1
|
Minhas JS, Rook W, Panerai RB, Hoiland RL, Ainslie PN, Thompson JP, Mistri AK, Robinson TG. Pathophysiological and clinical considerations in the perioperative care of patients with a previous ischaemic stroke: a multidisciplinary narrative review. Br J Anaesth 2020; 124:183-196. [PMID: 31813569 PMCID: PMC7034810 DOI: 10.1016/j.bja.2019.10.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 09/24/2019] [Accepted: 10/18/2019] [Indexed: 12/28/2022] Open
Abstract
With an ageing population and increasing incidence of cerebrovascular disease, an increasing number of patients presenting for routine and emergency surgery have a prior history of stroke. This presents a challenge for pre-, intra-, and postoperative management as the neurological risk is considerably higher. Evidence is lacking around anaesthetic practice for patients with vascular neurological vulnerability. Through understanding the pathophysiological changes that occur after stroke, insight into the susceptibilities of the cerebral vasculature to intrinsic and extrinsic factors can be developed. Increasing understanding of post-stroke systemic and cerebral haemodynamics has provided improved outcomes from stroke and more robust secondary prevention, although this knowledge has yet to be applied to our delivery of anaesthesia in those with prior stroke. This review describes the key pathophysiological and clinical considerations that inform clinicians providing perioperative care for patients with a prior diagnosis of stroke.
Collapse
Affiliation(s)
- Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.
| | - William Rook
- Academic Department of Anaesthesia, Critical Care, Pain, and Resuscitation, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Ryan L Hoiland
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Phil N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Jonathan P Thompson
- Anaesthesia and Critical Care, Department of Cardiovascular Sciences, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Amit K Mistri
- University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| |
Collapse
|
2
|
Placek MM, Smielewski P, Wachel P, Budohoski KP, Czosnyka M, Kasprowicz M. Can interhemispheric desynchronization of cerebral blood flow anticipate upcoming vasospasm in aneurysmal subarachnoid haemorrhage patients? J Neurosci Methods 2019; 325:108358. [PMID: 31306719 DOI: 10.1016/j.jneumeth.2019.108358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 06/12/2019] [Accepted: 07/11/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND Asymmetry of cerebral autoregulation (CA) was demonstrated in patients after aneurysmal subarachnoid haemorrhage (aSAH). A classical method for CA assessment requires simultaneous measurement of both arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). In this study, we have proposed a cerebral blood flow asymmetry index based only on CBFV and analysed its association with the occurrence of vasospasm after aSAH. NEW METHOD The phase shifts (PS) between slow oscillations in left and right CBFV (side-to-side PS) and between ABP and CBFV (CBFV-ABP PS) were estimated using multichannel matching pursuit (MMP) and cross-spectral analysis. RESULTS We retrospectively analysed data collected from 45 aSAH patients (26 with vasospasm). Data were analysed up to 7th day after aSAH unless the vasospasm was detected earlier. A progressive asymmetry, manifested by a gradual increase in side-to-side PS on consecutive days after aSAH, was observed in patients who developed vasospasm (Radj2 = 0.14, p = 0.009). In these patients, early side-to-side PS was more positive than in patients without vasospasm (2.8° ± 5.6° vs -1.7° ± 5.7°, p = 0.011). No such a difference was found in CBFV-ABP PS. Patients with positive side-to-side PS were more likely to develop vasospasm than patients with negative side-to-side PS (21/7 vs 5/12, p = 0.0047). COMPARISON WITH EXISTING METHOD MMP, in contrast to the spectral approach, accounts for non-stationarity of analysed signals. MMP applied to the PS estimation reflects the cerebral blood flow asymmetry in aSAH better than the spectral analysis. CONCLUSIONS Changes in side-to-side PS might be helpful to identify patients who are at risk of vasospasm.
Collapse
Affiliation(s)
- Michał M Placek
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław, Poland; Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Hills Road, Cambridge CB2 0QQ, United Kingdom.
| | - Peter Smielewski
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Hills Road, Cambridge CB2 0QQ, United Kingdom
| | - Paweł Wachel
- Department of Control Systems and Mechatronics, Faculty of Electronics, Wrocław University of Science and Technology, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Karol P Budohoski
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Hills Road, Cambridge CB2 0QQ, United Kingdom
| | - Marek Czosnyka
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Hills Road, Cambridge CB2 0QQ, United Kingdom
| | - Magdalena Kasprowicz
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
3
|
Bor-Seng-Shu E, de-Lima-Oliveira M, Nogueira RC, Almeida KJ, Paschoal EHA, Paschoal FM. Decompressive Craniectomy for Traumatic Brain Injury: Postoperative TCD Cerebral Hemodynamic Evaluation. Front Neurol 2019; 10:354. [PMID: 31031689 PMCID: PMC6473100 DOI: 10.3389/fneur.2019.00354] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 03/22/2019] [Indexed: 12/31/2022] Open
Abstract
Background: There are no studies describing the cerebral hemodynamic patterns that can occur in traumatic brain injury (TBI) patients following decompressive craniectomy (DC). Such data have potentially clinical importance for guiding the treatment. The objective of this study was to investigate the postoperative cerebral hemodynamic patterns, using transcranial Doppler (TCD) ultrasonography, in patients who underwent DC. The relationship between the cerebral circulatory patterns and the patients' outcome was also analyzed. Methods: Nineteen TBI patients with uncontrolled brain swelling were prospectively studied. Cerebral blood circulation was evaluated by TCD ultrasonography. Patients and their cerebral hemispheres were categorized based on TCD-hemodynamic patterns. The data were correlated with neurological status, midline shift on CT scan, and Glasgow outcome scale scores at 6 months after injury. Results: Different cerebral hemodynamic patterns were observed. One patient (5.3%) presented with cerebral oligoemia, 4 patients (21%) with cerebral hyperemia, and 3 patients (15.8%) with cerebral vasospasm. One patient (5.3%) had hyperemia in one cerebral hemisphere and vasospasm in the other hemisphere. Ten patients (52.6%) had nonspecific circulatory pattern. Abnormal TCD-circulatory patterns were found in 9 patients (47.4%). There was no association between TCD-cerebral hemodynamic findings and outcome. Conclusion: There is a wide heterogeneity of postoperative cerebral hemodynamic findings among TBI patients who underwent DC, including hemodynamic heterogeneity between their cerebral hemispheres. DC was proved to be effective for the treatment of cerebral oligoemia. Our data support the concept of heterogeneous nature of the pathophysiology of the TBI and suggest that DC as the sole treatment modality is insufficient.
Collapse
Affiliation(s)
- Edson Bor-Seng-Shu
- Laboratory for Neurosonology and Cerebral Hemodynamics, Division of Neurological Surgery, Hospital das Clinicas, São Paulo University Medical School, São Paulo, Brazil
| | - Marcelo de-Lima-Oliveira
- Laboratory for Neurosonology and Cerebral Hemodynamics, Division of Neurological Surgery, Hospital das Clinicas, São Paulo University Medical School, São Paulo, Brazil
| | - Ricardo Carvalho Nogueira
- Laboratory for Neurosonology and Cerebral Hemodynamics, Division of Neurological Surgery, Hospital das Clinicas, São Paulo University Medical School, São Paulo, Brazil
| | - Kelson James Almeida
- Department of Neurology, Federal University of Piauí Medical School, Teresina, Brazil
| | | | - Fernando Mendes Paschoal
- Laboratory for Neurosonology and Cerebral Hemodynamics, Division of Neurological Surgery, Hospital das Clinicas, São Paulo University Medical School, São Paulo, Brazil.,Department of Neurology, Federal University of Pará Medical School, São Paulo, Brazil
| |
Collapse
|
4
|
Cardim D, Robba C, Schmidt B, Donnelly J, Schmidt EA, Bohdanowicz M, Smielewski P, Czosnyka M. Midline shift in patients with closed traumatic brain injury may be driven by cerebral perfusion pressure not intracranial pressure. J Neurosurg Sci 2019; 65:383-390. [PMID: 30724053 DOI: 10.23736/s0390-5616.19.04604-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND In traumatic brain injury (TBI), swelling may disturb the potentially uniform pressure distribution in the brain, producing sustained intercompartmental pressure gradients which may associate with midline shift. The presence of pressure gradients is often neglected since bilateral invasive intracranial pressure (ICP) monitoring is not usually considered because of risks and high costs. We evaluated the presence of interhemispheric pressure gradients using bilateral transcranial Doppler (TCD) as means for non-invasive ICP (nICP) monitoring in TBI patients presenting midline shift. METHODS From a retrospective cohort of 97 TBI patients with arterial blood pressure (ABP), ICP and bilateral TCD monitoring, 24 presented unilateral lesion and midline shift confirmed by computer tomography. nICP and non-invasive cerebral perfusion pressure (nCPP) on the left and right brain hemispheres were retrospectively calculated using a mathematical model associating TCD-derived cerebral blood flow velocity and ABP. RESULTS The nCPP difference was correlated with midline shift (R=-0.34, p<.01) showing a tendency to record higher CPP at the side of expansion. Accordingly, nICP at the side of expansion was significantly lower in comparison to the compressed side (18.86 [±5.71] mmHg (mean ± standard deviation) versus 20.30 [±6.78] mmHg for expansion and compressed sides, respectively). Subsequently, nCPP was greater on the side of brain expansion (79.48±7.84, 78.03±8.93 mmHg [p<.01], for expansion and compressed sides, respectively). CONCLUSIONS TCD-based interhemispheric nCPP difference showed significant correlation with midline shift. Cerebral perfusion pressure was greater on the side of brain expansion, acting as the driving force to shift brain structures.
Collapse
Affiliation(s)
- Danilo Cardim
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Chiara Robba
- Neurosciences Critical Care Unit, Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK - .,Department of Neuroscience, University of Genoa, Genoa, Italy
| | - Bernhard Schmidt
- Department of Neurology, University Hospital Chemnitz, Chemnitz, Germany
| | - Joseph Donnelly
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Eric A Schmidt
- Service de Neurochirurgie, Hôpital Universitaire Toulouse-Purpan, Toulouse, France
| | - Michal Bohdanowicz
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Peter Smielewski
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| |
Collapse
|
5
|
An Efficient Automatic Midsagittal Plane Extraction in Brain MRI. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8112203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In this paper, a fully automatic and computationally efficient midsagittal plane (MSP) extraction technique in brain magnetic resonance images (MRIs) has been proposed. Automatic detection of MSP in neuroimages can significantly aid in registration of medical images, asymmetric analysis, and alignment or tilt correction (recenter and reorientation) in brain MRIs. The parameters of MSP are estimated in two steps. In the first step, symmetric features and principal component analysis (PCA)-based technique is used to vertically align the bilateral symmetric axis of the brain. In the second step, PCA is used to achieve a set of parallel lines (principal axes) from the selected two-dimensional (2-D) elliptical slices of brain MRIs, followed by a plane fitting using orthogonal regression. The developed algorithm has been tested on 157 real T1-weighted brain MRI datasets including 14 cases from the patients with brain tumors. The presented algorithm is compared with a state-of-the-art approach based on bilateral symmetry maximization. Experimental results revealed that the proposed algorithm is fast (<1.04 s per MRI volume) and exhibits superior performance in terms of accuracy and precision (a mean z-distance of 0.336 voxels and a mean angle difference of 0.06).
Collapse
|
6
|
Robba C, Bacigaluppi S, Cardim D, Donnelly J, Bertuccio A, Czosnyka M. Non-invasive assessment of intracranial pressure. Acta Neurol Scand 2016; 134:4-21. [PMID: 26515159 DOI: 10.1111/ane.12527] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2015] [Indexed: 11/29/2022]
Abstract
Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.
Collapse
Affiliation(s)
- C. Robba
- Neurosciences Critical Care Unit; Addenbrooke's Hospital; Cambridge United Kingdom
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - S. Bacigaluppi
- Department of Neurosurgery; Galliera Hospital; Genova Italy
| | - D. Cardim
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - J. Donnelly
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - A. Bertuccio
- Department of Neurosurgery; S. George's Hospital; University of London; United Kingdom
| | - M. Czosnyka
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| |
Collapse
|
7
|
Varsos GV, Budohoski KP, Kolias AG, Liu X, Smielewski P, Varsos VG, Hutchinson PJ, Pickard JD, Czosnyka M. Relationship of vascular wall tension and autoregulation following traumatic brain injury. Neurocrit Care 2015; 21:266-74. [PMID: 24682849 DOI: 10.1007/s12028-014-9971-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The vascular wall tension (WT) of small cerebral vessels can be quantitatively estimated through the concept of critical closing pressure (CrCP), which denotes the lower limit of arterial blood pressure (ABP), below which small cerebral arterial vessels collapse and blood flow ceases. WT can be expressed as the difference between CrCP and intracranial pressure (ICP) and represent active vasomotor tone. In this study, we investigated the association of WT and CrCP with autoregulation and outcome of a large group of patients after traumatic brain injury (TBI). METHODS We retrospectively analysed recordings of ABP, ICP and transcranial Doppler (TCD) blood flow velocity from 280 TBI patients (median age: 29 years; interquartile range: 20-43). CrCP and WT were calculated using the cerebrovascular impedance methodology. Autoregulation was assessed based on TCD-based indices, Mx and ARI. RESULTS Low values of WT were found to be associated with an impaired autoregulatory capacity, signified by its correlation to FV-based indices Mx (R = -0.138; p = 0.021) and ARI (R = 0.118; p = 0.048). No relationship could be established between CrCP and any of the autoregulatory indices. Neither CrCP nor WT was found to correlate with outcome. CONCLUSIONS Impaired autoregulation was found to be associated with a lower WT supporting the role of vasoparalysis in the loss of autoregulatory capacity. In contrast, no links between CrCP and autoregulation could be identified.
Collapse
Affiliation(s)
- Georgios V Varsos
- Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Hills Road, Cambridge, CB2 0QQ, UK,
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Wu H, Wang D, Shi L, Wen Z, Ming Z. Midsagittal plane extraction from brain images based on 3D SIFT. Phys Med Biol 2014; 59:1367-87. [PMID: 24583964 DOI: 10.1088/0031-9155/59/6/1367] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Midsagittal plane (MSP) extraction from 3D brain images is considered as a promising technique for human brain symmetry analysis. In this paper, we present a fast and robust MSP extraction method based on 3D scale-invariant feature transform (SIFT). Unlike the existing brain MSP extraction methods, which mainly rely on the gray similarity, 3D edge registration or parameterized surface matching to determine the fissure plane, our proposed method is based on distinctive 3D SIFT features, in which the fissure plane is determined by parallel 3D SIFT matching and iterative least-median of squares plane regression. By considering the relative scales, orientations and flipped descriptors between two 3D SIFT features, we propose a novel metric to measure the symmetry magnitude for 3D SIFT features. By clustering and indexing the extracted SIFT features using a k-dimensional tree (KD-tree) implemented on graphics processing units, we can match multiple pairs of 3D SIFT features in parallel and solve the optimal MSP on-the-fly. The proposed method is evaluated by synthetic and in vivo datasets, of normal and pathological cases, and validated by comparisons with the state-of-the-art methods. Experimental results demonstrated that our method has achieved a real-time performance with better accuracy yielding an average yaw angle error below 0.91° and an average roll angle error no more than 0.89°.
Collapse
Affiliation(s)
- Huisi Wu
- College of Computer Science and Software Engineering, Shenzhen University, Shenzhen, Guangdong, People's Republic of China
| | | | | | | | | |
Collapse
|
9
|
Czosnyka M, Smielewski P, Lavinio A, Czosnyka Z, Pickard JD. A synopsis of brain pressures: which? when? are they all useful? Neurol Res 2013; 29:672-9. [DOI: 10.1179/016164107x240053] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
10
|
Katsogridakis E, Dineen NE, Brodie FG, Robinson TG, Panerai RB. Signal-to-noise ratio of bilateral nonimaging transcranial Doppler recordings of the middle cerebral artery is not affected by age and sex. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:530-538. [PMID: 21420579 DOI: 10.1016/j.ultrasmedbio.2010.12.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 11/23/2010] [Accepted: 12/28/2010] [Indexed: 05/30/2023]
Abstract
Differences between transcranial Doppler ultrasonography (TCD) recordings of symmetrical vessels can show true physiologic differences, but can also be caused by measurement error and other sources of noise. The aim of this project was to assess the influence of noise on estimates of dynamic cerebral autoregulation (dCA), and of age, sex and breathing manoeuvres on the signal-to-noise ratio (SNR). Cerebral blood flow (CBF) was monitored in 30 young (<40 years) and 30 older volunteers (age >60 years) during baseline conditions, breath-holding and hyperventilation. Noise was defined as the difference between beat-to-beat values of the two mean CBF velocity (CBFV) signals. Magnitude squared coherence estimates of noise vs. ABP and ABP vs. CBFV were obtained and averaged. A similar approach was adopted for the CBFV step response. The effect of age and breathing manoeuvre on the SNR was assessed using a two-way analysis of variance (ANOVA), whilst the effect of sex was investigated using a Student's t test. No significant differences were observed in SNR (baseline 6.07 ± 3.07 dB and 7.33 ± 3.84 dB, breath-hold: 13.53 ± 3.93 dB and 14.64 ± 4.52 dB, and hyperventilation: 14.69 ± 4.04 dB and 14.84 ± 4.05 dB) estimates between young and old groups, respectively. The use of breathing manoeuvres significantly improved the SNR (p < 10(-4)) without a significant difference between manoeuvres. Sex does not appear to have an effect on SNR (p = 0.365). Coherence estimates were not influenced by the SNR, but significant differences were found in the amplitude of the CBFV step response.
Collapse
Affiliation(s)
- Emmanuel Katsogridakis
- Medical Physics Group, Department of Cardiovascular Sciences, University of Leicester, University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK.
| | | | | | | | | |
Collapse
|
11
|
Hu K, Lo MT, Peng CK, Novak V, Schmidt EA, Kumar A, Czosnyka M. Nonlinear pressure-flow relationship is able to detect asymmetry of brain blood circulation associated with midline shift. J Neurotrauma 2009; 26:227-33. [PMID: 19196074 DOI: 10.1089/neu.2008.0643] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Reliable and noninvasive assessment of cerebral blood flow regulation is a major challenge in acute care monitoring. This study assessed dynamics of flow regulation and its relationship to asymmetry of initial computed tomography (CT) scan using multimodal pressure flow (MMPF) analysis. Data of 27 patients (38 +/- 15 years old) with traumatic brain injury (TBI) were analyzed. Patients were selected from bigger cohort according to criteria of having midline shift on initial CT scan and intact skull (no craniotomy or bone flap). The MMPF analysis was used to extract the oscillations in cerebral perfusion pressure (CPP) and blood flow velocity (BFV) signals at frequency of artificial ventilation, and to calculate the instantaneous phase difference between CPP and BFV oscillations. Mean CPP-BFV phase difference was used to quantify pressure and flow relationship. The TBI subjects had smaller mean BP-BFV phase shifts (left, 8.7 +/- 9.6; right 10.2 +/- 8.3 MCAs, mean +/- SD) than values previously obtained in healthy subjects (left, 37.3 +/- 7.6 degrees; right, 38.0 +/- 8.9 degrees; p < 0.0001), suggesting impaired blood flow regulation after TBI. The difference in phase shift between CPP and BFV in the left and right side was strongly correlated to the midline shift (R = 0.78; p < 0.0001). These findings indicate that the MMPF method allows reliable assessment of alterations in pressure and flow relationship after TBI. Moreover, mean pressure-flow phase shift is sensitive to the displacement of midline of the brain, and may potentially serve as a marker of asymmetry of cerebral autoregulation.
Collapse
Affiliation(s)
- Kun Hu
- Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
| | | | | | | | | | | | | |
Collapse
|
12
|
Hemispheric differences in cerebral autoregulation in children with moderate and severe traumatic brain injury. Neurocrit Care 2008; 9:45-54. [PMID: 18084727 DOI: 10.1007/s12028-007-9036-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
INTRODUCTION To examine hemispheric differences in cerebral autoregulation in children with traumatic brain injury (TBI). After IRB approval and consent, subjects underwent static cerebral autoregulation testing during the first 9 days after PICU admission. Cerebral autoregulation was quantified using the autoregulatory index (ARI). RESULTS Forty-two (27 M:15 F) children (10 +/- 5 years) with TBI and admission Glasgow coma scale score (5 +/- 2) were enrolled. Seven (54%) of the 13 children with focal TBI and 8 (28%) of 29 children with diffuse TBI had impairment or absence of cerebral autoregulation of at least one hemisphere. In patients with isolated focal TBI, ARI was lower (0.40 +/- 0.40 vs. 0.67 +/- 0.40; P = 0.03) in the side of TBI than in the unaffected hemisphere, but cerebral autoregulation was often impaired on the side without TBI or shift (5/13) on head CT. There was no difference in ARI between hemispheres in children with diffuse TBI, with or without superimposed focal lesions (P = 0.17). Patients with bilateral intact cerebral autoregulation tended to have higher 6 month Glasgow Outcome Score (GOS) than patients with either unilateral or bilateral cerebral autoregulation impairment (GOS 4.0 +/- 0.60 vs. 3.6 +/- 0.80; P = 0.08). CONCLUSIONS Hemispheric differences in cerebral autoregulation were common in children with isolated focal TBI. Absence of TBI on CT was not always associated with intact cerebral autoregulation. Patients with bilaterally intact cerebral autoregulation tended to have better outcomes.
Collapse
|
13
|
Daboussi A, Fourcade O. [Cerebral ischemic threshold in clinical practice]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2006; 25:729-34. [PMID: 16690247 DOI: 10.1016/j.annfar.2006.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The ischemic threshold is reached when the availability of oxygen in the cerebral tissue does not cover oxygen requirement. For a patient sedated, with constant PaO(2) and haemoglobin, the cerebral blood flow (CBF) global and local is the essential factor to maintain such a balance. At a cellular level, ischemia occurs when the CBF is below 20-25 ml/min. However, this threshold probably varies with the patient and also within the normal or perilesional tissue. A cerebral perfusion pressure (CPP) of 60 mmHg, recommended for a cerebral perfusion allowing a sufficient CBF for normal brain, does not prevent ischemia. Monitoring aimed to control parameters of the aerobic metabolism (PtiO(2), SjO(2) and microdialysis) and to detect the ischemic threshold allows to adapt the CPP to each patient and continuously.
Collapse
Affiliation(s)
- A Daboussi
- Département d'anesthésie-réanimation, hôpital Purpan, CHU de Toulouse, place du Docteur-Baylac, 31059 Toulouse cedex 09, France
| | | |
Collapse
|