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Rezaei S, Seyedmirzaei H, Gharepapagh E, Mohagheghfard F, Hasankhani Z, Karbasi M, Delavari S, Aarabi MH. Effect of spaceflight experience on human brain structure, microstructure, and function: systematic review of neuroimaging studies. Brain Imaging Behav 2024:10.1007/s11682-024-00894-7. [PMID: 38777951 DOI: 10.1007/s11682-024-00894-7] [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: 05/02/2024] [Indexed: 05/25/2024]
Abstract
Spaceflight-induced brain changes have been commonly reported in astronauts. The role of microgravity in the alteration of the brain structure, microstructure, and function can be tested with magnetic resonance imaging (MRI) techniques. Here, we aim to provide a comprehensive overview of Spaceflight studies exploring the potential role of brain alterations identified by MRI in astronauts. We conducted a search on PubMed, Web of Science, and Scopus to find neuroimaging correlates of spaceflight experience using MRI. A total of 20 studies (structural MRI n = 8, diffusion-based MRI n = 2, functional MRI n = 1, structural MRI and diffusion-weighted MRI n = 6, structural MRI and functional MRI n = 3) met our inclusion criteria. Overall, the studies showed that regardless of the MRI techniques, mission duration significantly impacts the human brain, prompting the inclusion of various brain regions as features in the analyses. After spaceflight, notable alterations were also observed in the superior occipital gyrus and the precentral gyrus which show alterations in connectivity and activation during spaceflight. The results provided highlight the alterations in brain structure after spaceflight, the unique patterns of brain remodeling, the challenges in drawing unified conclusions, and the impact of microgravity on intracranial cerebrospinal fluid volume.
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Affiliation(s)
- Sahar Rezaei
- Clinical Research Development Unit of Tabriz Valiasr Hospital, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Nuclear Medicine, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Homa Seyedmirzaei
- Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Esmaeil Gharepapagh
- Department of Nuclear Medicine, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Fateme Mohagheghfard
- Department of para Medicine, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zahra Hasankhani
- Department of para Medicine, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahsa Karbasi
- Department of radiology, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Sahar Delavari
- Institute for the Developing Mind, Children's Hospital Los Angeles, Keck School of Medicine at the University of Southern California, Los Angeles, CA, USA
| | - Mohammad Hadi Aarabi
- Padova Neuroscience Center (PNC), University of Padova, Padova, Italy.
- Department of Neuroscience, University of Padova, Padova, Italy.
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Legé D, Gergelé L, Prud’homme M, Lapayre JC, Launey Y, Henriet J. A Deep Learning-Based Automated Framework for Subpeak Designation on Intracranial Pressure Signals. SENSORS (BASEL, SWITZERLAND) 2023; 23:7834. [PMID: 37765896 PMCID: PMC10537288 DOI: 10.3390/s23187834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
The intracranial pressure (ICP) signal, as monitored on patients in intensive care units, contains pulses of cardiac origin, where P1 and P2 subpeaks can often be observed. When calculable, the ratio of their relative amplitudes is an indicator of the patient's cerebral compliance. This characterization is particularly informative for the overall state of the cerebrospinal system. The aim of this study is to develop and assess the performances of a deep learning-based pipeline for P2/P1 ratio computation that only takes a raw ICP signal as an input. The output P2/P1 ratio signal can be discontinuous since P1 and P2 subpeaks are not always visible. The proposed pipeline performs four tasks, namely (i) heartbeat-induced pulse detection, (ii) pulse selection, (iii) P1 and P2 designation, and (iv) signal smoothing and outlier removal. For tasks (i) and (ii), the performance of a recurrent neural network is compared to that of a convolutional neural network. The final algorithm is evaluated on a 4344-pulse testing dataset sampled from 10 patient recordings. Pulse selection is achieved with an area under the curve of 0.90, whereas the subpeak designation algorithm identifies pulses with a P2/P1 ratio > 1 with 97.3% accuracy. Although it still needs to be evaluated on a larger number of labeled recordings, our automated P2/P1 ratio calculation framework appears to be a promising tool that can be easily embedded into bedside monitoring devices.
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Affiliation(s)
- Donatien Legé
- Sophysa, 91400 Orsay, France;
- DISC Department, FEMTO-ST, Université de Franche-Comté, 25000 Besançon, France; (J.-C.L.); (J.H.)
| | - Laurent Gergelé
- Intensive Care Unit, University Hospital of Saint-Etienne, 42100 Saint-Etienne, France;
| | | | - Jean-Christophe Lapayre
- DISC Department, FEMTO-ST, Université de Franche-Comté, 25000 Besançon, France; (J.-C.L.); (J.H.)
| | - Yoann Launey
- Intensive Care Unit, University Hospital of Rennes, 35000 Rennes, France;
| | - Julien Henriet
- DISC Department, FEMTO-ST, Université de Franche-Comté, 25000 Besançon, France; (J.-C.L.); (J.H.)
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3
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Ocamoto GN, Russo TL, Mendes Zambetta R, Frigieri G, Hayashi CY, Brasil S, Rabelo NN, Spavieri Júnior DL. Intracranial Compliance Concepts and Assessment: A Scoping Review. Front Neurol 2021; 12:756112. [PMID: 34759884 PMCID: PMC8573119 DOI: 10.3389/fneur.2021.756112] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 09/22/2021] [Indexed: 11/30/2022] Open
Abstract
Background: Intracranial compliance (ICC) has been studied to complement the interpretation of intracranial pressure (ICP) in neurocritical care and help predict brain function deterioration. It has been reported that ICC is related to maintaining ICP stability despite changes in intracranial volume. However, this has not been properly translated to clinical practice. Therefore, the main objective of this scoping review was to map the key concepts of ICC in the literature. This review also aimed to characterize the relationship between ICC and ICP and systematically describe the outcomes used to assess ICC using both invasive and non-invasive measurement methods. Methods: This review included the following: (1) population: animal and humans, (2) concept of compliance or its inverse “elastance,” and (3) context: neurocritical care. Therefore, literature searches without a time frame were conducted on several databases using a combination of keywords and descriptors. Results and Discussion: 43,339 articles were identified, and 297 studies fulfilled the inclusion criteria after the selection process. One hundred and five studies defined ICC. The concept was organized into three main components: physiological definition, clinical interpretation, and localization of the phenomena. Most of the studies reported the concept of compliance related to variations in volume and pressure or its inverse (elastance), primarily in the intracranial compartment. In addition, terms like “accommodation,” “compensation,” “reserve capacity,” and “buffering ability” were used to describe the clinical interpretation. The second part of this review describes the techniques (invasive and non-invasive) and outcomes used to measure ICC. A total of 297 studies were included. The most common method used was invasive, representing 57–88% of the studies. The most commonly assessed variables were related to ICP, especially the absolute values or pulse amplitude. ICP waveforms should be better explored, along with the potential of non-invasive methods once the different aspects of ICC can be measured. Conclusion: ICC monitoring could be considered a complementary resource for ICP monitoring and clinical examination. The combination and validation of invasive/non-invasive or non-invasive measurement methods are required.
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Affiliation(s)
| | | | | | | | - Cintya Yukie Hayashi
- Braincare, São Carlos, Brazil.,Department of Neurology, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
| | - Sérgio Brasil
- Department of Neurology, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
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Hosmann A, Angelmayr C, Hopf A, Rauscher S, Brugger J, Ritscher L, Bohl I, Schnackenburg P, Engel A, Plöchl W, Zeitlinger M, Reinprecht A, Rössler K, Gruber A. Detrimental effects of intrahospital transport on cerebral metabolism in patients suffering severe aneurysmal subarachnoid hemorrhage. J Neurosurg 2021; 135:1377-1384. [PMID: 33711812 DOI: 10.3171/2020.8.jns202280] [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: 06/12/2020] [Accepted: 08/31/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Intrahospital transport for CT scans is routinely performed for neurosurgical patients. Particularly in the sedated and mechanically ventilated patient, intracranial hypertension and blood pressure fluctuations that might impair cerebral perfusion are frequently observed during these interventions. This study quantifies the impact of intrahospital patient transport on multimodality monitoring measurements, with a particular focus on cerebral metabolism. METHODS Forty intrahospital transports in 20 consecutive patients suffering severe aneurysmal subarachnoid hemorrhage (SAH) under continuous intracranial pressure (ICP), brain tissue oxygen tension (pbtO2), and cerebral microdialysis monitoring were prospectively included. Changes in multimodality neuromonitoring data during intrahospital transport to the CT scanner and the subsequent 10 hours were evaluated using linear mixed models. Furthermore, the impact of risk factors at transportation, such as cerebral vasospasm, cerebral hypoxia (pbtO2 < 15 mm Hg), metabolic crisis (lactate-pyruvate ratio [LPR] > 40), and transport duration on cerebral metabolism, was analyzed. RESULTS During the transport, the mean ICP significantly increased from 7.1 ± 3.9 mm Hg to 13.5 ± 6.0 mm Hg (p < 0.001). The ICP exceeded 20 mm Hg in 92.5% of patients; pbtO2 showed a parallel rise from 23.1 ± 13.3 mm Hg to 28.5 ± 23.6 mm Hg (p = 0.02) due to an increase in the fraction of inspired oxygen during the transport. Both ICP and pbtO2 returned to baseline values thereafter. Cerebral glycerol significantly increased from 71.0 ± 54.9 µmol/L to 75.3 ± 56.0 µmol/L during the transport (p = 0.01) and remained elevated for the following 9 hours. In contrast, cerebral pyruvate and lactate levels were stable during the transport but showed a significant secondary increase 1-8 hours and 2-9 hours, respectively, thereafter (p < 0.05). However, the LPR remained stable over the entire observation period. Patients with extended transport duration (more than 25 minutes) were found to have significantly higher levels of cerebral pyruvate and lactate as well as lower glutamate concentrations in the posttransport period. CONCLUSIONS Intrahospital transport and horizontal positioning during CT scans induce immediate intracranial hypertension and an increase in cerebral glycerol, suggesting neuronal injury. Afterward, sustained impairment of neuronal metabolism for several hours could be observed, which might increase the risk of secondary ischemic events. Therefore, intrahospital transport for neuroradiological imaging should be strongly reconsidered and only indicated if the expected benefit of imaging results outweighs the risks of transportation.
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Affiliation(s)
- Arthur Hosmann
- 1Department of Neurosurgery, Medical University of Vienna, Austria
| | - Carmen Angelmayr
- 1Department of Neurosurgery, Medical University of Vienna, Austria
| | - Andreas Hopf
- 1Department of Neurosurgery, Medical University of Vienna, Austria
- 2Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn
| | - Steffen Rauscher
- 1Department of Neurosurgery, Medical University of Vienna, Austria
- 3Department of Neurosurgery, University Hospital Essen, Germany
| | - Jonas Brugger
- 4Institute for Medical Statistics, Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Austria
| | - Lavinia Ritscher
- 1Department of Neurosurgery, Medical University of Vienna, Austria
| | - Isabelle Bohl
- 1Department of Neurosurgery, Medical University of Vienna, Austria
| | | | - Adrian Engel
- 1Department of Neurosurgery, Medical University of Vienna, Austria
- 5Department of Neurosurgery, University Hospital Düsseldorf, Germany
| | - Walter Plöchl
- Departments of6Anesthesia, General Intensive Care Medicine and Pain Management and
| | | | | | - Karl Rössler
- 1Department of Neurosurgery, Medical University of Vienna, Austria
| | - Andreas Gruber
- 8Department of Neurosurgery, Johannes Kepler University, Linz, Austria
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McKnight I, Hart C, Park IH, Shim JW. Genes causing congenital hydrocephalus: Their chromosomal characteristics of telomere proximity and DNA compositions. Exp Neurol 2021; 335:113523. [PMID: 33157092 PMCID: PMC7750280 DOI: 10.1016/j.expneurol.2020.113523] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/10/2020] [Accepted: 10/30/2020] [Indexed: 01/06/2023]
Abstract
Congenital hydrocephalus (CH) is caused by genetic mutations, but whether factors impacting human genetic mutations are disease-specific remains elusive. Given two factors associated with high mutation rates, we reviewed how many disease-susceptible genes match with (i) proximity to telomeres or (ii) high adenine and thymine (A + T) content in human CH as compared to other disorders of the central nervous system (CNS). We extracted genomic information using a genome data viewer. Importantly, 98 of 108 genes causing CH satisfied (i) or (ii), resulting in >90% matching rate. However, such a high accordance no longer sustained as we checked two factors in Alzheimer's disease (AD) and/or familial Parkinson's disease (fPD), resulting in 84% and 59% matching, respectively. A disease-specific matching of telomere proximity or high A + T content predicts causative genes of CH much better than neurodegenerative diseases and other CNS conditions, likely due to sufficient number of known causative genes (n = 108) and precise determination and classification of the genotype and phenotype. Our analysis suggests a need for identifying genetic basis of both factors before human clinical studies, to prioritize putative genes found in preclinical models into the likely (meeting at least one) and more likely candidate (meeting both), which predisposes human genes to mutations.
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Affiliation(s)
- Ian McKnight
- Department of Biomedical Engineering, Marshall University, Huntington, WV 25755, USA
| | - Christoph Hart
- Department of Biomedical Engineering, Marshall University, Huntington, WV 25755, USA
| | - In-Hyun Park
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Joon W Shim
- Department of Biomedical Engineering, Marshall University, Huntington, WV 25755, USA.
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Kramer LA, Hasan KM, Stenger MB, Sargsyan A, Laurie SS, Otto C, Ploutz-Snyder RJ, Marshall-Goebel K, Riascos RF, Macias BR. Intracranial Effects of Microgravity: A Prospective Longitudinal MRI Study. Radiology 2020; 295:640-648. [DOI: 10.1148/radiol.2020191413] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Evensen KB, Eide PK. Measuring intracranial pressure by invasive, less invasive or non-invasive means: limitations and avenues for improvement. Fluids Barriers CNS 2020; 17:34. [PMID: 32375853 PMCID: PMC7201553 DOI: 10.1186/s12987-020-00195-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/19/2020] [Indexed: 12/20/2022] Open
Abstract
Sixty years have passed since neurosurgeon Nils Lundberg presented his thesis about intracranial pressure (ICP) monitoring, which represents a milestone for its clinical introduction. Monitoring of ICP has since become a clinical routine worldwide, and today represents a cornerstone in surveillance of patients with acute brain injury or disease, and a diagnostic of individuals with chronic neurological disease. There is, however, controversy regarding indications, clinical usefulness and the clinical role of the various ICP scores. In this paper, we critically review limitations and weaknesses with the current ICP measurement approaches for invasive, less invasive and non-invasive ICP monitoring. While risk related to the invasiveness of ICP monitoring is extensively covered in the literature, we highlight other limitations in current ICP measurement technologies, including limited ICP source signal quality control, shifts and drifts in zero pressure reference level, affecting mean ICP scores and mean ICP-derived indices. Control of the quality of the ICP source signal is particularly important for non-invasive and less invasive ICP measurements. We conclude that we need more focus on mitigation of the current limitations of today's ICP modalities if we are to improve the clinical utility of ICP monitoring.
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Affiliation(s)
- Karen Brastad Evensen
- Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway
- Department of Informatics, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, P.O. Box 4950, Nydalen, 0424, Oslo, Norway.
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
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8
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Herbowski L. From paradigm to paradox: divergency between intracranial pressure and intracranial pulse pressure during atmospheric pressure fall: a case study. J Neurosurg Sci 2019; 66:103-111. [PMID: 31680504 DOI: 10.23736/s0390-5616.19.04737-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The main objectives are to determine relation between intracranial pressure and its amplitude and to ascertain meteorological variables as possible confounding factors. This is a retrospective observational study of a patient with suspicion of normotensive hydrocephalus. METHODS The intracranial pressure, the blood pressure, atmospheric pressure and geomagnetic activity were continuously monitored capturing extraordinary sudden and unexpected atmospheric pressure fall. The physiological changes exceptionally observed during suddenweather changes were described by means of statistical parameters. The data from 73 consecutive hourly measurements was eligible for this analysis. It contained 1022 data points corresponding to all recorded parameters, both climate and physiological ones. RESULTS After initial stable period, the atmospheric pressure started to decrease from 767 mmHg to 746 mmHg. In parallel, the mean intracranial pressure increased significantly from 4 mmHg to 14 mmHg. Thus, the mean intracranial pressure changed inversely during atmospheric pressure drop. Whereas mean intracranial pressure increased by 10 mmHg during atmospheric pressure fall, the intracranial amplitude decreased by 5 mmHg. On timescale of several dozen hours in this study, the short-term periodic diurnal variations of intracranial pressure and blood pressure were displayed. The association between diurnal atmospheric pressure oscillation and geomagnetic activity variation was observed. Both intracranial and blood pressure variations differed significantly between day and night. CONCLUSIONS This study shows that increasing intracranial pressure is associated with its paradoxically decreasing amplitude under the influence of sudden and unexpected barometric pressure fall. This study suggests that abrupt changes in atmospheric pressure might impact intracranial pressure.
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Affiliation(s)
- Leszek Herbowski
- Neurosurgery and Neurotraumatology Department, District Hospital, Szczecin, Poland -
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Safety and feasibility of lumbar drainage in the management of poor grade aneurysmal subarachnoid hemorrhage. J Clin Neurosci 2019; 64:64-70. [DOI: 10.1016/j.jocn.2019.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 02/20/2019] [Accepted: 04/12/2019] [Indexed: 11/23/2022]
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Pineda B, Kosinski C, Kim N, Danish S, Craelius W. Assessing Cerebral Hemodynamic Stability After Brain Injury. ACTA NEUROCHIRURGICA. SUPPLEMENT 2018; 126:297-301. [PMID: 29492578 DOI: 10.1007/978-3-319-65798-1_58] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
OBJECTIVE Following brain injury, unstable cerebral hemodynamics can be characterized by abnormal rises in intracranial pressure (ICP). This behavior has been quantified by the RAP index: the correlation (R) between ICP pulse amplitude (A) and mean (P). While RAP could be a valuable indicator of autoregulatory processes, its prognostic ability is not well established and its validity has been questioned due to potential errors in measurement. Here, we test (1) whether RAP is a consistent measure of intracranial hemodynamics and (2) whether RAP has prognostic value in predicting hemodynamic instability following brain injury. MATERIALS AND METHODS RAP was tested in seven brain injured patients treated in a surgical intensive care unit. A sample of ICP data was randomly chosen and segmented into 1 hour periods. Hours were then categorized as either stable, which contained no sharp rises in ICP, or unstable, which contained ≥1 sharp rise-where a sharp rise is defined as ICP exceeding a mean slope of 0.15 mmHg/s. Equal numbers of stable and unstable segments were then selected for each patient. RAP was calculated as the Pearson's correlation coefficient between ICP pulse amplitude (AMP) and mean (mICP), determined in 6 second windows, according to established methods. RESULTS Results showed that (1) average AMP and ICP levels were similar between stable and unstable periods and (2) unstable periods were identified by RAP values exceeding 0.6 with an average positive predictive value of 74%. CONCLUSIONS We conclude that RAP can provide a valid measure of ICP dynamics, is not affected by sensor drift, and can better distinguish periods of instability than ICP or AMP alone.
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Affiliation(s)
- Bianca Pineda
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Colin Kosinski
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Nam Kim
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Shabbar Danish
- Department of Neurosurgery, Rutgers, Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - William Craelius
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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Kramer LA, Hasan KM, Sargsyan AE, Marshall-Goebel K, Rittweger J, Donoviel D, Higashi S, Mwangi B, Gerlach DA, Bershad EM. Quantitative MRI volumetry, diffusivity, cerebrovascular flow, and cranial hydrodynamics during head-down tilt and hypercapnia: the SPACECOT study. J Appl Physiol (1985) 2017; 122:1155-1166. [DOI: 10.1152/japplphysiol.00887.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/24/2017] [Accepted: 02/11/2017] [Indexed: 01/17/2023] Open
Abstract
To improve the pathophysiological understanding of visual changes observed in astronauts, we aimed to use quantitative MRI to measure anatomic and physiological responses during a ground-based spaceflight analog (head-down tilt, HDT) combined with increased ambient carbon dioxide (CO2). Six healthy, male subjects participated in the double-blinded, randomized crossover design study with two conditions: 26.5 h of −12° HDT with ambient air and with 0.5% CO2, both followed by 2.5-h exposure to 3% CO2. Volume and mean diffusivity quantification of the lateral ventricle and phase-contrast flow sequences of the internal carotid arteries and cerebral aqueduct were acquired at 3 T. Compared with supine baseline, HDT (ambient air) resulted in an increase in lateral ventricular volume ( P = 0.03). Cerebral blood flow, however, decreased with HDT in the presence of either ambient air or 0.5% CO2( P = 0.002 and P = 0.01, respectively); this was partially reversed by acute 3% CO2exposure. Following HDT (ambient air), exposure to 3% CO2increased aqueductal cerebral spinal fluid velocity amplitude ( P = 0.01) and lateral ventricle cerebrospinal fluid (CSF) mean diffusivity ( P = 0.001). We concluded that HDT causes alterations in cranial anatomy and physiology that are associated with decreased craniospinal compliance. Brief exposure to 3% CO2augments CSF pulsatility within the cerebral aqueduct and lateral ventricles.NEW & NOTEWORTHY Head-down tilt causes increased lateral ventricular volume and decreased cerebrovascular flow after 26.5 h. Additional short exposure to 3% ambient carbon dioxide levels causes increased cerebrovascular flow associated with increased cerebrospinal fluid pulsatility at the cerebral aqueduct. Head-down tilt with chronically elevated 0.5% ambient carbon dioxide and acutely elevated 3% ambient carbon dioxide causes increased mean diffusivity of cerebral spinal fluid within the lateral ventricles.
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Affiliation(s)
- Larry A. Kramer
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | - Khader M. Hasan
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | | | - Karina Marshall-Goebel
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Department of Medicine, University of Cologne, Cologne, Germany
| | - Jörn Rittweger
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Department of Neurology, University of Cologne, Cologne, Germany
| | - Dorit Donoviel
- Department of Pharmacology and Space Medicine, Baylor College of Medicine, Houston, Texas
| | - Saki Higashi
- Tokushima University Medical School, Tokushima, Japan
| | - Benson Mwangi
- Department of Behavioral Sciences, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas; and
| | - Darius A. Gerlach
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Eric M. Bershad
- Neurology and Space Medicine, Baylor College of Medicine, Houston, Texas
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Gwer S, Kazungu M, Chengo E, Ohuma EO, Idro R, Birch T, Marchbanks R, Kirkham FJ, Newton CR. Abnormal intra-aural pressure waves associated with death in African children with acute nontraumatic coma. Pediatr Res 2015; 78:38-43. [PMID: 25790276 PMCID: PMC5357619 DOI: 10.1038/pr.2015.57] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 12/12/2014] [Indexed: 11/09/2022]
Abstract
BACKGROUND We explored the relationship between tympanic membrane displacement (TMD) measurements, a tool to monitor intracranial pressure noninvasively, and clinical features and death in children with acute coma in Kilifi, Kenya. METHODS Between November 2007 and September 2009, we made serial TMD measurements and clinical observations on children with acute coma (Blantyre coma score (BCS) ≤ 2) on the pediatric high dependency unit of Kilifi District Hospital, and on well children presenting to the hospital's outpatient department for routine follow-up. We examined middle ear function using tympanometry and measured cardiac pulse (CPA) and respiratory pulse pressure amplitudes (RPA) using the TMD analyzer. RESULTS We recruited 75 children (32 (43%) females; median age 3.3 (IQR: 2.0, 4.3) years). Twenty-one (28%) children died. Higher TMD measurements predicted death. Adjusting for diagnosis, every 50 nl rise in both semirecumbent and recumbent CPA was associated with increased odds of death associated with intracranial herniation (OR: 1.61, 95% confidence interval (CI): 1.07, 2.41; P = 0.02 and OR: 1.35, 95% CI: 1.10, 1.66; P ≤ 0.01 respectively). CONCLUSION Raised TMD pulse pressure measurements are associated with death and may be useful in detecting and monitoring risk of intracranial herniation and intracranial pressure in childhood coma.
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Affiliation(s)
- Samson Gwer
- Department of Medical Physiology, School of Medicine, Kenyatta University, Nairobi, Kenya,Clinical Research, Afya Research Africa, Nairobi, Kenya
| | - Michael Kazungu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Eddie Chengo
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Eric O. Ohuma
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Richard Idro
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya,Centre for Tropical Medicine, Nuffield Department of Medicine, Oxford University, Oxford, UK,Department of Paediatrics and Child Health, Mulago Teaching Hospital, Makerere University, Kampala, Uganda
| | - Tony Birch
- Neurological Physics Group, Department of Medical Physics and Bioengineering, Southampton University Hospital NHS Trust, Southampton, UK
| | - Robert Marchbanks
- Neurological Physics Group, Department of Medical Physics and Bioengineering, Southampton University Hospital NHS Trust, Southampton, UK
| | - Fenella J. Kirkham
- Neurosciences Unit, Institute of Child Health, University College of London, London, UK,Department of Child Health, University Hospital Southampton NHS Foundation Trust, Southampton, UK,()
| | - Charles R. Newton
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya,Neurosciences Unit, Institute of Child Health, University College of London, London, UK,Department of Psychiatry, University of Oxford, Oxford, UK
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Eide PK, Sorteberg A, Meling TR, Sorteberg W. The effect of baseline pressure errors on an intracranial pressure-derived index: results of a prospective observational study. Biomed Eng Online 2014; 13:99. [PMID: 25052470 PMCID: PMC4125597 DOI: 10.1186/1475-925x-13-99] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 07/17/2014] [Indexed: 11/29/2022] Open
Abstract
Background In order to characterize the intracranial pressure-volume reserve capacity, the correlation coefficient (R) between the ICP wave amplitude (A) and the mean ICP level (P), the RAP index, has been used to improve the diagnostic value of ICP monitoring. Baseline pressure errors (BPEs), caused by spontaneous shifts or drifts in baseline pressure, cause erroneous readings of mean ICP. Consequently, BPEs could also affect ICP indices such as the RAP where in the mean ICP is incorporated. Methods A prospective, observational study was carried out on patients with aneurysmal subarachnoid hemorrhage (aSAH) undergoing ICP monitoring as part of their surveillance. Via the same burr hole in the scull, two separate ICP sensors were placed close to each other. For each consecutive 6-sec time window, the dynamic mean ICP wave amplitude (MWA; measure of the amplitude of the single pressure waves) and the static mean ICP, were computed. The RAP index was computed as the Pearson correlation coefficient between the MWA and the mean ICP for 40 6-sec time windows, i.e. every subsequent 4-min period (method 1). We compared this approach with a method of calculating RAP using a 4-min moving window updated every 6 seconds (method 2). Results The study included 16 aSAH patients. We compared 43,653 4-min RAP observations of signals 1 and 2 (method 1), and 1,727,000 6-sec RAP observations (method 2). The two methods of calculating RAP produced similar results. Differences in RAP ≥0.4 in at least 7% of observations were seen in 5/16 (31%) patients. Moreover, the combination of a RAP of ≥0.6 in one signal and <0.6 in the other was seen in ≥13% of RAP-observations in 4/16 (25%) patients, and in ≥8% in another 4/16 (25%) patients. The frequency of differences in RAP >0.2 was significantly associated with the frequency of BPEs (5 mmHg ≤ BPE <10 mmHg). Conclusions Simultaneous monitoring from two separate, close-by ICP sensors reveals significant differences in RAP that correspond to the occurrence of BPEs. As differences in RAP are of magnitudes that may alter patient management, we do not advocate the use of RAP in the management of neurosurgical patients.
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Affiliation(s)
- Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
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Eide PK, Sorteberg A, Meling TR, Sorteberg W. Baseline pressure errors (BPEs) extensively influence intracranial pressure scores: results of a prospective observational study. Biomed Eng Online 2014; 13:7. [PMID: 24472296 PMCID: PMC3922657 DOI: 10.1186/1475-925x-13-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/22/2014] [Indexed: 01/17/2023] Open
Abstract
Background Monitoring of intracranial pressure (ICP) is a cornerstone in the surveillance of neurosurgical patients. The ICP is measured against a baseline pressure (i.e. zero - or reference pressure). We have previously reported that baseline pressure errors (BPEs), manifested as spontaneous shift or drifts in baseline pressure, cause erroneous readings of mean ICP in individual patients. The objective of this study was to monitor the frequency and severity of BPEs. To this end, we performed a prospective, observational study monitoring the ICP from two separate ICP sensors (Sensors 1 and 2) placed in close proximity in the brain. We characterized BPEs as differences in mean ICP despite near to identical ICP waveform in Sensors 1 and 2. Methods The study enrolled patients with aneurysmal subarachnoid hemorrhage in need of continuous ICP monitoring as part of their intensive care management. The two sensors were placed close to each other in the brain parenchyma via the same burr hole. The monitoring was performed as long as needed from a clinical perspective and the ICP recordings were stored digitally for analysis. For every patient the mean ICP as well as the various ICP wave parameters of the two sensors were compared. Results Sixteen patients were monitored median 164 hours (ranges 70 – 364 hours). Major BPEs, as defined by marked differences in mean ICP despite similar ICP waveform, were seen in 9 of them (56%). The BPEs were of magnitudes that had the potential to alter patient management. Conclusions Baseline Pressure Errors (BPEs) occur in a significant number of patients undergoing continuous ICP monitoring and they may alter patient management. The current practice of measuring ICP against a baseline pressure does not comply with the concept of State of the Art. Monitoring of the ICP waves ought to become the new State of the Art as they are not influenced by BPEs.
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Affiliation(s)
- Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital - Rikshospitalet, Oslo, Norway.
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Teles AR, Franceschini PR, Kraemer JL. Intracranial pressure vs intracranial pressure-wave amplitude. Neurosurgery 2013; 71:E523-4; author reply E524-5. [PMID: 22811087 DOI: 10.1227/neu.0b013e31825a562a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Hamilton R, Baldwin K, Fuller J, Vespa P, Hu X, Bergsneider M. Intracranial pressure pulse waveform correlates with aqueductal cerebrospinal fluid stroke volume. J Appl Physiol (1985) 2012; 113:1560-6. [PMID: 22995390 DOI: 10.1152/japplphysiol.00357.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study identifies a novel relationship between cerebrospinal fluid (CSF) stroke volume through the cerebral aqueduct and the characteristic peaks of the intracranial pulse (ICP) waveform. ICP waveform analysis has become much more advanced in recent years; however, clinical practice remains restricted to mean ICP, mainly due to the lack of physiological understanding of the ICP waveform. Therefore, the present study set out to shed some light on the physiological meaning of ICP morphological metrics derived by the morphological clustering and analysis of continuous intracranial pulse (MOCAIP) algorithm by investigating their relationships with a well defined physiological variable, i.e., the stroke volume of CSF through the cerebral aqueduct. Seven patients received both overnight ICP monitoring along with a phase-contrast MRI (PC-MRI) of the cerebral aqueduct to quantify aqueductal stroke volume (ASV). Waveform morphological analysis of the ICP signal was performed by the MOCAIP algorithm. Following extraction of morphological metrics from the ICP signal, nine temporal ICP metrics and two amplitude-based metrics were compared with the ASV via Spearman's rank correlation. Of the nine temporal metrics correlated with the ASV, only the width of the P2 region (ICP-Wi2) reached significance. Furthermore, both ICP pulse pressure amplitude and mean ICP did not reach significance. In this study, we showed the width of the second peak (ICP-Wi2) of an ICP pulse wave is positively related to the volume of CSF movement through the cerebral aqueduct. This finding is an initial step in bridging the gap between ICP waveform morphology research and clinical practice.
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Affiliation(s)
- Robert Hamilton
- Neural Systems and Dynamics Laboratory, Department of Neurosurgery, the David Geffen School of Medicine, University of California-Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095, USA
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Eide PK, Holm S, Sorteberg W. Simultaneous monitoring of static and dynamic intracranial pressure parameters from two separate sensors in patients with cerebral bleeds: comparison of findings. Biomed Eng Online 2012; 11:66. [PMID: 22958653 PMCID: PMC3506507 DOI: 10.1186/1475-925x-11-66] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 07/02/2012] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND We recently reported that in an experimental setting the zero pressure level of solid intracranial pressure (ICP) sensors can be altered by electrostatics discharges. Changes in the zero pressure level would alter the ICP level (mean ICP); whether spontaneous changes in mean ICP happen in clinical settings is not known. This can be addressed by comparing the ICP parameters level and waveform of simultaneous ICP signals. To this end, we retrieved our recordings in patients with cerebral bleeds wherein the ICP had been recorded simultaneously from two different sensors. MATERIALS AND METHODS During a time period of 10 years, 17 patients with cerebral bleeds were monitored with two ICP sensors simultaneously; sensor 1 was always a solid sensor while Sensor 2 was a solid -, a fluid - or an air-pouch sensor. The simultaneous signals were analyzed with automatic identification of the cardiac induced ICP waves. The output was determined in consecutive 6-s time windows, both with regard to the static parameter mean ICP and the dynamic parameters (mean wave amplitude, MWA, and mean wave rise time, MWRT). Differences in mean ICP, MWA and MWRT between the two sensors were determined. Transfer functions between the sensors were determined to evaluate how sensors reproduce the ICP waveform. RESULTS Comparing findings in two solid sensors disclosed major differences in mean ICP in 2 of 5 patients (40%), despite marginal differences in MWA, MWRT, and linear phase magnitude and phase. Qualitative assessment of trend plots of mean ICP and MWA revealed shifts and drifts of mean ICP in the clinical setting. The transfer function analysis comparing the solid sensor with either the fluid or air-pouch sensors revealed more variable transfer function magnitude and greater differences in the ICP waveform derived indices. CONCLUSIONS Simultaneous monitoring of ICP using two solid sensors may show marked differences in static ICP but close to identity in dynamic ICP waveforms. This indicates that shifts in ICP baseline pressure (sensor zero level) occur clinically; trend plots of the ICP parameters also confirm this. Solid sensors are superior to fluid - and air pouch sensors when evaluating the dynamic ICP parameters.
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Affiliation(s)
- Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
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Characterisation of the intracranial pressure waveform during infusion studies by means of central tendency measure. Acta Neurochir (Wien) 2012; 154:1595-602. [PMID: 22805895 DOI: 10.1007/s00701-012-1441-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE In the present study an attempt was made to quantify and characterise the changes in the intracranial pressure (ICP) waveform over the wide pressure range covered during infusion studies by means of the central tendency measure (CTM). CTM is a non-linear approach using continuous chaotic modelling that summarises the degree of variability in a signal. METHODS CTM of the ICP wave in the lumbar subarachnoid space was analysed in 77 infusion studies performed in patients with idiopathic and secondary forms of normal pressure hydrocephalus (median age 74 years, range 22-88). Four artefact-free epochs were selected during the baseline, infusion, plateau and relaxation stages of every infusion study. The average pressure, pulse amplitude and CTM were determined for each epoch. Correlations among these parameters were explored. RESULTS CTM of the ICP waveform decreases, i.e. variability increases, as infusion studies progress from baseline pressure to the plateau stage. Significant correlations were found during all phases of infusion testing, except at baseline, between CTM and pressure, CTM and amplitude and pressure and amplitude. Partial correlations emphasised the relationship between CTM and amplitude. When pulse amplitude is held constant, CTM and the pressure range do not correlate. CONCLUSIONS Volume loading leads to increased variability of the ICP signal measured by means of CTM. This finding summarises numerically the long-established phenomenon of increasing amplitude and rounding of ICP pulses associated with ICP elevation during infusion studies. CTM could be a suitable approach to quantify and characterise the pulsatile nature of the ICP wave.
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Eide PK, Bentsen G, Sorteberg AG, Marthinsen PB, Stubhaug A, Sorteberg W. A randomized and blinded single-center trial comparing the effect of intracranial pressure and intracranial pressure wave amplitude-guided intensive care management on early clinical state and 12-month outcome in patients with aneurysmal subarachnoid hemorrhage. Neurosurgery 2012; 69:1105-15. [PMID: 21670714 DOI: 10.1227/neu.0b013e318227e0e1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND In patients with aneurysmal subarachnoid hemorrhage (SAH), preliminary results indicate that the amplitude of the single intracranial pressure (ICP) wave is a better predictor of the early clinical state and 6-month outcome than the mean ICP. OBJECTIVE To perform a randomized and blinded single-center trial comparing the effect of mean ICP vs mean ICP wave amplitude (MWA)-guided intensive care management on early clinical state and outcome in patients with aneurysmal SAH. METHODS Patients were randomized to 2 different types of ICP management: maintenance of mean ICP less than 20 mm Hg and MWA less than 5 mm Hg. Early clinical state was assessed daily using the Glasgow Coma Scale. The primary efficacy variable was 12-month outcome in terms of the Rankin Stroke Score. RESULTS Ninety-seven patients were included in the study. There were no significant differences in treatment between the 2 groups apart from a larger volume of cerebrospinal fluid drained during week 1 in the MWA group. There was a tendency toward higher Glasgow Coma Scale scores in the MWA group during weeks 1 (P = .08) and 2 (P = .07). Outcome in terms of Rankin Stroke Score at 12 months was significantly better in the MWA group (P < .05). CONCLUSION This randomized and blinded trial disclosed a significant better primary efficacy variable (Rankin Stroke Score after 12 months) in the MWA patient group. We suggest that proactive intensive care management with MWA-tailored cerebrospinal fluid drainage during the first week improves aneurysmal SAH outcome.
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Affiliation(s)
- Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, Oslo, Norway.
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20
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Eide PK, Sorteberg A, Bentsen G, Marthinsen PB, Stubhaug A, Sorteberg W. Pressure-derived versus pressure wave amplitude–derived indices of cerebrovascular pressure reactivity in relation to early clinical state and 12-month outcome following aneurysmal subarachnoid hemorrhage. J Neurosurg 2012; 116:961-71. [DOI: 10.3171/2012.1.jns111313] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Indices of cerebrovascular pressure reactivity (CPR) represent surrogate markers of cerebral autoregulation. Given that intracranial pressure (ICP) wave amplitude–guided management, as compared with static ICP-guided management, improves outcome following aneurysmal subarachnoid hemorrhage (SAH), indices of CPR derived from pressure wave amplitudes should be further explored. This study was undertaken to investigate the value of CPR indices derived from static ICP–arterial blood pressure (ABP) values (pressure reactivity index [PRx]) versus ICP-ABP wave amplitudes (ICP-ABP wave amplitude correlation [IAAC]) in relation to the early clinical state and 12-month outcome in patients with aneurysmal SAH.
Methods
The authors conducted a single-center clinical trial enrolling patients with aneurysmal SAH. The CPR indices of PRx and IAAC of Week 1 after hemorrhage were related to the early clinical state (Glasgow Coma Scale [GCS] score) and 12-month outcome (modified Rankin Scale score).
Results
Ninety-four patients were included in the study. The IAAC, but not the PRx, increased with decreasing GCS score; that is, the higher the IAAC, the worse the clinical state. The PRx could differentiate between survivors and nonsurvivors only, whereas the IAAC clearly distinguished the groups “independent,” “dependent,” and “dead.” In patients with an average IAAC ≥ 0.2, mortality was approximately 3-fold higher than in those with an IAAC < 0.2.
Conclusions
The IAAC, which is based on single ICP-ABP wave identification, relates significantly to the early clinical state and 12-month outcome following aneurysmal SAH. Impaired cerebrovascular pressure regulation during the 1st week after a bleed relates to a worse outcome. Clinical trial registration no.: NCT00248690.
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Affiliation(s)
- Per Kristian Eide
- 1Departments of Neurosurgery,
- 4Faculty of Medicine, University of Oslo, Norway
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21
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An evaluation of three measures of intracranial compliance in traumatic brain injury patients. Intensive Care Med 2012; 38:1061-8. [PMID: 22527085 DOI: 10.1007/s00134-012-2571-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 02/20/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE To compare intracranial pressure (ICP) amplitude, ICP slope, and the correlation of ICP amplitude and ICP mean (RAP index) as measures of compliance in a cohort of traumatic brain injury (TBI) patients. METHODS Mean values of the three measures were calculated in the 2-h periods before and after surgery (craniectomies and evacuations), and in the 12-h periods preceding and following thiopental treatment, and during periods of thiopental coma. The changes in the metrics were evaluated using the Wilcoxon test. The correlations of 10-day mean values for the three metrics with age, admission Glasgow Motor Score (GMS), and Extended Glasgow Outcome Score (GOSe) were evaluated. Patients under and over 60 years old were also compared using the Student t test. The correlation of ICP amplitude with systemic pulse amplitude was analyzed. RESULTS ICP amplitude was significantly correlated with GMS, and also with age for patients 35 years old and older. The correlations of ICP slope and the RAP index with GMS and with age were not significant. All three metrics indicated significant improvements in compliance following surgery and during thiopental coma. None of the metrics were significantly correlated with outcome, possibly due to confounding effects of treatment factors. The correlation of systemic pulse amplitude with ICP amplitude was low (R = 0.18), only explaining 3 % of the variance. CONCLUSIONS This study provides further validation for all three of these features of the ICP waveform as measures of compliance. ICP amplitude had the best performance in these tests.
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Eide PK, Bakken A. The baseline pressure of intracranial pressure (ICP) sensors can be altered by electrostatic discharges. Biomed Eng Online 2011; 10:75. [PMID: 21859487 PMCID: PMC3180435 DOI: 10.1186/1475-925x-10-75] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 08/22/2011] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The monitoring of intracranial pressure (ICP) has a crucial role in the surveillance of patients with brain injury. During long-term monitoring of ICP, we have seen spontaneous shifts in baseline pressure (ICP sensor zero point), which are of technical and not physiological origin. The aim of the present study was to explore whether or not baseline pressures of ICP sensors can be affected by electrostatics discharges (ESD's), when ESD's are delivered at clinically relevant magnitudes. METHODS We performed bench-testing of a set of commercial ICP sensors. In our experimental setup, the ICP sensor was placed in a container with 0.9% NaCl solution. A test person was charged 0.5-10 kV, and then delivered ESD's to the sensor by touching a metal rod that was located in the container. The continuous pressure signals were recorded continuously before/after the ESD's, and the pressure readings were stored digitally using a computerized system RESULTS A total of 57 sensors were tested, including 25 Codman ICP sensors and 32 Raumedic sensors. When charging the test person in the range 0.5-10 kV, typically ESD's in the range 0.5-5 kV peak pulse were delivered to the ICP sensor. Alterations in baseline pressure ≥ 2 mmHg was seen in 24 of 25 (96%) Codman sensors and in 17 of 32 (53%) Raumedic sensors. Lasting changes in baseline pressure > 10 mmHg that in the clinical setting would affect patient management, were seen frequently for both sensor types. The changes in baseline pressure were either characterized by sudden shifts or gradual drifts in baseline pressure. CONCLUSIONS The baseline pressures of commercial solid ICP sensors can be altered by ESD's at discharge magnitudes that are clinically relevant. Shifts in baseline pressure change the ICP levels visualised to the physician on the monitor screen, and thereby reveal wrong ICP values, which likely represent a severe risk to the patient.
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Affiliation(s)
- Per K Eide
- Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
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Vik-Mo EO, Reinlie S, Helseth E, Langmoen IA. Neurosurgery in Oslo. World Neurosurg 2011; 74:402-6. [PMID: 21492578 DOI: 10.1016/j.wneu.2010.10.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 10/12/2010] [Indexed: 11/18/2022]
Abstract
Neurosurgery in Oslo, Norway, was founded by the pioneer Vilhelm Magnus in the beginning of the 20th century. Through the contributions of important surgeons such as Arne Torkildsen, Kristian Kristiansen, and Helge Nornes, Norwegian neurosurgery has developed into an active clinical and technologically oriented surgical specialty. Since the unification of neurosurgical procedures in Oslo in January 2010 into one department, it is one of the largest neurosurgical departments in Europe with more than 4500 surgeries performed per year covering all aspects of neurosurgery. The department's scientific focus is on clinical studies, in close collaboration with supportive clinical departments; through interaction with basic science stem cell groups, an increasing effort is being made in translational cellular and molecular medicine.
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Wagshul ME, Eide PK, Madsen JR. The pulsating brain: A review of experimental and clinical studies of intracranial pulsatility. Fluids Barriers CNS 2011; 8:5. [PMID: 21349153 PMCID: PMC3042979 DOI: 10.1186/2045-8118-8-5] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 01/18/2011] [Indexed: 02/01/2023] Open
Abstract
The maintenance of adequate blood flow to the brain is critical for normal brain function; cerebral blood flow, its regulation and the effect of alteration in this flow with disease have been studied extensively and are very well understood. This flow is not steady, however; the systolic increase in blood pressure over the cardiac cycle causes regular variations in blood flow into and throughout the brain that are synchronous with the heart beat. Because the brain is contained within the fixed skull, these pulsations in flow and pressure are in turn transferred into brain tissue and all of the fluids contained therein including cerebrospinal fluid. While intracranial pulsatility has not been a primary focus of the clinical community, considerable data have accrued over the last sixty years and new applications are emerging to this day. Investigators have found it a useful marker in certain diseases, particularly in hydrocephalus and traumatic brain injury where large changes in intracranial pressure and in the biomechanical properties of the brain can lead to significant changes in pressure and flow pulsatility. In this work, we review the history of intracranial pulsatility beginning with its discovery and early characterization, consider the specific technologies such as transcranial Doppler and phase contrast MRI used to assess various aspects of brain pulsations, and examine the experimental and clinical studies which have used pulsatility to better understand brain function in health and with disease.
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Affiliation(s)
- Mark E Wagshul
- Albert Einstein College of Medicine, Department of Radiology, Bronx, NY 10461, USA.
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Eide PK, Sorteberg W. Simultaneous measurements of intracranial pressure parameters in the epidural space and in brain parenchyma in patients with hydrocephalus. J Neurosurg 2010; 113:1317-25. [DOI: 10.3171/2010.7.jns10483] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Object
In this study, the authors compare simultaneous measurements of static and pulsatile pressure parameters in the epidural space and brain parenchyma of hydrocephalic patients.
Methods
Simultaneous intracranial pressure (ICP) signals from the epidural space (ICPEPI) and the brain parenchyma (ICPPAR) were compared in 12 patients undergoing continuous ICP monitoring as part of their diagnostic workup for hydrocephalus. The static ICP was characterized by mean ICP and the frequency of B waves quantified in the time domain, while the pulsatile ICP was determined from the cardiac beat–induced single ICP waves and expressed by the ICP pulse pressure amplitude (dP) and latency (dT; that is, rise time).
Results
The 12 patients underwent a median of 22.5 hours (range 5.9–24.8 hours) of ICP monitoring. Considering the total recording period of each patient, the mean ICP (static ICP) differed between the 2 compartments by ≥ 5 mm Hg in 8 patients (67%) and by ≥ 10 mm Hg in 4 patients (33%). In contrast, for every patient the ICP pulse pressure readings from the 2 compartments showed near-identical results. Consequently, when sorting patients to shunt/no shunt treatment according to pulsatile ICP values, selection was independent of sensor placement. The frequency of B waves also compared well between the 2 compartments.
Conclusions
The pulsatile ICP is measured with equal confidence from the ICPEPI and ICPPAR signals. When using the pulsatile ICP for evaluation of hydrocephalic patients, valid measurements may thus be obtained from pressure monitoring in the epidural space. Recorded differences in the mean ICP between the epidural space and the brain parenchyma are best explained by differences in the zero setting of different sensors.
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