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Zhang W, Feng J, Liu W, Zhang S, Yu X, Liu J, Shan B, Ma L. Investigating Sea-Level Brain Predictors for Acute Mountain Sickness: A Multimodal MRI Study before and after High-Altitude Exposure. AJNR Am J Neuroradiol 2024; 45:809-818. [PMID: 38663991 PMCID: PMC11288600 DOI: 10.3174/ajnr.a8206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/23/2024] [Indexed: 06/09/2024]
Abstract
BACKGROUND AND PURPOSE Acute mountain sickness is a series of brain-centered symptoms that occur when rapidly ascending to high altitude. Predicting acute mountain sickness before high-altitude exposure is crucial for protecting susceptible individuals. The present study aimed to evaluate the feasibility of predicting acute mountain sickness after high-altitude exposure by using multimodal brain MR imaging features measured at sea level. MATERIALS AND METHODS We recruited 45 healthy sea-level residents who flew to the Qinghai-Tibet Plateau (3650 m). We conducted T1-weighted structural MR imaging, resting-state fMRI, and arterial spin-labeling perfusion MR imaging both at sea level and high altitude. Acute mountain sickness was diagnosed for 5 days using Lake Louise Scoring. Logistic regression with Least Absolute Shrinkage and Selection Operator logistic regression was performed for predicting acute mountain sickness using sea-level MR imaging features. We also validated the predictors by using MR images obtained at high altitude. RESULTS The incidence rate of acute mountain sickness was 80.0%. The model achieved an area under the receiver operating characteristic curve of 86.4% (sensitivity = 77.8%, specificity = 100.0%, and P < .001) in predicting acute mountain sickness At sea level, valid predictors included fractional amplitude of low-frequency fluctuations (fALFF) and degree centrality from resting-state fMRI, mainly distributed in the somatomotor network. We further learned that the acute mountain sickness group had lower levels of fALFF in the somatomotor network at high altitude, associated with smaller changes in CSF volume and higher Lake Louise Scoring, specifically relating to fatigue and clinical function. CONCLUSIONS Our study found that the somatomotor network function detected by sea-level resting-state fMRI was a crucial predictor for acute mountain sickness and further validated its pathophysiologic impact at high altitude. These findings show promise for pre-exposure prediction, particularly for individuals in need of rapid ascent, and they offer insight into the potential mechanism of acute mountain sickness.
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Affiliation(s)
- Wei Zhang
- From the Beijing Engineering Research Center of Radiographic Techniques and Equipment (W.Z., B.S.), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
- School of Nuclear Science and Technology (W.Z., B.S.), University of Chinese Academy of Sciences, Beijing, China
- Cognitive Neuroimaging Centre (W.Z.), Nanyang Technological University, Singapore
- Lee Kong Chian School of Medicine (W.Z.), Nanyang Technological University, Singapore
| | - Jie Feng
- The Graduate School (J.F., X.Y., L.M.), Medical School of Chinese People's Liberation Army, Beijing, China
- Department of Radiology (J.F., W.L., S.Z., X.Y., L.M.), The First Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
| | - Wenjia Liu
- Department of Radiology (J.F., W.L., S.Z., X.Y., L.M.), The First Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
| | - Shiyu Zhang
- Department of Radiology (J.F., W.L., S.Z., X.Y., L.M.), The First Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
- Department of Radiology (S.Z.), Capital Medical University Affiliated Beijing Friendship Hospital, Beijing, China
| | - Xiao Yu
- The Graduate School (J.F., X.Y., L.M.), Medical School of Chinese People's Liberation Army, Beijing, China
- Department of Radiology (J.F., W.L., S.Z., X.Y., L.M.), The First Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
- Department of Radiology (X.Y.), Beijing Jingmei Group General Hospital, Beijing, China
| | - Jie Liu
- Department of Radiology (J.L.), General Hospital of Tibet Military Region, Tibet, China
| | - Baoci Shan
- From the Beijing Engineering Research Center of Radiographic Techniques and Equipment (W.Z., B.S.), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
- School of Nuclear Science and Technology (W.Z., B.S.), University of Chinese Academy of Sciences, Beijing, China
| | - Lin Ma
- The Graduate School (J.F., X.Y., L.M.), Medical School of Chinese People's Liberation Army, Beijing, China
- Department of Radiology (J.F., W.L., S.Z., X.Y., L.M.), The First Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
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Zhang G, Yang G, Zhou Y, Cao Z, Yin M, Ma L, Fan M, Zhao YQ, Zhu L. Intermittent hypoxia training effectively protects against cognitive decline caused by acute hypoxia exposure. Pflugers Arch 2024; 476:197-210. [PMID: 37994929 DOI: 10.1007/s00424-023-02885-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 10/24/2023] [Accepted: 11/08/2023] [Indexed: 11/24/2023]
Abstract
Intermittent hypoxia training (IHT) is a promising approach that has been used to induce acclimatization to hypoxia and subsequently lower the risk of developing acute mountain sickness (AMS). However, the effects of IHT on cognitive and cerebrovascular function after acute hypoxia exposure have not been characterized. In the present study, we first confirmed that the simplified IHT paradigm was effective at relieving AMS at 4300 m. Second, we found that IHT improved participants' cognitive and neural alterations when they were exposed to hypoxia. Specifically, impaired working memory performance, decreased conflict control function, impaired cognitive control, and aggravated mental fatigue induced by acute hypoxia exposure were significantly alleviated in the IHT group. Furthermore, a reversal of brain swelling induced by acute hypoxia exposure was visualized in the IHT group using magnetic resonance imaging. An increase in cerebral blood flow (CBF) was observed in multiple brain regions of the IHT group after hypoxia exposure as compared with the control group. Based on these findings, the simplified IHT paradigm might facilitate hypoxia acclimatization, alleviate AMS symptoms, and increase CBF in multiple brain regions, thus ameliorating brain swelling and cognitive dysfunction.
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Affiliation(s)
- Guangbo Zhang
- Department of Cognition Sciences and Stress Medicine, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing, China
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
| | - Guochun Yang
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Beijing, China
| | - Yanzhao Zhou
- Department of Cognition Sciences and Stress Medicine, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing, China
| | | | - Ming Yin
- The First Medical Center of Chinese, PLA General Hospital, Beijing, China
| | - Lin Ma
- The First Medical Center of Chinese, PLA General Hospital, Beijing, China
| | - Ming Fan
- Department of Cognition Sciences and Stress Medicine, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing, China
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yong-Qi Zhao
- Department of Cognition Sciences and Stress Medicine, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing, China.
- Anhui Medical University, Hefei, China.
| | - Lingling Zhu
- Department of Cognition Sciences and Stress Medicine, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China.
- Anhui Medical University, Hefei, China.
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3
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Zhao N, Chung TD, Guo Z, Jamieson JJ, Liang L, Linville RM, Pessell AF, Wang L, Searson PC. The influence of physiological and pathological perturbations on blood-brain barrier function. Front Neurosci 2023; 17:1289894. [PMID: 37937070 PMCID: PMC10626523 DOI: 10.3389/fnins.2023.1289894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/06/2023] [Indexed: 11/09/2023] Open
Abstract
The blood-brain barrier (BBB) is located at the interface between the vascular system and the brain parenchyma, and is responsible for communication with systemic circulation and peripheral tissues. During life, the BBB can be subjected to a wide range of perturbations or stresses that may be endogenous or exogenous, pathological or therapeutic, or intended or unintended. The risk factors for many diseases of the brain are multifactorial and involve perturbations that may occur simultaneously (e.g., two-hit model for Alzheimer's disease) and result in different outcomes. Therefore, it is important to understand the influence of individual perturbations on BBB function in isolation. Here we review the effects of eight perturbations: mechanical forces, temperature, electromagnetic radiation, hypoxia, endogenous factors, exogenous factors, chemical factors, and pathogens. While some perturbations may result in acute or chronic BBB disruption, many are also exploited for diagnostic or therapeutic purposes. The resultant outcome on BBB function depends on the dose (or magnitude) and duration of the perturbation. Homeostasis may be restored by self-repair, for example, via processes such as proliferation of affected cells or angiogenesis to create new vasculature. Transient or sustained BBB dysfunction may result in acute or pathological symptoms, for example, microhemorrhages or hypoperfusion. In more extreme cases, perturbations may lead to cytotoxicity and cell death, for example, through exposure to cytotoxic plaques.
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Affiliation(s)
- Nan Zhao
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
| | - Tracy D. Chung
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Zhaobin Guo
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
| | - John J. Jamieson
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Lily Liang
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Raleigh M. Linville
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Alex F. Pessell
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Linus Wang
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Peter C. Searson
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, United States
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Retinal microvasculature is a potential biomarker for acute mountain sickness. SCIENCE CHINA. LIFE SCIENCES 2023:10.1007/s11427-022-2271-x. [PMID: 36811802 DOI: 10.1007/s11427-022-2271-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/21/2022] [Indexed: 02/24/2023]
Abstract
Increased cerebral blood flow resulting from altered capillary level autoregulation at high altitudes leads to capillary overperfusion and then vasogenic cerebral edema, which is the leading hypothesis of acute mountain sickness (AMS). However, studies on cerebral blood flow in AMS have been mostly restricted to gross cerebrovascular endpoints as opposed to the microvasculature. This study aimed to investigate ocular microcirculation alterations, the only visualized capillaries in the central neural system (CNS), during early-stage AMS using a hypobaric chamber. This study found that after high altitude simulation, the optic nerve showed retinal nerve fiber layer thickening (P=0.004-0.018) in some locations, and the area of the optic nerve subarachnoid space (P=0.004) enlarged. Optical coherence tomography angiography (OCTA) showed increased retinal radial peripapillary capillary (RPC) flow density (P=0.003-0.046), particularly on the nasal side of the nerve. The AMS-positive group had the largest increases in RPC flow density in the nasal sector (AMS-positive, Δ3.21±2.37; AMS-negative, Δ0.01±2.16, P=0.004). Among multiple ocular changes, OCTA increase in RPC flow density was associated with simulated early-stage AMS symptoms (beta=0.222, 95%CI, 0.009-0.435, P=0.042). The area under the receiver operating characteristics curve (AUC) for the changes in RPC flow density to predict early-stage AMS outcomes was 0.882 (95%CI, 0.746-0.998). The results further confirmed that overperfusion of microvascular beds is the key pathophysiologic change in early-stage AMS. RPC OCTA endpoints may serve as a rapid, noninvasive potential biomarker for CNS microvascular changes and AMS development during risk assessment of individuals at high altitudes.
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Dynamic cerebral blood flow changes with FOXOs stimulation are involved in neuronal damage associated with high-altitude cerebral edema in mice. Brain Res 2022; 1790:147987. [PMID: 35724762 DOI: 10.1016/j.brainres.2022.147987] [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: 03/06/2022] [Revised: 05/21/2022] [Accepted: 06/14/2022] [Indexed: 11/22/2022]
Abstract
Acute hypobaric hypoxia (AHH) exposure causes altitude mountain sickness (AMS) and life-threatening high altitude cerebral edema (HACE). Despite decades of research, the role of cerebral blood flow (CBF) changes in the pathophysiology of severe AMS remains unclear. The current study evaluated spatiotemporal responses of CBF associated with HACE in mice during the early stages of ascent to high altitudes. First, mice were exposed to AHH to test their tolerance to increasing altitudes (3000-8000 m). Because of its significant influence on both locomotor activity and rotarod behavior tests in mice, further observations were initiated at an altitude of 6000 m to investigate the specific pathophysiology of AMS. Compared with controls, laser speckle contrast imaging (LSCI) revealed a significant decrease in CBF during the early stage (0.5-24 h) at an altitude of 6000 m that was accompanied by a significant increase in brain water content (BWC). Moreover, observations of brain lipid oxidative damage and oxidative stress during the early stage of AHH exposure revealed DNA and cellular damage in cortical and hippocampal regions. Transcriptome profiling of the hippocampus revealed upregulation of forkhead box transcription factors. Similarly, western blot assays revealed upregulation of FOXO1a, FOXO3a, caspase-3 and Bax, and downregulation of Bcl-2, indicating a temporal influence of AHH on mitochondrial function and neuronal apoptosis. Thus, we found that the pathophysiology of HACE occurred with dynamic CBF changes, which triggered oxidative stress and neuronal damage in the mouse brain after AHH exposure. Our findings provide potential strategies for treatment of AHH in the future.
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Exposure to 16 h of normobaric hypoxia induces ionic edema in the healthy brain. Nat Commun 2021; 12:5987. [PMID: 34645793 PMCID: PMC8514510 DOI: 10.1038/s41467-021-26116-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/09/2021] [Indexed: 11/10/2022] Open
Abstract
Following prolonged exposure to hypoxic conditions, for example, due to ascent to high altitude, stroke, or traumatic brain injury, cerebral edema can develop. The exact nature and genesis of hypoxia-induced edema in healthy individuals remain unresolved. We examined the effects of prolonged, normobaric hypoxia, induced by 16 h of exposure to simulated high altitude, on healthy brains using proton, dynamic contrast enhanced, and sodium MRI. This dual approach allowed us to directly measure key factors in the development of hypoxia-induced brain edema: (1) Sodium signals as a surrogate of the distribution of electrolytes within the cerebral tissue and (2) Ktrans as a marker of blood–brain–barrier integrity. The measurements point toward an accumulation of sodium ions in extra- but not in intracellular space in combination with an intact endothelium. Both findings in combination are indicative of ionic extracellular edema, a subtype of cerebral edema that was only recently specified as an intermittent, yet distinct stage between cytotoxic and vasogenic edemas. In sum, here a combination of imaging techniques demonstrates the development of ionic edemas following prolonged normobaric hypoxia in agreement with cascadic models of edema formation. Prolonged hypoxia, which can be due to stroke or ascent to high altitude, can lead to cerebral edema. Here, the authors used a combination of sodium and proton MRI and experimentally induced hypoxic conditions to identify the cause for brain swelling: Ionic edema, an intermediate between cytotoxic and vasogenic edema defined by sodium ion accumulation in extracellular space and an intact endothelium.
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7
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Turner REF, Gatterer H, Falla M, Lawley JS. High-altitude cerebral edema: its own entity or end-stage acute mountain sickness? J Appl Physiol (1985) 2021; 131:313-325. [PMID: 33856254 DOI: 10.1152/japplphysiol.00861.2019] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
High-altitude cerebral edema (HACE) and acute mountain sickness (AMS) are neuropathologies associated with rapid exposure to hypoxia. However, speculation remains regarding the exact etiology of both HACE and AMS and whether they share a common mechanistic pathology. This review outlines the basic principles of HACE development, highlighting how edema could develop from 1) a progression from cytotoxic swelling to ionic edema or 2) permeation of the blood brain barrier (BBB) with or without ionic edema. Thereafter, discussion turns to the available neuroimaging literature in the context of cytotoxic, ionic, or vasogenic edema in both HACE and AMS. Although HACE is clearly caused by an increase in brain water of ionic and/or vasogenic origin, there is very little evidence that this type of edema is present when AMS develops. However, cerebral vasodilation, increased intracranial blood volume, and concomitant intracranial fluid shifts from the extracellular to the intracellular space, as interpreted from changes in diffusion indices within white matter, are observed consistently in persons acutely exposed to hypoxia and with AMS. Therefore, herein we explore the idea that intracellular swelling occurs alongside AMS, and is a critical precursor to extracellular ionic edema formation. We propose that this process produces a subtle modulation of the BBB, which either together with or independent of vasogenic edema provides a transvascular segue from the end-stage of AMS to HACE. Ultimately, this review seeks to shed light on the possible processes underlying HACE pathophysiology, and thus highlights potential avenues for future prevention and treatment.
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Affiliation(s)
- Rachel E F Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Marika Falla
- Center for Mind/Brain Sciences and Centre for Neurocognitive Rehabilitation, University of Trento, Rovereto, Italy
| | - Justin S Lawley
- Division of Performance Physiology & Prevention, Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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Gibbons TD, Ainslie PN, Thomas KN, Wilson LC, Akerman AP, Donnelly J, Campbell HA, Cotter JD. Influence of the mode of heating on cerebral blood flow, non-invasive intracranial pressure and thermal tolerance in humans. J Physiol 2021; 599:1977-1996. [PMID: 33586133 DOI: 10.1113/jp280970] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 02/01/2021] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS The human brain is particularly vulnerable to heat stress; this manifests as impaired cognition, orthostatic tolerance, work capacity and eventually, brain death. The brain's limitation in the heat is often ascribed to inadequate cerebral blood flow (CBF), but elevated intracranial pressure is commonly observed in mammalian models of heat stroke and can on its own cause functional impairment. The CBF response to incremental heat strain was dependent on the mode of heating, decreasing by 30% when exposed passively to hot, humid air (sauna), while remaining unchanged or increasing with passive hot-water immersion (spa) and exercising in a hot environment. Non-invasive intracranial pressure estimates (nICP) were increased universally by 18% at volitional thermal tolerance across all modes of heat stress, and therefore may play a contributing role in eliciting thermal tolerance. The sauna, more so than the spa or exercise, poses a greater challenge to the brain under mild to severe heating due to lower blood flow but similarly increased nICP. ABSTRACT The human brain is particularly vulnerable to heat stress; this manifests as impaired cognitive function, orthostatic tolerance, work capacity, and eventually, brain death. This vulnerability is often ascribed to inadequate cerebral blood flow (CBF); however, elevated intracranial pressure (ICP) is also observed in mammalian models of heat stroke. We investigated the changes in CBF with incremental heat strain under three fundamentally different modes of heating, and assessed whether heating per se increased ICP. Fourteen fit participants (seven female) were heated to thermal tolerance or 40°C core temperature (Tc ; oesophageal) via passive hot-water immersion (spa), passive hot, humid air exposure (sauna), cycling exercise, and cycling exercise with CO2 inhalation to prevent heat-induced hypocapnia. CBF was measured with duplex ultrasound at each 0.5°C increment in Tc and ICP was estimated non-invasively (nICP) from optic nerve sheath diameter at thermal tolerance. At thermal tolerance, CBF was decreased by 30% in the sauna (P < 0.001), but was unchanged in the spa or with exercise (P ≥ 0.140). CBF increased by 17% when end-tidal P C O 2 was clamped at eupnoeic pressure (P < 0.001). On the contrary, nICP increased universally by 18% with all modes of heating (P < 0.001). The maximum Tc was achieved with passive heating, and preventing hypocapnia during exercise did not improve exercise or thermal tolerance (P ≥ 0.146). Therefore, the regulation of CBF is dramatically different depending on the mode and dose of heating, whereas nICP responses are not. The sauna, more so than the spa or exercise, poses a greater challenge to the brain under equivalent heat strain.
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Affiliation(s)
- Travis D Gibbons
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Philip N Ainslie
- University of British Columbia, Okangan Campus, Kelowna, BC, V1V 1V7, Canada
| | - Kate N Thomas
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Luke C Wilson
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | | | | | - Holly A Campbell
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
| | - Jim D Cotter
- University of Otago, 55/47 Union St. W, Dunedin, Otago, 9016, New Zealand
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Barclay H, Mukerji S, Kayser B, O'Donnell T, Tzeng YC, Hill S, Knapp K, Legg S, Frei D, Fan JL. Respiratory alkalinization and posterior cerebral artery dilatation predict acute mountain sickness severity during 10 h normobaric hypoxia. Exp Physiol 2020; 106:175-190. [PMID: 33347666 DOI: 10.1113/ep088938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022]
Abstract
NEW FINDINGS What is the central question of this study? The pathophysiology of acute mountain sickness (AMS), involving the respiratory, renal and cerebrovascular systems, remains poorly understood. How do the early adaptations in these systems during a simulated altitude of 5000 m relate to AMS risk? What is the main finding and its importance? The rate of blood alkalosis and cerebral artery dilatation predict AMS severity during the first 10 h of exposure to a simulated altitude of 5000 m. Slow metabolic compensation by the kidneys of respiratory alkalosis attributable to a brisk breathing response together with excessive brain blood vessel dilatation might be involved in early development of AMS. ABSTRACT The complex pathophysiology of acute mountain sickness (AMS) remains poorly understood and is likely to involve maladaptive responses of the respiratory, renal and cerebrovascular systems to hypoxia. Using stepwise linear regression, we tested the hypothesis that exacerbated respiratory alkalosis, as a result of a brisk ventilatory response, sluggish renal compensation in acute hypoxia and dysregulation of cerebral perfusion predict AMS severity. We assessed the Lake Louise score (LLS, an index of AMS severity), fluid balance, ventilation, venous pH, bicarbonate, sodium and creatinine concentrations, body weight, urinary pH and cerebral blood flow [internal carotid artery (ICA) and vertebral artery (VA) blood flow and diameter], in 27 healthy individuals (13 women) throughout 10 h exposures to normobaric normoxia (fraction of inspired O2 = 0.21) and normobaric hypoxia (fraction of inspired O2 = 0.117, simulated 5000 m) in a randomized, single-blinded manner. In comparison to normoxia, hypoxia increased the LLS, ventilation, venous and urinary pH, and blood flow and diameter in the ICA and VA, while venous concentrations of both bicarbonate and creatinine were decreased (P < 0.001 for all). There were significant correlations between AMS severity and the rates of change in blood pH, sodium concentration and VA diameter and more positive fluid balance (P < 0.05). Stepwise regression found increased blood pH [beta coefficient (β) = 0.589, P < 0.001] and VA diameter (β = 0.418, P = 0.008) to be significant predictors of AMS severity in our cohort [F(2, 20) = 16.1, R2 = 0.617, P < 0.001, n = 24], accounting for 62% of the variance in peak LLS. Using classic regression variable selection, our data implicate the degree of respiratory alkalosis and cerebrovascular dilatation in the early stages of AMS development.
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Affiliation(s)
- Holly Barclay
- Wellington Medical Technology Group, Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand.,Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Saptarshi Mukerji
- Emergency Department, Wellington Regional Hospital, Capital & Coast District Health Board, Wellington, New Zealand
| | - Bengt Kayser
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Terrence O'Donnell
- Wellington Medical Technology Group, Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand.,Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand.,Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Stephen Hill
- School of Psychology, Massey University, Palmerston North, New Zealand
| | - Katie Knapp
- School of Psychology, Massey University, Palmerston North, New Zealand
| | - Stephen Legg
- Centre for Ergonomics, Occupational Health and Safety, Massey University, Palmerston North, New Zealand
| | - Dan Frei
- Department of Anaesthesia and Pain Medicine, Wellington Regional Hospital, Capital & Coast District Health Board, Wellington, New Zealand
| | - Jui-Lin Fan
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Biollaz J, Buclin T, Hildebrandt W, Décosterd LA, Nussberger J, Swenson ER, Bärtsch P. No renal dysfunction or salt and water retention in acute mountain sickness at 4,559 m among young resting males after passive ascent. J Appl Physiol (1985) 2020; 130:226-236. [PMID: 33180647 DOI: 10.1152/japplphysiol.00382.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study examined the role and function of the kidney at high altitude in relation to fluid balance and the development of acute mountain sickness (AMS), avoiding confounders that have contributed to conflicting results in previous studies. We examined 18 healthy male resting volunteers (18-40 yr) not acclimatized to high altitude while on a controlled diet for 24 h at Lausanne (altitude: 560 m) followed by a period of 44 h after reaching the Regina Margherita hut (4,559 m) by helicopter. AMS scores peaked after 20 h at 4,559 m. AMS was defined as functional Lake Louise score ≥ 2. There were no significant differences between 10 subjects with and 8 subjects without AMS for urinary flow, fluid balance, and weight change. Sodium excretion rate was lower in those with AMS after 24 h at altitude. Microalbuminuria increased at altitude but was not different between the groups. Creatinine clearance was not affected by altitude or AMS, whereas clearances of sinistrin and p-aminohippuric acid decreased slightly, somewhat more in those without AMS. Plasma concentrations of epinephrine, norepinephrine, atrial natriuretic factor, and vasopressin increased whereas renin activity, angiotensin, and aldosterone decreased at altitude. Circulating hormone concentrations did not differ between those with and without AMS. Summarizing, in healthy resting young men flown by helicopter to 4,559 m, renal function was not affected by hypoxia except for minor microalbuminuria, high altitude diuresis did not occur, and AMS was not associated with salt and water retention or renal dysfunction.NEW & NOTEWORTHY Kidney function remained essentially unaffected and acute mountain sickness (AMS) was not associated with salt and water retention in healthy young men flown to and resting at the Margherita hut (4,559 m) under strictly controlled conditions maintaining water, salt, and food intake at pre-exposure levels. Thus, renal dysfunction and fluid retention are not essential factors contributing to the pathophysiology of AMS.
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Affiliation(s)
- Jérôme Biollaz
- Service of Clinical Pharmacology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Thierry Buclin
- Service of Clinical Pharmacology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Wulf Hildebrandt
- Institute of Anatomy and Cell Biology, Philipps-University of Marburg, Marburg, Germany.,Department of Internal Medicine, University Clinic, Heidelberg, Germany
| | - Laurent A Décosterd
- Service of Clinical Pharmacology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Jürg Nussberger
- Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Erik R Swenson
- Department of Internal Medicine, University Clinic, Heidelberg, Germany.,Pulmonary and Critical Care Medicine, Medical Service, Veterans Affairs Puget Sound Health Care System, University of Washington, Seattle, Washington
| | - Peter Bärtsch
- Department of Internal Medicine, University Clinic, Heidelberg, Germany
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11
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Limper U, Fiala V, Tank J, Elmenhorst EM, Schaelte G, Hew YYM, Gauger P, Martus P, Jordan J. Sleeping with Elevated Upper Body Does Not Attenuate Acute Mountain Sickness: Pragmatic Randomized Clinical Trial. Am J Med 2020; 133:e584-e588. [PMID: 32081656 DOI: 10.1016/j.amjmed.2020.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/06/2020] [Accepted: 01/06/2020] [Indexed: 10/25/2022]
Abstract
PURPOSE Acute mountain sickness commonly occurs following ascent to high altitude and is aggravated following sleep. Cephalad fluid shifts have been implicated. We hypothesized that sleeping with the upper body elevated by 30º reduces the risk of acute mountain sickness. METHODS In a pragmatic, randomized, observer-blinded field study at 4554 meters altitude, we investigated 134 adults aged 18-70 years with a Lake Louise score between 3 and 12 points on the evening of their arrival at the altitude. The individuals were exposed to sleeping on an inflatable cushion elevating the upper body by 30º or on a sham pillow in a horizontal position. The primary endpoint was the change in the Acute Mountain Sickness-Cerebral (AMS-C) score in the morning after sleeping at an altitude of 4554 meters compared with the evening before. Sleep efficiency was the secondary endpoint. RESULTS Among 219 eligible mountaineers, 134 fulfilled the inclusion criteria and were randomized. The AMS-C score increased by 0.250 ± 0.575 in the control group and by 0.121 ± 0.679 in the intervention group (difference 0.105; 95% confidence interval, -0.098-0.308; P = .308). Oxygen saturation in the morning was 79% ± 6% in the intervention group and 78% ± 6% in the control group (P = .863). Sleep efficiency did not differ between groups (P = .115). CONCLUSIONS Sleeping with the upper body elevated by 30° does not lead to relevant reductions in acute mountain sickness symptoms or hypoxemia at high altitude.
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Affiliation(s)
- Ulrich Limper
- Department of Anesthesiology and Intensive Care Medicine, Merheim Medical Center, Hospitals of Cologne, University of Witten/Herdecke, Cologne, Germany; German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Vera Fiala
- Department of Anesthesiology, Medical Faculty, University Hospital RWTH Aachen, Aachen, Germany
| | - Jens Tank
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Eva-Maria Elmenhorst
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany; Institute for Occupational, Social and Environmental Medicine, Medical Faculty, University Hospital RWTH Aachen, Aachen, Germany
| | - Gereon Schaelte
- Department of Anesthesiology, Medical Faculty, University Hospital RWTH Aachen, Aachen, Germany
| | - Ya-Yu Monica Hew
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Peter Gauger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Peter Martus
- Institute of Medical Biometry, University of Tuebingen, Tuebingen, Germany
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany; Chair of Aerospace Medicine, Medical Faculty, University of Cologne, Cologne, Germany.
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12
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Zhang H, Lu S, Ren H, Zhao K, Li Y, Guan Y, Li H, Zheng Y, Hu P, Liu Z. Acute Oral Toxicity and Acute Intraperitoneal Studies of Thermally Treated Ceftiofur. Chem Pharm Bull (Tokyo) 2020; 68:1061-1068. [PMID: 32893223 DOI: 10.1248/cpb.c20-00483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ceftiofur (CEF) is a third-generation and the first animal-specific cephalosporin that is widely used in animal husbandry. As a heat-labile antibiotic, the cytotoxicity of CEF after thermal treatment has been reported. This study seeks to investigate the potential toxicity of thermally treated CEF (TTC) in vivo based on acute oral toxicity studies and acute intraperitoneal studies in mice. Our data indicated that TTC exhibited significant increased toxicity in mice compared with CEF. TTC resulted in weight gain, hypercholesterolemia, hepatocyte steatosis and hepatocyte mitochondrial damage, and downregulated β-oxidation-related genes in mice in acute oral toxicity studies. In addition, TTC caused acute pulmonary congestion, increased levels of reactive oxygen species (ROS), prolonged coagulation time, and even death in mice in acute intraperitoneal toxicity studies. Our data showed that thermal treatment enhanced the toxicity of CEF in vivo. Lung and liver are the main target organs in the pathological damage process mediated by TTC. These findings suggested that residual CEF in animal-derived food may represent a potential food safety risk and pose a potential threat to human health.
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Affiliation(s)
- Hong Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Shiying Lu
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Honglin Ren
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Ke Zhao
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Yansong Li
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Yuting Guan
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Hanxiao Li
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Yu Zheng
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Pan Hu
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
| | - Zengshan Liu
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University
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13
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Li Z, Li R, Xu Y, Xu Y. Study on the Oxygen Enrichment Effect of Individual Oxygen-Supply Device in a Tunnel of Plateau Mine. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17165934. [PMID: 32824194 PMCID: PMC7459575 DOI: 10.3390/ijerph17165934] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/30/2022]
Abstract
Complex characteristics of the plateau environment such as low oxygen content seriously restrict the exploitation of abundant mineral resources in plateau areas. To regulate the hypoxia environment and improve the comfort of workers engaged in intense physical labor like tunnel excavation operations in plateau mines, an individual oxygen-supply device for tunnel of plateau mine was proposed to create local oxygen enrichment in the area around the human nose. The Computational Fluid Dynamics (CFD) method was used to judge the application’s effect of the individual oxygen-supply device in plateau mine, revealing the oxygen diffusion law under the influence of different oxygen enrichment factors. The orthogonal design and range analysis were used to measure the degree of influence of major factors such as oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The results demonstrate that the oxygen mass fraction of the air inhaled by the human had a positive correlation exponential function, a positive correlation linear function, and a negative correlation exponential function, respectively, concerning oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The range analysis revealed that the major influencing factors of oxygen enrichment in the tunnel of the plateau mine were, in a descending sequence, as follows: oxygen-supply concentration, tunnel airflow velocity, and oxygen-supply velocity, and the corresponding ranges were 2.86, 2.63, and 1.83, respectively. The individual oxygen-supply device achieved the best oxygen enrichment effect when the oxygen-supply velocity was 5 m/s, the oxygen-supply concentration was 60%, and the tunnel airflow velocity was 0.2 m/s, which increased the oxygen mass fraction of air inhaled by the human to 30.42%. This study has a positive guiding significance for the improvement of the respiration environment in the tunnel of plateau mine.
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14
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Manferdelli G, Marzorati M, Easton C, Porcelli S. Changes in prefrontal cerebral oxygenation and microvascular blood volume in hypoxia and possible association with acute mountain sickness. Exp Physiol 2020; 106:76-85. [DOI: 10.1113/ep088515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/24/2020] [Indexed: 01/30/2023]
Affiliation(s)
- Giorgio Manferdelli
- Institute of Biomedical Technologies National Research Council Segrate Italy
- School of Health and Exercise Sciences University of the West of Scotland Paisley UK
| | - Mauro Marzorati
- Institute of Biomedical Technologies National Research Council Segrate Italy
| | - Chris Easton
- School of Health and Exercise Sciences University of the West of Scotland Paisley UK
| | - Simone Porcelli
- Institute of Biomedical Technologies National Research Council Segrate Italy
- Department of Molecular Physiology University of Pavia Pavia Italy
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15
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Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis. Mil Med Res 2019; 6:38. [PMID: 31813379 PMCID: PMC6900850 DOI: 10.1186/s40779-019-0228-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/13/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND When lowlanders rapidly ascend to altitudes > 2500 m, they may develop acute mountain sickness (AMS). The individual susceptibility, ascending velocity, time spent at altitude, activity levels and altitude reached are considered risk factors for AMS. However, it is not clear whether sex is a risk factor. The results have been inconclusive. We conducted a meta-analysis to test whether there were sex-based differences in the prevalence of AMS using Lake Louise Scoring System. METHODS Systematic searches were performed in August 2019 in EMBASE, PubMed, and Web of Science for prospective studies with AMS data for men and women. The titles and abstracts were independently checked in the primary screening step, and the selected full-text articles were independently assessed in the secondary screening step by the two authors (YPH and JLW) based on pre-defined inclusion criteria. The meta-analysis was performed using by the STATA 14.1 software program. A random-effects model was employed. RESULTS Eighteen eligible prospective studies were included. A total of 7669 participants (2639 [34.4%] women) were tested. The results showed that there was a statistically significant higher prevalence rate of AMS in women than in men (RR = 1.24, 95%CI 1.09-1.41), regardless of age or race. Howerver, the heterogeneity was significant in the analysis (Tau2 = 0.0403, Chi2 = 50.15, df = 17; I2 = 66.1%, P = 0.000), it was main caused by different numbers of subjects among the studies (coefficient = - 2.17, P = 0.049). Besides, the results showed that there was no evidence of significant publication bias in the combined studies on the basis of Egger's test (bias coefficient = 1.48, P = 0.052) and Begg's test (P = 0.130). CONCLUSIONS According to this study, the statistically significant finding emerging from this study was that women have a higher prevalence of AMS. However, the authors could not exclude studies where patients were on acetazolamide. Our analysis provided a direction for future studies of the relationship of sex and the risk of AMS, such as the pathological mechanism and prevention research.
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16
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Kühn S, Gerlach D, Noblé HJ, Weber F, Rittweger J, Jordan J, Limper U. An Observational Cerebral Magnetic Resonance Imaging Study Following 7 Days at 4554 m. High Alt Med Biol 2019; 20:407-416. [DOI: 10.1089/ham.2019.0056] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Sven Kühn
- German Air Force Center of Aerospace Medicine, Fürstenfeldbruck, Germany
| | - Darius Gerlach
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Hans-Jürgen Noblé
- German Air Force Center of Aerospace Medicine, Fürstenfeldbruck, Germany
| | - Frank Weber
- German Air Force Center of Aerospace Medicine, Fürstenfeldbruck, Germany
| | - Jörn Rittweger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
- Institute of Aerospace Medicine, University of Cologne, Cologne, Germany
| | - Ulrich Limper
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
- Department of Anesthesiology and Intensive Care Medicine, Merheim Medical Center, Hospitals of Cologne, University of Witten/Herdecke, Cologne, Germany
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17
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Wang X, Hou Y, Li Q, Li X, Wang W, Ai X, Kuang T, Chen X, Zhang Y, Zhang J, Hu Y, Meng X. Rhodiola crenulata attenuates apoptosis and mitochondrial energy metabolism disorder in rats with hypobaric hypoxia-induced brain injury by regulating the HIF-1α/microRNA 210/ISCU1/2(COX10) signaling pathway. JOURNAL OF ETHNOPHARMACOLOGY 2019; 241:111801. [PMID: 30878546 DOI: 10.1016/j.jep.2019.03.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/06/2019] [Accepted: 03/10/2019] [Indexed: 06/09/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Rhodiola crenulata, a traditional Tibetan medicine, has shown promise in the treatment of hypobaric hypoxia (HH)-induced brain injury. However, the underlying mechanisms remain unclear. This study investigated the protective effects of R. crenulata aqueous extract (RCAE) on HH-induced brain injury in rats. MATERIALS AND METHODS An animal model of high-altitude hypoxic brain injury was established in SD rats using an animal decompression chamber for 24 h. Serum and hippocampus levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), and lactate dehydrogenase (LDH) were then determined using commercial biochemical kits. Neuron morphology and vitality were also evaluated using H&E and Nissl staining, and TUNEL staining was used to examine apoptosis. Gene and protein expression of HIF-1α, microRNA 210, ISCU1/2, COX10, Apaf-1, cleaved Caspase-3, Caspase-3, Bax, Bcl-2, and Cyto-c were determined by western blot, immunohistochemical and qRT-PCR analysis. RESULTS RCAE administration attenuated HH-induced brain injury as evidenced by decreased levels of MDA, LDH, and GSSG, increased GSH and SOD, improvements in hippocampus histopathological changes, increased cell vitality and ATP level, and reduced apoptotic cell numbers. RCAE treatment also enhanced HIF-1α, ISCU1/2, COX10, and Bcl-2 protein expression, while dramatically inhibiting expression of Apaf-1, Bax, Cyto-c, and cleaved Caspase-3. Treatment also increased gene levels of HIF-1α, microRNA 210, ISCU1/2, and COX10, and decreased Caspase-3 gene production. CONCLUSIONS RCAE attenuated HH-induced brain injury by regulating apoptosis and mitochondrial energy metabolism via the HIF-1α/microRNA 210/ISCU1/2 (COX10) signaling pathway.
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Affiliation(s)
- Xiaobo Wang
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China; Interdisciplinary Laboratory of Exercise and Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Ya Hou
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China; Interdisciplinary Laboratory of Exercise and Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Qiuyue Li
- Ethnic Medicine College, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Xuanhao Li
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China; Ethnic Medicine College, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Wenxiang Wang
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Xiaopeng Ai
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Tingting Kuang
- Ethnic Medicine College, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Xiaorui Chen
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Yi Zhang
- Ethnic Medicine College, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China
| | - Jing Zhang
- Ethnic Medicine College, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China.
| | - Yao Hu
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China; Interdisciplinary Laboratory of Exercise and Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China.
| | - Xianli Meng
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China; Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, PR China.
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18
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Lochner P, Czosnyka M, Naldi A, Lyros E, Pelosi P, Mathur S, Fassbender K, Robba C. Optic nerve sheath diameter: present and future perspectives for neurologists and critical care physicians. Neurol Sci 2019; 40:2447-2457. [PMID: 31367861 DOI: 10.1007/s10072-019-04015-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/16/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Estimation of intracranial pressure (ICP) may be helpful in the management of neurological critically ill patients. It has been shown that ultrasonography of the optic nerve sheath diameter (ONSD) is a reliable tool for non-invasive estimation of increased intracranial pressure (ICP) at hospital admission or in intensive care. Less is known about the estimation of increased ICP and usefulness of ONSD in the prehospital setting. The aim of this review was to elucidate both prevailing and novel applications of ONSD for neurologists and critical care physicians. METHODS In this review, we discuss the technique and the novel approach of ONSD measurement, the clinical applications of ONSD in neurology and critical care patients. RESULTS ONSD measurement is simple, easy to learn, and has diverse applications. ONSD has utility for ICP measurement in intracranial hemorrhage and ischemic stroke, meningitis and encephalitis, and idiopathic intracranial hypertension (IIH). It is also valuable for lesser known syndromes, where an increase of ICP is postulated, such as acute mountain sickness and posterior reversible encephalopathy syndrome. ONSD changes develop in inflammatory or ischemic optic neuropathies. Some papers demonstrate the usefulness of ONSD studies in symptomatic intracranial hypotension. CONCLUSIONS ONSD is a safe and low-cost bedside tool with the potential of screening patients who need other neuroimaging and those who may need an invasive measurement of ICP.
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Affiliation(s)
- Piergiorgio Lochner
- Department of Neurology, Saarland University Medical Center, Homburg, Germany.
| | - Marek Czosnyka
- Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University, Cambridge, UK
| | - Andrea Naldi
- Department of Neurosciences "Rita Levi Montalcini", University of Turin, Turin, Italy
| | - Epameinondas Lyros
- Department of Neurology, Saarland University Medical Center, Homburg, Germany
| | - Paolo Pelosi
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy.,Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - Shrey Mathur
- Department of Neurology, Saarland University Medical Center, Homburg, Germany
| | - Klaus Fassbender
- Department of Neurology, Saarland University Medical Center, Homburg, Germany
| | - Chiara Robba
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy
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McGuire SA, Ryan MC, Sherman PM, Sladky JH, Rowland LM, Wijtenburg SA, Hong LE, Kochunov PV. White matter and hypoxic hypobaria in humans. Hum Brain Mapp 2019; 40:3165-3173. [PMID: 30927318 DOI: 10.1002/hbm.24587] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/05/2019] [Accepted: 03/18/2019] [Indexed: 12/18/2022] Open
Abstract
Occupational exposure to hypobaria (low atmospheric pressure) is a risk factor for reduced white matter integrity, increased white matter hyperintensive burden, and decline in cognitive function. We tested the hypothesis that a discrete hypobaric exposure will have a transient impact on cerebral physiology. Cerebral blood flow, fractional anisotropy of water diffusion in cerebral white matter, white matter hyperintensity volume, and concentrations of neurochemicals were measured at baseline and 24 hr and 72 hr postexposure in N = 64 healthy aircrew undergoing standard US Air Force altitude chamber training and compared to N = 60 controls not exposed to hypobaria. We observed that hypobaric exposure led to a significant rise in white matter cerebral blood flow (CBF) 24 hr postexposure that remained elevated, albeit not significantly, at 72 hr. No significant changes were observed in structural measurements or gray matter CBF. Subjects with higher baseline concentrations of neurochemicals associated with neuroprotection and maintenance of normal white matter physiology (glutathione, N-acetylaspartate, glutamate/glutamine) showed proportionally less white matter CBF changes. Our findings suggest that discrete hypobaric exposure may provide a model to study white matter injury associated with occupational hypobaric exposure.
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Affiliation(s)
- Stephen A McGuire
- Department of Neurology, University of Texas Health Science Center, San Antonio, Texas
| | - Meghann C Ryan
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Paul M Sherman
- U.S. Air Force School of Aerospace Medicine, 59MDW-USAFSAM/FHOH, San Antonio, Texas
| | - John H Sladky
- U.S. Air Force School of Aerospace Medicine, 59MDW-USAFSAM/FHOH, San Antonio, Texas
| | - Laura M Rowland
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - S Andrea Wijtenburg
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - L Elliot Hong
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Peter V Kochunov
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
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20
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Burman R, Shah AH, Benveniste R, Jimsheleishvili G, Lee SH, Loewenstein D, Alperin N. Comparing invasive with MRI-derived intracranial pressure measurements in healthy elderly and brain trauma cases: A pilot study. J Magn Reson Imaging 2019; 50:975-981. [PMID: 30801895 DOI: 10.1002/jmri.26695] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Intracranial pressure (ICP) is an important physiological parameter in several neurological disorders. Considerable effort has been made to measure ICP noninvasively. MR-based ICP (MR-ICP) is a nonempirical method based on principles of cerebrospinal fluid (CSF) physiology, where ICP is obtained from measurements of blood and CSF flows to and from the cranium during the cardiac cycle. PURPOSE To compare MR-ICP with invasive ICP measurements obtained using lumbar puncture (LP) or external ventricular drainage (EVD). STUDY TYPE Prospective, cross-sectional, observational study. SUBJECTS Ten cognitively healthy elderly subjects (age 69.6 ± 6.6 years; seven females) and six brain trauma patients (age 36.8 ± 19.7 years; two females). FIELD STRENGTH Velocity encoding cine phase-contrast at 1.5 T and 3 T. ASSESSMENT MR-ICP and craniospinal compliance distribution were estimated from arterial inflow and venous outflow to and from cranium, and craniospinal CSF flow at the upper cervical region, measured using cine phase contrast MRI. LP (done 177 ± 163 days after scan) and EVD measurements (at the time of scan) were performed in lateral recumbent and supine positions, respectively. STATISTICAL TESTS Linear regression was used to assess the relationships of MR-ICP with invasive ICP, and the dependency of these measurements on age, weight, height, and BMI. A Shapiro-Wilks test and Bland-Altman plot were respectively used to evaluate the normality and agreement between these two pressure distributions. Student's t-test was used throughout the analysis to compare differences between the EVD and LP cohorts. RESULTS In the combined cohort, MR-ICP and invasive ICP were positively correlated (r = 0.95, P < 0.001), with invasive ICP being higher than MR-ICP by 2.2 mmHg on average. In the healthy cohort, the cranial contribution to total craniospinal compliance was negatively correlated with MR-ICP (r = -0.90, P < 0.001). DATA CONCLUSION MR-ICP provides a reliable estimate of ICP, with 14 out of 16 datapoints within the clinically acceptable error. Craniospinal compliance distribution plays a role in modulating ICP in supine position. LEVEL OF EVIDENCE 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:975-981.
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Affiliation(s)
- Ritambhar Burman
- University of Miami, Biomedical Engineering Department, Coral Gables, Florida, USA
| | - Ashish H Shah
- University of Miami, Department of Neurological Surgery, Florida, USA
| | - Ronald Benveniste
- University of Miami, Department of Neurological Surgery, Florida, USA
| | | | - Sang H Lee
- University of Miami, Radiology Department, Miami, Florida, USA
| | - David Loewenstein
- University of Miami, Department of Psychiatry and Behavioral Sciences, Florida, USA
| | - Noam Alperin
- University of Miami, Biomedical Engineering Department, Coral Gables, Florida, USA.,University of Miami, Radiology Department, Miami, Florida, USA
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21
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Rowland MJ, Ezra M, Winkler A, Garry P, Lamb C, Kelly M, Okell TW, Westbrook J, Wise RG, Douaud G, Pattinson KT. Calcium channel blockade with nimodipine reverses MRI evidence of cerebral oedema following acute hypoxia. J Cereb Blood Flow Metab 2019; 39:285-301. [PMID: 28857714 PMCID: PMC6360646 DOI: 10.1177/0271678x17726624] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acute cerebral hypoxia causes rapid calcium shifts leading to neuronal damage and death. Calcium channel antagonists improve outcomes in some clinical conditions, but mechanisms remain unclear. In 18 healthy participants we: (i) quantified with multiparametric MRI the effect of hypoxia on the thalamus, a region particularly sensitive to hypoxia, and on the whole brain in general; (ii) investigated how calcium channel antagonism with the drug nimodipine affects the brain response to hypoxia. Hypoxia resulted in a significant decrease in apparent diffusion coefficient (ADC), a measure particularly sensitive to cell swelling, in a widespread network of regions across the brain, and the thalamus in particular. In hypoxia, nimodipine significantly increased ADC in the same brain regions, normalizing ADC towards normoxia baseline. There was positive correlation between blood nimodipine levels and ADC change. In the thalamus, there was a significant decrease in the amplitude of low frequency fluctuations (ALFF) in resting state functional MRI and an apparent increase of grey matter volume in hypoxia, with the ALFF partially normalized towards normoxia baseline with nimodipine. This study provides further evidence that the brain response to acute hypoxia is mediated by calcium, and importantly that manipulation of intracellular calcium flux following hypoxia may reduce cerebral cytotoxic oedema.
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Affiliation(s)
- Matthew J Rowland
- 1 Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Martyn Ezra
- 1 Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Anderson Winkler
- 2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK
| | - Payashi Garry
- 1 Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Catherine Lamb
- 3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Michael Kelly
- 4 Preclinical Imaging Facility, Core Biotechnology Services, University of Leicester, Leicester, UK
| | - Thomas W Okell
- 2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK
| | - Jon Westbrook
- 1 Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Richard G Wise
- 5 Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Gwenaëlle Douaud
- 2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK
| | - Kyle Ts Pattinson
- 1 Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,2 FMRIB, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.,3 Neurosciences Intensive Care Unit, Oxford University Hospitals NHS Trust, Oxford, UK
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22
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Li Y, Zhang Y, Zhang Y. Research advances in pathogenesis and prophylactic measures of acute high altitude illness. Respir Med 2018; 145:145-152. [DOI: 10.1016/j.rmed.2018.11.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 09/14/2018] [Accepted: 11/06/2018] [Indexed: 12/30/2022]
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23
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Strapazzon G, Pun M, Cappello TD, Procter E, Lochner P, Brugger H, Piccoli A. Total Body Water Dynamics Estimated with Bioelectrical Impedance Vector Analysis and B-Type Natriuretic Peptide After Exposure to Hypobaric Hypoxia: A Field Study. High Alt Med Biol 2017; 18:384-391. [PMID: 29035594 PMCID: PMC5743030 DOI: 10.1089/ham.2017.0056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/07/2017] [Indexed: 01/15/2023] Open
Abstract
Strapazzon, Giacomo, Matiram Pun, Tomas Dal Cappello, Emily Procter, Piergiorgio Lochner, Hermann Brugger, and Antonio Piccoli. Total body water dynamics estimated with bioelectrical impedance vector analysis and B-type natriuretic peptide after exposure to hypobaric hypoxia: A field study. High Alt Med Biol. 18:384-391, 2017.-The relationship between total body water (TBW) dynamics and N-terminal pro-B-type natriuretic peptide (NT-proBNP), a stable metabolite of B-type natriuretic peptide, during acute high altitude exposure is not known. To investigate this, we transported 19 healthy lowland subjects to 3830 m with a helicopter after baseline measurements (262 m). The physiological measurements and clinical assessments were taken at 9, 24, 48, and 72 hours and on the eighth day of altitude exposure. A bioelectrical impedance vector analysis (BIVA) from height corrected Resistance-Reactance (R-Xc graph) was used to estimate TBW status. NT-proBNP was measured from venous blood samples. The changes in impedance vector were lengthened at 9 (p = 0.011), 48 (p = 0.033), and 72 hours (p = 0.015) indicating dehydration compared to baseline. However, there was no dehydration at 24 hours (p > 0.05) from the baseline and the subjects trended to get euhydrated from 9 to 24 hours (p = 0.097). The maximum percent changes in vector length from the baseline were within 10%-15%. There was a significant increase of natural logarithm (ln)(NT-proBNP) after ascent with a peak at 24 hours, although similarly to BIVA values, ln(NT-proBNP) returned to baseline after 8 days of altitude exposure. The changes in impedance vector length were not correlated with the changes in ln(NT-proBNP) (r = -0.101, p = 0.656). In conclusion, the dehydration at high altitude as reflected by 10%-15% vector lengthening falls within "appropriate dehydration" in healthy lowland subjects. NT-proBNP does not simply reflect the TBW status during acute high altitude exposure and needs further investigation.
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Affiliation(s)
| | - Matiram Pun
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
| | | | - Emily Procter
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
| | - Piergiorgio Lochner
- Department of Neurology, Saarland University Medical Center, Homburg, Germany
| | - Hermann Brugger
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
| | - Antonio Piccoli
- Department of Medicine DIMED, University Hospital of Padova, Padova, Italy
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24
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Davis C, Hackett P. Advances in the Prevention and Treatment of High Altitude Illness. Emerg Med Clin North Am 2017; 35:241-260. [PMID: 28411926 DOI: 10.1016/j.emc.2017.01.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
High altitude illness encompasses a spectrum of clinical entities to include: acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. These illnesses occur as a result of a hypobaric hypoxic environment. Although a mild case of acute mountain sickness may be self-limited, high altitude cerebral edema and high altitude pulmonary edema represent critical emergencies that require timely intervention. This article reviews recent advances in the prevention and treatment of high altitude illness, including new pharmacologic strategies for prophylaxis and revised treatment guidelines.
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Affiliation(s)
- Christopher Davis
- Department of Emergency Medicine, University of Colorado School of Medicine, 12401 East 17th Avenue, Aurora, CO 80045, USA.
| | - Peter Hackett
- Institute for Altitude Medicine, PO Box 1229, Telluride, CO 81435, USA
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25
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Sagoo RS, Hutchinson CE, Wright A, Handford C, Parsons H, Sherwood V, Wayte S, Nagaraja S, Ng'Andwe E, Wilson MH, Imray CH. Magnetic Resonance investigation into the mechanisms involved in the development of high-altitude cerebral edema. J Cereb Blood Flow Metab 2017; 37:319-331. [PMID: 26746867 PMCID: PMC5167111 DOI: 10.1177/0271678x15625350] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/08/2015] [Accepted: 11/27/2015] [Indexed: 11/20/2022]
Abstract
Rapid ascent to high altitude commonly results in acute mountain sickness, and on occasion potentially fatal high-altitude cerebral edema. The exact pathophysiological mechanisms behind these syndromes remain to be determined. We report a study in which 12 subjects were exposed to a FiO2 = 0.12 for 22 h and underwent serial magnetic resonance imaging sequences to enable measurement of middle cerebral artery velocity, flow and diameter, and brain parenchymal, cerebrospinal fluid and cerebral venous volumes. Ten subjects completed 22 h and most developed symptoms of acute mountain sickness (mean Lake Louise Score 5.4; p < 0.001 vs. baseline). Cerebral oxygen delivery was maintained by an increase in middle cerebral artery velocity and diameter (first 6 h). There appeared to be venocompression at the level of the small, deep cerebral veins (116 cm3 at 2 h to 97 cm3 at 22 h; p < 0.05). Brain white matter volume increased over the 22-h period (574 ml to 587 ml; p < 0.001) and correlated with cumulative Lake Louise scores at 22 h (p < 0.05). We conclude that cerebral oxygen delivery was maintained by increased arterial inflow and this preceded the development of cerebral edema. Venous outflow restriction appeared to play a contributory role in the formation of cerebral edema, a novel feature that has not been observed previously.
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Affiliation(s)
- Ravjit S Sagoo
- Department of Imaging, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK
| | - Charles E Hutchinson
- Department of Imaging, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK.,Warwick Medical School, University of Warwick, Coventry, West Midlands, UK
| | - Alex Wright
- College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Charles Handford
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Helen Parsons
- Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, West Midlands, UK
| | - Victoria Sherwood
- Department of Medical Physics, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK
| | - Sarah Wayte
- Department of Medical Physics, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK
| | - Sanjoy Nagaraja
- Department of Imaging, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK
| | - Eddie Ng'Andwe
- Department of Imaging, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK
| | - Mark H Wilson
- Department of Neurosurgery, Imperial College Healthcare NHS Trust, London, UK
| | - Christopher He Imray
- Warwick Medical School, University of Warwick, Coventry, West Midlands, UK .,Department of Surgery, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, West Midlands, UK.,Coventry University, West Midlands, UK
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26
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Brain injury after moderate drowning: subtle alterations detected by functional magnetic resonance imaging. Brain Imaging Behav 2016; 11:1412-1421. [DOI: 10.1007/s11682-016-9619-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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27
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Lawley JS, Macdonald JH, Oliver SJ, Mullins PG. Unexpected reductions in regional cerebral perfusion during prolonged hypoxia. J Physiol 2016; 595:935-947. [PMID: 27506309 DOI: 10.1113/jp272557] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/04/2016] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Cognitive performance is impaired by hypoxia despite global cerebral oxygen delivery and metabolism being maintained. Using arterial spin labelled (ASL) magnetic resonance imaging, this is the first study to show regional reductions in cerebral blood flow (CBF) in response to decreased oxygen supply (hypoxia) at 2 h that increased in area and became more pronounced at 10 h. Reductions in CBF were seen in brain regions typically associated with the 'default mode' or 'task negative' network. Regional reductions in CBF, and associated vasoconstriction, within the default mode network in hypoxia is supported by increased vasodilatation in these regions to a subsequent hypercapnic (5% CO2 ) challenge. These results suggest an anatomical mechanism through which hypoxia may cause previously reported deficits in cognitive performance. ABSTRACT Hypoxia causes an increase in global cerebral blood flow, which maintains global cerebral oxygen delivery and metabolism. However, neurological deficits are abundant under hypoxic conditions. We investigated regional cerebral microvascular responses to acute (2 h) and prolonged (10 h) poikilocapnic normobaric hypoxia. We found that 2 h of hypoxia caused an expected increase in frontal cortical grey matter perfusion but unexpected perfusion decreases in regions of the brain normally associated with the 'default mode' or 'task negative' network. After 10 h in hypoxia, decreased blood flow to the major nodes of the default mode network became more pronounced and widespread. The use of a hypercapnic challenge (5% CO2 ) confirmed that these reductions in cerebral blood flow from hypoxia were related to vasoconstriction. Our findings demonstrate steady-state deactivation of the default network under acute hypoxia, which become more pronounced over time. Moreover, these data provide a unique insight into the nuanced localized cerebrovascular response to hypoxia that is not attainable through traditional methods. The observation of reduced perfusion in the posterior cingulate and cuneal cortex, which are regions assumed to play a role in declarative and procedural memory, provides an anatomical mechanism through which hypoxia may cause deficits in working memory.
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Affiliation(s)
- Justin S Lawley
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Gwynedd, UK.,Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX, USA
| | - Jamie H Macdonald
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Gwynedd, UK
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Gwynedd, UK
| | - Paul G Mullins
- Bangor Imaging Centre, School of Psychology, Bangor University, Gwynedd, UK
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Verges S, Rupp T, Villien M, Lamalle L, Troprés I, Poquet C, Warnking JM, Estève F, Bouzat P, Krainik A. Multiparametric Magnetic Resonance Investigation of Brain Adaptations to 6 Days at 4350 m. Front Physiol 2016; 7:393. [PMID: 27660613 PMCID: PMC5014870 DOI: 10.3389/fphys.2016.00393] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/23/2016] [Indexed: 11/26/2022] Open
Abstract
Objective: Hypoxic exposure in healthy subjects can induce acute mountain sickness including headache, lethargy, cerebral dysfunction, and substantial cerebral structural alterations which, in worst case, can lead to potentially fatal high altitude cerebral edema. Within this context, the relationships between high altitude-induced cerebral edema, changes in cerebral perfusion, increased brain parenchyma volume, increased intracranial pressure, and symptoms remain unclear. Methods: In 11 subjects before and after 6 days at 4350 m, we performed multiparametric magnetic resonance investigations including anatomical, apparent diffusion coefficient and arterial spin labeling sequences. Results: After the altitude stay, while subjects were asymptomatic, white matter volume (+0.7 ± 0.4%, p = 0.005), diffusion (+1.7 ± 1.4%, p = 0.002), and cerebral blood flow (+28 ± 38%; p = 0.036) were significantly increased while cerebrospinal fluid volume was reduced (−1.4 ± 1.1%, p = 0.009). Optic nerve sheath diameter (used as an index of increased intracranial pressure) was unchanged from before (5.84 ± 0.53 mm) to after (5.92 ± 0.60 mm, p = 0.390) altitude exposure. Correlations were observed between increases in white matter volume and diffusion (rho = 0.81, p = 0.016) and between changes in CSF volume and changes in ONSD s (rho = −0.92, p = 0.006) and symptoms during the altitude stay (rho = −0.67, p = 0.031). Conclusions: These data demonstrate white matter alterations after several days at high altitude when subjects are asymptomatic that may represent the normal brain response to prolonged high altitude exposure.
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Affiliation(s)
- Samuel Verges
- HP2 Laboratory, Université Grenoble AlpesGrenoble, France; U1042, Institut National de la Santé et de la Recherche MédicaleGrenoble, France
| | - Thomas Rupp
- HP2 Laboratory, Université Grenoble AlpesGrenoble, France; U1042, Institut National de la Santé et de la Recherche MédicaleGrenoble, France; Inter-Universitary Laboratory of Human Movement Biology, Université Savoie Mont BlancChambéry, France
| | - Marjorie Villien
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
| | - Laurent Lamalle
- U836, Institut National de la Santé et de la Recherche Médicale Grenoble, France
| | - Irène Troprés
- U836, Institut National de la Santé et de la Recherche Médicale Grenoble, France
| | - Camille Poquet
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
| | - Jan M Warnking
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
| | - François Estève
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
| | - Pierre Bouzat
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
| | - Alexandre Krainik
- Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France
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29
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Imray C. Lessons from altitude: cerebral perfusion insights and their potential translational clinical significance. Exp Physiol 2016; 101:1167-1172. [PMID: 27061345 DOI: 10.1113/ep085813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/30/2016] [Indexed: 01/28/2023]
Abstract
What is the topic of this review? The long-held assumption that transcranial Doppler middle cerebral artery velocity is a surrogate for cerebral blood flow has been questioned in certain circumstances, particularly where tissue oxygenation changes. What advances does it highlight? Cerebral venous outflow restriction appears to be implicated in the development of high-altitude cerebral oedema. Rapid ascent to high altitude commonly results in acute mountain sickness and, on occasion, potentially fatal high-altitude cerebral oedema. The exact pathophysiological mechanisms behind these syndromes remain to be determined. One of the main theories to explain the development of acute mountain sickness is an increase in intracranial pressure. Vasogenic (extracellular water accumulation attributable to increased permeability of the blood-brain barrier) and cytotoxic (intracellular) oedema have also been postulated as potential mechanisms that underlie high-altitude cerebral oedema. Recently published findings derived from a very challenging field study (obtained at altitudes of up to 7950 m), substantiated by sea-level hypoxic magnetic resonance angiography studies, have given new insights into the maintenance of cerebral blood flow at altitude. This report provides new perspectives and potential mechanisms to account for the maintenance of cerebral oxygen delivery at high and extreme altitude. In particular, the long-held assumption that transcranial Doppler middle cerebral artery velocity is a surrogate for cerebral blood flow has been shown to be incorrect in certain circumstances. The emerging evidence for a potential third mechanism, namely the restrictive venous outflow hypothesis, in the development of high-altitude cerebral oedema, over and above the accepted vasogenic and cytotoxic hypotheses, is also appraised.
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Affiliation(s)
- Chris Imray
- Department of Vascular Surgery, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK.,Warwick Medical School, Warwick University, Coventry, UK.,Coventry University, Coventry, UK
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30
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Strapazzon G, Malacrida S, Vezzoli A, Dal Cappello T, Falla M, Lochner P, Moretti S, Procter E, Brugger H, Mrakic-Sposta S. Oxidative stress response to acute hypobaric hypoxia and its association with indirect measurement of increased intracranial pressure: a field study. Sci Rep 2016; 6:32426. [PMID: 27579527 PMCID: PMC5006564 DOI: 10.1038/srep32426] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/03/2016] [Indexed: 12/28/2022] Open
Abstract
High altitude is the most intriguing natural laboratory to study human physiological response to hypoxic conditions. In this study, we investigated changes in reactive oxygen species (ROS) and oxidative stress biomarkers during exposure to hypobaric hypoxia in 16 lowlanders. Moreover, we looked at the potential relationship between ROS related cellular damage and optic nerve sheath diameter (ONSD) as an indirect measurement of intracranial pressure. Baseline measurement of clinical signs and symptoms, biological samples and ultrasonography were assessed at 262 m and after passive ascent to 3830 m (9, 24 and 72 h). After 24 h the imbalance between ROS production (+141%) and scavenging (−41%) reflected an increase in oxidative stress related damage of 50–85%. ONSD concurrently increased, but regression analysis did not infer a causal relationship between oxidative stress biomarkers and changes in ONSD. These results provide new insight regarding ROS homeostasis and potential pathophysiological mechanisms of acute exposure to hypobaric hypoxia, plus other disease states associated with oxidative-stress damage as a result of tissue hypoxia.
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Affiliation(s)
| | - Sandro Malacrida
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Alessandra Vezzoli
- CNR Institute of Bioimaging and Molecular Physiology, Segrate (Milano), Italy
| | | | - Marika Falla
- Department of Neurology, General Hospital of Bolzano, Bolzano, Italy.,Department of Neurology and Psychiatry, Sapienza University, Roma, Italy
| | | | - Sarah Moretti
- CNR Institute of Bioimaging and Molecular Physiology, Segrate (Milano), Italy
| | - Emily Procter
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
| | - Hermann Brugger
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
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31
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Robba C, Bacigaluppi S, Cardim D, Donnelly J, Bertuccio A, Czosnyka M. Non-invasive assessment of intracranial pressure. Acta Neurol Scand 2016; 134:4-21. [PMID: 26515159 DOI: 10.1111/ane.12527] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2015] [Indexed: 11/29/2022]
Abstract
Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.
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Affiliation(s)
- C. Robba
- Neurosciences Critical Care Unit; Addenbrooke's Hospital; Cambridge United Kingdom
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - S. Bacigaluppi
- Department of Neurosurgery; Galliera Hospital; Genova Italy
| | - D. Cardim
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - J. Donnelly
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
| | - A. Bertuccio
- Department of Neurosurgery; S. George's Hospital; University of London; United Kingdom
| | - M. Czosnyka
- Brain Physics Lab; Division of Neurosurgery; Department of Clinical Neurosciences; University of Cambridge; United Kingdom
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32
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Lawley JS, Levine BD, Williams MA, Malm J, Eklund A, Polaner DM, Subudhi AW, Hackett PH, Roach RC. Cerebral spinal fluid dynamics: effect of hypoxia and implications for high-altitude illness. J Appl Physiol (1985) 2016; 120:251-62. [DOI: 10.1152/japplphysiol.00370.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/17/2015] [Indexed: 12/24/2022] Open
Abstract
The pathophysiology of acute mountain sickness and high-altitude cerebral edema, the cerebral forms of high-altitude illness, remain uncertain and controversial. Persistently elevated or pathological fluctuations in intracranial pressure are thought to cause symptoms similar to those reported by individuals suffering cerebral forms of high-altitude illness. This review first focuses on the basic physiology of the craniospinal system, including a detailed discussion of the long-term and dynamic regulation of intracranial pressure. Thereafter, we critically examine the available literature, based primarily on invasive pressure monitoring, that suggests intracranial pressure is acutely elevated at altitude due to brain swelling and/or elevated sagittal sinus pressure, but normalizes over time. We hypothesize that fluctuations in intracranial pressure occur around a slightly elevated or normal mean intracranial pressure, in conjunction with oscillations in arterial Po2 and arterial blood pressure. Then these modest fluctuations in intracranial pressure, in concert with direct vascular stretch due to dilatation and/or increased blood pressure transmission, activate the trigeminal vascular system and cause symptoms of acute mountain sickness. Elevated brain water (vasogenic edema) may be due to breakdown of the blood-brain barrier. However, new information suggests cerebral spinal fluid flux into the brain may be an important factor. Regardless of the source (or mechanisms responsible) for the excess brain water, brain swelling occurs, and a “tight fit” brain would be a major risk factor to produce symptoms; activities that produce large changes in brain volume and cause fluctuations in blood pressure are likely contributing factors.
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Affiliation(s)
- Justin S. Lawley
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas
- UT Southwestern Medical Center, Dallas, Texas
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas
- UT Southwestern Medical Center, Dallas, Texas
| | - Michael A. Williams
- Sandra and Malcolm Berman Brain & Spine Institute, Dept. of Neurology, Sinai Hospital, Baltimore, Maryland
| | - Jon Malm
- Department of Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - David M. Polaner
- Departments of Anesthesiology and Pediatrics, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, Colorado
| | - Andrew W. Subudhi
- Department of Biology, University of Colorado, Colorado Springs, Colorado
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | | | - Robert C. Roach
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
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Alperin N, Loftus JR, Oliu CJ, Bagci AM, Lee SH, Ertl-Wagner B, Sekula R, Lichtor T, Green BA. Imaging-Based Features of Headaches in Chiari Malformation Type I. Neurosurgery 2016; 77:96-103; discussion 103. [PMID: 25812067 DOI: 10.1227/neu.0000000000000740] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Suboccipital cough-induced headaches are considered a hallmark symptom of Chiari malformation type I (CMI). However, non--Valsalva-related suboccipital headaches and headaches in other locations are also common in CMI. The diagnostic significance and the underlying factors associated with these different headaches types are not well understood. OBJECTIVE To compare cranial morphology and hydrodynamics in 3 types of headaches in CMI to better understand the pathophysiological basis for the different headache characteristics. METHODS Twenty-two cranial physiological and morphological measures were obtained with specialized magnetic resonance imaging scans from 63 symptomatic pretreated CMI patients, 40 with suboccipital headaches induced by Valsalva maneuvers (34 women; age, 36 ± 10 years), 15 with non--Valsalva-related suboccipital headaches (10 women; age, 33 ± 9 years), 8 with nonsuboccipital non--Valsalva-induced headaches (8 women; age, 39 ± 13 years), and 37 control subjects (24 women; age, 36 ± 12 years). Group differences were identified with the use of the 2-tailed Student t test. RESULTS Posterior cranial fossa markers of CMI were similar among the 3 headache subtypes. However, the Valsalva-related suboccipital headaches cohort demonstrated a significantly lower intracranial compliance index than the non--Valsalva-related suboccipital headaches cohort (7.5 ± 3.4 vs 10.9 ± 4.9), lower intracranial volume change during the cardiac cycle (0.48 ± 0.19 vs 0.61 ± 0.16 mL), and higher magnetic resonance imaging--derived intracranial pressure (11.1 ± 4.3 vs 7.7 ± 2.8 mm Hg; P = .02). The Valsalva-related suboccipital headaches cohort had smaller intracranial and lateral ventricular volumes compared with the healthy cohort. The non--Valsalva-related suboccipital headaches cohort had reduced venous drainage through the jugular veins. CONCLUSION Valsalva-induced worsening of occipital headaches appears to be related to a small intracranial volume rather than the smaller posterior cranial fossa. This explains the reduced intracranial compliance and corresponding higher pressure measured in CMI patients with headaches affected by Valsalva maneuvers.
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Affiliation(s)
- Noam Alperin
- *Department of Radiology and ‖Department of Neurological Surgery, University of Miami, Miami, Florida; ‡Institute of Clinical Radiology, Ludwig-Maximilian University, Munich, Germany; §Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania; ¶Department of Neurosurgery, Rush University, Chicago, Illinois
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Guo C, Xu J, Wang M, Yan T, Yang L, Sun Z. Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 13:ijerph13010064. [PMID: 26703703 PMCID: PMC4730455 DOI: 10.3390/ijerph13010064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/11/2015] [Accepted: 12/16/2015] [Indexed: 11/16/2022]
Abstract
The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO₂. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.
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Affiliation(s)
- Chun Guo
- Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
| | - Jianfeng Xu
- Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
| | - Mingnian Wang
- Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
| | - Tao Yan
- Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
| | - Lu Yang
- College of Foreign Languages, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
| | - Zhitao Sun
- Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, 610031 Chengdu, China.
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Shah NM, Hussain S, Cooke M, O’Hara JP, Mellor A. Wilderness medicine at high altitude: recent developments in the field. Open Access J Sports Med 2015; 6:319-28. [PMID: 26445563 PMCID: PMC4590685 DOI: 10.2147/oajsm.s89856] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Travel to high altitude is increasingly popular. With this comes an increased incidence of high-altitude illness and therefore an increased need to improve our strategies to prevent and accurately diagnose these. In this review, we provide a summary of recent advances of relevance to practitioners who may be advising travelers to altitude. Although the Lake Louise Score is now widely used as a diagnostic tool for acute mountain sickness (AMS), increasing evidence questions the validity of doing so, and of considering AMS as a single condition. Biomarkers, such as brain natriuretic peptide, are likely correlating with pulmonary artery systolic pressure, thus potential markers of the development of altitude illness. Established drug treatments include acetazolamide, nifedipine, and dexamethasone. Drugs with a potential to reduce the risk of developing AMS include nitrate supplements, propagators of nitric oxide, and supplemental iron. The role of exercise in the development of altitude illness remains hotly debated, and it appears that the intensity of exercise is more important than the exercise itself. Finally, despite copious studies demonstrating the value of preacclimatization in reducing the risk of altitude illness and improving performance, an optimal protocol to preacclimatize an individual remains elusive.
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Affiliation(s)
- Neeraj M Shah
- Division of Asthma, Allergy and Lung Biology, King’s College London, UK
| | - Sidra Hussain
- School of Medicine, University College London, London, UK
| | - Mark Cooke
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
| | - John P O’Hara
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
| | - Adrian Mellor
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
- Academic Department of Military Anaesthesia and Critical Care, Royal Centre for Defence Medicine, Birmingham, UK
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Lochner P, Falla M, Brigo F, Pohl M, Strapazzon G. Ultrasonography of the Optic Nerve Sheath Diameter for Diagnosis and Monitoring of Acute Mountain Sickness: A Systematic Review. High Alt Med Biol 2015; 16:195-203. [DOI: 10.1089/ham.2014.1127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Piergiorgio Lochner
- Department of Neurology, General Hospital of Merano, Merano, Italy
- Department of Neurology, University A. Avogadro, Novara, Italy
| | - Marika Falla
- Department of Neurology and Psychiatry, Sapienza University, Roma, Italy
- Department of Neurology, General Hospital of Bolzano, Bolzano, Italy
| | - Francesco Brigo
- Department of Neurology, General Hospital of Merano, Merano, Italy
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - Michael Pohl
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
- Landeskrankenhaus Bregenz, Austria
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Wilson MH, Imray CHE. The cerebral venous system and hypoxia. J Appl Physiol (1985) 2015; 120:244-50. [PMID: 26294747 DOI: 10.1152/japplphysiol.00327.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/13/2015] [Indexed: 01/24/2023] Open
Abstract
Most hypobaric hypoxia studies have focused on oxygen delivery and therefore cerebral blood inflow. Few have studied venous outflow. However, the volume of blood entering and leaving the skull (∼700 ml/min) is considerably greater than cerebrospinal fluid production (0.35 ml/min) or edema formation rates and slight imbalances of in- and outflow have considerable effects on intracranial pressure. This dynamic phenomenon is not necessarily appreciated in the currently taught static "Monro-Kellie" doctrine, which forms the basis of the "Tight-Fit" hypothesis thought to underlie high altitude headache, acute mountain sickness, and high altitude cerebral edema. Investigating both sides of the cerebral circulation was an integral part of the 2007 Xtreme Everest Expedition. The results of the relevant studies performed as part of and subsequent to this expedition are reviewed here. The evidence from recent studies suggests a relative venous outflow insufficiency is an early step in the pathogenesis of high altitude headache. Translation of knowledge gained from high altitude studies is important. Many patients in a critical care environment develop hypoxemia akin to that of high altitude exposure. An inability to drain the hypoxemic induced increase in cerebral blood flow could be an underappreciated regulatory mechanism of intracranial pressure.
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Affiliation(s)
- Mark H Wilson
- The Centre for Altitude, Space and Extreme Environment Medicine, University College London, London, United Kingdom; The Birmingham Medical Research Expeditionary Society, Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom; Imperial Neurotrauma Centre, Imperial College, St Mary's Hospital, London, United Kingdom; Institute of Pre-Hospital Care, London's Air Ambulance, Royal London Hospital, Whitechapel, United Kingdom; and
| | - Christopher H E Imray
- The Centre for Altitude, Space and Extreme Environment Medicine, University College London, London, United Kingdom; The Birmingham Medical Research Expeditionary Society, Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom; Department of Surgery, Warwick Medical School, UHCW NHS Trust, Warwick, United Kingdom
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Kayser B. The International Hypoxia Symposium 2015 in Lake Louise: A Report. High Alt Med Biol 2015; 16:261-6. [PMID: 25955961 DOI: 10.1089/ham.2015.0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Bengt Kayser
- Institute of Sports Sciences of the University of Lausanne and Department of Physiology of the Faculty of Biology and Medicine , Lausanne, Switzerland
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Lu H, Wang R, Xiong J, Xie H, Kayser B, Jia Z. In search for better pharmacological prophylaxis for acute mountain sickness: looking in other directions. Acta Physiol (Oxf) 2015; 214:51-62. [PMID: 25778288 DOI: 10.1111/apha.12490] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 02/23/2015] [Accepted: 03/11/2015] [Indexed: 12/15/2022]
Abstract
Despite decades of research, the exact pathogenic mechanisms underlying acute mountain sickness (AMS) are still poorly understood. This fact frustrates the search for novel pharmacological prophylaxis for AMS. The prevailing view is that AMS results from an insufficient physiological response to hypoxia and that prophylaxis should aim at stimulating the response. Starting off from the opposite hypothesis that AMS may be caused by an initial excessive response to hypoxia, we suggest that directly or indirectly blunting-specific parts of the response might provide promising research alternatives. This reasoning is based on the observations that (i) humans, once acclimatized, can climb Mt Everest experiencing arterial partial oxygen pressures (PaO2) as low as 25 mmHg without AMS symptoms; (ii) paradoxically, AMS usually develops at much higher PaO2 levels; and (iii) several biomarkers, suggesting initial activation of specific pathways at such PaO2, are correlated with AMS. Apart from looking for substances that stimulate certain hypoxia triggered effects, such as the ventilatory response to hypoxia, we suggest to also investigate pharmacological means aiming at blunting certain other specific hypoxia-activated pathways, or stimulating their agonists, in the quest for better pharmacological prophylaxis for AMS.
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Affiliation(s)
- H. Lu
- Key Laboratory of the Plateau of Environmental Damage Control; Lanzhou General Hospital of Lanzhou Military Command; Lanzhou China
| | - R. Wang
- Key Laboratory of the Plateau of Environmental Damage Control; Lanzhou General Hospital of Lanzhou Military Command; Lanzhou China
| | - J. Xiong
- Key Laboratory of the Plateau of Environmental Damage Control; Lanzhou General Hospital of Lanzhou Military Command; Lanzhou China
| | - H. Xie
- Key Laboratory of the Plateau of Environmental Damage Control; Lanzhou General Hospital of Lanzhou Military Command; Lanzhou China
| | - B. Kayser
- Institute of Sports Sciences and Department of Physiology; University of Lausanne; Lausanne Switzerland
| | - Z.P. Jia
- Key Laboratory of the Plateau of Environmental Damage Control; Lanzhou General Hospital of Lanzhou Military Command; Lanzhou China
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Alperin N, Lee SH, Bagci AM. MRI measurements of intracranial pressure in the upright posture: The effect of the hydrostatic pressure gradient. J Magn Reson Imaging 2015; 42:1158-63. [DOI: 10.1002/jmri.24882] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 02/19/2015] [Accepted: 02/20/2015] [Indexed: 11/11/2022] Open
Affiliation(s)
- Noam Alperin
- Department of Radiology; University of Miami; Miami Florida USA
| | - Sang H. Lee
- Department of Radiology; University of Miami; Miami Florida USA
| | - Ahmet M. Bagci
- Department of Radiology; University of Miami; Miami Florida USA
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41
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Sightings edited by Erik Swenson and Peter Bärtsch. High Alt Med Biol 2014. [DOI: 10.1089/ham.2014.1543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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