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Wilkinson CM, Kung TF, Jickling GC, Colbourne F. A translational perspective on intracranial pressure responses following intracerebral hemorrhage in animal models. BRAIN HEMORRHAGES 2021. [DOI: 10.1016/j.hest.2020.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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Tayler H, Miners JS, Güzel Ö, MacLachlan R, Love S. Mediators of cerebral hypoperfusion and blood-brain barrier leakiness in Alzheimer's disease, vascular dementia and mixed dementia. Brain Pathol 2021; 31:e12935. [PMID: 33410232 PMCID: PMC8412075 DOI: 10.1111/bpa.12935] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/18/2020] [Accepted: 12/29/2020] [Indexed: 12/31/2022] Open
Abstract
In vascular dementia (VaD) and Alzheimer’s disease (AD), cerebral hypoperfusion and blood‐brain barrier (BBB) leakiness contribute to brain damage. In this study, we have measured biochemical markers and mediators of cerebral hypoperfusion and BBB in the frontal (BA6) and parietal (BA7) cortex and underlying white matter, to investigate the pathophysiology of vascular dysfunction in AD, VaD and mixed dementia. The ratio of myelin‐associated glycoprotein to proteolipid protein‐1 (MAG:PLP1), a post‐mortem biochemical indicator of the adequacy of ante‐mortem cerebral perfusion; the concentration of fibrinogen adjusted for haemoglobin level, a marker of blood‐brain barrier (BBB) leakiness; the level of vascular endothelial growth factor‐A (VEGF), a marker of tissue hypoxia; and endothelin‐1 (EDN1), a potent vasoconstrictor, were measured by ELISA in the frontal and parietal cortex and underlying white matter in 94 AD, 20 VaD, 33 mixed dementia cases and 58 age‐matched controls. All cases were assessed neuropathologically for small vessel disease (SVD), cerebral amyloid angiopathy (CAA) severity, Aβ and phospho‐tau parenchymal load, and Braak tangle stage. Aβ40 and Aβ42 were measured by ELISA in guanidine‐HCl tissue extracts. We found biochemical evidence of cerebral hypoperfusion in AD, VaD and mixed dementia to be associated with SVD, Aβ level, plaque load, EDN1 level and Braak tangle stage, and to be most widespread in mixed dementia. There was evidence of BBB leakiness in AD—limited to the cerebral cortex and related to EDN1 level. In conclusion, abnormalities of cerebral perfusion and BBB function in common types of dementia can largely be explained by a combination of arteriolosclerosis, and Aβ‐, tau‐ and endothelin‐related vascular dysfunction. The relative contributions of these processes vary considerably both between and within the diseases.
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Affiliation(s)
- Hannah Tayler
- Dementia Research Group, Institute of Clinical Neurosciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - J Scott Miners
- Dementia Research Group, Institute of Clinical Neurosciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Özge Güzel
- Dementia Research Group, Institute of Clinical Neurosciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Rob MacLachlan
- Dementia Research Group, Institute of Clinical Neurosciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Seth Love
- Dementia Research Group, Institute of Clinical Neurosciences, Bristol Medical School, University of Bristol, Bristol, UK
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Wolf MS, Rakkar J, Horvat CM, Simon DW, Kochanek PM, Clermont G, Clark RSB. Assessment of Dynamic Intracranial Compliance in Children with Severe Traumatic Brain Injury: Proof-of-Concept. Neurocrit Care 2020; 34:209-217. [PMID: 32556856 PMCID: PMC7299131 DOI: 10.1007/s12028-020-01004-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Background and Aims Intracranial compliance refers to the relationship between a change in intracranial volume and the resultant change in intracranial pressure (ICP). Measurement of compliance is useful in managing cardiovascular and respiratory failure; however, there are no contemporary means to assess intracranial compliance. Knowledge of intracranial compliance could complement ICP and cerebral perfusion pressure (CPP) monitoring in patients with severe traumatic brain injury (TBI) and may enable a proactive approach to ICP management. In this proof-of-concept study, we aimed to capitalize on the physiologic principles of intracranial compliance and vascular reactivity to CO2, and standard-of-care neurocritical care monitoring, to develop a method to assess dynamic intracranial compliance. Methods Continuous ICP and end-tidal CO2 (ETCO2) data from children with severe TBI were collected after obtaining informed consent in this Institutional Review Board-approved study. An intracranial pressure-PCO2 Compliance Index (PCI) was derived by calculating the moment-to-moment correlation between change in ICP and change in ETCO2. As such, “good” compliance may be reflected by a lack of correlation between time-synched changes in ICP in response to changes in ETCO2, and “poor” compliance may be reflected by a positive correlation between changes in ICP in response to changes in ETCO2. Results A total of 978 h of ICP and ETCO2 data were collected and analyzed from eight patients with severe TBI. Demographic and clinical characteristics included patient age 7.1 ± 5.8 years (mean ± SD); 6/8 male; initial Glasgow Coma Scale score 3 [3–7] (median [IQR]); 6/8 had decompressive surgery; 7.1 ± 1.4 ICP monitor days; ICU length of stay (LOS) 16.1 ± 6.8 days; hospital LOS 25.9 ± 8.4 days; and survival 100%. The mean PCI for all patients throughout the monitoring period was 0.18 ± 0.04, where mean ICP was 13.7 ± 2.1 mmHg. In this cohort, PCI was observed to be consistently above 0.18 by 12 h after monitor placement. Percent time spent with PCI thresholds > 0.1, 0.2, and 0.3 were 62% [24], 38% [14], and 23% [15], respectively. The percentage of time spent with an ICP threshold > 20 mmHg was 5.1% [14.6]. Conclusions Indirect assessment of dynamic intracranial compliance in TBI patients using standard-of-care monitoring appears feasible and suggests a prolonged period of derangement out to 5 days post-injury. Further study is ongoing to determine if the PCI—a new physiologic index, complements utility of ICP and/or CPP in guiding management of patients with severe TBI. Electronic supplementary material The online version of this article (10.1007/s12028-020-01004-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael S Wolf
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Pediatrics, Division of Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jaskaran Rakkar
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Christopher M Horvat
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Faculty Pavilion, Suite 2000, Brain Care Institute, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Dennis W Simon
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Faculty Pavilion, Suite 2000, Brain Care Institute, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Faculty Pavilion, Suite 2000, Brain Care Institute, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Gilles Clermont
- Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,The Clinical Research, Investigation, and Systems Modeling of Acute Illness (CRISMA) Center, Pittsburgh, PA, USA
| | - Robert S B Clark
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. .,Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. .,Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. .,Faculty Pavilion, Suite 2000, Brain Care Institute, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
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Racosta JM, Kimpinski K. Autonomic function and brain volume. Clin Auton Res 2016; 26:377-383. [PMID: 27568208 DOI: 10.1007/s10286-016-0380-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/18/2016] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The aim of this study is to review the evidence on the role of the autonomic nervous system as a determinant of brain volume. Brain volume measures have gained increasing attention given its biological importance, particularly as a measurement of neurodegeneration. METHODS Using an integrative approach, we reviewed publications addressing the anatomical and physiological characteristics of brain autonomic innervation focusing on evidence from diverse clinical populations with respect to brain volume. RESULTS Multiple mechanisms contribute to changes in brain volume. Autonomic influence on cerebral blood volume is of significant interest. CONCLUSION We suggest a role for the autonomic innervation of brain vessels in fluctuations of cerebral blood volume. Further investigation in several clinical populations including multiple sclerosis is warranted to understand the specific role of parenchyma versus blood vessels changes on final brain volume.
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Affiliation(s)
- Juan M Racosta
- Department of Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, London, ON, Canada.
- Schulich School of Medicine and Dentistry, Western University, 339 Windermere Road, London, ON, Canada.
| | - Kurt Kimpinski
- Department of Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, London, ON, Canada
- Schulich School of Medicine and Dentistry, Western University, 339 Windermere Road, London, ON, Canada
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Cerebral blood flow and transcranial doppler sonography measurements of CO2-reactivity in acute traumatic brain injured patients. Neurocrit Care 2015; 20:54-9. [PMID: 22700360 DOI: 10.1007/s12028-012-9727-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Cerebral blood flow (CBF) measurements are helpful in managing patients with traumatic brain injury (TBI), and testing the cerebrovascular reactivity to CO(2) provides information about injury severity and outcome. The complexity and potential hazard of performing CBF measurements limits routine clinical use. An alternative approach is to measure the CBF velocity using bedside, non-invasive, and transcranial Doppler (TCD) sonography. This study was performed to investigate if TCD is a useful alternative to CBF in patients with severe TBI. METHOD CBF and TCD flow velocity measurements and cerebrovascular reactivity to hypocapnia were simultaneously evaluated in 27 patients with acute TBI. Measurements were performed preoperatively during controlled normocapnia and hypocapnia in patients scheduled for hematoma evacuation under general anesthesia. MAIN FINDING AND CONCLUSION Although the lack of statistical correlation between the calculated reactivity indices, there was a significant decrease in TCD-mean flow velocity and a decrease in CBF with hypocapnia. CBF and TCD do not seem to be directly interchangeable in determining CO(2)-reactivity in TBI, despite both methods demonstrating deviation in the same direction during hypocapnia. TCD and CBF measurements both provide useful information on cerebrovascular events which, although not interchangeable, may complement each other in clinical scenarios.
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Kwak HJ, Kim JY, Lee KC, Kim HS, Kim JY. Effect of mild hypocapnia on hemodynamic and bispectral index responses to tracheal intubation during propofol anesthesia in children. J Clin Monit Comput 2014; 29:29-33. [PMID: 24526409 DOI: 10.1007/s10877-014-9564-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 02/07/2014] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to investigate the effect of mild hypocapnia on hypertension and arousal response after tracheal intubation in children during propofol anesthesia. Forty-four children, American Society of Anesthesiologists physical status I-II patients, aged 3-9 years were randomly allocated to either the normocapnia group [end-tidal carbon dioxide tension (ETCO2=35 mmHg, n=22)] or the hypocapnia group (ETCO2=25 mmHg, n=22). Anesthesia was induced with propofol 2.5 mg/kg. Five minutes after the administration of rocuronium 0.6 mg/kg, laryngoscopy was attempted. The mean arterial pressure (MAP), heart rate (HR), SpO2 and bispectral index (BIS) were measured during induction and intubation periods. The maximal change in the BIS with tracheal intubation (ΔBIS) was defined as the difference between the baseline value and the maximal value within the first 5 min after intubation. Before tracheal intubation, the change in BIS over time was not different between the groups. After tracheal intubation, the changes in the MAP, HR and BIS over time were not significantly different between the groups. The mean value±SD of ΔBIS was 5.7±5.2 and 7.4±5.5 in the normocapnia and hypocapnia groups, respectively, without any intergroup difference. This study showed that mild hypocapnia did not attenuate hemodynamic and BIS responses to tracheal intubation in children during propofol anesthesia. Our results suggested that hyperventilation has no beneficial effect on hemodynamic and arousal responses to tracheal intubation in children.
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Affiliation(s)
- Hyun Jeong Kwak
- Department of Anesthesiology and Pain Medicine, Gil Medical Center, Gachon University, Incheon, Korea
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de Vasconcellos K, Sneyd JR. Nitrous oxide: are we still in equipoise? A qualitative review of current controversies. Br J Anaesth 2013; 111:877-85. [PMID: 23801743 DOI: 10.1093/bja/aet215] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This review considers the current position of nitrous oxide in anaesthetic practice and balances potential beneficial and disadvantageous effects. The classic adverse characteristics of nitrous oxide, such as diffusion hypoxia, expansion of gas-filled spaces, and postoperative nausea and vomiting, are often cited as reasons to avoid this old drug. Recent concerns regarding neurotoxicity, adverse cardiovascular outcomes, and wound complications have further hardened many practitioners against nitrous oxide. New evidence and underpinning mechanistic data, however, suggest potential beneficial effects on the central nervous system, cardiovascular system, and acute and chronic pain. While we await the outcome of large studies including ENIGMA-II, many clinicians have already decided against this agent. The authors argue that this abandonment may be premature. Clinical Trial Registration None required.
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Affiliation(s)
- K de Vasconcellos
- Department of Anaesthetics and Critical Care, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
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Is nitrous oxide use appropriate in neurosurgical and neurologically at-risk patients? Curr Opin Anaesthesiol 2010; 23:544-50. [PMID: 20689409 DOI: 10.1097/aco.0b013e32833e1520] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW To address controversial issues surrounding the use of nitrous oxide as a component of anesthesia in neurosurgical and neurologically at-risk patients. RECENT FINDINGS Nitrous oxide has been used as a component of general anesthesia for over 160 years and has contributed to countless apparently uneventful anesthetics in neurologically at-risk patients. Avoidance of nitrous oxide in specific circumstances, such as pre-existing pneumocephalus, during acute venous air embolism, and in patients with disorders of folate metabolism, is warranted. However, various controversies exist regarding the use of this drug in the general neurosurgical population. Specifically, some suggest a possible association between nitrous oxide and the postoperative development of tension pneumocephalus despite lack of data to support this notion. Additionally, data describing alterations of cerebral hemodynamics and metabolism and exacerbation of ischemic neurologic injury by nitrous oxide are inconsistent. Recent data derived from humans having cerebral aneurysm clipping failed to show any long-term adverse effect from the use of nitrous oxide on gross neurologic or cognitive function. SUMMARY Except in a few specific circumstances, there exists no conclusive evidence to support the dogmatic avoidance of nitrous oxide in neurosurgical patients.
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Mark CI, Fisher JA, Pike GB. Improved fMRI calibration: precisely controlled hyperoxic versus hypercapnic stimuli. Neuroimage 2010; 54:1102-11. [PMID: 20828623 DOI: 10.1016/j.neuroimage.2010.08.070] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 07/11/2010] [Accepted: 08/31/2010] [Indexed: 10/19/2022] Open
Abstract
The calibration of functional magnetic resonance imaging (fMRI) for the estimation of neuronal activation-induced changes in cerebral metabolic rate of oxygen (CMRO(2)) has been achieved through hypercapnic-induced iso-metabolic increases in cerebral blood flow (CBF). Hypercapnia (HC) has been traditionally implemented through alterations in the fixed inspired fractional concentrations of carbon dioxide (F(I)CO(2)) without otherwise controlling end-tidal partial pressures of carbon dioxide (P(ET)CO(2)) or oxygen (P(ET)O(2)). There are several shortcomings to the use of this manual HC method that may be improved by using precise targeting of P(ET)CO(2) while maintaining iso-oxia. Similarly, precise control of blood gases can be used to induce isocapnic hyperoxia (HO) to reduce venous deoxyhaemoglobin (dHb) and thus increase BOLD signals, without appreciably altering CMRO(2) or CBF. The aim of our study was to use precise end-tidal targeting to compare the calibration of BOLD signals under an isocapnic hyperoxic protocol (HOP) (rises in P(ET)O(2) to 140, 240 and 340 mm Hg from baseline) to that of an iso-oxic hypercapnic protocol (HCP) (rises in P(ET)CO(2) of 3, 5, 7 and 9 mm Hg from baseline). Nine healthy volunteers were imaged at 3T while monitoring end-tidal gas concentrations and simultaneously measuring BOLD and CBF signals, via arterial spin labeling (ASL), during graded HCP and HOP, alternating with normocapnic states in a blocked experimental design. The variability of the calibration constant obtained under HOP (M(HOP)) was 0.3-0.5 that of the HCP one (M(HCP)). In addition, M-variances with precise gas targeting (M(HCP) and M(HOP)) were less than those reported in studies using traditional F(I)CO(2) and F(I)O(2) methods (M(HC) and M(HO), respectively). We conclude that precise controlled gas delivery markedly improves BOLD-calibration for fMRI studies of oxygen metabolism with both the HCP and the more precise HOP-alternative.
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Affiliation(s)
- Clarisse I Mark
- McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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Lee Y, Lee JH, Yoon DI, Lee Y, Kim KO, Chung S, In J, Choi JG, Cho H. Hypocapnia attenuates, and nitrous oxide disturbs the cerebral oximetric response to the rapid introduction of desflurane. J Korean Med Sci 2009; 24:1051-7. [PMID: 19949659 PMCID: PMC2775851 DOI: 10.3346/jkms.2009.24.6.1051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 01/19/2009] [Indexed: 11/26/2022] Open
Abstract
The aim of this study was to develop a nonlinear mixed-effects model for the increase in cerebral oximetry (rSO(2)) during the rapid introduction of desflurane, and to determine the effect of hypocapnia and N(2)O on the model. Twelve American Society of Anesthesiologist physical status class 1 and 2 subjects were allocated randomly into an Air and N(2)O group. After inducing anesthesia, desflurane was then increased abruptly from 4.0 to 12.0%. The PET(CO2), PET(DESF) and rSO(2) were recorded at 12 predetermined periods for the following 10 min. The maximum increase in rSO(2) reached +24-25% during normocapnia. The increase in rSO(2) could be fitted to a four parameter logistic equation as a function of the logarithm of PET(DESF). Hypocapnia reduced the maximum response of rSO(2), shifted the EC(50) to the right, and increased the slope in the Air group. N(2)O shifted the EC(50) to the right, and reduced the slope leaving the maximum rSO(2) unchanged. The N(2)O-effects disappeared during hypocapnia. The cerebrovascular reactivity of rSO(2) to CO(2) is still preserved during the rapid introduction of desflurane. N(2)O slows the response of rSO(2). Hypocapnia overwhelms all the effects of N(2)O.
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Affiliation(s)
- Younsuk Lee
- Department of Anesthesiology and Pain Medicine, and Medical Research Institute, Dongguk University College of Medicine, Goyang, Korea.
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Szabó EZ, Luginbuehl I, Bissonnette B. Impact of anesthetic agents on cerebrovascular physiology in children. Paediatr Anaesth 2009; 19:108-18. [PMID: 19040505 DOI: 10.1111/j.1460-9592.2008.02826.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of the pediatric neuroanesthetist is to provide comprehensive care to children with neurologic pathologies. The cerebral physiology is influenced by the developmental stage of the child. The understanding of the effects of anesthetic agents on the physiology of cerebral vasculature in the pediatric population has significantly increased in the past decade allowing a more rationale decision making in anesthesia management. Although no single anesthetic technique can be recommended, sound knowledge of the principles of cerebral physiology and anesthetic neuropharmacology will facilitate the care of pediatric neurosurgical patients.
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Affiliation(s)
- Elöd Z Szabó
- Department of Anaesthesia, University of Toronto, Toronto, ON, Canada.
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Lehmberg J, Waldner M, Baethmann A, Uhl E. Inflammatory response to nitrous oxide in the central nervous system. Brain Res 2008; 1246:88-95. [DOI: 10.1016/j.brainres.2008.09.064] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2008] [Revised: 09/13/2008] [Accepted: 09/16/2008] [Indexed: 12/18/2022]
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Bulte D, Chiarelli P, Wise R, Jezzard P. Measurement of cerebral blood volume in humans using hyperoxic MRI contrast. J Magn Reson Imaging 2008; 26:894-9. [PMID: 17896390 DOI: 10.1002/jmri.21096] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a new method of measuring quantitative regional cerebral blood volume (CBV) using epochs of hyperoxia as an intravenous contrast agent with T2*-weighted MRI. MATERIALS AND METHODS Images were acquired from six subjects (four male, two female, mean age 29 +/- 3.7 years) using a sequence combining pulsed arterial spin labeling interleaved with a gradient echo echo-planar imaging (EPI) blood oxygenation level-dependent (BOLD) sequence at 3T. The hyperoxia paradigm lasted 28 minutes consisting of 4 minutes of normoxia, two 6-minute blocks of hyperoxia separated by 6 minutes of normoxia. During the hyperoxic blocks the subjects were delivered a fractional oxygen concentration of 0.5. RESULTS The mean CBV was calculated to be 3.77 +/- 1.05 mL/100 g globally, 3.93 +/- 0.90 mL/100 g in gray matter (GM), and 2.52 +/- 0.78 mL/100 g in white matter (WM). The mean GM/WM ratio was thus found to be 1.56. These values are comparable to those obtained in other studies. CONCLUSION The hyperoxia technique for measuring CBV may be particularly useful for patient groups where an injected bolus of contrast agent is contraindicated. As more functional studies are employing epochs of inspired gases for calibration purposes, this method is easily incorporated into existing paradigms to produce a noninvasive, repeatable, easily tolerated, and quantitative measurement of regional CBV.
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Affiliation(s)
- Daniel Bulte
- FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford, UK.
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Human Cerebral Blood Volume (CBV) Measured by Dynamic Susceptibility Contrast MRI and 99mTc-RBC SPECT. J Neurosurg Anesthesiol 2008; 20:41-4. [DOI: 10.1097/ana.0b013e31815d4c70] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chiarelli PA, Bulte DP, Wise R, Gallichan D, Jezzard P. A calibration method for quantitative BOLD fMRI based on hyperoxia. Neuroimage 2007; 37:808-20. [PMID: 17632016 DOI: 10.1016/j.neuroimage.2007.05.033] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 05/01/2007] [Accepted: 05/10/2007] [Indexed: 10/23/2022] Open
Abstract
The estimation of changes in CMR(O2) using functional MRI involves an essential calibration step using a vasoactive agent to induce an isometabolic change in CBF. This calibration procedure is performed most commonly using hypercapnia as the isometabolic stimulus. However, hypercapnia possesses a number of detrimental side effects. Here, a new method is presented using hyperoxia to perform the same calibration step. This procedure requires independent measurement of Pa(O2), the BOLD signal, and CBF. We demonstrate that this method yields results that are comparable to those derived using other methods. Further, the hyperoxia technique is able to provide an estimate of the calibration constant that has lower overall intersubject and intersession variability compared to the hypercapnia approach.
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Affiliation(s)
- Peter A Chiarelli
- FMRIB Centre, Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
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Karsli C, Luginbuehl I, Bissonnette B. The Cerebrovascular Response to Hypocapnia in Children Receiving Propofol. Anesth Analg 2004; 99:1049-1052. [PMID: 15385348 DOI: 10.1213/01.ane.0000132778.84943.8d] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Hypocapnia is used to treat acute increases in intracranial pressure during neurosurgery. Cerebrovascular reactivity to carbon dioxide (CCO(2)R) is preserved above 35 mm Hg ETco(2) in children during propofol anesthesia; however, a plateau effect has been suggested below 35 mm Hg. To further delineate this phenomenon, we measured CCO(2)R by transcranial Doppler (TCD) sonography over small increments in ETco(2) in 27 healthy children. Anesthesia comprised a standardized propofol infusion and a caudal epidural block. A TCD probe was placed to measure middle cerebral artery blood flow velocity (V(mca)). ETco(2) was adjusted between 24 and 40 mm Hg at 1-2 mm Hg increments using an exogenous source of CO(2). There was an exponential relationship between ETco(2) and V(mca) above an ETco(2) value of 30 mm Hg (r = 0.82). However, V(mca) did not change with ETco(2) less than 30 mm Hg (r = 0.06). There were no significant changes in heart rate or arterial blood pressure. We conclude that when contemplating methods to decrease brain volume and intracranial pressure, hyperventilation to ETco(2) values less than 30 mm Hg may not be necessary in children receiving propofol, as no further reduction in cerebral blood flow velocity will be achieved.
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Affiliation(s)
- Cengiz Karsli
- From the Department of Anesthesia, The Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada
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Wilson-Smith E, Karsli C, Luginbuehl I, Bissonnette B. Effect of nitrous oxide on cerebrovascular reactivity to carbon dioxide in children during sevoflurane anaesthesia. Br J Anaesth 2003; 91:190-5. [PMID: 12878616 DOI: 10.1093/bja/aeg171] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Sevoflurane and nitrous oxide have intrinsic cerebral vasodilatory activity. To determine the effects of nitrous oxide on cerebrovascular reactivity to carbon dioxide (CCO(2)R) during sevoflurane anaesthesia in children, middle cerebral artery blood flow velocity (V(mca)) was measured over a range of end-tidal carbon dioxide concentrations (E'(CO(2))), using transcranial Doppler (TCD) ultrasonography. METHODS Ten children aged 1.5-6 yr were anaesthetized with sevoflurane and received a caudal block. Patients were allocated randomly to receive either air-nitrous oxide or nitrous oxide-air. Further randomization determined the sequence of E'(CO(2)) (25, 35, 45, and 55 mm Hg) and sevoflurane (1.0 then 1.5 MAC or 1.5 then 1.0 MAC) concentrations. Once steady state had been reached, three measurements of V(mca), mean arterial pressure (MAP), and heart rate (HR) were recorded. RESULTS Cerebrovascular carbon dioxide reactivity was reduced in the 25-35 mm Hg E'(CO(2)) range on the addition of nitrous oxide to 1.5 MAC, but not 1.0 MAC sevoflurane. A plateau in CCO(2)R of 0.4-0.6% per mm Hg was seen in all groups between E'(CO(2)) values of 45 and 55 mm Hg. Mean HR and MAP remained constant throughout the study period. CONCLUSIONS Cerebrovascular carbon dioxide reactivity is reduced at and above an E'(CO(2)) of 45 mm Hg during 1.0 and 1.5 MAC sevoflurane anaesthesia. The addition of nitrous oxide to 1.5 MAC sevoflurane diminishes CCO(2)R in the hypocapnic range. This should be taken into consideration when hyperventilation techniques for reduction of brain bulk are being contemplated in children with raised intracranial pressure.
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Affiliation(s)
- E Wilson-Smith
- Department of Anesthesia, The Hospital for Sick Children and the University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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Doepp F, Schreiber SJ, Brunecker P, Valdueza JM. Ultrasonographic assessment of global cerebral blood volume in healthy adults. J Cereb Blood Flow Metab 2003; 23:972-7. [PMID: 12902841 DOI: 10.1097/01.wcb.0000071884.63724.69] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The authors describe a new ultrasonographic method for analysis of global cerebral blood volume (CBV) and its application under controlled hyperventilation. CBV was determined as the product of global cerebral blood flow volume (CBF) and global cerebral circulation time. CBF was measured by duplex sonography and calculated as the sum of flow volumes in both internal carotid arteries and vertebral arteries. Extracranial Doppler assessed cerebral circulation time by determining the time interval of echo-contrast bolus arrival between internal carotid artery and contralateral internal jugular vein. Forty-four healthy volunteers (mean age 45 +/- 19 years, range 20-79 years) were studied. Mean CBV was 77 +/- 13 mL. CBV did not correlate with age, end-tidal carbon dioxide level, heart rate, or blood pressure. Hypocapnia was induced in 10 subjects by controlled hyperventilation. Mean reduction of end-tidal carbon dioxide values by 9 +/- 1 mm Hg led to a significant increase in cerebral circulation time (6.1 +/- 0.9 to 8.4 +/- 1.1 second, P < 0.0001) and a significant CBF decrease (742 +/- 85 to 526 +/- 77 mL/min, P < 0.0001), whereas CBV remained unchanged (75 +/- 6 to 73 +/- 10 mL).
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Affiliation(s)
- Florian Doepp
- Department of Neurology, University Hospital Charité, Schumannstr. 20/21, 10117 Berlin, Germany.
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Schreiber SJ, Doepp F, Valdueza JM. Multimodal ultrasound assessment of cerebral hemodynamics in a patient with a diffuse cerebral angiomatosis. ULTRASOUND IN MEDICINE & BIOLOGY 2003; 29:501-505. [PMID: 12749920 DOI: 10.1016/s0301-5629(02)00782-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent newly developed ultrasound (US) techniques extend our ability to study the cerebral hemodynamics in patients with arteriovenous malformations (AVM) beyond the conventional cerebral blood flow velocity (CBFV) analysis. We present US data of global cerebral blood flow (CBF) and global cerebral circulation time (CCT) in a patient with a unique bihemispherial diffuse cerebral angiomatosis and compare them with 10 age-matched controls. In addition, the estimation of an US-derived global cerebral blood volume (CBV) is proposed. Duplex sonographic CBF analysis revealed 2620 mL/min in the patient and 754 +/- 93 mL/min in controls. Doppler sonographic CCT was 2.9 s and 6.3 +/- 1.5 s and CBV 126 mL and 79 +/- 19 mL, respectively. US allows a simple, minimal invasive bedside analysis of several global hemodynamic parameters that might provide valuable additional information in patients with diffusely altered cerebral hemodynamics.
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Wilson-Smith E, Karsli C, Luginbuehl IA, Bissonnette B. The effect of nitrous oxide on cerebral blood flow velocity in children anesthetized with propofol. Acta Anaesthesiol Scand 2003; 47:307-11. [PMID: 12648197 DOI: 10.1034/j.1399-6576.2003.00060.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Propofol for maintenance of anesthesia by continuous infusion is gaining popularity for use in pediatric patients. Nitrous oxide (N2O) has been shown to increase cerebral blood flow velocity (CBFV) in both children and adults. To determine the effects of N2O on middle cerebral artery blood flow velocity (Vmca) during propofol anesthesia in children, Vmca was measured with and without N2O using transcranial Doppler (TCD) sonography. METHODS Thirty ASA I or II children aged 18 months to 6 years undergoing elective urological surgery were enrolled. Anesthesia comprised propofol aimed at producing an estimated steady-state serum concentration of 3 micro g.ml-1 and a caudal epidural block. A transcranial Doppler probe was used to measure middle cerebral artery blood flow velocity. Each patient was randomized to receive a sequence of either Air/N2O/Air or N2O/Air/N2O in 35% oxygen. Fifteen min after each change in the N2O concentration, three measurements of cerebral blood flow velocity, blood pressure and heart rate were recorded. Ventilatory parameters and EtCO2 were kept constant throughout the study period. RESULTS CBFV increased by 12.4% when air was replaced by N2O, and returned to baseline when N2O was subsequently removed. There was a 14% decrease in CBFV when N2O was replaced with air, which increased to baseline when air was subsequently replaced with N2O. Mean heart rate and blood pressure remained constant throughout the study period. CONCLUSION The effects of nitrous oxide on CBFV are preserved in children during propofol anesthesia.
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Affiliation(s)
- E Wilson-Smith
- Department of Anaesthesia, Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada
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Thees C, Scheufler KM, Nadstawek J, Zentner J, Lehnert A, Hoeft A. Monitoring of cerebral perfusion pressure during intracranial hypertension: a sufficient parameter of adequate cerebral perfusion and oxygenation? Intensive Care Med 2003; 29:386-90. [PMID: 12541158 DOI: 10.1007/s00134-002-1625-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2002] [Accepted: 11/28/2002] [Indexed: 11/28/2022]
Abstract
OBJECTIVE A cerebral perfusion pressure (CPP) oriented treatment is a widely accepted standard for patients with intracranial hypertension. In an animal model of controlled intracranial hypertension we investigated whether CPP is a reliable parameter of sufficient cerebral perfusion and oxygenation. Using near-infrared reflexion spectroscopy the effect of decreasing CPP due to increasing intracranial pressure (ICP) on cerebral tissue oxygenation was studied. METHODS Ten rabbits were subjected to artificially elevated ICP using the cisterna-magna infusion technique. Regional cerebral O(2) saturation of hemoglobin (tiSO(2)), regional tissue concentration of hemoglobin (tiHb), and CPP were recorded continuously. CPP was investigated with respect to tiSO(2). Electrocortical activity was simultaneously recorded by two-channel EEG to determine the onset of ischemia. RESULTS Reduced CPP due to increased ICP led to a continuous decrease in tiSO(2.) There was progressive suppression of EEG frequency and amplitude with decreasing CPP in all animals. Onset of EEG-silence due to elevated ICP was observed in a wide range of CPP-values between 9 and 42 mmHg. At the same time tiSO(2) varied merely between 0 and 5%. CONCLUSIONS Regarding the EEG effects due to increased ICP (EEG silence), CPP values showed a wide interindividual variability, in contrast to tiSO(2). In our animal model the sole calculation of CPP did not reflect adequate cerebral perfusion.
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Affiliation(s)
- Christof Thees
- Department of Anesthesia and Intensive Care Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.
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Karsli C, Luginbuehl I, Farrar M, Bissonnette B. Cerebrovascular carbon dioxide reactivity in children anaesthetized with propofol. Paediatr Anaesth 2003; 13:26-31. [PMID: 12535035 DOI: 10.1046/j.1460-9592.2003.01017.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anaesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in paediatric patients. To determine the effects of propofol on carbon dioxide cerebrovascular reactivity in children, middle cerebral artery blood flow velocity was measured at different levels of endtidal (PECO2) by transcranial Doppler sonography. METHODS Ten ASA I or II children, aged 1-6 years undergoing elective urological surgery were enrolled. Anaesthesia comprized propofol aimed at producing an estimated steady-state serum concentration of 3 microg x ml-1 and a caudal epidural block. PECO2 was adjusted randomly in an increasing or decreasing fashion between 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) with an exogenous source of CO2 while maintaining ventilation parameters constant. RESULTS Cerebral blood flow velocity increased as PECO2 increased from 3.3 to 5.2 kPa (25-40 mmHg) (P < 0.001) and from 5.2 to 7.2 kPa (40-55 mmHg) (P < 0.001). Mean heart rate and blood pressure did not change significantly. CONCLUSIONS This study demonstrates that cerebrovascular CO2 reactivity is maintained over PECO2 values of 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) in healthy children anaesthetized with propofol.
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Affiliation(s)
- Cengiz Karsli
- Department of Anaesthesia, University of Toronto, Toronto, Ontario, Canada
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