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Meng L, Sun Y, Zhao X, Rasmussen M, Al-Tarshan Y, Meng DM, Liu Z, Adams DC, McDonagh DL. Noradrenaline-induced changes in cerebral blood flow in health, traumatic brain injury and critical illness: a systematic review with meta-analysis. Anaesthesia 2024. [PMID: 38831595 DOI: 10.1111/anae.16313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2024] [Indexed: 06/05/2024]
Abstract
BACKGROUND Noradrenaline is a standard treatment for hypotension in acute care. The precise effects of noradrenaline on cerebral blood flow in health and disease remain unclear. METHODS We systematically reviewed and synthesised data from studies examining changes in cerebral blood flow in healthy participants and patients with traumatic brain injury and critical illness. RESULTS Twenty-eight eligible studies were included. In healthy subjects and patients without critical illness or traumatic brain injury, noradrenaline did not significantly change cerebral blood flow velocity (-1.7%, 95%CI -4.7-1.3%) despite a 24.1% (95%CI 19.4-28.7%) increase in mean arterial pressure. In patients with traumatic brain injury, noradrenaline significantly increased cerebral blood flow velocity (21.5%, 95%CI 11.0-32.0%), along with a 33.8% (95%CI 14.7-52.9%) increase in mean arterial pressure. In patients who were critically ill, noradrenaline significantly increased cerebral blood flow velocity (20.0%, 95%CI 9.7-30.3%), along with a 32.4% (95%CI 25.0-39.9%) increase in mean arterial pressure. Our analyses suggest intact cerebral autoregulation in healthy subjects and patients without critical illness or traumatic brain injury., and impaired cerebral autoregulation in patients with traumatic brain injury and who were critically ill. The extent of mean arterial pressure changes and the pre-treatment blood pressure levels may affect the magnitude of cerebral blood flow changes. Studies assessing cerebral blood flow using non-transcranial Doppler methods were inadequate and heterogeneous in enabling meaningful meta-analysis. CONCLUSIONS Noradrenaline significantly increases cerebral blood flow in humans with impaired, not intact, cerebral autoregulation, with the extent of changes related to the severity of functional impairment, the extent of mean arterial pressure changes and pre-treatment blood pressure levels.
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Affiliation(s)
- Lingzhong Meng
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yanhua Sun
- Department of Anesthesiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Xu Zhao
- Department of Anesthesiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Mads Rasmussen
- Department of Anesthesiology, Section of Neuroanesthesia, Aarhus University Hospital, Aarhus, Denmark
| | | | - Deyi M Meng
- Choate Rosemary Hall School, Wallingford, CT, USA
| | - Ziyue Liu
- Department of Biostatistics and Health Data Science, Indiana University School of Medicine, Indianapolis, IN, USA
| | - David C Adams
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, USA
| | - David L McDonagh
- Departments of Anesthesiology and Pain Management, Neurological Surgery, Neurology, UT Southwestern Medical Center, Dallas, TX, USA
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2
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Salvagno M, Geraldini F, Coppalini G, Robba C, Gouvea Bogossian E, Annoni F, Vitali E, Sterchele ED, Balestra C, Taccone FS. The Impact of Inotropes and Vasopressors on Cerebral Oxygenation in Patients with Traumatic Brain Injury and Subarachnoid Hemorrhage: A Narrative Review. Brain Sci 2024; 14:117. [PMID: 38391692 PMCID: PMC10886736 DOI: 10.3390/brainsci14020117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 01/17/2024] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
Abstract
Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are critical neurological conditions that necessitate specialized care in the Intensive Care Unit (ICU). Managing cerebral perfusion pressure (CPP) and mean arterial pressure (MAP) is of primary importance in these patients. To maintain targeted MAP and CPP, vasopressors and/or inotropes are commonly used. However, their effects on cerebral oxygenation are not fully understood. The aim of this review is to provide an up-to date review regarding the current uses and pathophysiological issues related to the use of vasopressors and inotropes in TBI and SAH patients. According to our findings, despite achieving similar hemodynamic parameters and CPP, the effects of various vasopressors and inotropes on cerebral oxygenation, local CBF and metabolism are heterogeneous. Therefore, a more accurate understanding of the cerebral activity of these medications is crucial for optimizing patient management in the ICU setting.
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Affiliation(s)
- Michele Salvagno
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
| | - Federico Geraldini
- Department of Anesthesia and Intensive Care, Ospedale Università di Padova, 35128 Padova, Italy
| | - Giacomo Coppalini
- Department of Anesthesia and Intensive Care, Humanitas Clinical and Research Center, 20089 Milano, Italy
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, 20072 Milano, Italy
| | - Chiara Robba
- Anaesthesia and Intensive Care, IRCCS Policlinico San Martino, 16132 Genova, Italy
- Dipartimento di Scienze Chirurgiche Diagnostiche e Integrate, Università di Genova, 16132 Genova, Italy
| | - Elisa Gouvea Bogossian
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
| | - Filippo Annoni
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
| | - Eva Vitali
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
| | - Elda Diletta Sterchele
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
| | - Costantino Balestra
- Department Environmental, Occupational, Aging (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), 1160 Brussels, Belgium
- Anatomical Research and Clinical Studies, Vrije Universiteit Brussels (VUB), 1090 Brussels, Belgium
- DAN Europe Research Division (Roseto-Brussels), 1160 Brussels, Belgium
- Motor Sciences Department, Physical Activity Teaching Unit, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Fabio Silvio Taccone
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1070 Brussels, Belgium
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3
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Olsen MH, Capion T, Riberholt CG, Bache S, Ebdrup SR, Rasmussen R, Mathiesen T, Berg RMG, Møller K. Effect of controlled blood pressure increase on cerebral blood flow velocity and oxygenation in patients with subarachnoid haemorrhage. Acta Anaesthesiol Scand 2023; 67:1054-1060. [PMID: 37192754 DOI: 10.1111/aas.14277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/24/2023] [Accepted: 05/01/2023] [Indexed: 05/18/2023]
Abstract
BACKGROUND Patients with aneurysmal subarachnoid haemorrhage (SAH) might have impaired cerebral autoregulation, that is, CBF - and thereby oxygen delivery - passively increase with an increase in CPP. This physiological study aimed to investigate the cerebral haemodynamic effects of controlled blood pressure increase in the early phase after SAH before any signs of delayed cerebral ischaemia (DCI) occurred. METHODS The study was carried out within 5 days after ictus. Data were recorded at baseline and after 20 min of noradrenaline infusion to increase mean arterial blood pressure (MAP) by a maximum of 30 mmHg and to an absolute level of no more than 130 mmHg. The primary outcome was the difference in middle cerebral artery blood flow velocity (MCAv) measured by transcranial Doppler (TCD), while differences in intracranial pressure (ICP), brain tissue oxygen tension (PbtO2 ), and microdialysis markers of cerebral oxidative metabolism and cell injury were assessed as exploratory outcomes. Data were analysed using Wilcoxon signed-rank test with correction for multiplicity for the exploratory outcomes using the Benjamini-Hochberg correction. RESULTS Thirty-six participants underwent the intervention 4 (median, IQR: 3-4.75) days after ictus. MAP was increased from 82 (IQR: 76-85) to 95 (IQR: 88-98) mmHg (p-value: <.001). MCAv remained stable (baseline, median 57, IQR: 46-70 cm/s; controlled blood pressure increase, median: 55, IQR: 48-71 cm/s; p-value: .054), whereas PbtO2 increased significantly (baseline, median: 24, 95%CI: 19-31 mmHg; controlled blood pressure increase, median: 27, 95%CI: 24-33 mmHg; p-value <.001). The remaining exploratory outcomes were unchanged. CONCLUSION In this study of patients with SAH, MCAv was not significantly affected by a brief course of controlled blood pressure increase; despite this, PbtO2 increased. This suggests that autoregulation might not be impaired in these patients or other mechanisms could mediate the increase in brain oxygenation. Alternatively, a CBF increase did occur that, in turn, increased cerebral oxygenation, but was not detected by TCD. TRIAL REGISTRATION clinicaltrials.gov (NCT03987139; 14 June 2019).
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Affiliation(s)
- Markus Harboe Olsen
- Department of Neuroanaesthesiology, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Tenna Capion
- Department of Neurosurgery, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Christian Gunge Riberholt
- Department of Neuroanaesthesiology, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
- Department of Brain and Spinal Cord Injury, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Søren Bache
- Department of Neuroanaesthesiology, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Søren Røddik Ebdrup
- Department of Neuroanaesthesiology, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Rune Rasmussen
- Department of Neurosurgery, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Tiit Mathiesen
- Department of Neurosurgery, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Ronan M G Berg
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Denmark
- Centre for Physical Activity Research, Copenhagen University Hospital, Rigshospitalet, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Kirsten Møller
- Department of Neuroanaesthesiology, The Neuroscience Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
- Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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4
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Sainbhi AS, Froese L, Gomez A, Marquez I, Amenta F, Batson C, Stein KY, Zeiler FA. High spatial and temporal resolution cerebrovascular reactivity for humans and large mammals: A technological description of integrated fNIRS and niABP mapping system. Front Physiol 2023; 14:1124268. [PMID: 36755788 PMCID: PMC9899997 DOI: 10.3389/fphys.2023.1124268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 01/10/2023] [Indexed: 01/24/2023] Open
Abstract
Introduction: The process of cerebral vessels maintaining cerebral blood flow (CBF) fairly constant over a wide range of arterial blood pressure is referred to as cerebral autoregulation (CA). Cerebrovascular reactivity is the mechanism behind this process, which maintains CBF through constriction and dilation of cerebral vessels. Traditionally CA has been assessed statistically, limited by large, immobile, and costly neuroimaging platforms. However, with recent technology advancement, dynamic autoregulation assessment is able to provide more detailed information on the evolution of CA over long periods of time with continuous assessment. Yet, to date, such continuous assessments have been hampered by low temporal and spatial resolution systems, that are typically reliant on invasive point estimations of pulsatile CBF or cerebral blood volume using commercially available technology. Methods: Using a combination of multi-channel functional near-infrared spectroscopy and non-invasive arterial blood pressure devices, we were able to create a system that visualizes CA metrics by converting them to heat maps drawn on a template of human brain. Results: The custom Python heat map module works in "offline" mode to visually portray the CA index per channel with the use of colourmap. The module was tested on two different mapping grids, 8 channel and 24 channel, using data from two separate recordings and the Python heat map module was able read the CA indices file and represent the data visually at a preselected rate of 10 s. Conclusion: The generation of the heat maps are entirely non-invasive, with high temporal and spatial resolution by leveraging the recent advances in NIRS technology along with niABP. The CA mapping system is in its initial stage and development plans are ready to transform it from "offline" to real-time heat map generation.
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Affiliation(s)
- Amanjyot Singh Sainbhi
- Biomedical Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada,*Correspondence: Amanjyot Singh Sainbhi,
| | - Logan Froese
- Biomedical Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Izzy Marquez
- Undergraduate Engineering Program, Department of Biosystems Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Fiorella Amenta
- Undergraduate Engineering Program, Department of Biosystems Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Carleen Batson
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kevin Y. Stein
- Biomedical Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Frederick A. Zeiler
- Biomedical Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada,Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden,Division of Anaesthesia, Department of Medicine, Addenbrooke’s Hospital, University of Cambridge, Cambridge, United Kingdom
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5
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Sainbhi AS, Gomez A, Froese L, Slack T, Batson C, Stein KY, Cordingley DM, Alizadeh A, Zeiler FA. Non-Invasive and Minimally-Invasive Cerebral Autoregulation Assessment: A Narrative Review of Techniques and Implications for Clinical Research. Front Neurol 2022; 13:872731. [PMID: 35557627 PMCID: PMC9087842 DOI: 10.3389/fneur.2022.872731] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/30/2022] [Indexed: 12/13/2022] Open
Abstract
The process of cerebral vessels regulating constant cerebral blood flow over a wide range of systemic arterial pressures is termed cerebral autoregulation (CA). Static and dynamic autoregulation are two types of CA measurement techniques, with the main difference between these measures relating to the time scale used. Static autoregulation looks at the long-term change in blood pressures, while dynamic autoregulation looks at the immediate change. Techniques that provide regularly updating measures are referred to as continuous, whereas intermittent techniques take a single at point in time. However, a technique being continuous or intermittent is not implied by if the technique measures autoregulation statically or dynamically. This narrative review outlines technical aspects of non-invasive and minimally-invasive modalities along with providing details on the non-invasive and minimally-invasive measurement techniques used for CA assessment. These non-invasive techniques include neuroimaging methods, transcranial Doppler, and near-infrared spectroscopy while the minimally-invasive techniques include positron emission tomography along with magnetic resonance imaging and radiography methods. Further, the advantages and limitations are discussed along with how these methods are used to assess CA. At the end, the clinical considerations regarding these various techniques are highlighted.
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Affiliation(s)
- Amanjyot Singh Sainbhi
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
- *Correspondence: Amanjyot Singh Sainbhi
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Logan Froese
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Trevor Slack
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Carleen Batson
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kevin Y. Stein
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Dean M. Cordingley
- Applied Health Sciences Program, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB, Canada
- Pan Am Clinic Foundation, Winnipeg, MB, Canada
| | - Arsalan Alizadeh
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Frederick A. Zeiler
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Centre on Aging, University of Manitoba, Winnipeg, MB, Canada
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
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6
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Svedung Wettervik T, Fahlström M, Enblad P, Lewén A. Cerebral Pressure Autoregulation in Brain Injury and Disorders-A Review on Monitoring, Management, and Future Directions. World Neurosurg 2021; 158:118-131. [PMID: 34775084 DOI: 10.1016/j.wneu.2021.11.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022]
Abstract
The role of cerebral pressure autoregulation (CPA) in brain injury and disorders has gained increased interest. The CPA is often disturbed as a consequence of acute brain injury, which contributes to further brain damage and worse outcome. Specifically, in severe traumatic brain injury, CPA disturbances predict worse clinical outcome and targeting an autoregulatory-oriented optimal cerebral perfusion pressure threshold may improve brain energy metabolism and clinical outcome. In aneurysmal subarachnoid hemorrhage, cerebral vasospasm in combination with distal autoregulatory disturbances precipitate delayed cerebral ischemia. The role of optimal cerebral perfusion pressure targets is less clear in aneurysmal subarachnoid hemorrhage, but high cerebral perfusion pressure targets are generally favorable in the vasospasm phase. In acute ischemia, autoregulatory disturbances may occur and autoregulatory-oriented blood pressure (optimal mean arterial pressure) management reduces the risk of hemorrhagic transformation, brain edema, and unfavorable outcome. In chronic occlusive disease such as moyamoya, the gradual reduction of the cerebral circulation leads to compensatory distal vasodilation and the residual CPA capacity predicts the risk for cerebral ischemia. In spontaneous intracerebral hemorrhage, the role of autoregulatory disturbances is less clear, but CPA disturbances correlate with worse clinical outcome. Also, in community-acquired bacterial meningitis, CPA dysfunction is frequent and correlates with worse clinical outcome, but autoregulatory management is yet to be evaluated. In this review, we discuss the role of CPA in different types of brain injury and disease, the strengths and limitations of the monitoring methods, the potentials of autoregulatory management, and future directions in the field.
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Affiliation(s)
| | - Markus Fahlström
- Department of Surgical Sciences, Section of Radiology, Uppsala University, Uppsala, Sweden
| | - Per Enblad
- Department of Neuroscience, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
| | - Anders Lewén
- Department of Neuroscience, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
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7
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Launey Y, Fryer TD, Hong YT, Steiner LA, Nortje J, Veenith TV, Hutchinson PJ, Ercole A, Gupta AK, Aigbirhio FI, Pickard JD, Coles JP, Menon DK. Spatial and Temporal Pattern of Ischemia and Abnormal Vascular Function Following Traumatic Brain Injury. JAMA Neurol 2021; 77:339-349. [PMID: 31710336 PMCID: PMC6865302 DOI: 10.1001/jamaneurol.2019.3854] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Question How does 15oxygen positron emission tomography characterization of cerebral physiology after traumatic brain injury inform clinical practice? Findings In this single-center observational cohort study of 68 patients and 27 control participants, early ischemia was common in patients, but hyperemia coexisted in different brain regions. Cerebral blood volume was consistently increased, despite low cerebral blood flow. Meaning Per this analysis, pathophysiologic heterogeneity indicates that bedside physiological monitoring with devices that measure global (jugular venous saturation) or focal (tissue oximetry) brain oxygenation should be interpreted with caution. Importance Ischemia is an important pathophysiological mechanism after traumatic brain injury (TBI), but its incidence and spatiotemporal patterns are poorly characterized. Objective To comprehensively characterize the spatiotemporal changes in cerebral physiology after TBI. Design, Setting, and Participants This single-center cohort study uses 15oxygen positron emission tomography data obtained in a neurosciences critical care unit from February 1998 through July 2014 and analyzed from April 2018 through August 2019. Patients with TBI requiring intracranial pressure monitoring and control participants were recruited. Exposures Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral oxygen metabolism (CMRO2), and oxygen extraction fraction. Main Outcomes and Measures Ratios (CBF/CMRO2 and CBF/CBV) were calculated. Ischemic brain volume was compared with jugular venous saturation and brain tissue oximetry. Results A total of 68 patients with TBI and 27 control participants were recruited. Results from 1 patient with TBI and 7 health volunteers were excluded. Sixty-eight patients with TBI (13 female [19%]; median [interquartile range (IQR)] age, 29 [22-47] years) underwent 90 studies at early (day 1 [n = 17]), intermediate (days 2-5 [n = 54]), and late points (days 6-10 [n = 19]) and were compared with 20 control participants (5 female [25%]; median [IQR] age, 43 [31-47] years). The global CBF and CMRO2 findings for patients with TBI were less than the ranges for control participants at all stages (median [IQR]: CBF, 26 [22-30] mL/100 mL/min vs 38 [29-49] mL/100 mL/min; P < .001; CMRO2, 62 [55-71] μmol/100 mL/min vs 131 [101-167] μmol/100 mL/min; P < .001). Early CBF reductions showed a trend of high oxygen extraction fraction (suggesting classical ischemia), but this was inconsistent at later phases. Ischemic brain volume was elevated even in the absence of intracranial hypertension and highest at less than 24 hours after TBI (median [IQR], 36 [10-82] mL), but many patients showed later increases (median [IQR] 6-10 days after TBI, 24 [4-42] mL; across all points: patients, 10 [5-39] mL vs control participants, 1 [0-3] mL; P < 001). Ischemic brain volume was a poor indicator of jugular venous saturation and brain tissue oximetry. Patients’ CBF/CMRO2 ratio was higher than controls (median [IQR], 0.42 [0.35-0.49] vs 0.3 [0.28-0.33]; P < .001) and their CBF/CBV ratio lower (median [IQR], 7.1 [6.4-7.9] vs 12.3 [11.0-14.0]; P < .001), suggesting abnormal flow-metabolism coupling and vascular reactivity. Patients’ CBV was higher than controls (median [IQR], 3.7 [3.4-4.1] mL/100 mL vs 3.0 [2.7-3.6] mL/100 mL; P < .001); although values were lower in patients with intracranial hypertension, these were still greater than controls (median [IQR], 3.7 [3.2-4.0] vs 3.0 [2.7-3.6] mL/100 mL; P = .002), despite more profound reductions in partial pressure of carbon dioxide (median [IQR], 4.3 [4.1-4.6] kPa vs 4.7 [4.3-4.9] kPa; P = .001). Conclusions and Relevance Ischemia is common early, detectable up to 10 days after TBI, possible without intracranial hypertension, and inconsistently detected by jugular or brain tissue oximetry. There is substantial between-patient and within-patient pathophysiological heterogeneity; ischemia and hyperemia commonly coexist, possibly reflecting abnormalities in flow-metabolism coupling. Increased CBV may contribute to intracranial hypertension but can coexist with abnormal CBF/CBV ratios. These results emphasize the need to consider cerebrovascular pathophysiological complexity when managing patients with TBI.
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Affiliation(s)
- Yoann Launey
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.,Department of Anaesthesia and Critical Care Medicine, Centre Hospitalier Universitaire de Rennes, Rennes, France
| | - Tim D Fryer
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Young T Hong
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Luzius A Steiner
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.,Department of Anaesthesiology, University Hospital Basel, Basel, Switzerland.,Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Jurgens Nortje
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.,Department of Anaesthesia, Norfolk and Norwich University Hospitals National Health Service Foundation Trust, Norwich, United Kingdom
| | - Tonny V Veenith
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.,Birmingham Acute Care Research Group, Department of Critical Care Medicine, Queen Elizabeth Hospital, University of Birmingham, Birmingham, United Kingdom
| | - Peter J Hutchinson
- Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Ari Ercole
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Arun K Gupta
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Franklin I Aigbirhio
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - John D Pickard
- Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan P Coles
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - David K Menon
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
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8
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Froese L, Dian J, Gomez A, Unger B, Zeiler FA. The cerebrovascular response to norepinephrine: A scoping systematic review of the animal and human literature. Pharmacol Res Perspect 2020; 8:e00655. [PMID: 32965778 PMCID: PMC7510331 DOI: 10.1002/prp2.655] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/14/2020] [Accepted: 08/20/2020] [Indexed: 12/12/2022] Open
Abstract
Intravenous norepinephrine (NE) is utilized commonly in critical care for cardiovascular support. NE's impact on cerebrovasculature is unclear and may carry important implications during states of critical neurological illness. The aim of the study was to perform a scoping review of the literature on the cerebrovascular/cerebral blood flow (CBF) effects of NE. A search of MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and Cochrane Library from inception to December 2019 was performed. All manuscripts pertaining to the administration of NE, in which the impact on CBF/cerebral vasculature was recorded, were included. We identified 62 animal studies and 26 human studies. Overall, there was a trend to a direct vasoconstriction effect of NE on the cerebral vasculature, with conflicting studies having demonstrated both increases and decreases in regional CBF (rCBF) or global CBF. Healthy animals and those undergoing cardiopulmonary resuscitation demonstrated a dose-dependent increase in CBF with NE administration. However, animal models and human patients with acquired brain injury had varied responses in CBF to NE administration. The animal models indicate an increase in cerebral vasoconstriction with NE administration through the alpha receptors in vessels. Global and rCBF during the injection of NE displays a wide variation depending on treatment and model/patient.
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Affiliation(s)
- Logan Froese
- Biomedical EngineeringFaculty of EngineeringUniversity of ManitobaWinnipegCanada
| | - Joshua Dian
- Section of NeurosurgeryDepartment of SurgeryRady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
| | - Alwyn Gomez
- Section of NeurosurgeryDepartment of SurgeryRady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
- Department of Anatomy and Cell ScienceRady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
| | - Bertram Unger
- Section of Critical CareDepartment of MedicineRady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
| | - Frederick A. Zeiler
- Biomedical EngineeringFaculty of EngineeringUniversity of ManitobaWinnipegCanada
- Department of Anatomy and Cell ScienceRady Faculty of Health SciencesUniversity of ManitobaWinnipegCanada
- Centre on AgingUniversity of ManitobaWinnipegCanada
- Division of AnaesthesiaDepartment of MedicineAddenbrooke’s HospitalUniversity of CambridgeCambridgeUK
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Lloyd-Donald P, Spencer W, Cheng J, Romero L, Jithoo R, Udy A, Fitzgerald MC. In adult patients with severe traumatic brain injury, does the use of norepinephrine for augmenting cerebral perfusion pressure improve neurological outcome? A systematic review. Injury 2020; 51:2129-2134. [PMID: 32739152 DOI: 10.1016/j.injury.2020.07.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/24/2020] [Accepted: 07/24/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND OBJECTIVE Despite multiple interventions, mortality due to severe traumatic brain injury (sTBI) within mature Trauma Systems has remained unchanged over the last decade. During this time, the use of vasoactive infusions (commonly norepinephrine) to achieve a target blood pressure and cerebral perfusion pressure (CPP) has been a mainstay of sTBI management. However, evidence suggests that norepinephrine, whilst raising blood pressure, may reduce cerebral oxygenation. This study aimed to review the available evidence that links norepinephrine augmented CPP to clinical outcomes for these patients. METHODS A systematic review examining the evidence for norepinephrine augmented CPP in TBI patients was undertaken. Strict inclusion and exclusion criteria were developed for a dedicated literature search of multiple scientific databases. Two dedicated reviewers screened articles, whilst a third dedicated reviewer resolved conflicts. RESULTS The systematic review yielded 4,809 articles, of which 1,197 duplicate articles were removed. After abstract/title screening, 45 articles underwent full text review, resulting in the identification of two articles that investigated the effect of norepinephrine administration on clinical outcomes in patients following TBI when compared to other vasopressors. Neither study found a difference in neurological outcome between the vasopressor groups. No articles measured the effect of norepinephrine compared to no vasopressor use on the clinical outcome of patients with sTBI. CONCLUSIONS Despite being a mainstay of pharmacological management for hypotension in patients following sTBI, there is minimal clinical evidence supporting the use of norepinephrine in targeting a CPP for either improving neurological outcomes or reducing mortality. Outcomes-based clinical trials exploring the role of brain tissue perfusion and oxygenation monitoring are required to validate any benefit.
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Affiliation(s)
- Patryck Lloyd-Donald
- Trauma Services, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia; National Trauma Research Institute, Level 4, 89 Commercial Rd, Melbourne 3004, VIC, Australia
| | - William Spencer
- Trauma Services, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia; National Trauma Research Institute, Level 4, 89 Commercial Rd, Melbourne 3004, VIC, Australia.
| | - Jacinta Cheng
- Trauma Services, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia; National Trauma Research Institute, Level 4, 89 Commercial Rd, Melbourne 3004, VIC, Australia.
| | - Lorena Romero
- Library Services, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia.
| | - Ron Jithoo
- National Trauma Research Institute, Level 4, 89 Commercial Rd, Melbourne 3004, VIC, Australia; Department of Neurosurgery, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia.
| | - Andrew Udy
- Department of Intensive Care and Hyperbaric Medicine, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia; Australian and New Zealand Intensive Care Research Centre, School of Public and Preventive Medicine, Monash University, 553 St Kilda Road, Melbourne VIC, Australia.
| | - Mark C Fitzgerald
- Trauma Services, The Alfred Hospital, 89 Commercial Rd, Melbourne VIC, Australia; National Trauma Research Institute, Level 4, 89 Commercial Rd, Melbourne 3004, VIC, Australia.
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Effects of Vasopressors on Cerebral Circulation and Oxygenation: A Narrative Review of Pharmacodynamics in Health and Traumatic Brain Injury. J Neurosurg Anesthesiol 2020; 32:18-28. [DOI: 10.1097/ana.0000000000000596] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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11
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Management of Head Trauma in the Neurocritical Care Unit. Neurocrit Care 2019. [DOI: 10.1017/9781107587908.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Kim W, Taw B, Yokosako S, Koyanagi M, Fukuda H, Sinclair D, Sirhan D, Teitelbaum J, Lui MW, Kasuya H, Angle M, Lo BW. The future of non-invasive cerebral oximetry in neurosurgical procedures: A systematic review. ACTA ACUST UNITED AC 2018. [DOI: 10.12688/mniopenres.12779.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background:Cerebral hypoxia is one of the most important causes of secondary brain injury during neurosurgical procedures and in neurointensive care. In patients with brain injury, cerebrovascular reactivity may be impaired and a decrease in mean arterial pressure or cerebral perfusion pressure may lead to inadequate cerebral blood flow and secondary ischemia. There are several techniques available to measure brain oxygenation. In particular, near infrared spectroscopy (NIRS) is a non-invasive neuromonitoring technique and there has been a rapid expansion of clinical evidence that NIRS reduces perioperative neurologic complications. Methods:This systematic review synthesizes prospective and retrospective cohort studies that investigate the benefit of using NIRS in prevention of perioperative neurologic complications. The methodological quality of these studies is appraised.Results:Seven studies were included in this systematic review. The methodological quality of each study was assessed. They had representative patient populations, clear selection criteria and clear descriptions of study designs. Reproducible study protocols with ethics board approval were present. Clinical results were described in sufficient detail and were applicable to patient undergoing neurosurgical procedures and in neurointensive care. Limitations included small sample sizes and lack of reference standard.Conclusions:This systematic review synthesizes the most current evidence of non-invasive, inexpensive, and continuous measurement of cerebral oxygenation by NIRS. Results gained from these studies are clinically useful and shed light on how this neuromonitoring technique is beneficial in preventing perioperative neurological complications.
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Johnson MA, Borgman MA, Cannon JW, Kuppermann N, Neff LP. Severely Elevated Blood Pressure and Early Mortality in Children with Traumatic Brain Injuries: The Neglected End of the Spectrum. West J Emerg Med 2018; 19:452-459. [PMID: 29760839 PMCID: PMC5942007 DOI: 10.5811/westjem.2018.2.36404] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 01/01/2018] [Accepted: 02/08/2018] [Indexed: 11/11/2022] Open
Abstract
Introduction In adults with traumatic brain injuries (TBI), hypotension and hypertension at presentation are associated with mortality. The effect of age-adjusted blood pressure in children with TBI has been insufficiently studied. We sought to determine if age-adjusted hypertension in children with severe TBI is associated with mortality. Methods This was a retrospective analysis of the Department of Defense Trauma Registry (DoDTR) between 2001 and 2013. We included for analysis patients <18 years with severe TBI defined as Abbreviated Injury Severity (AIS) scores of the head ≥3. We defined hypertension as moderate for systolic blood pressures (SBP) between the 95th and 99th percentile for age and gender and severe if greater than the 99th percentile. Hypotension was defined as SBP <90 mmHg for children >10 years or < 70mmHg + (2 × age) for children ≤10 years. We performed multivariable logistic regression and Cox regression to determine if BP categories were associated with mortality. Results Of 4,990 children included in the DoDTR, 740 met criteria for analysis. Fifty patients (6.8%) were hypotensive upon arrival to the ED, 385 (52.0%) were normotensive, 115 (15.5%) had moderate hypertension, and 190 (25.7%) had severe hypertension. When compared to normotensive patients, moderate and severe hypertension patients had similar Injury Severity Scores, similar AIS head scores, and similar frequencies of neurosurgical procedures. Multivariable logistic regression demonstrated that hypotension (odd ratio [OR] 2.85, 95 confidence interval [CI] 1.26–6.47) and severe hypertension (OR 2.58, 95 CI 1.32–5.03) were associated with increased 24-hour mortality. Neither hypotension (Hazard ratio (HR) 1.52, 95 CI 0.74–3.11) nor severe hypertension (HR 1.65, 95 CI 0.65–2.30) was associated with time to mortality. Conclusion Pediatric age-adjusted hypertension is frequent after severe TBI. Severe hypertension is strongly associated with 24-hour mortality. Pediatric age-adjusted blood pressure needs to be further evaluated as a critical marker of early mortality.
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Affiliation(s)
- M Austin Johnson
- University of California Davis Medical Center, Department of Emergency Medicine, Sacramento, California
| | - Matthew A Borgman
- Brooke Army Medical Center, Department of Pediatrics, Ft Sam Houston, Texas.,Uniformed Services University of the Health Sciences, Department of Pediatrics, Bethesda, Maryland
| | - Jeremy W Cannon
- Perelman School of Medicine at the University of Pennsylvania, Department of Surgery, Philadelphia, Pennsylvania
| | - Nathan Kuppermann
- University of California Davis Medical Center, Department of Emergency Medicine, Sacramento, California
| | - Lucas P Neff
- David Grant USAF Medical Center, Travis Air Force Base, Department of General Surgery, Fairfield, California.,University of California Davis Medical Center, Department of Surgery, Sacramento, California.,Uniformed Services University of the Health Sciences, Department of Surgery, Bethesda, Maryland
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14
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Zeiler FA, Donnelly J, Calviello L, Menon DK, Smielewski P, Czosnyka M. Pressure Autoregulation Measurement Techniques in Adult Traumatic Brain Injury, Part I: A Scoping Review of Intermittent/Semi-Intermittent Methods. J Neurotrauma 2017. [PMID: 28648106 DOI: 10.1089/neu.2017.5085] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The purpose of this study was to perform a systematic, scoping review of commonly described intermittent/semi-intermittent autoregulation measurement techniques in adult traumatic brain injury (TBI). Nine separate systematic reviews were conducted for each intermittent technique: computed tomographic perfusion (CTP)/Xenon-CT (Xe-CT), positron emission tomography (PET), magnetic resonance imaging (MRI), arteriovenous difference in oxygen (AVDO2) technique, thigh cuff deflation technique (TCDT), transient hyperemic response test (THRT), orthostatic hypotension test (OHT), mean flow index (Mx), and transfer function autoregulation index (TF-ARI). MEDLINE®, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library (inception to December 2016), and reference lists of relevant articles were searched. A two tier filter of references was conducted. The total number of articles utilizing each of the nine searched techniques for intermittent/semi-intermittent autoregulation techniques in adult TBI were: CTP/Xe-CT (10), PET (6), MRI (0), AVDO2 (10), ARI-based TCDT (9), THRT (6), OHT (3), Mx (17), and TF-ARI (6). The premise behind all of the intermittent techniques is manipulation of systemic blood pressure/blood volume via either chemical (such as vasopressors) or mechanical (such as thigh cuffs or carotid compression) means. Exceptionally, Mx and TF-ARI are based on spontaneous fluctuations of cerebral perfusion pressure (CPP) or mean arterial pressure (MAP). The method for assessing the cerebral circulation during these manipulations varies, with both imaging-based techniques and TCD utilized. Despite the limited literature for intermittent/semi-intermittent techniques in adult TBI (minus Mx), it is important to acknowledge the availability of such tests. They have provided fundamental insight into human autoregulatory capacity, leading to the development of continuous and more commonly applied techniques in the intensive care unit (ICU). Numerous methods of intermittent/semi-intermittent pressure autoregulation assessment in adult TBI exist, including: CTP/Xe-CT, PET, AVDO2 technique, TCDT-based ARI, THRT, OHT, Mx, and TF-ARI. MRI-based techniques in adult TBI are yet to be described, with the main focus of MRI techniques on metabolic-based cerebrovascular reactivity (CVR) and not pressure-based autoregulation.
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Affiliation(s)
- Frederick A Zeiler
- 1 Division of Anaesthesia, University of Cambridge , Cambridge, United Kingdom .,2 Clinician Investigator Program, University of Manitoba , Winnipeg, Canada .,3 Section of Neurosurgery, Department of Surgery, University of Manitoba , Winnipeg, Canada
| | - Joseph Donnelly
- 4 Section of Brain Physics, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom
| | - Leanne Calviello
- 4 Section of Brain Physics, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom
| | - David K Menon
- 1 Division of Anaesthesia, University of Cambridge , Cambridge, United Kingdom
| | - Peter Smielewski
- 4 Section of Brain Physics, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom
| | - Marek Czosnyka
- 4 Section of Brain Physics, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom
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Abstract
This article provides a review of cerebral autoregulation, particularly as it relates to the clinician scientist experienced in neuroscience in anesthesia and critical care. Topics covered are biological mechanisms; methods used for assessment of autoregulation; effects of anesthetics; role in control of cerebral hemodynamics in health and disease; and emerging areas, such as role of age and sex in contribution to dysautoregulation. Emphasis is placed on bidirectional translational research wherein the clinical informs the study design of basic science studies, which, in turn, informs the clinical to result in development of improved therapies for treatment of central nervous system conditions.
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Affiliation(s)
- William M Armstead
- Department of Anesthesiology and Critical Care, University of Pennsylvania, 3620 Hamilton Walk, JM3, Philadelphia, PA l9l04, USA; Department of Pharmacology, University of Pennsylvania, Philadelphia, PA l9l04, USA.
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16
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Capillary transit time heterogeneity and flow-metabolism coupling after traumatic brain injury. J Cereb Blood Flow Metab 2014; 34:1585-98. [PMID: 25052556 PMCID: PMC4269727 DOI: 10.1038/jcbfm.2014.131] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 06/10/2014] [Accepted: 06/20/2014] [Indexed: 12/26/2022]
Abstract
Most patients who die after traumatic brain injury (TBI) show evidence of ischemic brain damage. Nevertheless, it has proven difficult to demonstrate cerebral ischemia in TBI patients. After TBI, both global and localized changes in cerebral blood flow (CBF) are observed, depending on the extent of diffuse brain swelling and the size and location of contusions and hematoma. These changes vary considerably over time, with most TBI patients showing reduced CBF during the first 12 hours after injury, then hyperperfusion, and in some patients vasospasms before CBF eventually normalizes. This apparent neurovascular uncoupling has been ascribed to mitochondrial dysfunction, hindered oxygen diffusion into tissue, or microthrombosis. Capillary compression by astrocytic endfeet swelling is observed in biopsies acquired from TBI patients. In animal models, elevated intracranial pressure compresses capillaries, causing redistribution of capillary flows into patterns argued to cause functional shunting of oxygenated blood through the capillary bed. We used a biophysical model of oxygen transport in tissue to examine how capillary flow disturbances may contribute to the profound changes in CBF after TBI. The analysis suggests that elevated capillary transit time heterogeneity can cause critical reductions in oxygen availability in the absence of 'classic' ischemia. We discuss diagnostic and therapeutic consequences of these predictions.
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Effect of moderate hyperventilation and induced hypertension on cerebral tissue oxygenation after cardiac arrest and therapeutic hypothermia. Resuscitation 2013; 84:1540-5. [DOI: 10.1016/j.resuscitation.2013.05.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 11/20/2022]
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Bouzat P, Sala N, Payen JF, Oddo M. Beyond intracranial pressure: optimization of cerebral blood flow, oxygen, and substrate delivery after traumatic brain injury. Ann Intensive Care 2013; 3:23. [PMID: 23837598 PMCID: PMC3716965 DOI: 10.1186/2110-5820-3-23] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/25/2013] [Indexed: 02/17/2023] Open
Abstract
Monitoring and management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is a standard of care after traumatic brain injury (TBI). However, the pathophysiology of so-called secondary brain injury, i.e., the cascade of potentially deleterious events that occur in the early phase following initial cerebral insult—after TBI, is complex, involving a subtle interplay between cerebral blood flow (CBF), oxygen delivery and utilization, and supply of main cerebral energy substrates (glucose) to the injured brain. Regulation of this interplay depends on the type of injury and may vary individually and over time. In this setting, patient management can be a challenging task, where standard ICP/CPP monitoring may become insufficient to prevent secondary brain injury. Growing clinical evidence demonstrates that so-called multimodal brain monitoring, including brain tissue oxygen (PbtO2), cerebral microdialysis and transcranial Doppler among others, might help to optimize CBF and the delivery of oxygen/energy substrate at the bedside, thereby improving the management of secondary brain injury. Looking beyond ICP and CPP, and applying a multimodal therapeutic approach for the optimization of CBF, oxygen delivery, and brain energy supply may eventually improve overall care of patients with head injury. This review summarizes some of the important pathophysiological determinants of secondary cerebral damage after TBI and discusses novel approaches to optimize CBF and provide adequate oxygen and energy supply to the injured brain using multimodal brain monitoring.
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Affiliation(s)
- Pierre Bouzat
- Department of Intensive Care Medicine, CHUV-University Hospital, Rue du Bugnon 46, BH 08,623, CH-1011 Lausanne, Switzerland.
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Armstead WM, Riley J, Vavilala MS. Dopamine prevents impairment of autoregulation after traumatic brain injury in the newborn pig through inhibition of Up-regulation of endothelin-1 and extracellular signal-regulated kinase mitogen-activated protein kinase. Pediatr Crit Care Med 2013; 14:e103-11. [PMID: 23314184 PMCID: PMC3567252 DOI: 10.1097/pcc.0b013e3182712b44] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Traumatic brain injury contributes to morbidity in children and boys are disproportionately represented. Autoregulation is impaired more in male compared with female piglets after traumatic brain injury through sex-dependent up-regulation of the spasmogen endothelin-1 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK), a family of three kinases: ERK, p38, and JNK). Elevation of mean arterial pressure leading to increased cerebral perfusion pressure via phenylephrine improves impairment of autoregulation after traumatic brain injury in female but not male piglets through modulation of endothelin-1 and ERK MAPK up-regulation, blocked in females, but aggravated in males. We hypothesized that pressor choice to elevate cerebral perfusion pressure is important in improving cerebral hemodynamics after traumatic brain injury and that dopamine will prevent impairment of autoregulation in both male and female piglets through blockade of endothelin-1 and ERK MAPK. DESIGN Prospective, randomized animal study. SETTING University laboratory. SUBJECTS Newborn (1-5 days old) pigs. INTERVENTIONS Cerebral perfusion pressure and pial artery diameter were determined before and after lateral fluid percussion brain injury was produced in piglets equipped with a closed cranial window. Dopamine (15 µg/kg/min IV) was administered 30 mins post fluid percussion injury. Cerebrospinal fluid ERK MAPK was determined by enzyme-linked immunosorbent assay. MEASUREMENTS AND MAIN RESULTS Dopamine increased cerebral perfusion pressure equivalently in both sexes and prevented sex-dependent reductions in pial artery diameter after fluid percussion injury. Loss of pial artery dilation during hypotension was greater in male than in female piglets after fluid percussion injury, but dopamine prevented such impairment equivalently in both sexes post injury. endothelin-1 and ERK MAPK release was greater in male compared to female piglets after fluid percussion injury, but dopamine also blocked their up-regulation equivalently in male and female piglets after fluid percussion injury. CONCLUSIONS These data indicate that dopamine is protective of autoregulation after fluid percussion injury in both sexes. These observations advocate for the consideration of development of sex based therapies for treatment of hemodynamic sequalae of pediatric traumatic brain injury.
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Affiliation(s)
- William M Armstead
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA.
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Stocchetti N, Le Roux P, Vespa P, Oddo M, Citerio G, Andrews PJ, Stevens RD, Sharshar T, Taccone FS, Vincent JL. Clinical review: neuromonitoring - an update. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2013; 17:201. [PMID: 23320763 PMCID: PMC4057243 DOI: 10.1186/cc11513] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Critically ill patients are frequently at risk of neurological dysfunction as a result of primary neurological conditions or secondary insults. Determining which aspects of brain function are affected and how best to manage the neurological dysfunction can often be difficult and is complicated by the limited information that can be gained from clinical examination in such patients and the effects of therapies, notably sedation, on neurological function. Methods to measure and monitor brain function have evolved considerably in recent years and now play an important role in the evaluation and management of patients with brain injury. Importantly, no single technique is ideal for all patients and different variables will need to be monitored in different patients; in many patients, a combination of monitoring techniques will be needed. Although clinical studies support the physiologic feasibility and biologic plausibility of management based on information from various monitors, data supporting this concept from randomized trials are still required.
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Abstract
The main purpose of neurointensive care is to fight against cerebral ischaemia. Ischaemia is the cell energy failure following inadequacy between supply of glucose and oxygen and demand. Ischemia monitoring starts with a global approach, especially with cerebral perfusion pressure (CPP) determined by mean arterial pressure and intracranial pressure (ICP). However, global monitoring is insufficient to detect "regional" ischaemia, leading to development of local monitoring such as brain oxygen partial pressure (PtiO(2)). PtiO(2) is measured on a volume of a few mm(3) from a probe implanted in the cerebral tissue. The normal value is classically included between 25 and 35 mmHg and critical ischemic threshold is 10 mmHg. Understanding what exactly is PtiO(2) is still a matter of debate. PtiO(2) is more an indicator of oxygen diffusion depending of oxygen arterial pressure (PaO(2)) and local cerebral blood flow (CBF). Increase PaO(2) to treat PtiO(2) would hide information about local CBF. PtiO(2) is useful for the detection of low local CBF even when ICP is low as in hypocapnia-induced vasoconstriction. PtiO(2)-guided management could lead to a continuous optimization of arterial oxygen transport for an optimal cerebral tissue oxygenation. Finally, PtiO(2) has probably a global prognostic value because studies showed that hypoxic values for a long period of time lead to an unfavourable neurologic outcome. In conclusion, PtiO(2) provides additional information for regional monitoring of cerebral ischaemia and deserves more intensive use to better understand it and probably improve neurointensive care management.
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Baron JC, Jones T. Oxygen metabolism, oxygen extraction and positron emission tomography: Historical perspective and impact on basic and clinical neuroscience. Neuroimage 2012; 61:492-504. [DOI: 10.1016/j.neuroimage.2011.12.036] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 10/14/2022] Open
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Armstead WM, Riley J, Vavilala MS. TBI sex dependently upregulates ET-1 to impair autoregulation, which is aggravated by phenylephrine in males but is abrogated in females. J Neurotrauma 2012; 29:1483-90. [PMID: 22335188 PMCID: PMC3335106 DOI: 10.1089/neu.2011.2248] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Traumatic brain injury (TBI) contributes to morbidity in children, and boys are disproportionately represented. Endothelin-1 (ET-1) contributes to impaired autoregulation via oxygen (O₂⁻) after TBI in piglets, but its relative role in males compared with females has not been previously investigated. Increased cerebral perfusion pressure (CPP) via phenylephrine (Phe) sex dependently improves impairment of autoregulation after TBI through modulation of extracellular signal-related kinase (ERK) mitogen-activated protein kinase (MAPK) upregulation, aggravated in males, but blocked in females. Activation of adenosine-5'-triphosphate (ATP) and Ca sensitive K channels produce vasodilation, contributing to autoregulation. We hypothesized that ET-1 upregulation is greater in males after TBI and that disturbed autoregulation will be prevented by Phe in a sex-dependent manner through modulation of ET-1, O₂⁻, and ERK. Results show that ET-1 release was greater in males after fluid percussion injury (FPI), blunted by Phe in females, but aggravated in males. K channel vasodilation was impaired more in males than in females after TBI. Phe prevented reductions in K channel vasodilation in females, but further reduced dilation in males after TBI. Co-administration of BQ-123, U0126, or PEG-SOD (ET-1, ERK antagonist, and O₂⁻ scavenger) with Phe restored dilation to K agonists and hypotension in males after TBI. ERK upregulation was blocked by BQ-123 and PEG-SOD. These data indicate that TBI upregulates ET-1 more in males than in females. Elevation of CPP with Phe sex dependently prevents impairment of cerebral autoregulation after TBI through modulation of ET-1, O₂⁻, and ERK mediated impairment of K channel vasodilation. These observations advocate for the consideration of development of sex-based therapies for the treatment of hemodynamic sequelae of pediatric TBI.
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Affiliation(s)
- William M Armstead
- Department of Anesthesiology and Critical Care, 3620 Hamilton Walk, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Diringer MN, Zazulia AR, Powers WJ. Does Ischemia Contribute to Energy Failure in Severe TBI? Transl Stroke Res 2011; 2:517-23. [DOI: 10.1007/s12975-011-0119-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 10/12/2011] [Accepted: 10/14/2011] [Indexed: 12/12/2022]
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Vigué B. [Hypernatremia in neurointensive care]. ACTA ACUST UNITED AC 2010; 29:e189-92. [PMID: 20650596 DOI: 10.1016/j.annfar.2010.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Hypernatremia invariably denotes hyperosmolarity and, at least transiently, causes cellular dehydration. Because of blood brain barrier properties, cerebral tissue volume is modified by acute changes in osmolarity. An acute hyperosmolarity (by intravenous sodium or mannitol) temporally decreases intracranial pressure. This treatment is thus useful in critical situations, allowing time for diagnosis and, if possible, other treatment. But in cases of sustained hypernatremia, cellular dehydration is rapidly counterbalanced by an increase in cellular osmolarity. For the brain, it has been shown that cerebral volume is restored in a few hours during prolonged hypernatremia. Moreover, the plasmatic osmotic load induces an increase in diuresis and natriuresis. A tight control is then necessary to prevent hypovolemia and electrolytes disorders. Teams using this treatment should undertake controlled randomized studies to ascertain any beneficial effect that cannot be explained by physiology.
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Affiliation(s)
- B Vigué
- Département d'anesthésie-réanimation, CHU de Bicêtre, AP-HP, Le Kremlin-Bicêtre, France.
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Abstract
INTRODUCTION Posttraumatic brain ischemia or hypoxia is a major potential cause of secondary injury that may lead to poor outcome. Avoidance, or amelioration, of this secondary injury depends on early diagnosis and intervention before permanent injury occurs. However, tools to monitor brain oxygenation continuously in the neuro-intensive care unit have been lacking. DISCUSSION In recent times, methods of monitoring aspects of brain oxygenation continuously by the bedside have been evaluated in several experimental and clinical series and are potentially changing the way we manage head-injured patients. These monitors have the potential to alert the clinician to possible secondary injury and enable intervention, help interpret pathophysiological changes (e.g., hyperemia causing raised intracranial pressure), monitor interventions (e.g., hyperventilation for increased intracranial pressure), and prognosticate. This review focuses on jugular venous saturation, brain tissue oxygen tension, and near-infrared spectroscopy as practical methods that may have an important role in managing patients with brain injury, with a particular focus on the available evidence in children. However, to use these monitors effectively and to understand the studies in which these monitors are employed, it is important for the clinician to appreciate the technical characteristics of each monitor, as well as respective strengths and limitations of each. It is equally important that the clinician understands relevant aspects of brain oxygen physiology and head trauma pathophysiology to enable correct interpretation of the monitored data and therefore to direct an appropriate therapeutic response that is likely to benefit, not harm, the patient.
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Affiliation(s)
- Ursula K Rohlwink
- Division of Neurosurgery, School of Child and Adolescent Health, Red Cross Children's Hospital, University of Cape Town, Cape Town, South Africa
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Figaji AA, Zwane E, Fieggen AG, Argent AC, Le Roux PD, Siesjo P, Peter JC. Pressure autoregulation, intracranial pressure, and brain tissue oxygenation in children with severe traumatic brain injury. J Neurosurg Pediatr 2009; 4:420-8. [PMID: 19877773 DOI: 10.3171/2009.6.peds096] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECT Cerebral pressure autoregulation is an important neuroprotective mechanism that stabilizes cerebral blood flow when blood pressure (BP) changes. In this study the authors examined the association between autoregulation and clinical factors, BP, intracranial pressure (ICP), brain tissue oxygen tension (PbtO(2)), and outcome after pediatric severe traumatic brain injury (TBI). In particular we examined how the status of autoregulation influenced the effect of BP changes on ICP and PbtO(2). METHODS In this prospective observational study, 52 autoregulation tests were performed in 24 patients with severe TBI. The patients had a mean age of 6.3 +/- 3.2 years, and a postresuscitation Glasgow Coma Scale score of 6 (range 3-8). All patients underwent continuous ICP and PbtO(2) monitoring, and transcranial Doppler ultrasonography was used to examine the autoregulatory index (ARI) based on blood flow velocity of the middle cerebral artery after increasing mean arterial pressure by 20% of the baseline value. Impaired autoregulation was defined as an ARI < 0.4 and intact autoregulation as an ARI >or= 0.4. The relationships between autoregulation (measured as both a continuous and dichotomous variable), outcome, and clinical and physiological variables were examined using multiple logistic regression analysis. RESULTS Autoregulation was impaired (ARI < 0.4) in 29% of patients (7 patients). The initial Glasgow Coma Scale score was significantly associated with the ARI (p = 0.02, r = 0.32) but no other clinical factors were associated with autoregulation status. Baseline values at the time of testing for ICP, PbtO(2), the ratio of PbtO(2)/PaO(2), mean arterial pressure, and middle cerebral artery blood flow velocity were similar in the patients with impaired or intact autoregulation. There was an inverse relationship between ARI (continuous and dichotomous) with a change in ICP (continuous ARI, p = 0.005; dichotomous ARI, p = 0.02); that is, ICP increased with the BP increase when ARI was low (weak autoregulation). The ARI (continuous and dichotomous) was also inversely associated with a change in PbtO(2) (continuous ARI, p = 0.002; dichotomous ARI, p = 0.02). The PbtO(2) increased when BP was increased in most patients, even when the ARI was relatively high (stronger autoregulation), but the magnitude of this response was still associated with the ARI. There was no relationship between the ARI and outcome. CONCLUSIONS These data demonstrate the influence of the strength of autoregulation on the response of ICP and PbtO(2) to BP changes and the variability of this response between individuals. The findings suggest that autoregulation testing may assist clinical decision-making in pediatric severe TBI and help better define optimal BP or cerebral perfusion pressure targets for individual patients.
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Affiliation(s)
- Anthony A Figaji
- Division of Neurosurgery, School of Child and Adolescent Health, University of Cape Town, Red Cross Children's Hospital, Cape Town, South Africa.
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Focal cerebral oxygenation and neurological outcome with or without brain tissue oxygen-guided therapy in patients with traumatic brain injury. Acta Neurochir (Wien) 2009; 151:1399-409. [PMID: 19727549 DOI: 10.1007/s00701-009-0398-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 04/26/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND In patients with severe traumatic brain injury (TBI), the depth and duration of cerebral hypoxia are independent predictors of outcome. This study aimed to evaluate the efficacy of brain oxygen-guided therapy in improving cerebral oxygenation and neurological outcome in severe TBI patients. METHODS Thirty TBI patients had brain oxygen monitors placed contralateral to the side of mass lesions, or to the non-dominant side if injury was diffuse. The first 10 patients (Group 1, observational) had brain tissue oxygen (PbrO2) monitored, but not treated. The next 20 patients (Group 2, interventional) were treated according to brain tissue oxygen-guided algorithms aiming to improve cerebral oxygen availability. The 6-month neurological outcome of Group 2 patients was compared with that of Group 1 patients and with contemporary control patients (Group 3) treated without the use of brain oxygen monitoring. FINDINGS The mean duration of brain hypoxic episodes (PbrO2 <15 mmHg) was 106 minutes in Group 1, and 34 minutes in Group 2 (p=0.01). Brain tissue oxygen was <15 mmHg for 10% of monitoring time in Group 1 and 2.8% in Group 2 (p=0.12). The peak incidence of cerebral hypoxic events in both groups occurred during post-injury day 5. The mean Injury Severity Score (ISS) of patients experiencing cerebral hypoxia was higher than that of patients without cerebral hypoxic episodes (33.7 vs 24.2, p=0.04). There was no statistically significant difference in neurological outcome between those patients treated with and those without brain oxygen-guided therapy. CONCLUSIONS In TBI patients, brain tissue oxygen-guided therapy is associated with decreased duration of episodes of cerebral hypoxia. Larger studies are indicated to determine the effects of this therapy on neurological outcome.
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Narotam PK, Morrison JF, Nathoo N. Brain tissue oxygen monitoring in traumatic brain injury and major trauma: outcome analysis of a brain tissue oxygen-directed therapy. J Neurosurg 2009; 111:672-82. [PMID: 19463048 DOI: 10.3171/2009.4.jns081150] [Citation(s) in RCA: 215] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Cerebral ischemia is the leading cause of preventable death in cases of major trauma with severe traumatic brain injury (TBI). Intracranial pressure (ICP) control and cerebral perfusion pressure (CPP) manipulation have significantly reduced the mortality but not the morbidity rate in these patients. In this study, the authors describe their 5-year experience with brain tissue oxygen (PbtO(2)) monitoring, and the effect of a brain tissue oxygen-directed critical care guide (PbtO(2)-CCG) on the 6-month clinical outcome (based on the 6-month Glasgow Outcome Scale score) in patients with TBIs. METHODS One hundred thirty-nine patients admitted to Creighton University Medical Center with major traumatic injuries (Injury Severity Scale [ISS] scores >or= 16) and TBI underwent prospective evaluation. All patients were treated with a PbtO(2)-CCG to maintain a brain oxygen level > 20 mm Hg, and control ICP < 20 mm Hg. The role of demographic, clinical, and imaging parameters in the identification of patients at risk for cerebral hypooxygenation and the influence of hypooxygenation on clinical outcome were recorded. Outcomes were compared with those in a historical ICP/CPP patient cohort. Subgroup analysis of severe TBI was performed and compared to data reported in the Traumatic Coma Data Bank. RESULTS The majority of injuries were sustained in motor vehicle crashes (63%), and diffuse brain injury was the most common abnormality (58%). Mechanism of injury, severity of TBI, pathological entity, neuroimaging results, and trauma indices were not predictive of ischemia. Factors affecting death included gunshot injury, poor trauma indices, subarachnoid hemorrhage, and coma. After standard resuscitation, 65% of patients had an initially low PbtO(2). Data are presented as means +/- SDs. Treatment with the PbtO(2)-CCG resulted in a 44% improvement in mean PbtO(2) (16.21 +/- 12.30 vs 23.65 +/- 14.40 mm Hg; p < 0.001), control of ICP (mean 12.76 +/- 6.42 mm Hg), and the maintenance of CPP (mean 76.13 +/- 15.37 mm Hg). Persistently low cerebral oxygenation was seen in 37% of patients at 2 hours, 31% at 24 hours, and 18% at 48 hours of treatment. Thus elevated ICP and a persistent low PbtO(2) after 2 hours represented increasing odds of death (OR 14.3 at 48 hours). Survivors and patients with good outcomes generally had significantly higher mean daily PbtO(2) and CPP values compared to nonsurvivors. Polytrauma, associated with higher ISS scores, presented an increased risk of vegetative outcome (OR 9.0). Compared to the ICP/CPP cohort, the mean Glasgow Outcome Scale score at 6 months in patients treated with PbtO(2)-CCG was higher (3.55 +/- 1.75 vs 2.71 +/- 1.65, p < 0.01; OR for good outcome 2.09, 95% CI 1.031-4.24) as was the reduction in mortality rate (25.9 vs 41.50%; relative risk reduction 37%), despite higher ISS scores in the PbtO(2) group (31.6 +/- 13.4 vs 27.1 +/- 8.9; p < 0.05). Subgroup analysis of severe closed TBI revealed a significant relative risk reduction in mortality rate of 37-51% compared with the Traumatic Coma Data Bank data, and an increased OR for good outcome especially in patients with diffuse brain injury without mass lesions (OR 4.9, 95% CI 2.9-8.4). CONCLUSIONS The prevention and aggressive treatment of cerebral hypooxygenation and control of ICP with a PbtO(2)-directed protocol reduced the mortality rate after TBI in major trauma, but more importantly, resulted in improved 6-month clinical outcomes over the standard ICP/CPP-directed therapy at the authors' institution.
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Abstract
Raised intracranial pressure (ICP) is a life threatening condition that is common to many neurological and non-neurological illnesses. Unless recognized and treated early it may cause secondary brain injury due to reduced cerebral perfusion pressure (CPP), and progress to brain herniation and death. Management of raised ICP includes care of airway, ventilation and oxygenation, adequate sedation and analgesia, neutral neck position, head end elevation by 20 degrees-30 degrees, and short-term hyperventilation (to achieve PCO(2) 32-35 mm Hg) and hyperosmolar therapy (mannitol or hypertonic saline) in critically raised ICP. Barbiturate coma, moderate hypothermia and surgical decompression may be helpful in refractory cases. Therapies aimed directly at keeping ICP <20 mmHg have resulted in improved survival and neurological outcome. Emerging evidence suggests that cerebral perfusion pressure targeted therapy may offer better outcome than ICP targeted therapies.
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Abstract
Clinical trials in traumatic brain injury have shown little success in providing an evidence base for the introduction of successful new therapies into clinical practice. In addition to the problems that are common to all such studies in critical illness, trials in traumatic brain injury are complicated by the extremely short temporal window for intervention, failure of many candidate drugs to cross the blood-brain barrier, ethical and regulatory obstacles associated with research in subjects who cannot provide consent, the tendency to use small sample sizes in anticipation of unrealistic treatment benefits, and difficulty in translating experimental success into clinical practice. This article reviews the potential causes of these problems and suggests some solutions. These include the changes in regulatory frameworks that are making waived consent an acceptable strategy once more, and an increasing trend toward appropriately large trials. Other encouraging developments include the increasing use of human experimental medicine strategies before phase III trials to assess blood-brain barrier penetration and dose ranging, and provide proof of concept and proof of mechanism. Novel approaches to trial design, such as sliding dichotomy, coupled with robust outcome prediction models, can increase statistical power and improve trial design.
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Abstract
Head injury remains a major cause of preventable death and serious morbidity in young adults. Based on the available evidence, it appears that a cerebral perfusion pressure of 50 to 70 mm Hg is generally adequate to ensure cerebral oxygen delivery and prevent ischemia. However, evidence suggests that perfusion requirements may not only vary across the injured brain but also differ depending on the time since injury. Such heterogeneity, both within and between subjects, suggests that individualized therapy may be an appropriate treatment strategy. Future studies should aim to assess which groups of patients, and what regional pathophysiological derangements, may benefit with improvements in functional outcome from therapeutic increases or decreases in cerebral perfusion pressure beyond these proposed limits. Such functional improvements may be of immense importance to patients and require formal neurocognitive assessments to discriminate improvements.
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Affiliation(s)
- Monica Trivedi
- Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Jonathan P. Coles
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom, Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom,
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Hemoglobin-based oxygen carrying compound-201 as salvage therapy for severe neuro- and polytrauma (Injury Severity Score = 27-41). Crit Care Med 2008; 36:2838-48. [PMID: 18766094 DOI: 10.1097/ccm.0b013e318186f6b3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE A prehospital trial in trauma patients has been proposed to evaluate Hemopure (hemoglobin glutamer-250 [bovine], hemoglobin-based oxygen carrying compound [HBOC]-201, Biopure). We tested the hypothesis that HBOC-201 would improve cerebrovascular resuscitation in a unique polytrauma model. DESIGN Prospective, randomized, blinded animal study. SUBJECTS Thirty-two anesthetized swine (42 +/- 1 kg). INTERVENTIONS Blunt trauma to the head, right chest, and bilateral femurs (Injury Severity Score = 27-41) with captive bolt guns was followed by hypoventilation. Resuscitation was divided into phases to simulate conventional treatment in the prehospital, emergency room, and early intensive care unit. For 30-60 mins postinjury, 500 mL of either normal saline (control, n = 14) or HBOC-201 (n = 14) was administered. All received similar care thereafter. For 60-120 mins, normal saline maintained systolic arterial pressure >100 mm Hg and heart rate <100 beats/min plus mannitol (250 mg/kg) for intracranial hypertension. For 120-480 mins, phenylephrine, normal saline, and dextrose were administered to maintain cerebral perfusion pressure >70 mm Hg, filling pressure >12 mm Hg, and plasma glucose >60 mg%, respectively. Two formulations of HBOC-201 (average MW = 250 kDa) were tested: one with <3% 65 kDa tetramers (n = 7) and the other with <0.3% 65 kDa tetramers (n = 7). MEASUREMENTS AND MAIN RESULTS Injury severity is reflected by the death of 2 of 32 swine within 30 mins. In survivors (n = 30), systolic arterial pressure was 83 +/- 6 mm Hg, heart rate was 115 +/- 5 beats/min, and lactate was 5.8 +/- 0.4 mM. Intracranial pressure rose from 8 +/- 1 to 18 +/- 1 mm Hg and brain tissue PO2 fell from 17 +/- 1 to 2 +/- 1 mm Hg. Without immediate resuscitation, death occurred within 60 mins (n = 2). With normal saline resuscitation (n = 14), systemic hemodynamics, mixed venous oxygen, renal oxygen, portal oxygen, and muscle oxygen corrected but there were four deaths (two at 45 mins, one at 100 mins, and one at 200 mins). Cerebral perfusion pressure was not restored until mannitol and pressor therapy were initiated at 120 mins. In contrast, with HBOC-201 at 30 mins (n = 14), systolic arterial pressure and cerebral perfusion pressure corrected immediately (both p < 0.05) and there were no deaths (p = 0.0978). After 8 hrs, in both groups, cerebral perfusion pressure, systolic arterial pressure, and heart rate were stable; peripheral oxygen saturations were near normal; lactate was cleared; urine output was adequate. However, with HBOC-201, pressor and fluid requirements were reduced by half, which improved intracranial pressure and brain tissue PO2 (all p < 0.05 vs. control). Reducing tetramer content had no significant effect on the actions of HBOC-201. CONCLUSIONS 1) A single bolus of HBOC-201 at initial resuscitation rapidly restored cerebral perfusion pressure and stabilized hemodynamics with improved intracranial pressure and brain oxygen for the first 8 hrs; and 2) HBOC-201 could be an effective salvage therapy after severe neurotrauma or as a temporizing measure during prolonged transport of a polytrauma patient.
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Tissue oxygenation during management of cerebral perfusion pressure with phenylephrine or vasopressin*. Crit Care Med 2008; 36:2641-50. [DOI: 10.1097/ccm.0b013e3181847af3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Halliday J, Absalom AR. Traumatic brain injury: from impact to rehabilitation. Br J Hosp Med (Lond) 2008; 69:284-9. [DOI: 10.12968/hmed.2008.69.5.29362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- J Halliday
- University of Cambridge School of Clinical Medicine, and
| | - AR Absalom
- University Division of Anaesthesia, Box 93, Addenbrooke's Hospital, Cambridge CB2 2QQ
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Abstract
Effective management of intracranial hypertension involves meticulous avoidance of factors that precipitate or aggravate increased intracranial pressure. When intracranial pressure becomes elevated, it is important to rule out new mass lesions that should be surgically evacuated. Medical management of increased intracranial pressure should include sedation, drainage of cerebrospinal fluid, and osmotherapy with either mannitol or hypertonic saline. For intracranial hypertension refractory to initial medical management, barbiturate coma, hypothermia, or decompressive craniectomy should be considered. Steroids are not indicated and may be harmful in the treatment of intracranial hypertension resulting from traumatic brain injury.
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Affiliation(s)
- Leonardo Rangel-Castillo
- Department of Neurosurgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shankar Gopinath
- Department of Neurosurgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Claudia S. Robertson
- Department of Neurosurgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Reductions in qEEG slowing over 1 year and after treatment with Cerebrolysin in patients with moderate-severe traumatic brain injury. J Neural Transm (Vienna) 2008; 115:683-92. [PMID: 18273537 DOI: 10.1007/s00702-008-0024-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 01/18/2008] [Indexed: 10/22/2022]
Abstract
Changes in quantitative EEG (qEEG) recordings over a 1-year period and the effects of Cerebrolysin (Cere) on qEEG slowing and cognitive performance were investigated in postacute moderate-severe traumatic brain injury (TBI) patients. Time-related changes in qEEG activity frequency bands (increases of alpha and beta, and reductions of theta and delta relative power) and in qEEG slowing (reduction of EEG power ratio) were statistically significant in patients with a disease progress of less than 2 years at baseline, but not in those patients having a longer disease progress time. Slowing of qEEG activity was also found to be significantly reduced in TBI patients after 1 month of treatment with Cere and 3 months later. Therefore, Cere seems to accelerate the time-related reduction of qEEG slowing occurring in untreated patients. The decrease of qEEG slowing induced by Cere correlated with the improvement of attention and working memory. Results of this exploratory study suggest that Cere might improve the functional recovery after brain injury and encourage the conduction of further controlled clinical trials.
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Effect of hyperoxia on regional oxygenation and metabolism after severe traumatic brain injury: preliminary findings. Crit Care Med 2008; 36:273-81. [PMID: 18090356 DOI: 10.1097/01.ccm.0000292014.60835.15] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine the effect of normobaric hyperoxia on cerebral metabolism in patients with severe traumatic brain injury. DESIGN Prospective clinical investigation. SETTING Neurosciences critical care unit of a university hospital. PATIENTS Eleven patients with severe traumatic brain injury. INTERVENTIONS Cerebral microdialysis, brain tissue oximetry (PbO2), and oxygen-15 positron emission tomography (15O-PET) were undertaken at normoxia and repeated at hyperoxia (FiO2 increase of between 0.35 and 0.50). MEASUREMENTS AND MAIN RESULTS Established models were used to image cerebral blood flow, blood volume, oxygen metabolism, and oxygen extraction fraction. Physiology was characterized in a focal region of interest (surrounding the microdialysis catheter) and correlated with microdialysis and oximetry. Physiology was also characterized in a global region of interest (including the whole brain), and a physiologic region of interest (defined using a critical cerebral metabolic rate of oxygen threshold). Hyperoxia increased mean +/- sd PbO2 from 28 +/- 21 mm Hg to 57 +/- 47 mm Hg (p = .015). Microdialysate lactate and pyruvate were unchanged, but the lactate/pyruvate ratio showed a statistically significant reduction across the study population (34.1 +/- 9.5 vs. 32.5 +/- 9.0, p = .018). However, the magnitude of reduction was small, and its clinical significance doubtful. The focal region of interest and global 15O-PET variables were unchanged. "At-risk" tissue defined by the physiologic region of interest, however, showed a universal increase in cerebral metabolic rate of oxygen from a median (interquartile range) of 23 (22-25) micromol x 100 mL(-1) x min(-1) to 30 (28-36) micromol x 100 mL(-1) x min(-1) (p < .01). CONCLUSIONS In severe traumatic brain injury, hyperoxia increases PbO2 with a variable effect on lactate and lactate/pyruvate ratio. Microdialysis does not, however, predict the universal increases in cerebral metabolic rate of oxygen in at-risk tissue, which imply preferential metabolic benefit with hyperoxia.
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Effects of catecholamines on cerebral blood vessels in patients with traumatic brain injury. Eur J Anaesthesiol 2008; 42:98-103. [DOI: 10.1017/s0265021507003407] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Hutchinson PJ, O'Connell MT, Rothwell NJ, Hopkins SJ, Nortje J, Carpenter KLH, Timofeev I, Al-Rawi PG, Menon DK, Pickard JD. Inflammation in human brain injury: intracerebral concentrations of IL-1alpha, IL-1beta, and their endogenous inhibitor IL-1ra. J Neurotrauma 2007; 24:1545-57. [PMID: 17970618 DOI: 10.1089/neu.2007.0295] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Following traumatic brain injury (TBI), cascades of inflammatory processes occur. Laboratory studies implicate the cytokines interleukin-1alpha (IL-1alpha) and IL-1beta in the pathophysiology of TBI and cerebral ischemia, whilst exogenous and endogenous interleukin-1 receptor antagonist (IL-1ra) is neuroprotective. We analyzed IL-1alpha, IL-1beta, and IL-1ra in brain microdialysates (100-kDa membrane) in 15 TBI patients. We also analyzed energy-related molecules (glucose, lactate, pyruvate, glutamate, and the lactate/pyruvate ratio) in these brain microdialysates. Mean of mean (+/-SD) in vitro microdialysis percentage recoveries (extraction efficiencies) were IL-1alpha 19.7+/-7.6%, IL-1beta 23.9+/-10.5%, and IL-1ra 20.9+/-6.3%. In the patients' brain microdialysates, mean of mean cytokine concentrations (not corrected for percentage recovery) were IL-1alpha 5.6+/-14.8 pg/mL, IL-1beta 10.4+/-14.7 pg/mL, and IL-1ra 2796+/-2918 pg/mL. IL-1ra was consistently much higher than IL-1alpha and IL-1beta. There were no significant relationships between IL-1 family cytokines and energy-related molecules. There was a significant correlation between increasing IL-1beta and increasing IL-1ra (Spearman r=0.59, p=0.028). There was also a significant relationship between increasing IL-1ra and decreasing intracranial pressure (Spearman r=-0.57, p=0.041). High concentrations of IL-1ra, and also high IL-1ra/IL-1beta ratio, were associated with better outcome (Mann Whitney, p=0.018 and p=0.0201, respectively), within these 15 patients. It is unclear whether these IL-1ra concentrations are sufficient to antagonize the effects of IL-1beta in vivo. This study demonstrates feasibility of our microdialysis methodology in recovering IL-1 family cytokines for assessing their inter-relationships in the injured human brain, and suggests a neuroprotective role for IL-1ra. It remains to be seen whether exogenous IL-1ra or other agents can be used to manipulate cytokine levels in the brain, for potential therapeutic effect.
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Affiliation(s)
- Peter J Hutchinson
- Academic Unit of Neurosurgery, Department of Clinical Neurosciences, Wolfson Brain Imaging Centre, University of Cambridge, and Addenbrooke's Hospital, Cambridge, United Kingdom.
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Leone M, Visintini P, Martin C. Modulation of Blood Pressure in Traumatic Brain Injury. Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
BACKGROUND Clinical markers of the adequacy of cerebral perfusion may be misleading. The effects of isolated changes in systemic blood pressure, Paco2, Pao2, and cerebral edema on cerebral blood flow and oxygenation are relatively well known, but the quantitative effects of interactions between these factors are not easily calculated. We aimed to investigate the relationship between these factors using a computational model. METHODS Using a validated, quantitative, computational model of cerebral blood flow, the simulated effects of changes in systemic blood pressure (50-180 mm Hg), Paco2 (33-55 mm Hg [4.3-7.3 kPa]), Sao2 (0.8-1.0), and cerebral edema (0%-10% increase in intercapillary distance) on middle cerebral artery flow velocity (MCAFV), brain tissue oxygenation (Pbo2), and jugular venous oxygen saturation (Sjo2) were recorded. RESULTS Individual markers of adequacy of cerebral perfusion (MCAFV, Sjo2, and Pbo2 behave in accordance with clinical data with single changes in the parameters studied: the lower limit of autoregulation for MCAFV and Sjo2 lies around 60 mm Hg mean arterial blood pressure. In our model, the upper limit of autoregulation lies around 170 mm Hg, but is much less distinct for Sjo2 and Pbo2 than for MCAFV. Significant cerebral ischemia appears unlikely to occur with isolated physiological changes according to our simulation. However, the combination of hypotension, hypoxia, and edema makes ischemia much more likely in this model. Edema increases the Sjo2:Pbo2 gradient, confirming that diffusion-limited oxygen delivery may make Sjo2 values falsely reassuring. CONCLUSION The simulated effects of pathophysiological changes on cerebral oxygenation and perfusion have been quantitatively described. Significant cerebral ischemia is predicted in the presence of two or more physiological derangements. Cerebral edema is associated with an increased gradient between Sjo2 and Pbo2.
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Affiliation(s)
- Iain K Moppett
- Division of Anaesthesia and Intensive Care, Queen's Medical Centre Campus, Nottingham University Hospitals, Nottingham, UK.
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44
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Abstract
Head injury remains an important cause of death and disability in young adults. This review will discuss the role of structural imaging using computed tomography (CT) and magnetic resonance imaging (MRI) and physiological imaging using CT perfusion, 131Xe CT, MRI and spectroscopy (MRS), single photon emission computed tomography, and positron emission tomography (PET) in the assessment, management, and prediction of outcome after head injury. CT allows rapid assessment of brain pathology which ensures patients who require urgent surgical intervention receive appropriate care. Although MRI provides greater spatial resolution, particularly within the posterior fossa and deep white matter, a complete assessment of the burden of injury requires imaging of cerebral physiology. Physiological imaging techniques can only provide 'snap shots' of physiology within the injured brain, but they can be repeated, and such data can be used to assess the impact of therapeutic interventions. Perfusion imaging based on CT techniques (xenon CT and CT perfusion) can be implemented easily in most hospital centres, and provide quantitative perfusion data in addition to structural images. PET imaging provides unparalleled insights into cerebral physiology and pathophysiology, but is not widely available and is primarily a research tool. MR technology continues to develop and is becoming generally available. Using a complex variety of sequences, MR can provide data concerning both structural and physiological derangements. Future developments with such imaging techniques should improve understanding of the pathophysiology of brain injury and provide data that should improve management and prediction of functional outcome.
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Affiliation(s)
- J P Coles
- University Department of Anaesthesia, Addenbrooke's Hospital, Box 93, Hills Road, Cambridge CB2 2QQ, UK.
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45
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Abstract
Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. The modern management of severe TBI has fallen into the domain of a multidisciplinary team led by neurointensivists, neuroanaesthetists, and neurosurgeons and is based on the avoidance of secondary injury, maintenance of cerebral perfusion pressure (CPP), and optimization of cerebral oxygenation. In this review, we will discuss the intensive care management of severe TBI with emphasis on the specific measures directed at the control of intracranial pressure and CPP.
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Affiliation(s)
- A Helmy
- Neurosciences Critical Care Unit, Addenbrooke's Hospital, Cambridge, UK
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46
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Abstract
Effective treatment of intracranial hypertension involves meticulous avoidance of factors that precipitate or aggravate increased intracranial pressure. When intracranial pressure becomes elevated, it is important to rule out new mass lesions that should be surgically evacuated. medical management of increased intracranial pressure should include sedation and paralysis, drainage of cerebrospinal fluid, and osmotherapy with either mannitol or hypertonic saline. For intracranial hypertension refractory to initial medical management, barbiturate coma, hypothermia, or decompressive craniectomy should be considered. Steroids are not indicated and may be harmful in the treatment of intracranial hypertension resulting from traumatic brain injury.
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Affiliation(s)
- Leonardo Rangel-Castillo
- Research Assistant, Department of Neurosurgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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47
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Haitsma IK, Maas AIR. Monitoring cerebral oxygenation in traumatic brain injury. PROGRESS IN BRAIN RESEARCH 2007; 161:207-16. [PMID: 17618979 DOI: 10.1016/s0079-6123(06)61014-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Ischemia is a common problem after traumatic brain injury (TBI) that eludes detection with standard monitoring. In this review we will discuss four available techniques (SjVO2, PET, NIRS and PbrO2) to monitor cerebral oxygenation. We present technical data including strengths and weaknesses of these systems, information from clinical studies and formulate a vision for the future.
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Affiliation(s)
- Iain K Haitsma
- Department of Neurosurgery, Erasmus Medical Center, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
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Abstract
PURPOSE OF REVIEW To describe the role of O2 positron emission tomography in studies aimed at understanding ischaemia in head injury. It has been difficult to use cerebral blood flow levels to provide a secure definition of cerebral ischaemia in head injury, since primary changes in cerebral metabolism may be responsible for coupled reductions in cerebral blood flow. Further, regional heterogeneity of pathophysiology can confound global measures of adequacy of cerebral oxygen delivery. There is a need for a technique that can provide a comprehensive and quantitative description of cerebral physiology in this setting. RECENT FINDINGS O2 positron emission tomography can image cerebral blood flow, cerebral blood volume, cerebral metabolic rate for oxygen and oxygen extraction fraction, and thus allows a robust and specific definition of true ischaemia. When used in combination with other monitoring tools and imaging modalities, positron emission tomography has also been used to validate and refine bedside monitors of cerebrovascular physiology, study the impact of therapeutic interventions and provide clues to novel pathophysiology. SUMMARY There is a clear role for O2 positron emission tomography in elucidating pathophysiology in head injury. The technique may provide most information when combined with other imaging and monitoring tools.
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Affiliation(s)
- David K Menon
- Division of Anaesthesia, University of Cambridge, Honorary Consultant, Neurosciences Critical Care Unit, Addenbrooke's Hospital, Cambridge, UK.
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Andrews PJD, Citerio G. Lund Therapy - pathophysiology-based therapy or contrived over-interpretation of limited data? Intensive Care Med 2006; 32:1461-3. [PMID: 16896858 DOI: 10.1007/s00134-006-0295-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Accepted: 06/21/2006] [Indexed: 10/24/2022]
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50
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Leone M, Textoris J, Boyadjiev I, Martin C. Comment moduler la pression artérielle en cas de lésion cérébrale ? ACTA ACUST UNITED AC 2006; 25:845-51. [PMID: 16675187 DOI: 10.1016/j.annfar.2006.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One of the goals of the medical management of head injured patients is to get a cerebral perfusion pressure between 60 and 70 mmHg. To reach such a goal, catecholamines are used after fluid challenge. Systemic effects of catecholamines depend on their affinity for the receptors alpha and beta. The topical application of norepinephrine (alpha predominant) induced a vasoconstriction on large cerebral arteries only. Cerebral blood flow increased in the pericontusionnal area, suggesting a loss of autoregulation. The topical application of dopamine at low concentration relaxed large cerebral arteries. Dopamine increased cerebral blood flow in the pericontusional area but data suggest a possible raise in the volume of contusion. Four human comparative studies have been published. The first study, which was not randomized, showed an intracranial pressure increase associated with dopamine. Two randomized clinical trials, published by the same group, demonstrated a better predictability with norepinephrine. The fourth study did not find any difference regarding cerebral haemodynamics. In conclusion, the quality of data on the effects of catecholamines on cerebral haemodynamics of head injured patients do not make it possible to conclude about their use.
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Affiliation(s)
- M Leone
- Département d'Anesthésie et de Réanimation, CHU Nord, boulevard Pierre-Dramard, 13915 Marseille cedex 20, France.
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