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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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2
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Sperna Weiland NH, Hermanides J, Hollmann MW, Preckel B, Stok WJ, van Lieshout JJ, Immink RV. Novel method for intraoperative assessment of cerebral autoregulation by paced breathing. Br J Anaesth 2019; 119:1141-1149. [PMID: 29028933 DOI: 10.1093/bja/aex333] [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] [Accepted: 08/22/2017] [Indexed: 11/14/2022] Open
Abstract
Background Cerebral autoregulation (CA) is the mechanism that maintains constancy of cerebral blood flow (CBF) despite variations in blood pressure (BP). Patients with attenuated CA have been shown to have an increased incidence of peri-operative stroke. Studies of CA in anaesthetized subjects are rare, because a simple and non-invasive method to quantify the integrity of CA is not available. In this study, we set out to improve non-invasive quantification of CA during surgery. For this purpose, we introduce a novel method to amplify spontaneous BP fluctuations during surgery by imposing mechanical positive pressure ventilation at three different frequencies and quantify CA from the resulting BP oscillations. Methods Fourteen patients undergoing sevoflurane anaesthesia were included in the study. Continuous non-invasive BP and transcranial Doppler-derived CBF velocity (CBF V ) were obtained before surgery during 3 min of paced breathing at 6, 10, and 15 bpm and during surgery from mechanical positive pressure ventilation at identical frequencies. Data were analysed using frequency domain analysis to obtain CBF V -to-BP phase lead as a continuous measure of CA efficacy. Group averages were calculated. Values are means ( sd ), and P <0.05 was used to indicate statistical significance. Results Preoperative vs intraoperative CBF V -to-BP phase lead was 43 (9) vs 45 (8)°, 25 (8) vs 24 (10)°, and 4 (6) vs -2 (12)° during 6, 10, and 15 bpm, respectively (all P =NS). Conclusions During surgery, cerebral autoregulation indices were similar to values determined before surgery. This indicates that CA can be quantified reliably and non-invasively using this novel method and confirms earlier evidence that CA is unaffected by sevoflurane anaesthesia. Clinical trial registration NCT03071432.
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Affiliation(s)
- N H Sperna Weiland
- Department of Anaesthesiology.,Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
| | | | | | | | - W J Stok
- Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
| | - J J van Lieshout
- Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology.,Department of Internal Medicine, Academic Medical Centre AMC Amsterdam, University of Amsterdam, PO Box 22660, 1100DD Amsterdam, The Netherlands.,MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK
| | - R V Immink
- Department of Anaesthesiology.,Department of Medical Biology, Laboratory for Clinical Cardiovascular Physiology
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3
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Abstract
PURPOSE OF REVIEW Cerebral autoregulation (CA) is a mechanism that maintains cerebral blood flow constant despite fluctuations in systemic arterial blood pressure. This review will focus on recent studies that measured CA non-invasively in acute cerebrovascular events, a feature unique to the transcranial Doppler ultrasound. We will summarize the rationale for CA assessment in acute cerebrovascular disorders and specifically evaluate the existing data on the value of CA measures in relation to clinical severity, guiding management decisions, and prognostication. RECENT FINDINGS Existing data suggest that CA is generally impaired in various cerebrovascular disorders. In patients with small vessel ischemic stroke, CA has been shown to be impaired in both hemispheres, whereas in large territorial strokes, CA impairment has been limited to the affected hemisphere. In these latter patients, impaired CA is also predictive of secondary complications such as hemorrhagic transformation and cerebral edema, hence worse functional outcome. In patients with carotid stenosis, impaired CA may also be associated with a higher ipsilateral hemispheric stroke risk. CA is also strongly linked to outcome in patients with intracranial hemorrhage. In patients with intraparenchymal hemorrhage, CA impairment correlated with clinical and imaging severity, whereas in those with subarachnoid hemorrhage, CA measures have a predictive value for development of delayed cerebral ischemia and radiographic vasospasm. Assessment of CA is increasingly more accessible in acute cerebrovascular disorders and promises to be a valuable measure in guiding hemodynamic management and predicting secondary complication, thus enhancing the care of these patients in the acute setting.
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Affiliation(s)
- Pedro Castro
- Department of Neurology, São João Hospital Center, Porto, Portugal.,Department of Clinical Neurosciences and Mental Health, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Elsa Azevedo
- Department of Neurology, São João Hospital Center, Porto, Portugal.,Department of Clinical Neurosciences and Mental Health, Faculty of Medicine of University of Porto, Porto, Portugal
| | - Farzaneh Sorond
- Department of Neurology, Division of Stroke and Neurocritical, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Ward 12-140, Chicago, IL, 60611, USA.
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4
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Akın A. Partial correlation-based functional connectivity analysis for functional near-infrared spectroscopy signals. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-10. [PMID: 29243416 DOI: 10.1117/1.jbo.22.12.126003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 11/20/2017] [Indexed: 05/20/2023]
Abstract
A theoretical framework, a partial correlation-based functional connectivity (PC-FC) analysis to functional near-infrared spectroscopy (fNIRS) data, is proposed. This is based on generating a common background signal from a high passed version of fNIRS data averaged over all channels as the regressor in computing the PC between pairs of channels. This approach has been employed to real data collected during a Stroop task. The results show a strong significance in the global efficiency (GE) metric computed by the PC-FC analysis for neutral, congruent, and incongruent stimuli (NS, CS, IcS; GEN=0.10±0.009, GEC=0.11±0.01, GEIC=0.13±0.015, p=0.0073). A positive correlation (r=0.729 and p=0.0259) is observed between the interference of reaction times (incongruent-neutral) and interference of GE values (GEIC-GEN) computed from [HbO] signals.
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Affiliation(s)
- Ata Akın
- Acibadem University, Department of Medical Engineering, Atasehir, Istanbul, Turkey
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5
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Semenyutin VB, Asaturyan GA, Nikiforova AA, Aliev VA, Panuntsev GK, Iblyaminov VB, Savello AV, Patzak A. Predictive Value of Dynamic Cerebral Autoregulation Assessment in Surgical Management of Patients with High-Grade Carotid Artery Stenosis. Front Physiol 2017; 8:872. [PMID: 29163214 PMCID: PMC5673646 DOI: 10.3389/fphys.2017.00872] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 10/17/2017] [Indexed: 01/20/2023] Open
Abstract
Dynamic cerebral autoregulation (DCA) capacity along with the degree of internal carotid artery (ICA) stenosis and characteristics of the plaque can also play an important role in selection of appropriate treatment strategy. This study aims to classify the patients with severe ICA stenosis according to preoperative state of DCA and to assess its dynamics after surgery. Thirty-five patients with severe ICA stenosis having different clinical type of disease underwent reconstructive surgery. DCA was assessed with transfer function analysis (TFA) by calculating phase shift (PS) between Mayer waves of blood flow velocity (BFV) and blood pressure (BP) before and after operation. In 18 cases, regardless of clinical type, preoperative PS on ipsilateral side was within the normal range and did not change considerably after surgery. In other 17 cases preoperative PS was reliably lower both in patients with symptomatic and asymptomatic stenosis. Surgical reconstruction led to restoration of impaired DCA evidenced by significant increase of PS in postoperative period. Our data suggest that regardless clinical type of disease various state of DCA may be present in patients with severe ICA stenosis. This finding can contribute to establishing the optimal treatment strategy, and first of all for asymptomatic patients. Patients with compromised DCA should be considered as ones with higher risk of stroke and first candidates for reconstructive surgery.
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Affiliation(s)
- Vladimir B Semenyutin
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Gregory A Asaturyan
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Anna A Nikiforova
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Vugar A Aliev
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia.,Department of Neurosurgery, Municipal Hospital of Saint Martyr Elizabeth, Saint-Petersburg, Russia
| | - Grigory K Panuntsev
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Vadim B Iblyaminov
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Alexander V Savello
- Laboratory of Brain Circulation Pathology, Federal Almazov Medical Research Center, Saint-Petersburg, Russia
| | - Andreas Patzak
- Johannes-Mueller Institute of Physiology University Hospital Charite, Humboldt University of Berlin, Berlin, Germany
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6
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Semenyutin VB, Asaturyan GА, Nikiforova АА, Panuntsev GК, Aliev VA, Iblyaminov VB, Savello AV, Patzak А, Laptev KV, Dudanov IP, Pavlov ОА. [Severe carotid stenosis: cerebral autoregulation in the ipsilateral region]. Zh Nevrol Psikhiatr Im S S Korsakova 2017; 117:76-84. [PMID: 28884722 DOI: 10.17116/jnevro20171178176-84] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIM To study cerebral autoregulation (CA) in region of the stenotic carotid artery. MATERIAL AND METHODS The study involved 35 patients with critical stenosis of the carotid arteries, including 24 patients were asymptomatic and 11 patients with symptomatic course. Blood flow velocity in middle cerebral arteries was monitored using Multi Dop X (DWL, Germany) with simultaneous noninvasive systemic blood pressure registration (CNAP, Austria). CA was assessed by calculating the phase shift (PS) between spontaneous oscillations of blood flow velocity and blood pressure within the range of systemic Mayer waves (80-120 mHz). RESULTS In 18 patients, the CA indicators were in the normal range (PS 1.2±0.3 rad). Seventeen patients, including asymptomatic as well as symptomatic types, had impaired CA (PS 0.2±0.2 rad and 0.3±0.2 rad, respectively). Reconstructive surgery, irrespective of clinical manifestations, led to the significant increase in PS (p<0.001) in the early postoperative period (0.9±0.5 and 0.9±0.3 rad, respectively). CONCLUSION A significant variability in the cerebrovascular reserve capacity in symptomatic and asymptomatic types of carotid artery stenosis was found. CA can be used in determining the indications for surgical treatment and evaluation of its effectiveness in patients with stenosis of carotid arteries.
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Affiliation(s)
- V B Semenyutin
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - G А Asaturyan
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - А А Nikiforova
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - G К Panuntsev
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - V A Aliev
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - V B Iblyaminov
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - A V Savello
- Almazov Northwest Federal Medical Research Centre, St. Petersburg, Russia
| | - А Patzak
- Johannes-Mueller Institute of Physiology University Hospital Charite, Humboldt-University of Berlin, Berlin, Germany
| | - K V Laptev
- Municipal Mariinsky Hospital, St. Petersburg, Russia
| | - I P Dudanov
- Municipal Mariinsky Hospital, St. Petersburg, Russia
| | - О А Pavlov
- Municipal Mariinsky Hospital, St. Petersburg, Russia
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7
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Sperna Weiland NH, Brevoord D, Jöbsis DA, de Beaumont EMFH, Evers V, Preckel B, Hollmann MW, van Dieren S, de Mol BAJM, Immink RV. Cerebral oxygenation during changes in vascular resistance and flow in patients on cardiopulmonary bypass - a physiological proof of concept study. Anaesthesia 2016; 72:49-56. [DOI: 10.1111/anae.13631] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 12/17/2022]
Affiliation(s)
- N. H. Sperna Weiland
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - D. Brevoord
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - D. A. Jöbsis
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | | | - V. Evers
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - B. Preckel
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - M. W. Hollmann
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - S. van Dieren
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
| | - B. A. J. M. de Mol
- Department of Cardiothoracic Surgery; Academic Medical Center; Amsterdam The Netherlands
| | - R. V. Immink
- Department of Anaesthesiology; Academic Medical Center; Amsterdam The Netherlands
- Laboratory for Clinical Cardiovascular Physiology; Department of Anatomy and Embryology; Academic Medical Center; Amsterdam The Netherlands
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8
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Oldag A, Neumann J, Goertler M, Hinrichs H, Heinze HJ, Kupsch A, Sweeney-Reed CM, Kopitzki K. Near-infrared spectroscopy and transcranial sonography to evaluate cerebral autoregulation in middle cerebral artery steno-occlusive disease. J Neurol 2016; 263:2296-2301. [PMID: 27544503 DOI: 10.1007/s00415-016-8262-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/06/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
The measurement of autoregulatory delay by near-infrared spectroscopy (NIRS) has been proposed as an alternative technique to assess cerebral autoregulation, which is routinely assessed via transcranial Doppler sonography (TCD) in most centers. Comparitive studies of NIRS and TCD, however, are largely missing. We investigated whether cerebrovascular reserve (CVR), as assessed via TCD, correlates with the delay of the autoregulatory response to changes in arterial blood pressure (ABP) as assessed by NIRS, i.e., if impaired upstream vasomotor reactivity is reflected by downstream cortical autoregulation. Twenty patients with unilateral high-grade steno-occlusion of the middle cerebral artery (MCA) underwent bilateral multichannel NIRS of the cortical MCA distributions over a period of 6 min while breathing at a constant rate of 6 cycles/min to induce stable oscillations in ABP. The phase shift φ between ABP and cortical blood oxygenation was calculated as a measure of autoregulatory latency. In a subgroup of 13 patients, CO2 reactivity of the MCAs was determined by TCD to assess CVR in terms of normalized autoregulatory response (NAR). Mean phase shift between ABP and blood oxygenation was significantly increased over the hemisphere ipsilateral to the steno-occlusion (n = 20, p = 0.042). The interhemispheric difference Δφ in phase shift was significantly larger in patients with markedly diminished or exhausted CVR (NAR < 10) than in patients with normal NAR values (NAR ≥ 10) (p = 0.007). Within the MCA core distribution territory, a strong correlation existed between Δφ and CO2 reactivity of the affected MCA (n = 13, r = -0.78, p = 0.011). NIRS may provide an alternative or supplementary approach to evaluate cerebral autoregulation in risk assessment of ischemic events in steno-occlusive disease of cerebral arteries, especially in patients with insufficient bone windows for TCD.
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Affiliation(s)
- Andreas Oldag
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Jens Neumann
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Michael Goertler
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany
| | - Hermann Hinrichs
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany
| | - Hans-Jochen Heinze
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany.,German Center for Neurodegenerative Diseases (DZNE), Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Andreas Kupsch
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Catherine M Sweeney-Reed
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany
| | - Klaus Kopitzki
- Clinic for Neurology and Stereotactic Neurosurgery, Otto-von-Guericke University, Leipziger Strasse 44, 39120, Magdeburg, Germany. .,Leibniz Institute for Neurobiology, Brenneckestrasse 6, 39118, Magdeburg, Germany.
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9
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Haubrich C, Czosnyka M, Diehl R, Smielewski P, Czosnyka Z. Ventricular Volume Load Reveals the Mechanoelastic Impact of Communicating Hydrocephalus on Dynamic Cerebral Autoregulation. PLoS One 2016; 11:e0158506. [PMID: 27415784 PMCID: PMC4944997 DOI: 10.1371/journal.pone.0158506] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 06/16/2016] [Indexed: 11/18/2022] Open
Abstract
Several studies have shown that the progression of communicating hydrocephalus is associated with diminished cerebral perfusion and microangiopathy. If communicating hydrocephalus similarly alters the cerebrospinal fluid circulation and cerebral blood flow, both may be related to intracranial mechanoelastic properties as, for instance, the volume pressure compliance. Twenty-three shunted patients with communicating hydrocephalus underwent intraventricular constant-flow infusion with Hartmann's solution. The monitoring included transcranial Doppler (TCD) flow velocities (FV) in the middle (MCA) and posterior cerebral arteries (PCA), intracranial pressure (ICP), and systemic arterial blood pressure (ABP). The analysis covered cerebral perfusion pressure (CPP), the index of pressure-volume compensatory reserve (RAP), and phase shift angles between Mayer waves (3 to 9 cpm) in ABP and MCA-FV or PCA-FV. Due to intraventricular infusion, the pressure-volume reserve was exhausted (RAP) 0.84+/-0.1 and ICP was increased from baseline 11.5+/-5.6 to plateau levels of 20.7+/-6.4 mmHg. The ratio dRAP/dICP distinguished patients with large 0.1+/-0.01, medium 0.05+/-0.02, and small 0.02+/-0.01 intracranial volume compliances. Both M wave phase shift angles (r = 0.64; p<0.01) and CPP (r = 0.36; p<0.05) displayed a gradual decline with decreasing dRAP/dICP gradients. This study showed that in communicating hydrocephalus, CPP and dynamic cerebral autoregulation in particular, depend on the volume-pressure compliance. The results suggested that the alteration of mechanoelastic characteristics contributes to a reduced cerebral perfusion and a loss of autonomy of cerebral blood flow regulation. Results warrant a prospective TCD follow-up to verify whether the alteration of dynamic cerebral autoregulation may indicate a progression of communicating hydrocephalus.
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Affiliation(s)
- Christina Haubrich
- Department of Academic Neurosurgery, Addenbrooke’s Hospital, Cambridge, United Kingdom
- Department of Neurology, University Hospital Aachen, Aachen, Germany
- * E-mail:
| | - Marek Czosnyka
- Department of Academic Neurosurgery, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Rolf Diehl
- Department of Neurology, Alfried-Krupp-Krankenhaus, Essen, Germany
| | - Peter Smielewski
- Department of Academic Neurosurgery, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Zofia Czosnyka
- Department of Academic Neurosurgery, Addenbrooke’s Hospital, Cambridge, United Kingdom
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10
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Lang EW, Kasprowicz M, Smielewski P, Santos E, Pickard J, Czosnyka M. Short pressure reactivity index versus long pressure reactivity index in the management of traumatic brain injury. J Neurosurg 2015; 122:588-94. [DOI: 10.3171/2014.10.jns14602] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
The pressure reactivity index (PRx) correlates with outcome after traumatic brain injury (TBI) and is used to calculate optimal cerebral perfusion pressure (CPPopt). The PRx is a correlation coefficient between slow, spontaneous changes (0.003–0.05 Hz) in intracranial pressure (ICP) and arterial blood pressure (ABP). A novel index—the so-called long PRx (L-PRx)—that considers ABP and ICP changes (0.0008–0.008 Hz) was proposed.
METHODS
The authors compared PRx and L-PRx for 6-month outcome prediction and CPPopt calculation in 307 patients with TBI. The PRx- and L-PRx–based CPPopt were determined and the predictive power and discriminant abilities were compared.
RESULTS
The PRx and L-PRx correlation was good (R = 0.7, p < 0.00001; Spearman test). The PRx, age, CPP, and Glasgow Coma Scale score but not L-PRx were significant fatal outcome predictors (death and persistent vegetative state). There was a significant difference between the areas under the receiver operating characteristic curves calculated for PRx and L-PRx (0.61 ± 0.04 vs 0.51 ± 0.04; z-statistic = −3.26, p = 0.011), which indicates a better ability by PRx than L-PRx to predict fatal outcome. The CPPopt was higher for L-PRx than for PRx, without a statistical difference (median CPPopt for L-PRx: 76.9 mm Hg, interquartile range [IQR] ± 10.1 mm Hg; median CPPopt for PRx: 74.7 mm Hg, IQR ± 8.2 mm Hg). Death was associated with CPP below CPPopt for PRx (χ2 = 30.6, p < 0.00001), and severe disability was associated with CPP above CPPopt for PRx (χ2 = 7.8, p = 0.005). These relationships were not statistically significant for CPPopt for L-PRx.
CONCLUSIONS
The PRx is superior to the L-PRx for TBI outcome prediction. Individual CPPopt for L-PRx and PRx are not statistically different. Deviations between CPP and CPPopt for PRx are relevant for outcome prediction; those between CPP and CPPopt for L-PRx are not. The PRx uses the entire B-wave spectrum for index calculation, whereas the L-PRX covers only one-third of it. This may explain the performance discrepancy.
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Affiliation(s)
| | - Magdalena Kasprowicz
- 2Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland; and
| | - Peter Smielewski
- 3Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom
| | - Edgar Santos
- 4Department of Neurosurgery, University of Heidelberg, Germany
| | - John Pickard
- 3Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom
| | - Marek Czosnyka
- 3Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom
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11
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Reinhard M, Schumacher FK, Rutsch S, Oeinck M, Timmer J, Mader I, Schelter B, Weiller C, Kaller CP. Spatial mapping of dynamic cerebral autoregulation by multichannel near-infrared spectroscopy in high-grade carotid artery disease. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:97005. [PMID: 25253194 DOI: 10.1117/1.jbo.19.9.097005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 09/02/2014] [Indexed: 05/03/2023]
Abstract
The exact spatial distribution of impaired cerebral autoregulation in carotid artery disease is unknown. In this pilot study, we present a new approach of multichannel near-infrared spectroscopy (mcNIRS) for non-invasive spatial mapping of dynamic autoregulation in carotid artery disease. In 15 patients with unilateral severe carotid artery stenosis or occlusion, cortical hemodynamics in the bilateral frontal cortex were assessed from changes in oxyhemoglobin concentration using 52-channel NIRS (spatial resolution ∼2 cm). Dynamic autoregulation was graded by the phase shift between respiratory-induced 0.1 Hz oscillations of blood pressure and oxyhemoglobin. Ten of 15 patients showed regular phase values in the expected (patho) physiological range.Five patients had clearly outlying irregular phase values mostly due to artifacts. In patients with a regular phase pattern, a significant side-to-side difference of dynamic autoregulation was observed for the cortical border zone area between the middle and anterior cerebral artery (p < 0.05). In conclusion, dynamic cerebral autoregulation can be spatially assessed from slow hemodynamic oscillations with mcNIRS. In high-grade carotid artery disease,cortical dynamic autoregulation is affected mostly in the vascular border zone. Spatial mapping of dynamic autoregulation may serve as a powerful tool for identifying brain regions at specific risks for hemodynamic infarction.
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Affiliation(s)
- Matthias Reinhard
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, Germany
| | - F Konrad Schumacher
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, GermanybUniversity of Freiburg, BrainLinks-BrainTools Cluster of Excellence, D-79104 Freiburg, GermanycUniversity of Freiburg, Freiburg Brain Imaging Center, D-79106 Freiburg
| | - Sebastian Rutsch
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, Germany
| | - Maximilian Oeinck
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, Germany
| | - Jens Timmer
- University of Freiburg, Center for Data Analysis and Modeling, D-79104 Freiburg, Germany
| | - Irina Mader
- University Medical Center Freiburg, Department of Neuroradiology, D-79106 Freiburg, Germany
| | - Björn Schelter
- University of Freiburg, BrainLinks-BrainTools Cluster of Excellence, D-79104 Freiburg, GermanycUniversity of Freiburg, Freiburg Brain Imaging Center, D-79106 Freiburg, GermanyeUniversity of Freiburg, Center for Data Analysis and Modeling, D-79104 Freiburg
| | - Cornelius Weiller
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, GermanybUniversity of Freiburg, BrainLinks-BrainTools Cluster of Excellence, D-79104 Freiburg, GermanycUniversity of Freiburg, Freiburg Brain Imaging Center, D-79106 Freiburg
| | - Christoph P Kaller
- University Medical Center Freiburg, Department of Neurology, D-79106 Freiburg, GermanybUniversity of Freiburg, BrainLinks-BrainTools Cluster of Excellence, D-79104 Freiburg, GermanycUniversity of Freiburg, Freiburg Brain Imaging Center, D-79106 Freiburg
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12
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Phillip D, Iversen HK, Schytz HW, Selb J, Boas DA, Ashina M. Altered Low Frequency Oscillations of Cortical Vessels in Patients with Cerebrovascular Occlusive Disease - A NIRS Study. Front Neurol 2013; 4:204. [PMID: 24379801 PMCID: PMC3864103 DOI: 10.3389/fneur.2013.00204] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/03/2013] [Indexed: 11/30/2022] Open
Abstract
Analysis of cerebral autoregulation by measuring spontaneous oscillations in the low frequency spectrum of cerebral cortical vessels might be a useful tool for assessing risk and investigating different treatment strategies in carotid artery disease and stroke. Near infrared spectroscopy (NIRS) is a non-invasive optical method to investigate regional changes in oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb) in the outermost layers of the cerebral cortex. In the present study we examined oxyHb low frequency oscillations, believed to reflect cortical cerebral autoregulation, in 16 patients with both symptomatic carotid occlusive disease and cerebral hypoperfusion in comparison to healthy controls. Each hemisphere was examined with two NIRS channels using a 3 cm source detector distance. Arterial blood pressure (ABP) was measured via a finger plethysmograph. Using transfer function analysis ABP-oxyHb phase shift and gain as well as inter-hemispheric phase shift and amplitude ratio were assessed. We found that inter-hemispheric amplitude ratio was significantly altered in hypoperfusion patients compared to healthy controls (P = 0.010), because of relatively lower amplitude on the hypoperfusion side. The inter-hemispheric phase shift showed a trend (P = 0.061) toward increased phase shift in hypoperfusion patients compared to controls. We found no statistical difference between hemispheres in hypoperfusion patients for phase shift or gain values. There were no differences between the hypoperfusion side and controls for phase shift or gain values. These preliminary results suggest an impairment of autoregulation in hypoperfusion patients at the cortical level detected by NIRS.
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Affiliation(s)
- Dorte Phillip
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Helle K Iversen
- Stroke Unit, Department of Neurology, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Henrik W Schytz
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Juliette Selb
- Photon Migration Imaging Laboratory, Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School , Boston, MA , USA
| | - David A Boas
- Photon Migration Imaging Laboratory, Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School , Boston, MA , USA
| | - Messoud Ashina
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
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13
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Phillip D, Schytz HW, Selb J, Payne S, Iversen HK, Skovgaard LT, Boas DA, Ashina M. Low frequency oscillations in cephalic vessels assessed by near infrared spectroscopy. Eur J Clin Invest 2012; 42:1180-8. [PMID: 22897146 PMCID: PMC3730271 DOI: 10.1111/j.1365-2362.2012.02704.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND METHODS Low frequency oscillations (LFO) of cerebral vessels are believed to reflect cerebral autoregulation. We investigated day-to-day and hemispheric variations in 0.1 Hz LFO with near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) to determine phase shift and gain of oxygenated haemoglobin (oxyHb) and the velocity of the middle cerebral artery (Vmca) to the arterial blood pressure (ABP). The direct left-right phase shifts of oxyHb and Vmca were also assessed. We examined 44 healthy volunteers by simultaneous recordings of ABP, oxyHb and Vmca during spontaneous and paced breathing at 6 breaths per minute on two separate days. RESULTS The variation between hemispheres had a prediction interval (PI) of ± 39° for ABP-oxyHb phase shift and ± 69% for gain. ABP-Vmca showed ± 57° PI phase shift and ± 158% PI for gain. The variation from day to day showed ± 61° PI for ABP-oxyHb phase shift and ± 297% PI for gain. ABP-Vmca showed ± 45° PI phase shift and ± 166% PI for gain. We found a linear relation between phase shift of oxyHb and Vmca at paced breathing (P=0.0005), but not at rest (P=0.235). CONCLUSION Our results show that LFO phase shift ABP-oxyHb may be used as a robust measurement of differences in autoregulation between hemispheres and over time. In addition, we found a strong relation between oxyHb and Vmca during paced breathing. Gain showed too large variation for clinical use, as the SD was up to 100-fold of mean values.
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Affiliation(s)
- Dorte Phillip
- Danish Headache Center, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark
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14
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Schytz HW, Hansson A, Phillip D, Selb J, Boas DA, Iversen HK, Ashina M. Spontaneous low-frequency oscillations in cerebral vessels: applications in carotid artery disease and ischemic stroke. J Stroke Cerebrovasc Dis 2011; 19:465-74. [PMID: 20864356 DOI: 10.1016/j.jstrokecerebrovasdis.2010.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 12/02/2009] [Indexed: 11/30/2022] Open
Abstract
The etiology behind and physiological significance of spontaneous oscillations in the low-frequency spectrum in both systemic and cerebral vessels remain unknown. Experimental studies have proposed that spontaneous oscillations in cerebral blood flow reflect impaired cerebral autoregulation (CA). Analysis of CA by measurement of spontaneous oscillations in the low-frequency spectrum in cerebral vessels might be a useful tool for assessing risk and investigating different treatment strategies in carotid artery disease (CAD) and stroke. We reviewed studies exploring spontaneous oscillations in the low-frequency spectrum in patients with CAD and ischemic stroke, conditions known to involve impaired CA. Several studies have reported changes in oscillations after CAD and stroke after surgery and over time compared with healthy controls. Phase shift in the frequency domain and correlation coefficients in the time domain are the most frequently used parameters for analyzing spontaneous oscillations in systemic and cerebral vessels. At present, there is no gold standard for analyzing spontaneous oscillations in the low-frequency spectrum, and simplistic models of CA have failed to predict or explain the spontaneous oscillation changes found in CAD and stroke studies. Near-infrared spectroscopy is suggested as a future complementary tool for assessing changes affecting the cortical arterial system.
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Affiliation(s)
- Henrik W Schytz
- Danish Headache Center, Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark.
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15
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Lorenz MW, Loesel N, Thoelen N, Gonzalez M, Lienerth C, Dvorak F, Rölz W, Humpich M, Sitzer M. Effects of poor bone window on the assessment of cerebral autoregulation with transcranial Doppler sonography - a source of systematic bias and strategies to avoid it. J Neurol Sci 2009; 283:49-56. [PMID: 19268307 DOI: 10.1016/j.jns.2009.02.329] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The consequences of poor insonation conditions on autoregulation parameters assessed with transcranial Doppler (TCD) are unclear. METHODS We present two new complementary methods to assess the quality of a TCD signal. Inserting a thin aluminium foil between TCD probe and skin makes a simple model to artificially worsen a good insonation window. Validation studies are presented. We assessed insonation quality and cerebral autoregulation parameters with transfer function analysis and cross correlation in 46 healthy volunteers with and without the aluminium foil model. The same studies were operated on 45 patients with good insonation windows, naïve, after worsening the bone window and during constant infusion of an ultrasound contrast agent. For studying reproducibility, we assessed autoregulation twice in 30 patients with poor bone windows, with and without constant contrast infusion. RESULTS Both methods to measure insonation quality are valid and reproducible. The aluminium foil model realistically simulates a natural poor bone window, reducing the signal quality (e.g. energy of the signal spectrum from 33.4+/-3.5 to 26.2+/-2.5 dB, p<0.001). Thereby, the autoregulation parameters are systematically biased (e.g. phase difference from 37.3+/-10.1 degrees to 25.9+/-15.1 degrees , p<0.001); while with the use of an ultrasound contrast agent this can be largely compensated (phase difference 35.7+/-10.7 degrees , p<0.001). The reproducibility is significantly improved (ICC from 0.76 to 0.90, p<0.05). CONCLUSIONS Poor bone windows can cause considerable bias in TCD autoregulation parameters. This bias might be avoided by the use of ultrasound contrast agents, which may greatly improve the credibility of TCD autoregulation assessment in elderly patients.
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Affiliation(s)
- Matthias W Lorenz
- Department of Neurology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
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16
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Hu K, Peng C, Huang NE, Wu Z, Lipsitz LA, Cavallerano J, Novak V. Altered Phase Interactions between Spontaneous Blood Pressure and Flow Fluctuations in Type 2 Diabetes Mellitus: Nonlinear Assessment of Cerebral Autoregulation. PHYSICA A 2008; 387:2279-2292. [PMID: 18432311 PMCID: PMC2329796 DOI: 10.1016/j.physa.2007.11.052] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Cerebral autoregulation (CA) is an important mechanism that involves dilation and constriction in arterioles to maintain relatively s cerebral blood flow in response to changes of systemic blood pressure. Traditional assessments of CA focus on the changes of cerebral blood flow velocity in response to large blood pressure fluctuations induced by interventions. This approach is not feasible for patients with impaired autoregulation or cardiovascular regulation. Here we propose a newly developed technique-the multimodal pressure-flow (MMPF) analysis, which assesses CA by quantifying nonlinear phase interactions between spontaneous oscillations in blood pressure and flow velocity during resting conditions. We show that CA in healthy subjects can be characterized by specific phase shifts between spontaneous blood pressure and flow velocity oscillations, and the phase shifts are significantly reduced in diabetic subjects. Smaller phase shifts between oscillations in the two variables indicate more passive dependence of blood flow velocity on blood pressure, thus suggesting impaired cerebral autoregulation. Moreover, the reduction of the phase shifts in diabetes is observed not only in previously-recognized effective region of CA (<0.1Hz), but also over the higher frequency range from ~0.1 to 0.4Hz. These findings indicate that Type 2 diabetes alters cerebral blood flow regulation over a wide frequency range and that this alteration can be reliably assessed from spontaneous oscillations in blood pressure and blood flow velocity during resting conditions. We also show that the MMPF method has better performance than traditional approaches based on Fourier transform, and is more sui for the quantification of nonlinear phase interactions between nonstationary biological signals such as blood pressure and blood flow.
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Affiliation(s)
- Kun Hu
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - C.K. Peng
- Division of Interdisciplinary Medicine & Biotechnology and Margret and H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA
| | - Norden E. Huang
- Research Center for Data Analysis, National Central University, Chungli, Taiwan, ROC
| | - Zhaohua Wu
- Center for Ocean-Land-Atmosphere Studies, Calverton, Maryland
| | - Lewis A. Lipsitz
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
- Hebrew SeniorLife, Boston MA
| | | | - Vera Novak
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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17
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Lorenz MW, Thoelen N, Loesel N, Lienerth C, Gonzalez M, Humpich M, Roelz W, Dvorak F, Sitzer M. Assessment of cerebral autoregulation with transcranial Doppler sonography in poor bone windows using constant infusion of an ultrasound contrast agent. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:345-353. [PMID: 17976899 DOI: 10.1016/j.ultrasmedbio.2007.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/22/2007] [Accepted: 09/04/2007] [Indexed: 05/25/2023]
Abstract
Cerebral autoregulation is an important pathophysiological and prognostic parameter for a variety of neurologic conditions. It can be assessed quickly and safely using transcranial Doppler sonography (TCD). In elderly patients, poor insonation conditions decrease the number of examinable patients and can cause a systematic bias in autoregulation parameters. The aim of this study was to investigate whether a constant infusion of an ultrasound contrast agent (Levovist((R))) can counteract these effects. We examined two cohorts of unselected neurologic patients. In 45 patients with good insonation windows (cohort 1), we used a thin aluminium foil between the skin and the TCD probe to artificially decrease the insonation quality. We determined two parameters of cerebral autoregulation (phase difference [PD] and a cross-correlation coefficient [Mx]) in native patients, with aluminium foil and with aluminium foil and a constant infusion of Levovist. In 30 patients with poor insonation windows (cohort 2), we measured the autoregulation twice, with and without an infusion of Levovist, to assess the reproducibility of the autoregulation parameters. In cohort 1, the foil model significantly decreased the Doppler signal quality, i.e., the mean spectrum energy decreased from 33.9 +/- 2.7 dB to 26.3 +/- 2.4 dB (p < 0.001). This introduced a significant bias to all autoregulation parameters (PD: decreased from 38.2 +/- 10.0 degrees to 27.9 +/- 12.5 degrees (p < 0.001); Mx: decreased from 0.308 +/- 0.170 to 0.254 +/- 0.162 (p < 0.01)). Both effects were compensated largely by a constant infusion of Levovist (300 mg/min). In cohort 2, infusion of the contrast agent at the same rate increased insonation quality, too, but to a lesser degree (27.4 +/- 2.4 dB to 32.0 +/- 3.7 dB, p < 0.001). This smaller increase did not cause a significant change in the autoregulation parameters, but the reproducibility of the PD was significantly improved (intraclass coefficient coefficient [ICC] 0.76, 95% confidence interval [0.59-0.87] in native poor bone window compared with ICC 0.90, 95% confidence interval [0.81-0.95] with infusion of the contrast agent). Our data show that constant infusion of an ultrasound contrast agent during the assessment of cerebral autoregulation can avoid potential bias introduced by poor insonation conditions. Furthermore, infusion of the contrast agent can improve reproducibility and contribute to the credibility of autoregulation assessment in the elderly. (E-mail: matthias.lorenz@em.uni-frankfurt.de).
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Affiliation(s)
- Matthias W Lorenz
- Department of Neurology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
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18
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Lo MT, Hu K, Liu Y, Peng CK, Novak V. Multimodal Pressure Flow Analysis: Application of Hilbert Huang Transform in Cerebral Blood Flow Regulation. EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2008; 2008:785243. [PMID: 18725996 PMCID: PMC2518653 DOI: 10.1155/2008/785243] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Quantification of nonlinear interactions between two nonstationary signals presents a computational challenge in different research fields, especially for assessments of physiological systems. Traditional approaches that are based on theories of stationary signals cannot resolve nonstationarity-related issues and, thus, cannot reliably assess nonlinear interactions in physiological systems. In this review we discuss a new technique "Multi-Modal Pressure Flow method (MMPF)" that utilizes Hilbert-Huang transformation to quantify dynamic cerebral autoregulation (CA) by studying interaction between nonstationary cerebral blood flow velocity (BFV) and blood pressure (BP). CA is an important mechanism responsible for controlling cerebral blood flow in responses to fluctuations in systemic BP within a few heart-beats. The influence of CA is traditionally assessed from the relationship between the well-pronounced systemic BP and BFV oscillations induced by clinical tests. Reliable noninvasive assessment of dynamic CA, however, remains a challenge in clinical and diagnostic medicine.In this brief review we: 1) present an overview of transfer function analysis (TFA) that is traditionally used to quantify CA; 2) describe the a MMPF method and its modifications; 3) introduce a newly developed automatic algorithm and engineering aspects of the improved MMPF method; and 4) review clinical applications of MMPF and its sensitivity for detection of CA abnormalities in clinical studies. The MMPF analysis decomposes complex nonstationary BP and BFV signals into multiple empirical modes adaptively so that the fluctuations caused by a specific physiologic process can be represented in a corresponding empirical mode. Using this technique, we recently showed that dynamic CA can be characterized by specific phase delays between the decomposed BP and BFV oscillations, and that the phase shifts are significantly reduced in hypertensive, diabetics and stroke subjects with impaired CA. In addition, the new technique enables reliable assessment of CA using both data collected during clinical test and spontaneous BP/BFV fluctuations during baseline resting conditions.
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Affiliation(s)
- Men-Tzung Lo
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
- Division of Interdisciplinary Medicine & Biotechnology and Margret & H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
- Research Center for Adaptive Data Analysis, National Central University, Chungli, Taiwan, ROC
| | - Kun Hu
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | | | - C.-K. Peng
- Division of Interdisciplinary Medicine & Biotechnology and Margret & H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Vera Novak
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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19
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Lorenz MW, Gonzalez M, Lienerth C, Loesel N, Thoelen N, Sitzer M. Influence of temporal insonation window quality on the assessment of cerebral autoregulation with transcranial Doppler sonography. ULTRASOUND IN MEDICINE & BIOLOGY 2007; 33:1540-5. [PMID: 17544566 DOI: 10.1016/j.ultrasmedbio.2007.04.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 04/03/2007] [Accepted: 04/21/2007] [Indexed: 05/15/2023]
Abstract
Cerebral autoregulation can be assessed quickly and noninvasively using transcranial Doppler sonography (TCD). A poor transtemporal insonation window is a common limitation in TCD examinations. The effects of insonation quality on TCD autoregulation measurements have never been investigated. We developed two methods to quantitatively measure insonation quality. We also validated a model to artificially worsen the insonation window. This involves inserting a thin aluminium foil between the TCD probe and the skin. Forty-six healthy volunteers underwent TCD examination before and after artificial reduction of the transtemporal insonation quality. Two autoregulation parameters, the phase difference (PD) and a cross-correlation coefficient (Mx), were calculated from the recordings. The aluminium foil model realistically simulates poor insonation conditions, producing a decrease in the signal power from 36.4 +/- 2.8 dB to 32.0 +/- 1.5 dB. In corrupted insonation windows, the PD is artificially low (native: 34.2 +/- 9.3 degrees , corrupted: 29.9 +/- 9.7 degrees , p = 0.002), but the Mx is not significantly different. Insonation quality may introduce a systematic bias of clinically relevant magnitude into TCD-based cerebral autoregulation studies. This must be considered when studies of elderly patients are planned. This article discusses strategies to account for this bias.
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Affiliation(s)
- Matthias W Lorenz
- Department of Neurology, Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
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20
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Haubrich C, Kruska W, Diehl RR, Möller-Hartmann W, Klötzsch C. Recovery of the blood pressure - cerebral flow relation after carotid stenting in elderly patients. Acta Neurochir (Wien) 2007; 149:131-6; discussion 137. [PMID: 16964557 DOI: 10.1007/s00701-006-0888-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 07/27/2006] [Indexed: 11/27/2022]
Abstract
BACKGROUND As a sensitive and convenient means for the cerebral hemodynamic monitoring, dynamic cerebral autoregulation testing could be especially useful in medical conditions where less invasive diagnostics and therapies are preferred. This study analysed the effect of carotid stenting on dynamic autoregulation in elderly patients focussing on the relation between blood pressure and cerebral blood flow velocity. METHODS We examined 20 patients age 69 +/- 8 years with coexisting cerebrovascular and medical risk factors before and at least six month after stenting of severe carotid stenoses. Data were compared to 24 age-matched healthy controls. Slow spontaneous oscillations were studied in continuous recordings of Transcranial Doppler and beat-to-beat blood pressure. Analysis was based on the "high-pass filter model", which predicts a positive phase relationship between these oscillations. FINDINGS Whereas phase shift angles were diminished (20.4 +/- 14.1 degrees ) before stenting, after stenting these values were significantly increased to normal (48.1 +/- 16.6 degrees ), to the level of controls (46.7 +/- 15.9 degrees ). Medical conditions such as coronary artery disease, arterial hypertension, and dyslipidemia did not diminish this recovery. The level of increase was inversely correlated with the initial autoregulatory deficit (r = -0.68) which was largest with insufficient collateral blood supply and symptomatic carotid stenoses. CONCLUSIONS The study showed that an impaired cerebral autoregulation may recover after stent-guided carotid angioplasty even in the elderly with co-existing medical conditions. In this respect to regain vasomotor capability, patients with cerebrovascular risk factors seemed to benefit particularly.
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Affiliation(s)
- C Haubrich
- Department of Neurology, University Hospital Aachen, Aachen, Germany.
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21
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Reinhard M, Wehrle-Wieland E, Grabiak D, Roth M, Guschlbauer B, Timmer J, Weiller C, Hetzel A. Oscillatory cerebral hemodynamics--the macro- vs. microvascular level. J Neurol Sci 2006; 250:103-9. [PMID: 17011584 DOI: 10.1016/j.jns.2006.07.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 07/06/2006] [Accepted: 07/31/2006] [Indexed: 11/20/2022]
Abstract
The phase shift between oscillations of blood pressure (BP) and Doppler middle cerebral artery flow velocity (MCAFV) reflects continuous cerebral autoregulatory action. It is not known whether a similar phase shift exists for cortical hemodynamics ('microvascular level') assessed by near infrared spectroscopy (NIRS) and what the effects are of pathological conditions. This study investigates the phase relations between oscillations of BP, MCAFV and NIRS parameters in 38 healthy older adults and 28 patients with unilateral severe obstructive carotid disease. BP was recorded noninvasively by finger plethysmography. Stable 0.1 Hz oscillations of all hemodynamic parameters were induced by regular breathing at a rate of 6/min. Basic results were that: (1) BP-induced cortical microvascular oscillations (NIRS) follow those of macrovascular oscillations (MCAFV) with a phase of 80-90 degrees (corresponding to 2-2.5 s at 0.1 Hz), most likely reflecting a transit time phenomenon; (2) oxy- and deoxyhemoglobin thereby oscillate in counterphase; (3) hemodynamic compromise in carotid obstruction leads to (a) delayed NIRS oscillations in comparison to BP which are highly correlated to a shorter phase lead of MCAFV against BP and (b) a decoupling of the oxy-/deoxyhemoglobin counterphase to 240 degrees . Cortical hemodynamic responses to BP oscillations follow specific phase relationships due to cerebral autoregulatory action and circulatory transit times. With hemodynamic impairment, as in unilateral carotid obstruction, these phases are significantly changed reflecting disturbed autoregulation.
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Affiliation(s)
- Matthias Reinhard
- Department of Neurology and Clinical Neurophysiology, University of Freiburg, Neurocenter, Breisacherstr. 64, D-79106 Freiburg, Germany.
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22
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Haubrich C, Kohnke A, Kloetzsch C, Moeller-Hartmann W, Diehl RR. Bilateral vertebral artery disease: transcranial Doppler assessment of the hemodynamic vulnerability to changes in posture. ULTRASOUND IN MEDICINE & BIOLOGY 2006; 32:1485-91. [PMID: 17045868 DOI: 10.1016/j.ultrasmedbio.2006.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 06/01/2006] [Accepted: 06/08/2006] [Indexed: 05/12/2023]
Abstract
Posture changes may cause hemodynamic ischemic events, particularly in severe vertebrobasilar artery disease. It may be difficult and not without risk to prove this vulnerability to changes in posture during angiography. Therefore, TCD monitoring with passive tilting (PT) was used to evaluate cerebral hemodynamics distally to severe bilateral vertebral artery disease (BVAD). PCA flow velocity changes and dynamic cerebral autoregulation (DCA) were analyzed in supine and upright position. Despite a significant autoregulatory deficit distally to BVAD, the posterior cerebral blood supply seemed to be sufficiently maintained as long as systemic blood pressure changes were within normal limits. Posterior cerebral flow velocities, however, were significantly diminished when PT detected a systemic hypotension in upright position. This study proves the feasibility to combine PT and TCD monitoring of the PCA in patients with BVAD. In vertebrobasilar artery disease, the examination of spontaneous and tilt-induced autoregulatory responses could support the evaluation of a risk for hemodynamic ischemia.
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