unit, Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam
| | - W J Stok
- Medical Biology, Laboratory for Cardiovascular Physiology, AMC Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - F C Pott
- Bispebjerg Hospital Research Unit for Anesthesia and Intensive Care, University of Copenhagen, Copenhagen, Denmark
| | - J J van Lieshout
- Medical Biology, Laboratory for Cardiovascular Physiology, AMC Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,MRC/ARUK Centre for Musculoskeletal Ageing Research, School of Life Sciences, The Medical School, Queen's Medical Centre, University of Nottingham Medical School, Nottingham, UK
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Pfurtscheller G, Schwarz G, Schwerdtfeger A. Heart rate variability and impact of central pacemaker on cardiac activity. Clin Neurophysiol 2018; 129:2188-2190. [PMID: 30077523 DOI: 10.1016/j.clinph.2018.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 07/20/2018] [Accepted: 07/20/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Gert Pfurtscheller
- Institute of Neural Engineering, University of Technology Graz, Austria.
| | - Gerhard Schwarz
- Division of Special Anesthesiology, Pain and Intensive Care Medicine of Department of Anesthesiology and Intensive Care Medicine, Medical University of Graz, Austria.
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Janzarik WG, Gerber AK, Markfeld-Erol F, Sommerlade L, Allignol A, Reinhard M. No long-term impairment of cerebral autoregulation after preeclampsia. Pregnancy Hypertens 2018; 13:171-173. [DOI: 10.1016/j.preghy.2018.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 04/19/2018] [Accepted: 06/10/2018] [Indexed: 10/14/2022]
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