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Peter H Hackett - One of the best experts on this subject based on the ideXlab platform.
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Cerebral spinal fluid dynamics effect of hypoxia and implications for high altitude illness
Journal of Applied Physiology, 2016Co-Authors: Peter H Hackett, Justin S Lawley, Benjamin D Levine, Michael A Williams, Jan Malm, Anders Eklund, David M Polaner, Andrew W Subudhi, Robert C RoachAbstract: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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wilderness medical society practice guidelines for the prevention and treatment of acute altitude illness 2014 update
Wilderness & Environmental Medicine, 2014Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best preventive and therapeutic practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude Cerebral Edema, and high altitude pulmonary Edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each form of acute altitude illness that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2010 and subsequently updated as the WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness in 2014.
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wilderness medical society practice guidelines for the prevention and treatment of acute altitude illness 2014 update
Wilderness & Environmental Medicine, 2014Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude Cerebral Edema, and high altitude pulmonary Edema. These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations about their role in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each disorder that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine 2010;21(2):146–155.
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wilderness medical society consensus guidelines for the prevention and treatment of acute altitude illness
Wilderness & Environmental Medicine, 2010Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the prevention and treatment of acute mountain sickness (AMS), high altitude Cerebral Edema (HACE), and high altitude pulmonary Edema (HAPE). These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations for their roles in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to the prevention and management of each disorder that incorporate these recommendations.
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high altitude Cerebral Edema
High Altitude Medicine & Biology, 2004Co-Authors: Peter H Hackett, Robert C RoachAbstract:This review focuses on the epidemiology, clinical description, pathophysiology, treatment, and prevention of high altitude Cerebral Edema (HACE). HACE is an uncommon and sometimes fatal complication of traveling too high, too fast to high altitudes. HACE is distinguished by disturbances of consciousness that may progress to deep coma, psychiatric changes of varying degree, confusion, and ataxia of gait. It is most often a complication of acute mountain sickness or high altitude pulmonary Edema. The current leading theory of its pathophysiology is that HACE is a vasogenic Edema; that is, a disruption of the blood–brain barrier, and we review possible mechanisms to explain this. Treatment and prevention of HACE are similar to those for the other altitude illnesses, but with greater emphasis on descent and steroids. We conclude the review with several case histories to illustrate key clinical features of the disorder.
Peter Bartsch - One of the best experts on this subject based on the ideXlab platform.
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acute mountain sickness and high altitude Cerebral Edema
Therapeutische Umschau. Revue thérapeutique, 2017Co-Authors: Christoph Dehnert, Peter BartschAbstract:Zusammenfassung. Wenn unakklimatisierte Personen zu schnell in grosse Hohen aufsteigen, drohen hohenbedingte Erkrankungen wie akute Bergkrankheit (ABK), Hohenhirnodem (HHO) oder Hohenlungenodem (HL...
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the pattern of brain microhemorrhages after severe lung failure resembles the one seen in high altitude Cerebral Edema
Critical Care Medicine, 2015Co-Authors: Sebastian Riech, Kai Kallenberg, Peter Bartsch, Onnen Moerer, Peter Hellen, Michael Quintel, Michael KnauthAbstract:OBJECTIVES: After suffering from severe acute respiratory distress syndrome, several patients show generalized brain alterations and atrophy. A distinctive morphologic pattern of Cerebral injury, however, has not been found so far. DATA SOURCES: We present the history of three patients who survived severe acute respiratory distress syndrome. In these patients, MRI of the brain showed multiple microhemorrhages predominantly in the splenium of the corpus callosum. An identical pattern of microhemorrhages has previously been described in mountaineers who suffered from High-Altitude Cerebral Edema. CONCLUSIONS: This report demonstrates that patients after treatment for acute respiratory distress syndrome and High-Altitude Cerebral Edema show congruent Cerebral injuries. Further investigation into the similarities of the causative conditions and neurologic consequences might reveal underlying pathophysiologic mechanisms and clinical implications of this observation.
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hemosiderin deposition in the brain as footprint of high altitude Cerebral Edema
Neurology, 2013Co-Authors: Kai Schommer, Kai Kallenberg, Peter Bartsch, Kira Lutz, Michael KnauthAbstract:Objective: Based on recent findings of microhemorrhages (MHs) in the corpus callosum (CC) in 3 individuals after nonfatal High-Altitude Cerebral Edema (HACE), we hypothesized that hemosiderin depositions in the brain after High-Altitude exposure are specific for HACE and remain detectable over many years. Methods: This was a cross-sectional study involving 37 mountaineers in 4 groups: 10 had experienced HACE, 8 High-Altitude pulmonary Edema, 11 severe acute mountain sickness, and 8 had climbed to altitudes ≥6,962 m without developing any High-Altitude illness. HACE was defined as ataxia necessitating assistance with walking and/or decreased consciousness. Within Results: Unequivocal MHs located in the splenium of the CC were found in 8 subjects and questionable MHs were found in 2 subjects 1 to 35 months after HACE. They were located outside the CC in 5 more severe cases. MHs remained unchanged in those reexamined after 12 to 50 months. A few unequivocal MHs in the splenium of the CC were found in one subject after severe acute mountain sickness, while one subject with High-Altitude pulmonary Edema and 2 of the extreme altitude climbers had questionable lesions. In all other subjects, MHs were unequivocally absent. Conclusions: MHs detectable by susceptibility-weighted MRI predominantly in the splenium of the CC are long-lasting footprints of HACE.
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emerging concepts in acute mountain sickness and high altitude Cerebral Edema from the molecular to the morphological
Cellular and Molecular Life Sciences, 2009Co-Authors: Damian M Bailey, Michael Knauth, Peter Bartsch, Ralf W BaumgartnerAbstract:Acute mountain sickness (AMS) is a neurological disorder that typically affects mountaineers who ascend to high altitude. The symptoms have traditionally been ascribed to intracranial hypertension caused by extracellular vasogenic Edematous brain swelling subsequent to mechanical disruption of the blood–brain barrier in hypoxia. However, recent diffusion-weighted magnetic resonance imaging studies have identified mild astrocytic swelling caused by a net redistribution of fluid from the “hypoxia-primed” extracellular space to the intracellular space without any evidence for further barrier disruption or additional increment in brain Edema, swelling or pressure. These findings and the observation of minor vasogenic Edema present in individuals with and without AMS suggest that the symptoms are not explained by Cerebral Edema. This has led to a re-evaluation of the relevant pathogenic events with a specific focus on free radicals and their interaction with the trigeminovascular system. (Part of a multi-author review.)
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microhemorrhages in nonfatal high altitude Cerebral Edema
Journal of Cerebral Blood Flow and Metabolism, 2008Co-Authors: Kai Kallenberg, Damian M Bailey, Christoph Dehnert, Arnd Dorfler, Peter D Schellinger, Michael Knauth, Peter BartschAbstract:Vasogenic Edema in the corpus callosum is a characteristic finding in High-Altitude Cerebral Edema (HACE). Furthermore, microhemorrhages have been found at autopsies in brains of HACE victims. The objective of this study was to determine if microhemorrhages also occur in nonlethal HACE. Consequently, magnetic resonance imaging (MRI) was performed in patients who had suffered from HACE and in patients who had suffered from severe acute mountain sickness (AMS) by applying imaging techniques highly susceptible to blood or blood remnants. Two experienced neuroradiologists independently evaluated the exams blinded to clinical data. The MRI was performed 2 to 31 months after the event. The MRI of the HACE patients revealed multiple hemosiderin depositions in the brain—predominantly found in the corpus callosum—indicative of microhemorrhages. These changes were not present in the three AMS patients. In summary, hemosiderin deposits detectable by MRI predominantly in the corpus callosum indicate that microhemorrhages occur in nonlethal
Michael Knauth - One of the best experts on this subject based on the ideXlab platform.
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the pattern of brain microhemorrhages after severe lung failure resembles the one seen in high altitude Cerebral Edema
Critical Care Medicine, 2015Co-Authors: Sebastian Riech, Kai Kallenberg, Peter Bartsch, Onnen Moerer, Peter Hellen, Michael Quintel, Michael KnauthAbstract:OBJECTIVES: After suffering from severe acute respiratory distress syndrome, several patients show generalized brain alterations and atrophy. A distinctive morphologic pattern of Cerebral injury, however, has not been found so far. DATA SOURCES: We present the history of three patients who survived severe acute respiratory distress syndrome. In these patients, MRI of the brain showed multiple microhemorrhages predominantly in the splenium of the corpus callosum. An identical pattern of microhemorrhages has previously been described in mountaineers who suffered from High-Altitude Cerebral Edema. CONCLUSIONS: This report demonstrates that patients after treatment for acute respiratory distress syndrome and High-Altitude Cerebral Edema show congruent Cerebral injuries. Further investigation into the similarities of the causative conditions and neurologic consequences might reveal underlying pathophysiologic mechanisms and clinical implications of this observation.
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hemosiderin deposition in the brain as footprint of high altitude Cerebral Edema
Neurology, 2013Co-Authors: Kai Schommer, Kai Kallenberg, Peter Bartsch, Kira Lutz, Michael KnauthAbstract:Objective: Based on recent findings of microhemorrhages (MHs) in the corpus callosum (CC) in 3 individuals after nonfatal High-Altitude Cerebral Edema (HACE), we hypothesized that hemosiderin depositions in the brain after High-Altitude exposure are specific for HACE and remain detectable over many years. Methods: This was a cross-sectional study involving 37 mountaineers in 4 groups: 10 had experienced HACE, 8 High-Altitude pulmonary Edema, 11 severe acute mountain sickness, and 8 had climbed to altitudes ≥6,962 m without developing any High-Altitude illness. HACE was defined as ataxia necessitating assistance with walking and/or decreased consciousness. Within Results: Unequivocal MHs located in the splenium of the CC were found in 8 subjects and questionable MHs were found in 2 subjects 1 to 35 months after HACE. They were located outside the CC in 5 more severe cases. MHs remained unchanged in those reexamined after 12 to 50 months. A few unequivocal MHs in the splenium of the CC were found in one subject after severe acute mountain sickness, while one subject with High-Altitude pulmonary Edema and 2 of the extreme altitude climbers had questionable lesions. In all other subjects, MHs were unequivocally absent. Conclusions: MHs detectable by susceptibility-weighted MRI predominantly in the splenium of the CC are long-lasting footprints of HACE.
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emerging concepts in acute mountain sickness and high altitude Cerebral Edema from the molecular to the morphological
Cellular and Molecular Life Sciences, 2009Co-Authors: Damian M Bailey, Michael Knauth, Peter Bartsch, Ralf W BaumgartnerAbstract:Acute mountain sickness (AMS) is a neurological disorder that typically affects mountaineers who ascend to high altitude. The symptoms have traditionally been ascribed to intracranial hypertension caused by extracellular vasogenic Edematous brain swelling subsequent to mechanical disruption of the blood–brain barrier in hypoxia. However, recent diffusion-weighted magnetic resonance imaging studies have identified mild astrocytic swelling caused by a net redistribution of fluid from the “hypoxia-primed” extracellular space to the intracellular space without any evidence for further barrier disruption or additional increment in brain Edema, swelling or pressure. These findings and the observation of minor vasogenic Edema present in individuals with and without AMS suggest that the symptoms are not explained by Cerebral Edema. This has led to a re-evaluation of the relevant pathogenic events with a specific focus on free radicals and their interaction with the trigeminovascular system. (Part of a multi-author review.)
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microhemorrhages in nonfatal high altitude Cerebral Edema
Journal of Cerebral Blood Flow and Metabolism, 2008Co-Authors: Kai Kallenberg, Damian M Bailey, Christoph Dehnert, Arnd Dorfler, Peter D Schellinger, Michael Knauth, Peter BartschAbstract:Vasogenic Edema in the corpus callosum is a characteristic finding in High-Altitude Cerebral Edema (HACE). Furthermore, microhemorrhages have been found at autopsies in brains of HACE victims. The objective of this study was to determine if microhemorrhages also occur in nonlethal HACE. Consequently, magnetic resonance imaging (MRI) was performed in patients who had suffered from HACE and in patients who had suffered from severe acute mountain sickness (AMS) by applying imaging techniques highly susceptible to blood or blood remnants. Two experienced neuroradiologists independently evaluated the exams blinded to clinical data. The MRI was performed 2 to 31 months after the event. The MRI of the HACE patients revealed multiple hemosiderin depositions in the brain—predominantly found in the corpus callosum—indicative of microhemorrhages. These changes were not present in the three AMS patients. In summary, hemosiderin deposits detectable by MRI predominantly in the corpus callosum indicate that microhemorrhages occur in nonlethal
Damian M Bailey - One of the best experts on this subject based on the ideXlab platform.
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sea level assessment of dynamic Cerebral autoregulation predicts susceptibility to acute mountain sickness at high altitude
Stroke, 2011Co-Authors: Nicholas J Cochand, Kevin A Evans, Michael Wild, Julien V Brugniaux, Peter J Davies, Richard G Wise, Damian M BaileyAbstract:Background and Purpose—Dynamic Cerebral autoregulation is impaired in subjects who develop acute mountain sickness (AMS), a neurological disorder characterized by headache. The present study examined if the normoxic sea-level measurement of dynamic Cerebral autoregulation would predict subsequent susceptibility to AMS during rapid ascent to terrestrial high altitude. Methods—A dynamic Cerebral autoregulation index was determined in 18 subjects at sea level from continuous recordings of middle Cerebral artery blood flow velocity (Doppler ultrasonography) and arterial blood pressure (finger photoplethysmography) after recovery from transiently induced hypotension. Six hours after passive ascent to 3800 m (Mt Elbrus, Russia), the Lake Louise and Environmental Symptoms Cerebral Symptoms questionnaires were used to assess AMS. Results—AMS scores increased markedly at High-Altitude (Lake Louise: 32 points, P0.001 and Environmental Symptoms Cerebral Symptoms: 0.60.9 points, P0.0003 versus sea level). Inverse relationships were observed between the sea-level autoregulation index score and the High-Altitude-induced increases in the Lake Louise (r0.62, P0.007) and Environmental Symptoms Cerebral Symptoms (r0.78, P0.01) scores. One subject with a history of High-Altitude pulmonary and Cerebral Edema presented with the lowest sea-level autoregulation index score (3.7 versus group: 6.21.0 points) and later developed High-Altitude Cerebral Edema at 4800 m during the summit bid. Conclusions—These findings suggest that a lower baseline autoregulation index may be considered a potential risk factor for AMS. This laboratory measurement may prove a useful screening tool for the expedition doctor when considering targeted pharmacological prophylaxis in individuals deemed “AMS-susceptible.” (Stroke. 2011;42:3628-3630.)
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emerging concepts in acute mountain sickness and high altitude Cerebral Edema from the molecular to the morphological
Cellular and Molecular Life Sciences, 2009Co-Authors: Damian M Bailey, Michael Knauth, Peter Bartsch, Ralf W BaumgartnerAbstract:Acute mountain sickness (AMS) is a neurological disorder that typically affects mountaineers who ascend to high altitude. The symptoms have traditionally been ascribed to intracranial hypertension caused by extracellular vasogenic Edematous brain swelling subsequent to mechanical disruption of the blood–brain barrier in hypoxia. However, recent diffusion-weighted magnetic resonance imaging studies have identified mild astrocytic swelling caused by a net redistribution of fluid from the “hypoxia-primed” extracellular space to the intracellular space without any evidence for further barrier disruption or additional increment in brain Edema, swelling or pressure. These findings and the observation of minor vasogenic Edema present in individuals with and without AMS suggest that the symptoms are not explained by Cerebral Edema. This has led to a re-evaluation of the relevant pathogenic events with a specific focus on free radicals and their interaction with the trigeminovascular system. (Part of a multi-author review.)
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microhemorrhages in nonfatal high altitude Cerebral Edema
Journal of Cerebral Blood Flow and Metabolism, 2008Co-Authors: Kai Kallenberg, Damian M Bailey, Christoph Dehnert, Arnd Dorfler, Peter D Schellinger, Michael Knauth, Peter BartschAbstract:Vasogenic Edema in the corpus callosum is a characteristic finding in High-Altitude Cerebral Edema (HACE). Furthermore, microhemorrhages have been found at autopsies in brains of HACE victims. The objective of this study was to determine if microhemorrhages also occur in nonlethal HACE. Consequently, magnetic resonance imaging (MRI) was performed in patients who had suffered from HACE and in patients who had suffered from severe acute mountain sickness (AMS) by applying imaging techniques highly susceptible to blood or blood remnants. Two experienced neuroradiologists independently evaluated the exams blinded to clinical data. The MRI was performed 2 to 31 months after the event. The MRI of the HACE patients revealed multiple hemosiderin depositions in the brain—predominantly found in the corpus callosum—indicative of microhemorrhages. These changes were not present in the three AMS patients. In summary, hemosiderin deposits detectable by MRI predominantly in the corpus callosum indicate that microhemorrhages occur in nonlethal
Ken Zafren - One of the best experts on this subject based on the ideXlab platform.
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pediatric high altitude Cerebral Edema in the nepal himalayas
Wilderness & Environmental Medicine, 2019Co-Authors: Benjamin J Church, Buddha Basnyat, Ben Mattingly, Ken ZafrenAbstract:High altitude Cerebral Edema (HACE) is a rare complication of ascent to altitudes of over 2500 m (8200 ft). We are not aware of a previously published case report of HACE in a patient under the age of 18 y. We report on 2 cases of suspected HACE in 2 patients, aged 12 and 16 y, who presented to the Manang Himalayan Rescue Association clinic at 3500 m. The 16-y-old patient presented with severe headache, vomiting, and ataxia after rapid ascent to 3800 m. The 12-y-old patient presented with severe headache, vomiting, visual disturbances, and ataxia at 4500 m, which began to resolve with descent to the clinic at 3500 m. Our cases suggest that HACE can occur in children and adolescents. Because there are no specific guidelines for treatment of acute mountain sickness or HACE in patients under the age of 18 y, we recommend treatment as for adults: oxygen, immediate descent, and dexamethasone. Simulated descent in a portable hyperbaric chamber can be used if oxygen is not available and if actual descent is not possible.
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wilderness medical society practice guidelines for the prevention and treatment of acute altitude illness 2014 update
Wilderness & Environmental Medicine, 2014Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude Cerebral Edema, and high altitude pulmonary Edema. These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations about their role in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each disorder that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine 2010;21(2):146–155.
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wilderness medical society practice guidelines for the prevention and treatment of acute altitude illness 2014 update
Wilderness & Environmental Medicine, 2014Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best preventive and therapeutic practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude Cerebral Edema, and high altitude pulmonary Edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each form of acute altitude illness that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2010 and subsequently updated as the WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness in 2014.
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wilderness medical society consensus guidelines for the prevention and treatment of acute altitude illness
Wilderness & Environmental Medicine, 2010Co-Authors: Andrew M Luks, Colin K Grissom, George W Rodway, Robert B Schoene, Paul S. Auerbach, Scott E. Mcintosh, Ken Zafren, Peter H HackettAbstract:To provide guidance to clinicians about best practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the prevention and treatment of acute mountain sickness (AMS), high altitude Cerebral Edema (HACE), and high altitude pulmonary Edema (HAPE). These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations for their roles in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to the prevention and management of each disorder that incorporate these recommendations.