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Olsen MH, Riberholt CG, Berg RMG, Møller K. Myths and methodologies: Assessment of dynamic cerebral autoregulation by the mean flow index. Exp Physiol 2024; 109:614-623. [PMID: 38376110 PMCID: PMC10988760 DOI: 10.1113/ep091327] [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: 10/06/2023] [Accepted: 01/17/2024] [Indexed: 02/21/2024]
Abstract
The mean flow index-usually referred to as Mx-has been used for assessing dynamic cerebral autoregulation (dCA) for almost 30 years. However, concerns have arisen regarding methodological consistency, construct and criterion validity, and test-retest reliability. Methodological nuances, such as choice of input (cerebral perfusion pressure, invasive or non-invasive arterial pressure), pre-processing approach and artefact handling, significantly influence mean flow index values, and previous studies correlating mean flow index with other established dCA metrics are confounded by inherent methodological flaws like heteroscedasticity, while the mean flow index also fails to discriminate individuals with presumed intact versus impaired dCA (discriminatory validity), and its prognostic performance (predictive validity) across various conditions remains inconsistent. The test-retest reliability, both within and between days, is generally poor. At present, no single approach for data collection or pre-processing has proven superior for obtaining the mean flow index, and caution is advised in the further use of mean flow index-based measures for assessing dCA, as current evidence does not support their clinical application.
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Affiliation(s)
- Markus Harboe Olsen
- Department of Neuroanaesthesiology, The Neuroscience CentreCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
| | - Christian Gunge Riberholt
- Department of Neuroanaesthesiology, The Neuroscience CentreCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
- Department of Brain and Spinal Cord Injury, The Neuroscience CentreCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
| | - Ronan M. G. Berg
- Department of Clinical Physiology and Nuclear MedicineCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
- Centre for Physical Activity ResearchCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
- Department of Biomedical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Kirsten Møller
- Department of Neuroanaesthesiology, The Neuroscience CentreCopenhagen University Hospital − RigshospitaletCopenhagenDenmark
- Department of Clinical Medicine, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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2
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Ramachandran RV, Subramaniam B. Pro: Individualized Optimal Perfusion Pressure-Maximizing Patient Care During Cardiopulmonary Bypass. J Cardiothorac Vasc Anesth 2024; 38:563-565. [PMID: 38065696 DOI: 10.1053/j.jvca.2023.10.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 10/03/2023] [Accepted: 10/21/2023] [Indexed: 01/27/2024]
Abstract
Cardiopulmonary bypass (CPB) has revolutionized cardiac surgery but poses challenges such as hemodynamic instability and adverse clinical outcomes. Achieving optimal perfusion during CPB ensures adequate oxygen delivery to vital organs. Although mean arterial pressure is a key determinant of perfusion pressure, clear guidelines for optimal perfusion have yet to be established. Autoregulation, the organ's ability to maintain consistent blood flow, plays a vital role in perfusion. Individual variability in autoregulation responses and intraoperative factors necessitate an individualized approach to determining the autoregulation range. Continuous assessment of autoregulation during surgery allows for personalized perfusion targets, optimizing organ perfusion. Exploring techniques like multimodal intravenous anesthesia guided by electroencephalogram can enhance perfusion maintenance within the auto-regulatory range. By adopting an individualized approach to perfusion targets on CPB, we can improve outcomes and enhance patient care.
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3
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Ayasse T, Duranteau J, Harrois A, Pochard J. Cerebral autoregulation: every step counts. Crit Care 2023; 27:311. [PMID: 37553671 PMCID: PMC10410882 DOI: 10.1186/s13054-023-04595-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 08/01/2023] [Indexed: 08/10/2023] Open
Affiliation(s)
- Timothée Ayasse
- Department of Anaesthesia and Critical Care, AP-HP, Hôpital Kremlin Bicêtre, 94276, Le Kremlin Bicêtre, France.
| | - Jacques Duranteau
- Department of Anaesthesia and Critical Care, AP-HP, Hôpital Kremlin Bicêtre, 94276, Le Kremlin Bicêtre, France
- Inserm, UMRS 999, Université Paris Saclay, 94276, Le Kremlin Bicêtre, France
| | - Anatole Harrois
- Department of Anaesthesia and Critical Care, AP-HP, Hôpital Kremlin Bicêtre, 94276, Le Kremlin Bicêtre, France
- Inserm, UMRS 999, Université Paris Saclay, 94276, Le Kremlin Bicêtre, France
| | - Jonas Pochard
- Department of Anaesthesia and Critical Care, AP-HP, Hôpital Kremlin Bicêtre, 94276, Le Kremlin Bicêtre, France
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Dos Santos KRM, Katsidoniotaki MI, Miller EC, Petersen NH, Marshall RS, Kougioumtzoglou IA. Reduced-order modeling and analysis of dynamic cerebral autoregulation via diffusion maps. Physiol Meas 2023; 44:044001. [PMID: 36963111 DOI: 10.1088/1361-6579/acc780] [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: 12/19/2022] [Accepted: 03/24/2023] [Indexed: 03/26/2023]
Abstract
Objective.A data-driven technique for parsimonious modeling and analysis of dynamic cerebral autoregulation (DCA) is developed based on the concept of diffusion maps. Specifically, first, a state-space description of DCA dynamics is considered based on arterial blood pressure, cerebral blood flow velocity, and their time derivatives. Next, an eigenvalue analysis of the Markov matrix of a random walk on a graph over the dataset domain yields a low-dimensional representation of the intrinsic dynamics. Further dimension reduction is made possible by accounting only for the two most significant eigenvalues. The value of their ratio indicates whether the underlying system is governed by active or hypoactive dynamics, indicating healthy or impaired DCA function, respectively. We assessed the reliability of the technique by considering healthy individuals and patients with unilateral internal carotid artery (ICA) stenosis or occlusion. We computed the sensitivity of the technique to detect the presumed side-to-side difference in the DCA function of the second group (assuming hypoactive dynamics on the occluded or stenotic side), using McNemar's chi square test. The results were compared with transfer function analysis (TFA). The performance of the two methods was also compared under the assumption of missing data.Main results.Both diffusion maps and TFA suggested a physiological side-to-side difference in the DCA of ICA stenosis or occlusion patients with a sensitivity of 81% and 71%, respectively. Further, both two methods suggested the difference between the occluded or stenotic side and any two sides of the healthy group. However, the diffusion maps captured additional difference between the unoccluded side and the healthy group, that TFA did not. Furthermore, compared to TFA, diffusion maps exhibited superior performance when subject to missing data.Significance.The eigenvalues ratio derived using the diffusion maps technique can be potentially used as a reliable and robust biomarker for assessing how active the intrinsic dynamics of the autoregulation is and for indicating healthy versus impaired DCA function.
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Affiliation(s)
- K R M Dos Santos
- Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - M I Katsidoniotaki
- Department of Civil Engineering and Engineering Mechanics, Columbia University, New York, NY, United States of America
| | - E C Miller
- Neurology-Stroke Division, Neurological Institute of New York, Columbia University Medical Center, New York, NY, United States of America
| | - N H Petersen
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States of America
| | - R S Marshall
- Neurology-Stroke Division, Neurological Institute of New York, Columbia University Medical Center, New York, NY, United States of America
| | - I A Kougioumtzoglou
- Department of Civil Engineering and Engineering Mechanics, Columbia University, New York, NY, United States of America
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Trimmel NE, Podgoršak A, Oertel MF, Jucker S, Arras M, Schmid Daners M, Weisskopf M. Venous dynamics in anesthetized sheep govern postural-induced changes in cerebrospinal fluid pressure comparable to those in humans. Physiol Rep 2022; 10:e15525. [PMID: 36541216 PMCID: PMC9768641 DOI: 10.14814/phy2.15525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/01/2022] [Accepted: 11/11/2022] [Indexed: 06/17/2023] Open
Abstract
Sheep are popular large animals in which to model human disorders and to study physiological processes such as cerebrospinal fluid dynamics. However, little is known about vascular compensatory mechanisms affecting cerebrospinal fluid pressures during acute postural changes in sheep. Six female white Alpine sheep were anesthetized to investigate the interactions of the vascular and cerebrospinal fluid system by acquiring measurements of intracranial pressure and central and jugular venous pressure during passive postural changes induced by a tilt table. The cross-sectional area of the common jugular vein and venous blood flow velocity was recorded. Anesthetized sheep showed bi-phasic effects of postural changes on intracranial pressure during tilting. A marked collapse of the jugular vein was observed during head-over-body tilting; this is in accordance with findings in humans. Active regulatory effects of the arterial system on maintaining cerebral perfusion pressure were observed independent of tilting direction. Conclusion: Anesthetized sheep show venous dynamics in response to posture-induced changes in intracranial pressure that are comparable with those in humans.
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Affiliation(s)
- Nina Eva Trimmel
- Center for Surgical ResearchUniversity Hospital Zurich, University of ZurichZurichSwitzerland
| | - Anthony Podgoršak
- Department of Mechanical and Process Engineering, ETH ZurichZurichSwitzerland
| | - Markus Florian Oertel
- Department of NeurosurgeryUniversity Hospital Zurich, University of ZurichZurichSwitzerland
| | - Simone Jucker
- Center for Surgical ResearchUniversity Hospital Zurich, University of ZurichZurichSwitzerland
| | - Margarete Arras
- Center for Surgical ResearchUniversity Hospital Zurich, University of ZurichZurichSwitzerland
| | | | - Miriam Weisskopf
- Center for Surgical ResearchUniversity Hospital Zurich, University of ZurichZurichSwitzerland
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A novel computational model for cerebral blood flow rate control mechanisms to evaluate physiological cases. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2022.103851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kim J, Ha EJ, Kim HS, Park EY, Lee HC, Choo YH, Shim Y, Kim K, Kim K, Lee SB. Real-Time Evaluation of Cerebral Autoregulation Based on Near-Infrared Spectroscopy to Predict Clinical Outcome after Bypass Surgery in Moyamoya Disease. BIOMED RESEARCH INTERNATIONAL 2022; 2022:3091660. [PMID: 37251497 PMCID: PMC10212684 DOI: 10.1155/2022/3091660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 07/16/2022] [Accepted: 08/09/2022] [Indexed: 12/07/2023]
Abstract
Impaired cerebral autoregulation (CA) can cause negative outcomes in neurological conditions. Real-time CA monitoring can predict and thereby help prevent postoperative complications for neurosurgery patients, especially those suffering from moyamoya disease (MMD). We applied the concept of moving average to the correlation between mean arterial blood pressure (MBP) and cerebral oxygen saturation (SCO2) to monitor CA in real time, revealing optimal window size for the moving average. The experiment was conducted with 68 surgical vital-sign records containing MBP and SCO2. To evaluate CA, the cerebral oximetry index (COx) and coherence obtained from transfer function analysis (TFA) were calculated and compared between patients with postoperative infarction and those who without. For real-time monitoring, the moving average was applied to COx and coherence to determine the differences between groups, and the optimal moving-average window size was identified. The average COx and coherence within the very-low-frequency (VLF) range (0.02-0.07 Hz) during the entire surgery were significantly different between the groups (COx: AUROC = 0.78, p = 0.003; coherence: AUROC = 0.69, p = 0.029). For the case of real-time monitoring, COx showed a reasonable performance (AUROC > 0.74) with moving-average window sizes larger than 30 minutes. Coherence showed an AUROC > 0.7 for time windows of up to 60 minutes; however, for windows larger than this threshold, the performance became unstable. With an appropriate window size, COx showed stable performance as a predictor of postoperative infarction in MMD patients.
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Affiliation(s)
- Junmo Kim
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Eun-Jin Ha
- Department of Critical Care Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Hee-Soo Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Eun-Young Park
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Hyung-Chul Lee
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Yoon-Hee Choo
- Department of Neurosurgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Youngbo Shim
- Department of Critical Care Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Kwangsoo Kim
- Transdisciplinary Department of Medicine and Advanced Technology, Seoul National University Hospital, Seoul 03080, Republic of Korea
- Department of Medicine, College of Medicine, Seoul National University, Seoul 03080, Republic of Korea
| | - Keewon Kim
- Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Seung-Bo Lee
- Department of Medical Informatics, Keimyung University School of Medicine, Daegu 42403, Republic of Korea
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What Are We Measuring? A Refined Look at the Process of Disrupted Autoregulation and the Limitations of Cerebral Perfusion Pressure in Preventing Secondary Injury after Traumatic Brain Injury. Clin Neurol Neurosurg 2022; 221:107389. [PMID: 35961231 DOI: 10.1016/j.clineuro.2022.107389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 11/23/2022]
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Caldas J, Quispe-Cornejo AA, Crippa IA, Subira C, Creteur J, Panerai R, Taccone FS. Cerebral Autoregulation Indices Are Not Interchangeable in Patients With Sepsis. Front Neurol 2022; 13:760293. [PMID: 35350400 PMCID: PMC8957883 DOI: 10.3389/fneur.2022.760293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/26/2022] [Indexed: 12/21/2022] Open
Abstract
Introduction Dynamic cerebral autoregulation (dCA) is frequently altered in patients with sepsis and may be associated with sepsis-associated brain dysfunction. However, the optimal index to quantify dCA in patients with sepsis is currently unknown. Objective To assess the agreement between two validated dCA indices in patients with sepsis. Methods Retrospective analysis of prospectively collected data in patients with sepsis; those with acute or chronic intracranial disease, arrhythmias, mechanical cardiac support, or history of supra-aortic vascular disease were excluded. Transcranial Doppler was performed on the right or left middle cerebral artery (MCA) with a 2-MHz probe, and MCA blood flow velocity (FV) and arterial pressure (BP) signals were simultaneously recorded. We calculated two indices of dCA: the mean flow index (Mxa), which is the Pearson correlation coefficient between BP and FV (MATLAB, MathWorks), and the autoregulation index (ARI), which is the transfer function analysis of spontaneous fluctuations in BP and FV (custom-written FORTRAN code). Impaired dCA was defined as Mxa >0.3 or ARI ≤ 4. The agreement between the two indices was assessed by Cohen's kappa coefficient. Results We included 95 patients (age 64 ± 13 years old; male 74%); ARI was 4.38 [2.83–6.04] and Mxa was 0.32 [0.14–0.59], respectively. There was no correlation between ARI and Mxa (r = −0.08; p = 0.39). dCA was altered in 40 (42%) patients according to ARI and in 50 (53%) patients according to Mxa. ARI and Mxa were concordant in classifying 23 (24%) patients as having impaired dCA and 28 (29%) patients as having intact dCA. Cohen's kappa coefficient was 0.08, suggesting poor agreement. ARI was altered more frequently in patients on mechanical ventilation than others (27/52, 52% vs. 13/43, 30%, p = 0.04), whereas Mxa did not differ between those two groups. On the contrary, Mxa was altered more frequently in patients receiving sedatives than others (23/34, 68% vs. 27/61, 44%, p = 0.03), whereas ARI did not differ between these two groups. Conclusions Agreement between ARI and Mxa in assessing dCA in patients with sepsis was poor. The identification of specific factors influencing the dCA analysis might lead to a better selection of the adequate cerebral autoregulation (CAR) index in critically ill patients with sepsis.
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Affiliation(s)
- Juliana Caldas
- Escola Bahiana de Medicina e Saúde Pública, Salvador, Brazil
- Universidade de Salvador, Universidade y Faculdade Salvador (UNIFACS), Salvador, Brazil
- Instituto D'Or de Pesquisa e Ensino (IDOR), Salvador, Brazil
| | - Armin Alvaro Quispe-Cornejo
- Department of Intensive Care Unit, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
- *Correspondence: Armin Alvaro Quispe-Cornejo
| | - Ilaria Alice Crippa
- Department of Intensive Care Unit, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Carles Subira
- Department of Intensive Care Medicine, Alhaia Xarxa Assistencial Universitaria de Manresa, Barcelona, Spain
| | - Jacques Creteur
- Department of Intensive Care Unit, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Ronney Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, Leicester, United Kingdom
| | - Fabio Silvio Taccone
- Department of Intensive Care Unit, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
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Olsen MH, Capion T, Riberholt CG, Bache S, Berg RMG, Møller K. Reliability of cerebral autoregulation using different measures of perfusion pressure in patients with subarachnoid hemorrhage. Physiol Rep 2022; 10:e15203. [PMID: 35343649 PMCID: PMC8958499 DOI: 10.14814/phy2.15203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 05/29/2023] Open
Abstract
Dynamic cerebral autoregulation to spontaneous fluctuations in cerebral perfusion pressure (CPP) is often assessed by transcranial Doppler (TCD) in the time domain, yielding primarily the mean flow index (Mx), or in the frequency domain using transfer function analysis (TFA), yielding gain and phase. For both domains, the measurement of blood pressure is critical. This study assessed the inter-method reliability of dynamic cerebral autoregulation using three different methods of pressure measurement. In 39 patients with aneurysmal subarachnoid hemorrhage, non-invasive arterial blood pressure (ABP), invasive ABP (measured in the radial artery) and CPP were recorded simultaneously with TCD. Intraclass correlation coefficient (ICC) was used to quantify reliability. Mx was higher when calculated using invasive ABP (0.39; 95% confidence interval [95% CI]: 0.33; 0.44) compared to non-invasive ABP, and CPP. The overall ICC showed poor to good reliability (0.65; 95% CI: 0.11; 0.84; n = 69). In the low frequency domain, the comparison between invasively measured ABP and CPP showed good to excellent (normalized gain, ICC: 0.87, 95CI: 0.81; 0.91; n = 96; non-normalized gain: 0.89, 95% CI: 0.84; 0.92; n = 96) and moderate to good reliability (phase, ICC: 0.69, 95% CI: 0.55; 0.79; n = 96), respectively. Different methods for pressure measurement in the assessment of dynamic cerebral autoregulation yield different results and cannot be used interchangeably.
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Affiliation(s)
- Markus Harboe Olsen
- Department of NeuroanaesthesiologyThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
| | - Tenna Capion
- Department of NeurosurgeryThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
| | - Christian Gunge Riberholt
- Department of NeuroanaesthesiologyThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
- Department of Neurorehabilitation/Traumatic Brain Injury UnitThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
| | - Søren Bache
- Department of NeuroanaesthesiologyThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
| | - Ronan M. G. Berg
- Department of Clinical Physiology and Nuclear MedicineCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
- Centre for Physical Activity ResearchRigshospitaletCopenhagen University HospitalCopenhagenDenmark
- Department of Biomedical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- Neurovascular Research LaboratoryFaculty of Life Sciences and EducationUniversity of South WalesPontypriddUnited Kingdom
| | - Kirsten Møller
- Department of NeuroanaesthesiologyThe Neuroscience CentreCopenhagen University Hospital ‐ RigshospitaletCopenhagenDenmark
- Institute of Clinical MedicineFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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Olsen MH, Riberholt CG, Mehlsen J, Berg RM, Møller K. Reliability and validity of the mean flow index (Mx) for assessing cerebral autoregulation in humans: A systematic review of the methodology. J Cereb Blood Flow Metab 2022; 42:27-38. [PMID: 34617816 PMCID: PMC8721771 DOI: 10.1177/0271678x211052588] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cerebral autoregulation is a complex mechanism that serves to keep cerebral blood flow relatively constant within a wide range of cerebral perfusion pressures. The mean flow index (Mx) is one of several methods to assess dynamic cerebral autoregulation, but its reliability and validity have never been assessed systematically. The purpose of the present systematic review was to evaluate the methodology, reliability and validity of Mx.Based on 128 studies, we found inconsistency in the pre-processing of the recordings and the methods for calculation of Mx. The reliability in terms of repeatability and reproducibility ranged from poor to excellent, with optimal repeatability when comparing overlapping recordings. The discriminatory ability varied depending on the patient populations; in general, those with acute brain injury exhibited a higher Mx than healthy volunteers. The prognostic ability in terms of functional outcome and mortality ranged from chance result to moderate accuracy.Since the methodology was inconsistent between studies, resulting in varying reliability and validity estimates, the results were difficult to compare. The optimal method for deriving Mx is currently unknown.
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Affiliation(s)
- Markus Harboe Olsen
- Department of Neuroanaesthesiology, 53146Rigshospitalet, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Christian Gunge Riberholt
- Department of Neuroanaesthesiology, 53146Rigshospitalet, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Neurorehabilitation/Traumatic Brain Injury Unit, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Mehlsen
- Surgical Pathophysiology Unit, 53146Rigshospitalet, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ronan Mg Berg
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Kirsten Møller
- Department of Neuroanaesthesiology, 53146Rigshospitalet, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Liu Z, Ma H, Guo ZN, Wang L, Qu Y, Fan L, Liu X, Liu J, Zhu Y, Yang Y. Impaired dynamic cerebral autoregulation is associated with the severity of neuroimaging features of cerebral small vessel disease. CNS Neurosci Ther 2021; 28:298-306. [PMID: 34894087 PMCID: PMC8739047 DOI: 10.1111/cns.13778] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/21/2022] Open
Abstract
Aims Cerebral small vessel disease (CSVD) is characterized by functional and structural changes in small vessels. We aimed to elucidate the relationship between dynamic cerebral autoregulation (dCA) and neuroimaging characteristics of CSVD. Methods A case‐control study was performed. Cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries and spontaneous arterial blood pressure were simultaneously recorded. Transfer function analysis was used to calculate dCA parameters (phase, gain, and the rate of recovery of CBFV [RoRc]). Neuroimaging characteristics of CSVD patients were evaluated, including lacunes, white matter hyperintensities (WMH), cerebral microbleeds (CMBs), perivascular spaces (PVS), and the total CSVD burden. Results Overall, 113 patients and 83 controls were enrolled. Compared with the control group, the phase at low frequency and the RoRc in CSVD patients were lower, and the gain at very low and low frequencies were higher, indicating bilaterally impaired dCA. Total CSVD burden, WMH (total, periventricular and deep), severe PVS, and lobar CMBs were independently correlated with the phase at low frequency. Conclusions Our findings suggested that dCA was compromised in CSVD patients, and some specific neuroimaging characteristics (the total CSVD burden, WMH, severe PVS and lobar CMBs) might indicate more severe dCA impairment in CSVD patients.
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Affiliation(s)
- Zhaojun Liu
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Hongyin Ma
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Zhen-Ni Guo
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Le Wang
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Yang Qu
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Lei Fan
- Department of Neurology, The First Hospital of Hebei North University, Zhangjiakou, China
| | - Xingliang Liu
- Department of Neurology, The First Hospital of Hebei North University, Zhangjiakou, China
| | - Jie Liu
- Department of Neurology, The People's Hospital of Lixin County, Haozhou, China
| | - Yuanyuan Zhu
- Department of Neurology, The People's Hospital of Lixin County, Haozhou, China
| | - Yi Yang
- Stroke Center & Clinical Trial and Research Center for Stroke, Department of Neurology, The First Hospital of Jilin University, Changchun, China.,China National Comprehensive Stroke Center, Changchun, China.,Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
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Ye S, Yang M, Zhu Y, Gao X, Meng F, Wu R, Yu B. Numerical analysis of hemodynamic effect under different enhanced external counterpulsation (EECP) frequency for cerebrovascular disease: a simulation study. Comput Methods Biomech Biomed Engin 2021; 25:1169-1179. [PMID: 34797199 DOI: 10.1080/10255842.2021.2005034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Based on the changes in phase characteristics of blood flow and pressure, enhanced external counterpulsation (EECP) reduces cardiac load and improves cerebral perfusion in patients with cerebrovascular diseases. However, increased cerebral blood flow (CBF) is associated with the rise in blood pressure and its complications. Increased EECP frequency is a valuable solution when combined with the electrical equivalent impedance characteristics of the lumped parameter model (LPM) of the human blood circulation system. Herein, to investigate the effect of different EECP frequencies on CBF perfusion, an LPM was established with cardiopulmonary circulation and eight systemic blood flow units with cerebral autoregulation module of ischemic stroke patients. Then, using differential equations, we analyzed those parameters through hemodynamic simulations in four EECP modes. With related influencing parameters remaining constant, we adjusted the pressure frequency of EECP and found that when compared to the traditional sequential EECP mode, the relative increase rate of CBF was 16.68%, 18.95%, and 21.21% from 1 to 3 Hz, respectively. This study validates the effect of improving blood prefusion with increasing EECP frequency through numerical analysis.
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Affiliation(s)
- Siwei Ye
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Ming Yang
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yuanfei Zhu
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaochen Gao
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Fan Meng
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Ruiliang Wu
- Department of Rehabilitation, Shanghai General Hospital, Shanghai, China
| | - Bo Yu
- Department of Rehabilitation, Shanghai General Hospital, Shanghai, China
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The Effect of Data Length on the Assessment of Dynamic Cerebral Autoregulation with Transfer Function Analysis in Neurological ICU Patients. Neurocrit Care 2021; 36:21-29. [PMID: 34403122 PMCID: PMC8370057 DOI: 10.1007/s12028-021-01301-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/03/2021] [Indexed: 12/02/2022]
Abstract
Background Cerebral autoregulation plays an important role in safeguarding adequate cerebral perfusion and reducing the risk of secondary brain injury, which is highly important for patients in the neurological intensive care unit (neuro-ICU). Although the consensus white paper suggests that a minimum of 5 min of data are needed for assessing dynamic cerebral autoregulation with transfer function analysis (TFA), it remains unknown if the length of these data is valid for patients in the neuro-ICU, of whom are notably different than the general populations. We aimed to investigate the effect of data length using transcranial Doppler ultrasound combined with invasive blood pressure measurement for the assessment of dynamic cerebral autoregulation in patients in the neuro-ICU. Methods Twenty patients with various clinical conditions (severe acute encephalitis, ischemic stroke, subarachnoid hemorrhage, brain injury, cerebrovascular intervention operation, cerebral hemorrhage, intracranial space-occupying lesion, and toxic encephalopathy) were recruited for this study. Continuous invasive blood pressure, with a pressure catheter placed at the radial artery, and bilateral continuous cerebral blood flow velocity with transcranial Doppler ultrasound were simultaneously recorded for a length of 10 min for each patient. TFA was applied to derive phase shift, gain, and coherence function at all frequency bands from the first 2, 3, 4, 5, 6, 7, 8, 9, and 10 min of the 10-min recordings in each patient on both hemispheres. The variability in the autoregulatory parameters in each hemisphere was investigated by repeated measures analysis of variance. Results Forty-one recordings (82 hemispheres) were included in the study. According to the critical values of coherence provided by the Cerebral Autoregulation Research Network white paper, acceptable rates for the data were 100% with a length ≥ 7 min. The final analysis included 68 hemispheres. The effects of data length on trends in phase shift in the very low frequency (VLF) band (F1.801,120.669 = 6.321, P = 0.003), in the LF band (F1.274,85.343 = 4.290, P = 0.032), and in the HF band (F1.391,93.189 = 3.868, P = 0.039) were significant for 3–7 min, for 4–7 min, and for 5–8 min, respectively. Effects were also significant on the gain in the VLF band (F1.927,129.134 = 3.215, P = 0.045) for 2–8 min and on the coherence function in all frequency bands (VLF F2.846,190.671 = 90.247, P < 0.001, LF F2.515,168.492 = 55.770, P < 0.001, HF F2.411, 161.542 = 33.833, P < 0.001) for 2–10 min. Conclusions Considering the acceptable rates for the data and the variation in the TFA variables (phase shift and gain), we recommend recording data for a minimum length of 7 min for TFA in patients in the neuro-ICU.
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Lee YK, Rothwell PM, Payne SJ, Webb AJS. Reliability, reproducibility and validity of dynamic cerebral autoregulation in a large cohort with transient ischaemic attack or minor stroke. Physiol Meas 2020; 41:095002. [PMID: 32764198 PMCID: PMC7116588 DOI: 10.1088/1361-6579/abad49] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Objective Cerebral autoregulation (CA) is critical to maintenance of cerebral perfusion but its relevance to the risk of stroke and dementia has been under-studied due to small study sizes and a lack of consensus as to the optimal method of measurement. We determined the reliability and reproducibility of multiple CA indices and the effect of intensive data-processing in a large population with transient ischaemic attack or minor stroke. Approach Consecutive, consenting patients in the population-based OXVASC (Oxford Vascular Study) Phenotyped cohort underwent up to 10-min supine continuous blood pressure monitoring (Finometer) with bilateral middle cerebral artery (MCA) transcranial ultrasound (DWL-Dopplerbox). Un-processed waveforms (Un-A) were median-filtered, systematically reviewed, artefacts corrected and their quality blindly graded (optimal (A) to worst (E)). CA metrics were derived in time-domain (autoregulatory index (ARI), Pearson’s Mx, Sx, Dx) and in very-low (VLF) and low-frequency (LF) domains (WPS-SI: wavelet phase synchronisation, transfer function analysis), stratified by recording quality. Reliability and reproducibility (Cronbach’s Alpha) were determined comparing MCA sides and the first vs. second 5-min of monitoring. Main results In 453 patients, following manual data-cleaning, there was good reliability of indices when comparing MCA sides (Mx: 0.77; WPS-SI-VLF: 0.85; WPS-SI-LF 0.84), or repeated five minute epochs (Mx: 0.57; WPS-SI-VLF: 0.69; WPS-SI-LF 0.90), with persistently good reliability between sides even in lower quality Groups (Group D: Mx: 0.79; WPS-SI-VLF: 0.92; WPS-SI-LF: 0.91). Reliability was greatest for Pearson’s Mx and wavelet synchronisation index, with reasonable reliability of transfer function analyses, but ARI was prone to occasional, potentially defective, extreme estimates (Left vs right MCA: 0.68). Significance Resting-state measures of CA were valid, reproducible and robust to moderate noise, but require careful data-processing. Mx and wavelet synchronisation index were the most reliable indices for determining the prognostic value of CA in large epidemiological cohorts and its potential as a treatment target.
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Affiliation(s)
- Yun-Kai Lee
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, United Kingdom
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Nitzan M, Nitzan I, Arieli Y. The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation. SENSORS 2020; 20:s20174844. [PMID: 32867184 PMCID: PMC7506757 DOI: 10.3390/s20174844] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/12/2022]
Abstract
Adequate oxygen delivery to a tissue depends on sufficient oxygen content in arterial blood and blood flow to the tissue. Oximetry is a technique for the assessment of blood oxygenation by measurements of light transmission through the blood, which is based on the different absorption spectra of oxygenated and deoxygenated hemoglobin. Oxygen saturation in arterial blood provides information on the adequacy of respiration and is routinely measured in clinical settings, utilizing pulse oximetry. Oxygen saturation, in venous blood (SvO2) and in the entire blood in a tissue (StO2), is related to the blood supply to the tissue, and several oximetric techniques have been developed for their assessment. SvO2 can be measured non-invasively in the fingers, making use of modified pulse oximetry, and in the retina, using the modified Beer–Lambert Law. StO2 is measured in peripheral muscle and cerebral tissue by means of various modes of near infrared spectroscopy (NIRS), utilizing the relative transparency of infrared light in muscle and cerebral tissue. The primary problem of oximetry is the discrimination between absorption by hemoglobin and scattering by tissue elements in the attenuation measurement, and the various techniques developed for isolating the absorption effect are presented in the current review, with their limitations.
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Affiliation(s)
- Meir Nitzan
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
- Correspondence:
| | - Itamar Nitzan
- Monash Newborn, Monash Children’s Hospital, Melbourne 3168, Australia;
- Department of Neonatology, Shaare Zedek Medical Center, Shmuel Bait St 12, Jerusalem 9103102, Israel
| | - Yoel Arieli
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
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