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Han C, Zheng XX, Zhang WF. High altitude retinopathy: An overview and new insights. Travel Med Infect Dis 2024; 58:102689. [PMID: 38295966 DOI: 10.1016/j.tmaid.2024.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/30/2023] [Accepted: 01/15/2024] [Indexed: 02/04/2024]
Abstract
High altitude retinopathy (HAR) is a common ocular disorder that occurs on ascent to high altitude. There are many clinical symptoms, retinal vascular dilatation, retinal edema and hemorrhage are common. These usually do not or slightly affect vision; rarely, severe cases develop serious or permanent vision loss. At present, the research progress of HAR mainly focuses on hemodynamic changes, blood-retinal barrier damage, oxidative stress and inflammatory response. Although the related studies on HAR are limited, it shows that HAR still belongs to hypoxia, and hypobaric hypoxia plays an aggravating role in promoting the development of the disease. Various studies have demonstrated the correlation of HAR with acute mountain sickness (AMS) and high-altitude cerebral edema (HACE), so a deeper understanding of HAR is important. The slow ascent rates and ascent altitude are the key to preventing any altitude sickness. Research on traditional chinese medicine (TCM) and western medicine has been gradually carried out. Further exploration of the pathogenesis and prevention strategies of HAR will provide better guidance for doctors and high-altitude travelers.
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Affiliation(s)
- Cong Han
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Xing-Xing Zheng
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Wen-Fang Zhang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
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Raffa A, Raffa L, Kamal Y, Hassan T, Alaidarous K, Osaylan M, Almarzouki N. Pediatric optic nerve and globe measurements on magnetic resonance imaging: establishing norms for children. Acta Radiol 2023; 64:2162-2169. [PMID: 37097831 DOI: 10.1177/02841851231169176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
BACKGROUND Normal optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) may be beneficial for describing optic nerve pathway abnormality reflecting increased intracranial pressure. Nonetheless, magnetic resonance imaging (MRI) measurement of the normal ONSD range and its associations with clinical factors and eyeball transverse diameter (ETD) are not well established in children. PURPOSE To establish normal OND, ONSD, ETD, and OND/ONSD and ONSD/ETD measurements in children and their associations with age and sex. MATERIAL AND METHODS We evaluated and analyzed 336 brain MRI studies of children aged 0.5 months to 18 years. We measured a total of 672 optic nerves. The OND and ONSD were measured 1 cm anterior to the optic foramina and 3 mm behind the optic disc on an axial T2 sequence. RESULTS The mean OND 3 mm and 1 cm, ONSD 3 mm and 1 cm, and ETD were 0.23 ± 0.05 mm and 0.16 ± 0.04 mm, 0.53 ± 0.08 mm and 0.38 ± 0.06 mm, and 2.3 ± 0.13, respectively. Only ONSD 1 cm was independent of age (P = 0.247). ONSD 3 mm and ETD were significantly wider in boys compared to girls and significantly influenced by age (both P < 0.001). Age at scan and ETD were significantly correlated (P < 0.001). CONCLUSION We established MRI-based OND, ONSD, ETD, and ONSD/ETD and OND/ONSD ratio normative values in children, which can be helpful in pediatric populations with disease.
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Affiliation(s)
- Anas Raffa
- Department of Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Lina Raffa
- Department of Ophthalmology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
- Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Yumna Kamal
- Department of Ophthalmology, Ministry of National Guard Health Affairs, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Tasneem Hassan
- Department of Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Khadija Alaidarous
- Department of Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Majed Osaylan
- Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nawaf Almarzouki
- Department of Ophthalmology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
- Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
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Xie Y, Yang D, Huang AS, Yang Y, Han Y, Sun Y, Cao K, Wang H, Wu S, Zhu Q, Wang G, Wu T, Wang N. Retinal microvasculature is a potential biomarker for acute mountain sickness. Sci China Life Sci 2023. [PMID: 36811802 DOI: 10.1007/s11427-022-2271-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Lau T, Ahn JS, Manji R, Kim DJ. A Narrative Review of Point of Care Ultrasound Assessment of the Optic Nerve in Emergency Medicine. Life (Basel) 2023; 13:life13020531. [PMID: 36836888 PMCID: PMC9962087 DOI: 10.3390/life13020531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/05/2023] [Accepted: 02/14/2023] [Indexed: 02/17/2023] Open
Abstract
Point of care ultrasound (POCUS) of the optic nerve is easy to learn and has great diagnostic potential. Within emergency medicine, research has primarily focused on its use for the assessment of increased intracranial pressure, but many other applications exist, though the literature is heterogeneous and largely observational. This narrative review describes the principles of POCUS of the optic nerve including anatomy and scanning technique, as well as a summary of its best studied clinical applications of relevance in emergency medicine: increased intracranial pressure, idiopathic intracranial hypertension, optic neuritis, acute mountain sickness, and pediatric intracranial pressure assessment. In many of these applications, sonographic optic nerve sheath diameter (ONSD) has moderately high sensitivity and specificity, but the supporting studies are heterogeneous. Further studies should focus on standardization of the measurement of ONSD, establishment of consistent diagnostic thresholds for elevated intracranial pressure, and automation of ONSD measurement.
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Affiliation(s)
- Torey Lau
- Department of Emergency Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
- Department of Emergency Medicine, St. Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Justin S. Ahn
- Department of Emergency Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
- Department of Emergency Medicine, Royal Columbian Hospital, New Westminster, BC V3L 3W7, Canada
| | - Rahim Manji
- Department of Emergency Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
- Department of Emergency Medicine, St. Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Daniel J. Kim
- Department of Emergency Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
- Department of Emergency Medicine, Vancouver General Hospital, Vancouver, BC V5Z 1M9, Canada
- Correspondence: ; Tel.: +1-604-875-4855
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Lu CW, Huang ST, Cheng SJ, Lin CT, Hsu YC, Yao CT, Dong F, Hung CM, Kuo HC. Genomic architecture underlying morphological and physiological adaptation to high elevation in a songbird. Mol Ecol 2023; 32:2234-2251. [PMID: 36748940 DOI: 10.1111/mec.16875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/17/2023] [Accepted: 02/03/2023] [Indexed: 02/08/2023]
Abstract
Organisms often acquire physiological and morphological modifications to conquer ecological challenges when colonizing new environments which lead to their adaptive evolution. However, deciphering the genomic mechanism of ecological adaptation is difficult because ecological environments are often too complex for straightforward interpretation. Thus, we examined the adaptation of a widespread songbird-the rufous-capped babbler (Cyanoderma ruficeps)-to a relatively simple system: distinct environments across elevational gradients on the mountainous island of Taiwan. We focused on the genomic sequences of 43 birds from five populations to show that the Taiwan group split from its sister group in mainland China around 1-2 million years ago (Ma) and colonized the montane habitats of Taiwan at least twice around 0.03-0.22 Ma. The montane and lowland Taiwan populations diverged with gene flow between them, suggesting strong selection associated with different elevations. We found that the montane babblers had smaller beaks than the lowland ones, consistent with Allen's rule, and identified candidate genes-COL9A1 and SOX11-underlying the beak size changes. We also found that altitudinally divergent mutations were mostly located in noncoding regions and tended to accumulate in chromosomal inversions and autosomes. The altitudinally divergent mutations might regulate genes related to haematopoietic, metabolic, immune, auditory and vision functions, as well as cerebrum morphology and plumage development. The results reveal the genomic bases of morphological and physiological adaptation in this species to the low temperature, hypoxia and high UV light environment at high elevation. These findings improve our understanding of how ecological adaptation drives population divergence from the perspective of genomic architecture.
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Affiliation(s)
- Chia-Wei Lu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Shih-Ting Huang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Shun-Jen Cheng
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, Hualien, Taiwan
| | - Chen-Tau Lin
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Yu-Cheng Hsu
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, Hualien, Taiwan
| | - Cheng-Te Yao
- Division of Zoology, Endemic Species Research Institute, Nantou, Taiwan
| | - Feng Dong
- Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Chih-Ming Hung
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Hao-Chih Kuo
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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Benhur A, Sharma J, Karna ST, Shrivastava A, Saigal S, Waindeskar VV. Analysis of dynamic changes in optic nerve sheath diameter (ONSD) with ultrasound in post-craniotomy patients: Trends and correlation with computed tomography ONSD and Glasgow coma scale in post-operative period. J Neurosci Rural Pract 2022; 13:676-683. [PMID: 36743767 PMCID: PMC9893949 DOI: 10.25259/jnrp-2022-3-37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 09/20/2022] [Indexed: 12/05/2022] Open
Abstract
Objectives Intracranial pressure (ICP) monitoring in patients with intracranial tumors undergoing craniotomy is usually done in perioperative period in intensive care unit. Invasive measurement of ICP, though considered as the gold standard, has its own limitations such as availability of expertise, equipment, and associated complications. Period of raised ICP in post-operative period may impact patient outcomes. Post-craniotomy computed tomography (CT) assessment is done routinely and may need to be repeated if indicated during post-operative stay. Utility of sonographic serial optic nerve sheath diameter (ONSD) assessment in post-operative monitoring of patients who have undergone elective craniotomy was explored in this study. The primary objective of the study was to measure the dynamic change in ONSD as compared to baseline pre-operative measurement in the first 3 postoperative days after elective craniotomy. The secondary objective of the study was to evaluate correlation between ONSD value with Glasgow Coma Scale (GCS) and post-operative CT findings. Materials and Methods In this prospective, observational, and cohort study, we studied adult patients undergoing craniotomy for intracranial tumors. GCS assessment and sonographic measurement of ONSD were done preoperatively, immediate post-operative period, and 12, 24, and 48 h after surgery. CT scan to detect raised ICP was done at 24 h post-operative. Correlation of ONSD with GCS at respective period and correlation of CT scan finding with respective ONSD assessment were evaluated. Results A total of 57 patients underwent elective craniotomy for intracranial tumors. Significant difference was observed in ONSD value depending on time of measurement perioperatively (χ2 = 78.9, P = 0.00). There was initial increase in the first 12 h followed by decrease in ONSD in the next 48 h. Negative correlation was observed between baseline ONSD and 12 h GCS (ρ = -0.345, P = 0.013). There was significant change in GCS scores based on the status of ONSD (raised or normal) at 12 h after surgery (P = 0.014). Significant correlation between USG ONSD and CT ONSD was observed (ρ = 0.928, P = 0.000). Optimal cutoff value of ONSD to detect raised ICP with reference to CT signs was 4.8 mm with 80% sensitivity and 95% specificity. Conclusion ONSD undergoes dynamic changes, correlates with CT scan, and has good diagnostic accuracy to detect raised ICP post-craniotomy for intracranial tumors. It may serve as a useful tool in monitoring in resource-limited setup.
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Affiliation(s)
- Allan Benhur
- Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
| | - Jaiprakash Sharma
- Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
| | - Sunaina Tejpal Karna
- Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
| | - Adesh Shrivastava
- Department of Neurosurgery, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
| | - Saurabh Saigal
- Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
| | - Vaishali Vasant Waindeskar
- Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
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Yin X, Li Y, Ma Y, Xie Y, Wang K, Sun D, Liu X, Hao M, Liang M, Zhang S, Guo Y, Jin L, Wang N, Wang J. Thickened Retinal Nerve Fiber Layers Associated With High-Altitude Headache. Front Physiol 2022; 13:864222. [PMID: 35600299 PMCID: PMC9114875 DOI: 10.3389/fphys.2022.864222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose: This study aimed to quantify the different quadrants of the optic nerve head (ONH) and macular parameters and their changes during exposure to high altitude, and to assess their correlation with high-altitude headache (HAH).Methods: Spectral-domain optical coherence tomography (OCT) was used to quantify changes in the retinal structure in 109 healthy subjects during acute exposure to high altitude (3,700 m). Self-reported symptoms of HAH and acute mountain sickness AMS were assessed using Lake Louise Score (LLS), alongside measurements of physiological parameters (oxygen saturation [SpO2], heart rate [HR], hemoglobin level [Hb], and red blood cell [RBC] count). Measurements were taken before and after exposure to the high-altitude environment. The correlations of these parameters and changes at ONH were examined.Results: With the exposure to high altitude, the incidence of AMS was 44.0% and the frequency of HAH was 67.0% (54.1% mild, 12.9% moderate-severe). As for systemic parameters measured at high altitude, the participants exhibited significantly lower SpO2, higher resting HR, higher Hb, and a higher RBC (all p < 0.05). Key stereometric parameters used to describe ONH [superior, inferior, nasal, temporal, and mean retinal nerve fiber layer (RNFL) thickness] and macula (macular thickness) increased at high altitude compared with baseline. Most parameters of ONH changed, especially superior, inferior, and mean RNFL thickness (p < 0.05). There was a significant correlation between the ratios of RNFL at ONH and HAH [mean thickness (r = 0.246, p = 0.01); inferior (r = 0.216, p = 0.02); nasal (r = 0.193, p = 0.04)]. No associations between parameters of ONH and AMS or LLS were observed.Conclusion: The high-altitude environment can increase RNFL thickness at ONH. Furthermore, we found that the ratios of mean thickness, inferior area, and nasal area correlated positively with HAH, which provides new insights for understanding of the underlying pathological mechanisms of high-altitude retinopathy (HAR).
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Affiliation(s)
- Xianhong Yin
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Yi Li
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Institute for Six-Sector Economy, Fudan University, Shanghai, China
- International Human Phenome Institutes, Shanghai, China
| | - Yanyun Ma
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Institute for Six-Sector Economy, Fudan University, Shanghai, China
| | - Yuan Xie
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Kun Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Dayan Sun
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Xiaoyu Liu
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Meng Hao
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Meng Liang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Shixuan Zhang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Yuan Guo
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Li Jin
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- International Human Phenome Institutes, Shanghai, China
- Research Institute of Data Sciences, Fudan University, Shanghai, China
- Research Unit of Dissecting the Population Genetics and Developing New Technologies for Treatment and Prevention of Skin Phenotypes and Dermatological Diseases, Chinese Academy of Medical Sciences (2019RU058), Shanghai, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
| | - Ningli Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
| | - Jiucun Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Research Unit of Dissecting the Population Genetics and Developing New Technologies for Treatment and Prevention of Skin Phenotypes and Dermatological Diseases, Chinese Academy of Medical Sciences (2019RU058), Shanghai, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
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Wipplinger F, Holthof N, Lienert J, Maeder MB, Moens D. In reply to Vitiello, De Bernardo, Capasso, and Rosa. Wilderness Environ Med 2021; 32:408-409. [PMID: 34303606 DOI: 10.1016/j.wem.2021.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 05/17/2021] [Indexed: 11/17/2022]
Affiliation(s)
- Flavia Wipplinger
- Department of Anesthesiology and Pain Medicine, Inselspital Bern University Hospital, Bern, Switzerland
| | - Niels Holthof
- Department of Anesthesiology and Pain Medicine, Inselspital Bern University Hospital, Bern, Switzerland
| | - Jasmin Lienert
- Department of Emergency Medicine, Hôpital du Valais, Sion, Switzerland
| | - Monika Brodmann Maeder
- Department of Emergency Medicine, Inselspital Bern University Hospital, Bern, Switzerland; Institute for Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
| | - Didier Moens
- Department of Emergency Medicine, Liège University Hospital, Liège, Belgium
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Wipplinger F, Holthof N, Lienert J, Budowski A, Maeder MB, Moens D. Point-of-Care Ultrasound Diagnosis of Acute High Altitude Illness: A Case Report. Wilderness Environ Med 2021; 32:204-9. [DOI: 10.1016/j.wem.2020.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 02/04/2023]
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Pichamuthu K. Optic Nerve Sheath Ultrasound: Where do We Go from Here? Indian J Crit Care Med 2021; 25:360-361. [PMID: 34045797 PMCID: PMC8138630 DOI: 10.5005/jp-journals-10071-23795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
How to cite this article: Pichamuthu K. Optic Nerve Sheath Ultrasound: Where do We Go from Here? Indian J Crit Care Med 2021;25(4):360-361.
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Affiliation(s)
- Kishore Pichamuthu
- Division of Critical Care, Christian Medical College, Vellore, Tamil Nadu, India
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Tsai TY, Gozari G, Su YC, Lee YK, Tu YK. Optic nerve sheath diameter changes at high altitude and in acute mountain sickness: meta-regression analyses. Br J Ophthalmol 2020; 106:731-735. [PMID: 33310776 DOI: 10.1136/bjophthalmol-2020-317717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/09/2020] [Accepted: 11/17/2020] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIMS To assess changes in optic nerve sheath diameter (ONSD) at high altitude and in acute mountain sickness (AMS). METHODS Cochrane Library, EMBASE, Google Scholar and PubMed were searched for articles published from their inception to 31st of July 2020. Outcome measures were mean changes of ONSD at high altitude and difference in ONSD change between subjects with and without AMS. Meta-regressions were conducted to investigate the relation of ONSD change to altitude and time spent at that altitude. RESULTS Eight studies with 248 participants comparing ONSD from sea level to high altitude, and five studies with 454 participants comparing subjects with or without AMS, were included. ONSD increased by 0.14 mm per 1000 m after adjustment for time (95% CI: 0.10 to 0.18; p<0.01). Restricted cubic spline regression revealed an almost linear relation between ONSD change and time within 2 days. ONSD was greater in subjects with AMS (mean difference=0.47; 95% CI: 0.14 to 0.80; p=0.01; I2=89.4%). CONCLUSION Our analysis shows that ONSD changes correlate with altitude and tend to increase in subjects with AMS. Small study number and high heterogeneity are the limitations of our study. Further large prospective studies are required to verify our findings.
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Affiliation(s)
- Tou-Yuan Tsai
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan
| | - George Gozari
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan
| | - Yung-Cheng Su
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Yi-Kung Lee
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Yu-Kang Tu
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan .,Department of Dentistry, National Taiwan University Hospital and School of Dentistry, National Taiwan University, Taipei, Taiwan.,Research Center of Big Data and Meta-analysis, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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Siepen BM, Grubwinkler S, Wagner A, Gruber C, Dickopf A, Linker RA, Schlachetzki F, Baldaranov D. Neuromonitoring Using Neurosonography and Pupillometry in A Weaning and Early Neurorehabilitation Unit. J Neuroimaging 2020; 30:631-639. [PMID: 32592294 DOI: 10.1111/jon.12742] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/25/2020] [Accepted: 05/26/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Long-term surveillance of intracranial pressure (ICP) in neurological/neurosurgical patients during ventilator weaning and early neurorehabilitation currently relies on clinical observation because neuroimaging is rarely readily available. In this prospective study, multimodal neurosonography and pupillometry are evaluated for follow-up monitoring. METHODS Sonographic neuromonitoring was used to noninvasively examine patients' ICP during weaning and early neurorehabilitation. It allowed assessments of third ventricle width, possible midline shift, middle cerebral artery flow velocities, and bilateral optic nerve sheath diameters. Quantitative pupillometry was used to determine pupil size and reactivity. Other neuroimaging findings, spinal tap ICP measurements, and clinical follow-up data served as controls. RESULTS Seventeen patients-11 suffering from intracranial hemorrhage, four from encephalopathies, and two from ischemic stroke-were examined for ICP changes by using neurosonography and pupillometry during a mean observation period of 21 days. In total, 354 of 980 analyses (36.1%) yielded pathological results. In 15 of 17 patients (88.2%), pathological values were found during follow-up without a clear clinical correlate. In two patients (11.8%), clinically relevant changes in ICP occurred and were identified using neurosonography. Abnormal pupillometry findings displayed a high predictive value for absent clinical improvement. CONCLUSION Multimodal neurosonography may be a noninvasive means for long-term ICP assessment, whereas pupillometry may only detect rapid ICP changes during acute neurointensive care. The study also illustrates common pitfalls in neuromonitoring in general, with large numbers of pathological albeit nonsignificant findings. Additional controlled studies should validate the influence of detected subtle changes in ICP on neurological outcome.
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Affiliation(s)
- Bernhard M Siepen
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Stephan Grubwinkler
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Andrea Wagner
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Christine Gruber
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Alexander Dickopf
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Ralf A Linker
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Felix Schlachetzki
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
| | - Dobri Baldaranov
- Department of Neurology, University of Regensburg, Center for Vascular Neurology and Intensive Care, Regensburg, Germany
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13
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Abstract
Background: Both dynamic and static visual performances are essential for safety and motoric performance at altitude. There is a lack of information regarding alterations in dynamic visual performance (DVP) in oxygen-reduced environments. The purpose of this study was to analyze DVP in natural hypoxic conditions in a group of young, healthy hikers. Methods: DVP in four parafoveal subfields was analyzed using the computer-assisted Düsseldorf Test for Dynamic Vision. Measurements were performed twice at altitudes above 3500 m during an 8-day alpine hike. Results: On day 5 (3647 m), no changes in DVP were detected. On day 6 (4554 m), however, we found a significant reduction in DVP in the superior parafoveal retinal subfield, partly representing the lower visual field. The observed changes did not correlate with oxygen saturation, hematocrit, or cardiovascular parameters. We found no interrelation between symptoms of acute mountain sickness and DVP at altitude. Conclusions: Our data suggest that hiking at altitudes above 4500 m results in lower DVP in the visual field of healthy young people. The alteration might affect motor performance and coordination, increasing the risk of accidents.
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Affiliation(s)
- Till Krusche
- Department of Sports Medicine and Sports Nutrition, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Germany
| | - Mirjam Limmer
- Department of Sports Medicine and Sports Nutrition, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Germany.,Institute of Outdoor Sports and Environmental Science, German Sport University Cologne, Cologne, Germany
| | - Gernot Jendrusch
- Department of Sports Medicine and Sports Nutrition, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Germany
| | - Petra Platen
- Department of Sports Medicine and Sports Nutrition, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Germany
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14
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Schroeder C, Katsanos AH, Richter D, Tsivgoulis G, Gold R, Krogias C. Quantification of Optic Nerve and Sheath Diameter by Transorbital Sonography: A Systematic Review and Metanalysis. J Neuroimaging 2020; 30:165-174. [DOI: 10.1111/jon.12691] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/18/2020] [Accepted: 01/21/2020] [Indexed: 01/10/2023] Open
Affiliation(s)
| | - Aristeidis H. Katsanos
- Department of Neurology St. Josef‐Hospital, Ruhr University Bochum Germany
- Department of Neurology McMaster University/Population Health Research Institute Hamilton Ontario Canada
- Second Department of Neurology “Attikon” Hospital, School of Medicine National and Kapodistrian University of Athens Athens Greece
| | - Daniel Richter
- Department of Neurology St. Josef‐Hospital, Ruhr University Bochum Germany
| | - Georgios Tsivgoulis
- Second Department of Neurology “Attikon” Hospital, School of Medicine National and Kapodistrian University of Athens Athens Greece
- Department of Neurology University of Tennessee Health Science Center Memphis TN
| | - Ralf Gold
- Department of Neurology St. Josef‐Hospital, Ruhr University Bochum Germany
| | - Christos Krogias
- Department of Neurology St. Josef‐Hospital, Ruhr University Bochum Germany
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15
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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: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Alsup C, Lipman GS, Pomeranz D, Huang RW, Burns P, Juul N, Phillips C, Jurkiewicz C, Cheffers M, Evans K, Saraswathula A, Baumeister P, Lai L, Rainey J, Lobo V. Interstitial Pulmonary Edema Assessed by Lung Ultrasound on Ascent to High Altitude and Slight Association with Acute Mountain Sickness: A Prospective Observational Study. High Alt Med Biol 2019; 20:150-156. [DOI: 10.1089/ham.2018.0123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Carl Alsup
- Sierra Nevada Memorial Hospital, Emergency Medicine, Grass Valley, California
| | - Grant S. Lipman
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | | | - Rwo-Wen Huang
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Patrick Burns
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Nicholas Juul
- Department of Medicine, Stanford University School of Medicine, Stanford, California
| | - Caleb Phillips
- Department of Computational Science, University of Colorado, Boulder, Colorado
| | - Carrie Jurkiewicz
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Mary Cheffers
- Department of Emergency Medicine, University of Southern California, Los Angeles, California
| | - Kristina Evans
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Anirudh Saraswathula
- Department of Emergency Medicine, University of Chicago School of Medicine, Chicago, Illinois
| | - Peter Baumeister
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Lucinda Lai
- Stanford University School of Medicine, Stanford, California
| | - Jessica Rainey
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
| | - Viveta Lobo
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, California
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17
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Wang K, Zhang M, Li Y, Pu W, Ma Y, Wang Y, Liu X, Kang L, Wang X, Wang J, Qiao B, Jin L. Physiological, hematological and biochemical factors associated with high-altitude headache in young Chinese males following acute exposure at 3700 m. J Headache Pain 2018; 19:59. [PMID: 30046908 PMCID: PMC6060196 DOI: 10.1186/s10194-018-0878-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 07/02/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND High-altitude headache (HAH) is the most common sickness occurred in healthy people after rapid ascending to high altitude, and its risk factors were still not well understood. To investigate physiological, hematological and biochemical risk factors associated with high-altitude headache (HAH) after acute exposure to 3700 m, we conducted a two-stage, perspective observational study. In 72 h, total 318 young Han Chinese males ascended from sea level (altitude of 50 m) to altitude of 3700 m by train. Demographic data, physiological, hematological and biochemical parameters of all participants were collected within one week prior to the departure, and within 24 h after arrival. RESULTS The incidence of HAH was 74.84%. For parameters measured at sea level, participants with HAH exhibited significantly higher age and lower BUN (p < 0.05). For parameters measured at 3700 m, participants with HAH exhibited significantly lower blood oxygen saturation (SpO2), higher resting heart rate (HR), higher systolic blood pressure at resting (SBP) and lower blood urea nitrogen (BUN) (all p < 0.05). At 3700 m, the severity of HAH associated with SpO2, HR and BUN significantly (all p < 0.05). Multivariate logistic regression revealed that for parameters at sea level, BUN was associated with HAH [BUN (OR:0.77, 95% CI:0.60-0.99)] and for parameters at 3700 m, SpO2, HR and BUN were associated with HAH independently [SpO2 (OR:0.84, 95% CI:0.76-0.93); HR (OR:1.03, 95% CI:1.00-1.07); BUN (OR:0.64, 95% CI:0.46-0.88)]. No association between hematological parameters and HAH was observed. CONCLUSION We confirmed that higher HR, lower SpO2 are independent risk factors for HAH. Furthermore, we found that at both 50 m and 3700 m, lower BUN is a novel independent risk factor for HAH, providing new insights for understanding the pathological mechanisms.
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Affiliation(s)
- Kun Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Menghan Zhang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Yi Li
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
- Six Industrial Research Institute, Fudan University, Shanghai, 200433 China
| | - Weilin Pu
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
| | - Yanyun Ma
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
- Six Industrial Research Institute, Fudan University, Shanghai, 200433 China
| | - Yi Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Xiaoyu Liu
- Ministry of Education Key Laboratory of Contemporary Anthropology, Department of Anthropology and Human Genetics, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Longli Kang
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu University, Xianyang, 712082 China
| | - Xiaofeng Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Jiucun Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
- Six Industrial Research Institute, Fudan University, Shanghai, 200433 China
| | - Bin Qiao
- Institute of Cardiovascular Disease, General Hospital of Jinan Military Region, Jinan, 250022 Shandong China
| | - Li Jin
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200438 China
- Human Phenome Institute, Fudan University, Shanghai, 201203 China
- Six Industrial Research Institute, Fudan University, Shanghai, 200433 China
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18
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Weber U, Schiefer J, Mühlbacher J, Bernardi MH, Ortner CM, Jaksch P. High altitude trekking after lung transplantation: a prospective study using lung ultrasound to detect comets tails for interstitial pulmonary edema in lung transplant recipients and healthy volunteers. Transpl Int 2018; 31:1245-1253. [PMID: 29928768 DOI: 10.1111/tri.13307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 06/15/2018] [Indexed: 12/26/2022]
Abstract
The intensity of physical activity which can be tolerated after lung transplantation and the tolerance to prolonged exercise at high altitude are poorly investigated. Lung ultrasound comet tails have been used in the diagnosis of interstitial pulmonary edema and high pulmonary altitude edema. The aim was to assess the number of lung ultrasound comet tails and to monitor changes in the optic nerve sheath diameter (ONSD) during a climb to the top of Mount Kilimanjaro in 10 lung transplant recipients and 10 healthy controls at three different altitude levels: 1360, 3505, 4900 m. Lung transplant recipients showed a constant increase in comet tail scores with altitude, whereas control subjects only showed an increase at the highest measurement point. Differences between groups (transplant versus control) reached significance only after the first ascend: 0.9 (95% CI: -0.41; 2.21) vs. 0.1 (95% CI: -0.12; 0.32) (P = 0.2; 1360 m), 2.33 (95% CI: 0.64; 4.02) vs. 0.3 (95% CI: -0.18; 0.78) (P = 0.04; 3505 m), and 4.11 (95% CI: 0.13; 0.34) vs. 2.9 (95% CI: 0.49; 5.31) (P = 0.15; 4900 m); ONSD increased significantly in both groups from 3.53 (95% CI: 0.34; 0.66) at 1360 m to 4.11 (95% CI: 0.36; 0.71) at 4900 m (P < 0.05). Lungs of transplant recipients are able to adapt to altitude and capable of performing prolonged exercise at high altitude after slow ascend.
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Affiliation(s)
- Ulrike Weber
- Division of Cardiac Thoracic Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria
| | - Judith Schiefer
- Division of Cardiac Thoracic Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria
| | - Jakob Mühlbacher
- Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - Martin Hermann Bernardi
- Division of Cardiac Thoracic Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria
| | - Clemens Maria Ortner
- Division of Cardiac Thoracic Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria
| | - Peter Jaksch
- Department of Thoracic Surgery, Medical University of Vienna, Vienna, Austria
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Schatz A, Guggenberger V, Fischer MD, Schommer K, Bartz-Schmidt KU, Gekeler F, Willmann G. Optic nerve oedema at high altitude occurs independent of acute mountain sickness. Br J Ophthalmol 2018; 103:bjophthalmol-2018-312224. [PMID: 29973364 DOI: 10.1136/bjophthalmol-2018-312224] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 06/14/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND/AIMS The study aims to investigate changes in the optic nerve sheath diameter (ONSD) at high altitude and to assess correlation to optic disc oedema (ODE) and acute mountain sickness (AMS). This investigation is part of the Tübingen High Altitude Ophthalmology study. METHODS Fourteen volunteers ascended to 4559 m for 4 days before returning to low altitude. Ultrasonography of ONSD, quantification of optic disc parameters using a scanning laser ophthalmoscope and fluorescein angiography were performed at 341 m and at high altitude. Pearson's coefficient was used to correlate changes in ONSD with the optic disc and AMS. Assessment of AMS was performed using the Lake Louise (LL) and AMS-cerebral (AMS-C) scores of the Environmental Symptom Questionnaire-III. All volunteers were clinically monitored for heart rate (HR) and oxygen saturation (SpO2). RESULTS The mean ONSD at high altitude (4.6±0.3 mm, p<0.05) was significantly increased compared with baseline (3.8±0.4 mm) and remained enlarged throughout high-altitude exposure. This change in ONSD did not correlate with AMS (AMS-C, r=0.26, p=0.37; LL, r=0.21, p=0.48) and high-altitude headache (r=0.54, p=0.046), or clinical parameters of SpO2 (r=0.11, p=0.72) and HR (r=0.22, p=0.44). Increased ONSD did not correlate with altered key stereometric parameters of the optic disc describing ODE at high altitude (r<0.1, p>0.5). CONCLUSION High-altitude exposure leads to marked oedema formation of the optic nerve independent of AMS. Increased ONSD and ODE reflect hypoxia-driven oedema formation of the optic nerve at high altitude, providing important pathophysiological insight into high-altitude illness development and for future research.
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Affiliation(s)
- Andreas Schatz
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology, Katharinenhospital, Stuttgart, Germany
| | | | - M Dominik Fischer
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Kai Schommer
- Medizinischer Dienst der Krankenversicherungen, MDK Baden-Württemberg, Mannheim, Germany
| | | | - Florian Gekeler
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology, Katharinenhospital, Stuttgart, Germany
| | - Gabriel Willmann
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology, Katharinenhospital, Stuttgart, Germany
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20
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Yanamandra U, Gupta A, Yanamandra S, Das SK, Patyal S, Nair V. Bedside Ultrasonography as an Alternative to Computed Tomography Scan for the Measurement of Optic Nerve Sheath Diameter. J Neurosci Rural Pract 2018; 9:252-255. [PMID: 29725178 PMCID: PMC5912033 DOI: 10.4103/jnrp.jnrp_537_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background Optic nerve sheath diameter (ONSD) as measured by optic nerve sheath ultrasonography (ONSU) is used as a surrogate marker of intracranial pressure (ICP), especially in resource-limited settings. There is a growing interest in the use of ONSU in emergency and high-altitude setups. Notwithstanding multiple studies done on this subject, there is a paucity of data regarding standardization of techniques and comparison of ONSU with computed tomography (CT). Materials and Methods Thirty-five patients with a diagnosis of high-altitude cerebral edema were enrolled in the study. ONSD was measured in all patients using ONSU, along visual and coronal axis, and CT scan. We repeated ONSU in these patients on days 3, 7, 10, and 15 (day of discharge). Correlation between visual and coronal axis as well as CT scan was analyzed. Results The correlation of visual to coronal and coronal to visual was equally significant (both correlation coefficients being R2 = 0.983). Correlation of ONSD by visual axis to CT scan was better than coronal axis (correlation coefficient R2 = 0.986 vs. 0.96, respectively). Conclusion In our study, we found a strong correlation between the visual and coronal axes. Thus, either of the two axes can be used for monitoring ICP. However, it has been found that measurements along the coronal axis are challenging, especially in the emergency setup. ONSD measured along visual axis correlated better with CT scan as compared to the coronal axis.
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Affiliation(s)
- Uday Yanamandra
- Department of Hematology, Army Hospital (Research & Referral), New Delhi, India
| | - Amul Gupta
- Department of Radiology, Military Hospital, Jaipur, Rajasthan, India
| | - Sushma Yanamandra
- Research Associate, Army Hospital (Research & Referral), New Delhi, India
| | - Subrat Kumar Das
- Research Associate, Army Hospital (Research & Referral), New Delhi, India
| | | | - Velu Nair
- Ex-Director General Medical Services (Army), New Delhi, India
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Gharahbaghian L, Anderson KL, Lobo V, Huang RW, Poffenberger CM, Nguyen PD. Point-of-Care Ultrasound in Austere Environments. Emerg Med Clin North Am 2017; 35:409-441. [DOI: 10.1016/j.emc.2016.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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22
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Hiles LA, Donoviel DB, Bershad EM. Noninvasive Brain Physiology Monitoring for Extreme Environments: A Critical Review. J Neurosurg Anesthesiol 2015; 27:318-28. [PMID: 25811362 DOI: 10.1097/ANA.0000000000000175] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Our ability to monitor the brain physiology is advancing; however, most of the technology is bulky, expensive, and designed for traditional clinical settings. With long-duration space exploration, there is a need for developing medical technologies that are reliable, low energy, portable, and semiautonomous. Our aim was to review the state of the art for noninvasive technologies capable of monitoring brain physiology in diverse settings. A literature review of PubMed and the Texas Medical Center library sites was performed using prespecified search criteria to identify portable technologies for monitoring physiological aspects of the brain physiology. Most brain-monitoring technologies require a moderate to high degree of operator skill. Some are low energy, but many require a constant external power supply. Most of the technologies lack the accuracy seen in gold standard measures, due to the need for calibration, but may be useful for screening or monitoring relative changes in a parameter. Most of the technologies use ultrasound or electromagnetic radiation as energy sources. There is an important need for further development of portable technologies that can be operated in a variety of extreme environments to monitor brain health.
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Abstract
STUDY DESIGN Retrospective cohort. BACKGROUND Participating in sports at high altitude may have a protective effect on the brain, according to research studies. Research using validated data-collection methods in a previously unexplored cohort may better estimate the association between concussion injury risk and altitude. OBJECTIVES To determine the association between concussion rates and altitude during college football games. METHODS Athletic trainers from 21 Division I football programs provided exposure and injury data to the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) from the 2009-2010 to 2013-2014 academic years. The elevation of each stadium was determined. Concussion rates per 1000 athlete-exposures (AEs) were compared in 2 ways, based on the sample of stadium elevations: (1) median split (elevation higher than 178 m or lower than 178 m), and (2) quartile split. Rate ratios (RRs), rate differences, and 95% confidence intervals (CIs) were computed. RESULTS One hundred sixty-nine concussions were reported over 49 040 AEs (3.45/1000 AEs). Using the median split, the concussion rate above 178 m (RR = 4.18/1000 AEs) was 1.47 times the concussion rate below 178 m (RR = 2.84/1000 AEs; 95% CI: 1.09, 2.00; P = .01). The concussion rate at the highest altitude quartile (higher than 284 m; RR = 5.01/1000 AEs) was 1.67 times greater than the concussion rate at the lowest altitude quartile (lower than 43 m; RR = 3.00/1000 AEs; 95% CI: 1.13, 2.48; P = .01). CONCLUSION College football game concussion rates appear to increase at higher altitudes. The clinical significance of this relatively small increase is unknown. Future research should explore potential physiologic underpinnings associated with concussion risk at relatively higher and lower altitudes. LEVEL OF EVIDENCE Prognosis, level 2b.
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24
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Kanaan NC, Lipman GS, Constance BB, Holck PS, Preuss JF, Williams SR. Optic Nerve Sheath Diameter Increase on Ascent to High Altitude: Correlation With Acute Mountain Sickness. J Ultrasound Med 2015; 34:1677-1682. [PMID: 26269295 DOI: 10.7863/ultra.15.14.10060] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVES Elevated optic nerve sheath diameter on sonography is known to correlate with increased intracranial pressure and is observed in acute mountain sickness. This study aimed to determine whether optic nerve sheath diameter changes on ascent to high altitude are associated with acute mountain sickness incidence. METHODS Eighty-six healthy adults enrolled at 1240 m (4100 ft), drove to 3545 m (11,700 ft) and then hiked to and slept at 3810 m (12,500 ft). Lake Louise Questionnaire scores and optic nerve sheath diameter measurements were taken before, the evening of, and the morning after ascent. RESULTS The incidence of acute mountain sickness was 55.8%, with a mean Lake Louise Questionnaire score ± SD of 3.81 ± 2.5. The mean maximum optic nerve sheath diameter increased on ascent from 5.58 ± 0.79 to 6.13 ± 0.73 mm, a difference of 0.91 ± 0.55 mm (P = .09). Optic nerve sheath diameter increased at high altitude regardless of acute mountain sickness diagnosis; however, compared to baseline values, we observed a significant increase in diameter only in those with a diagnosis of acute mountain sickness (0.57 ± 0.77 versus 0.21 ± 0.76 mm; P = .04). This change from baseline, or Δ optic nerve sheath diameter, was associated with twice the odds of developing acute mountain sickness (95% confidence interval, 1.08-3.93). CONCLUSIONS The mean optic nerve sheath diameter increased on ascent to high altitude compared to baseline values, but not to a statistically significant degree. The magnitude of the observed Δ optic nerve sheath diameter was positively associated with acute mountain sickness diagnosis. No such significant association was found between acute mountain sickness and diameter elevation above standard cutoff values, limiting the utility of sonography as a diagnostic tool.
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Affiliation(s)
- Nicholas C Kanaan
- University of Utah, Salt Lake City, Utah USA (N.C.K.); Stanford University School of Medicine, Palo Alto, California USA (G.S.L., S.R.W.); Tacoma General Hospital, Tacoma, Washington USA (B.B.C.); University of Hawaii, Honolulu, Hawaii USA (P.S.H.); and Royal Perth Hospital, Perth, Western Australia, Australia (J.F.P.).
| | - Grant S Lipman
- University of Utah, Salt Lake City, Utah USA (N.C.K.); Stanford University School of Medicine, Palo Alto, California USA (G.S.L., S.R.W.); Tacoma General Hospital, Tacoma, Washington USA (B.B.C.); University of Hawaii, Honolulu, Hawaii USA (P.S.H.); and Royal Perth Hospital, Perth, Western Australia, Australia (J.F.P.)
| | - Benjamin B Constance
- University of Utah, Salt Lake City, Utah USA (N.C.K.); Stanford University School of Medicine, Palo Alto, California USA (G.S.L., S.R.W.); Tacoma General Hospital, Tacoma, Washington USA (B.B.C.); University of Hawaii, Honolulu, Hawaii USA (P.S.H.); and Royal Perth Hospital, Perth, Western Australia, Australia (J.F.P.)
| | - Peter S Holck
- University of Utah, Salt Lake City, Utah USA (N.C.K.); Stanford University School of Medicine, Palo Alto, California USA (G.S.L., S.R.W.); Tacoma General Hospital, Tacoma, Washington USA (B.B.C.); University of Hawaii, Honolulu, Hawaii USA (P.S.H.); and Royal Perth Hospital, Perth, Western Australia, Australia (J.F.P.)
| | - James F Preuss
- University of Utah, Salt Lake City, Utah USA (N.C.K.); Stanford University School of Medicine, Palo Alto, California USA (G.S.L., S.R.W.); Tacoma General Hospital, Tacoma, Washington USA (B.B.C.); University of Hawaii, Honolulu, Hawaii USA (P.S.H.); and Royal Perth Hospital, Perth, Western Australia, Australia (J.F.P.)
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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: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Olzowy B, Abendroth S, von Gleichenstein G, Mees K, Stelter K. No Evidence of Intracranial Hypertension in Trekkers with Acute Mountain Sickness When Assessed Noninvasively with Distortion Product Otoacoustic Emissions. High Alt Med Biol 2014; 15:364-70. [DOI: 10.1089/ham.2013.1120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Bernhard Olzowy
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Rostock Medical Center, Rostock, Germany
| | | | | | - Klaus Mees
- Department of Otorhinolaryngology, Head and Neck Surgery, Ludwig Maximilians University of Munich Medical Center, München, Germany
| | - Klaus Stelter
- Department of Otorhinolaryngology, Head and Neck Surgery, Ludwig Maximilians University of Munich Medical Center, München, Germany
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Affiliation(s)
- Mark H. Wilson
- The Brain Injury Centre—St Mary's Hospital, Imperial College, London, United Kingdom
- Birmingham Medical Research Expeditionary Society, Birmingham, United Kingdom
- The Institute of Pre-Hospital Care, London's Air Ambulance, Barts and the London Medical School, Queen Mary University of London, The Helipad, The Royal London Hospital, Whitechapel, United Kingdom
| | - Alex Wright
- Birmingham Medical Research Expeditionary Society, Birmingham, United Kingdom
| | - Christopher H.E. Imray
- University Hospital Coventry and Warwickshire NHS Trust and Warwick Medical School, Coventry, United Kingdom
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Willmann G, Gekeler F, Schommer K, Bärtsch P. Update on High Altitude Cerebral Edema Including Recent Work on the Eye. High Alt Med Biol 2014; 15:112-22. [DOI: 10.1089/ham.2013.1142] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Hall DP, MacCormick IJ, Phythian-Adams AT, Rzechorzek NM, Hope-Jones D, Cosens S, Jackson S, Bates MG, Collier DJ, Hume DA, Freeman T, Thompson AA, Baillie JK. Network analysis reveals distinct clinical syndromes underlying acute mountain sickness. PLoS One 2014; 9:e81229. [PMID: 24465370 DOI: 10.1371/journal.pone.0081229] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 10/10/2013] [Indexed: 11/23/2022] Open
Abstract
Acute mountain sickness (AMS) is a common problem among visitors at high altitude, and may progress to life-threatening pulmonary and cerebral oedema in a minority of cases. International consensus defines AMS as a constellation of subjective, non-specific symptoms. Specifically, headache, sleep disturbance, fatigue and dizziness are given equal diagnostic weighting. Different pathophysiological mechanisms are now thought to underlie headache and sleep disturbance during acute exposure to high altitude. Hence, these symptoms may not belong together as a single syndrome. Using a novel visual analogue scale (VAS), we sought to undertake a systematic exploration of the symptomatology of AMS using an unbiased, data-driven approach originally designed for analysis of gene expression. Symptom scores were collected from 292 subjects during 1110 subject-days at altitudes between 3650 m and 5200 m on Apex expeditions to Bolivia and Kilimanjaro. Three distinct patterns of symptoms were consistently identified. Although fatigue is a ubiquitous finding, sleep disturbance and headache are each commonly reported without the other. The commonest pattern of symptoms was sleep disturbance and fatigue, with little or no headache. In subjects reporting severe headache, 40% did not report sleep disturbance. Sleep disturbance correlates poorly with other symptoms of AMS (Mean Spearman correlation 0.25). These results challenge the accepted paradigm that AMS is a single disease process and describe at least two distinct syndromes following acute ascent to high altitude. This approach to analysing symptom patterns has potential utility in other clinical syndromes.
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Keyes LE, Paterson R, Boatright D, Browne V, Leadbetter G, Hackett P. Optic Nerve Sheath Diameter and Acute Mountain Sickness. Wilderness Environ Med 2013; 24:105-11. [DOI: 10.1016/j.wem.2012.11.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/21/2012] [Accepted: 11/01/2012] [Indexed: 01/29/2023]
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Bergauer A, Prosen G, Flis V, Šeruga T, Brvar M, Kobilica N. Contrast enhanced ultrasound imaging of the optic nerve sheath diameter – what are we really measuring? Crit Ultrasound J 2012. [PMCID: PMC3524491 DOI: 10.1186/2036-7902-4-s1-a2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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Ascaso FJ, Nerín MA, Villén L, Morandeira JR, Cristóbal JA. Acute mountain sickness and retinal evaluation by optical coherence tomography. Eur J Ophthalmol 2012; 22:580-9. [PMID: 22139614 DOI: 10.5301/ejo.5000091] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2011] [Indexed: 02/07/2023]
Abstract
PURPOSE Acute mountain sickness (AMS), the commonest form of altitude illness, might represent early-stage high altitude cerebral edema (HACE). Optical coherence tomography (OCT) was used to evaluate optic nerve head (ONH) consequences following a sojourn to extreme altitude. METHODS This prospective study included 4 high-altitude expeditions in Himalayas. Twenty-four eyes of 12 healthy male climbers underwent baseline and postexpedition complete ophthalmic evaluation, including OCT to measure the peripapillary retinal nerve fiber layer (RNFL) thickness, ONH parameters, and macular thickness and volume. Lake Louise Scoring (LLS) self-report questionnaire was used to estimate AMS severity. RESULTS All mountaineers experienced symptoms of AMS (LLS: 5.1±1.1, range 4.0-7.0). Average peripapillary RNFL thickness showed a significant increase in postexpedition examination (94±23 µm, 47-115), compared with baseline values (89±19 µm, range 45-114) (p=0.034). Superior (p=0.036) and temporal (p=0.010) quadrants also showed an increased RNFL thickness following exposure to high altitude. Vertical integrated rim area (VIRA) was significantly higher in postexpedition examination (0.71±0.43 mm(3), 0.14-1.50) than in baseline examination (0.51±0.26 mm(3), 0.11-1.00) (p=0.002). Horizontal integrated rim width was significantly higher in postexpedition examination (1.90±0.32 mm(2), range 1.37-2.34) than in baseline examination (1.77±0.27 mm(2), 1.27-2.08) (p=0.004). There was no correlation between LLS and OCT parameters (p>0.05). CONCLUSIONS In climbers with AMS, OCT was able to detect subtle increases in the peripapillary RNFL thickness and in some ONH measurements, even in absence of HACE and papilledema. These changes might be a sensitive parameter in physiologic acclimatization and in the pathogenesis of AMS.
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Lawley JS, Oliver SJ, Mullins P, Morris D, Junglee NA, Jelleyman C, Macdonald JH. Optic Nerve Sheath Diameter Is Not Related to High Altitude Headache: A Randomized Controlled Trial. High Alt Med Biol 2012; 13:193-9. [DOI: 10.1089/ham.2012.1019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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Fischer MD, Willmann G, Schatz A, Schommer K, Zhour A, Zrenner E, Bartz-Schmidt KU, Gekeler F. Structural and functional changes of the human macula during acute exposure to high altitude. PLoS One 2012; 7:e36155. [PMID: 22558365 PMCID: PMC3340355 DOI: 10.1371/journal.pone.0036155] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/27/2012] [Indexed: 11/18/2022] Open
Abstract
Background This study aimed to quantify structural and functional changes at the macula during acute exposure to high altitude and to assess their structure/function relationship. This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study. Methodology/Principal Findings Spectral domain optical coherence tomography and microperimetry were used to quantify changes of central retinal structure and function in 14 healthy subjects during acute exposure to high altitude (4559 m). High-resolution volume scans and fundus-controlled microperimetry of the posterior pole were performed in addition to best-corrected visual acuity (BCVA) measurements and assessment of acute mountain sickness. Analysis of measurements at altitude vs. baseline revealed increased total retinal thickness (TRT) in all four outer ETDRS grid subfields during acute altitude exposure (TRTouter = 2.80±1.00 μm; mean change±95%CI). This change was inverted towards the inner four subfields (TRTinner = −1.89±0.97 μm) with significant reduction of TRT in the fovea (TRTfoveal = −6.62±0.90 μm) at altitude. BCVA revealed no significant difference compared to baseline (0.06±0.08 logMAR). Microperimetry showed stable mean sensitivity in all but the foveal subfield (MSfoveal = −1.12±0.68 dB). At baseline recordings before and >2 weeks after high altitude exposure, all subjects showed equal levels with no sign of persisting structural or functional sequels. Conclusions/Significance During acute exposure to high altitude central retinal thickness is subject to minor, yet statistically significant changes. These alterations describe a function of eccentricity with an increase in regions with relatively higher retinal nerve fiber content and vascular arcades. However, these changes did not correlate with measures of central retinal function or acute mountain sickness. For the first time a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure.
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Affiliation(s)
| | - Gabriel Willmann
- Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
- * E-mail:
| | - Andreas Schatz
- Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Kai Schommer
- Department of Sports Medicine, Medical Clinic, University Hospital Heidelberg, Heidelberg, Germany
| | - Ahmad Zhour
- Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Eberhart Zrenner
- Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | | | - Florian Gekeler
- Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
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Fagenholz PJ, Murray AF, Noble VE, Baggish AL, Harris NS. Ultrasound for high altitude research. Ultrasound Med Biol 2012; 38:1-12. [PMID: 22104522 DOI: 10.1016/j.ultrasmedbio.2011.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 10/03/2011] [Accepted: 10/07/2011] [Indexed: 05/31/2023]
Abstract
This review describes ultrasound techniques of potential use to high altitude researchers and discusses technical issues related to using ultrasound for high altitude research. Ultrasound allows portable, noninvasive evaluation of many physiologic parameters of interest to high altitude researchers. We discuss techniques that have been extensively used and emerging techniques that can be used to assess parameters of particular interest to high altitude researchers. We do not provide a definitive description of all ultrasound scanning methods but references to instructive sources are included. Potential drawbacks of ultrasound use, such as the need for sometimes extensive training and the potential for interobserver variation, are discussed and strategies for mitigating these are suggested. This review is meant to encourage other high altitude researchers to consider using ultrasound, either as a primary investigative modality or as an adjunct for monitoring parameters of interest in studies of physiology, altitude illness, or therapeutics.
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Affiliation(s)
- Peter J Fagenholz
- Department of Surgery, Division of Trauma, Emergency Surgery, and Surgical Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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Abegão Pinto L, Vandewalle E, Pronk A, Stalmans I. Intraocular pressure correlates with optic nerve sheath diameter in patients with normal tension glaucoma. Graefes Arch Clin Exp Ophthalmol 2011; 250:1075-80. [DOI: 10.1007/s00417-011-1878-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 11/08/2011] [Accepted: 11/15/2011] [Indexed: 11/30/2022] Open
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Willmann G, Fischer MD, Schatz A, Schommer K, Messias A, Zrenner E, Bartz-Schmidt KU, Gekeler F. Quantification of optic disc edema during exposure to high altitude shows no correlation to acute mountain sickness. PLoS One 2011; 6:e27022. [PMID: 22069483 PMCID: PMC3206056 DOI: 10.1371/journal.pone.0027022] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 10/07/2011] [Indexed: 02/07/2023] Open
Abstract
Background The study aimed to quantify changes of the optic nerve head (ONH) during exposure to high altitude and to assess a correlation with acute mountain sickness (AMS). This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study. Methodology/Principal Findings A confocal scanning laser ophthalmoscope (cSLO, Heidelberg Retina Tomograph, HRT3®) was used to quantify changes at the ONH in 18 healthy participants before, during and after rapid ascent to high altitude (4559 m). Slitlamp biomicroscopy was used for clinical optic disc evaluation; AMS was assessed with Lake Louise (LL) and AMS-cerebral (AMS-c) scores; oxygen saturation (SpO2) and heart rate (HR) were monitored. These parameters were used to correlate with changes at the ONH. After the first night spent at high altitude, incidence of AMS was 55% and presence of clinical optic disc edema (ODE) 79%. Key stereometric parameters of the HRT3® used to describe ODE (mean retinal nerve fiber layer [RNFL] thickness, RNFL cross sectional area, optic disc rim volume and maximum contour elevation) changed significantly at high altitude compared to baseline (p<0.05) and were consistent with clinically described ODE. All changes were reversible in all participants after descent. There was no significant correlation between parameters of ODE and AMS, SpO2 or HR. Conclusions/Significance Exposure to high altitude leads to reversible ODE in the majority of healthy subjects. However, these changes did not correlate with AMS or basic physiologic parameters such as SpO2 and HR. For the first time, a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure. In conclusion, ODE presents a reaction of the body to high altitude exposure unrelated to AMS.
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Affiliation(s)
- Gabriel Willmann
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
| | - M. Dominik Fischer
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
- * E-mail:
| | - Andreas Schatz
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
| | - Kai Schommer
- Department of Sports Medicine, Medical Clinic, University Hospital Heidelberg, Heidelberg, Germany
| | - Andre Messias
- Department of Ophthalmology, Otorhinolaryngology and Head & Neck Surgery, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | - Eberhart Zrenner
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
| | - Karl U. Bartz-Schmidt
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
| | - Florian Gekeler
- Centre for Ophthalmology, University of Tuebingen, Tübingen, Baden-Württemberg, Germany
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Anderson PJ, Miller AD, O'Malley KA, Ceridon ML, Beck KC, Wood CM, Wiste HJ, Mueller JJ, Johnson JB, Johnson BD. Incidence and Symptoms of High Altitude Illness in South Pole Workers: Antarctic Study of Altitude Physiology (ASAP). Clin Med Insights Circ Respir Pulm Med 2011; 5:27-35. [PMID: 21695160 PMCID: PMC3114308 DOI: 10.4137/ccrpm.s6882] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Introduction: Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to altitude), cold, and immediate exertion would increase altitude illness risk. Methods: Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m2) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at altitude. Acetazolamide, while not mandatory, was used by 40% of participants. Results: At SP, the barometric pressure resulted in physiological altitudes that approached 3400 m, while T °C averaged −42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1–2, yet in >20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less altitude experience, worse symptoms on previous exposures, and less SP experience. Conclusion: The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar altitudes. Thus, the SP constitutes a more intense altitude exposure than might be expected considering physical altitude alone. Many symptoms persist, possibly due to extremely cold, arid conditions and the benefits of acetazolamide appeared negligible, though it may have prevented more severe symptoms in higher risk subjects.
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Affiliation(s)
- Paul J Anderson
- Health Partners Occupational and Environmental Medicine Residency, St. Paul, MN, USA
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Hamilton DR, Sargsyan AE, Melton SL, Garcia KM, Oddo B, Kwon DS, Feiveson AH, Dulchavsky SA. Sonography for determining the optic nerve sheath diameter with increasing intracranial pressure in a porcine model. J Ultrasound Med 2011; 30:651-659. [PMID: 21527613 DOI: 10.7863/jum.2011.30.5.651] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVES This study investigated whether it is feasible to use sonography to monitor changes in the optic nerve sheath diameter in a porcine model. METHODS A fiber-optic intracranial pressure transducer was surgically placed through the frontal sinus directly into the brain parenchyma of adult Yorkshire pigs (n = 5). A second bolt was placed on the contralateral side for intraparenchymal fluid infusion. Optic nerve sheath diameter measurements were acquired by each of 2 ultrasound operators around the leading edge of the nerve, 3 to 5 mm distal from the origin of the optic nerve. To induce a change in diameter, intracranial pressure was manipulated by injecting normal saline into the intraparenchymal infusion catheter located in the symmetric contralateral position as the pressure-monitoring probe. RESULTS Data from 1 pig were unusable because of a cerebrospinal fluid leak into the sinus and orbital fissure. Saline aliquots of 1 to 10 mL were able to generate intracranial pressures typically starting from 10 to 15 mm Hg and increasing to 75 to 90 mm Hg, which eventually evoked a Cushing response. Fluid injection was controlled to increase pressures by 60 mm Hg over a 15- to 20-minute period. Regression analysis of all animals showed that the optic nerve sheath diameter increased by 0.0034 mm/mm Hg of intracranial pressure; however, this slope ranged from 0.0025 to 0.0046, depending on the animal measured. There was no discernible effect of the ultrasound operator on the slope; however, measurements made by 1 operator were consistently higher than the others by about 8% of the overall diameter range. CONCLUSIONS These results suggest that the use of the optic nerve sheath diameter to noninvasively confirm acute changes in intracranial pressure over 1 hour is feasible in a porcine model. We recommend that this method be validated in humans using direct intracranial pressure measurement where possible to confirm it as a screening tool for acute and chronically increased diameters secondary to elevated pressure in clinical settings.
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Affiliation(s)
- Douglas R Hamilton
- Wyle Laboratories/ National Aeronautics and Space Administration, Houston, TX 77058, USA.
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Dubourg J, Javouhey E, Geeraerts T, Messerer M, Kassai B. Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis. Intensive Care Med. 2011;37:1059-1068. [PMID: 21505900 DOI: 10.1007/s00134-011-2224-2] [Citation(s) in RCA: 332] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 02/20/2011] [Indexed: 02/06/2023]
Abstract
PURPOSE To evaluate the diagnostic accuracy of ultrasonography of optic nerve sheath diameter (ONSD) for assessment of intracranial hypertension. METHODS Systematic review without language restriction based on electronic databases, with manual review of literature and conference proceedings until July 2010. Studies were eligible if they compared ultrasonography of ONSD with intracranial pressure (ICP) monitoring. Data were extracted independently by three authors. Random-effects meta-analysis and meta-regression were performed. RESULTS Six studies including 231 patients were reviewed. No significant heterogeneity was detected for sensitivity, specificity, positive and negative likelihood ratios or diagnostic odds ratio. For detection of raised intracranial pressure, pooled sensitivity was 0.90 [95% confidence interval (CI) 0.80-0.95; p for heterogeneity, p (het) = 0.09], pooled specificity was 0.85 (95% CI 0.73-0.93, p (het) = 0.13), and the pooled diagnostic odds ratio was 51 (95% CI 22-121). The area under the summary receiver-operating characteristic (SROC) curve was 0.94 (95% CI 0.91-0.96). CONCLUSIONS Ultrasonography of ONSD shows a good level of diagnostic accuracy for detecting intracranial hypertension. In clinical decision-making, this technique may help physicians decide to transfer patients to specialized centers or to place an invasive device when specific recommendations for this placement do not exist.
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Friedman LM, Tsung JW. Extending the Focused Assessment With Sonography for Trauma Examination in Children. Clinical Pediatric Emergency Medicine 2011; 12:2-17. [DOI: 10.1016/j.cpem.2010.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Querfurth HW, Lieberman P, Arms S, Mundell S, Bennett M, van Horne C. Ophthalmodynamometry for ICP prediction and pilot test on Mt. Everest. BMC Neurol 2010; 10:106. [PMID: 21040572 PMCID: PMC2987855 DOI: 10.1186/1471-2377-10-106] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 11/01/2010] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND A recent development in non-invasive techniques to predict intracranial pressure (ICP) termed venous ophthalmodynamometry (vODM) has made measurements in absolute units possible. However, there has been little progress to show utility in the clinic or field. One important application would be to predict changes in actual ICP during adaptive responses to physiologic stress such as hypoxia. A causal relationship between raised intracranial pressure and acute mountain sickness (AMS) is suspected. Several MRI studies report that modest physiologic increases in cerebral volume, from swelling, normally accompany subacute ascent to simulated high altitudes. OBJECTIVES 1) Validate and calibrate an advanced, portable vODM instrument on intensive patients with raised intracranial pressure and 2) make pilot, non-invasive ICP estimations of normal subjects at increasing altitudes. METHODS The vODM was calibrated against actual ICP in 12 neurosurgical patients, most affected with acute hydrocephalus and monitored using ventriculostomy/pressure transducers. The operator was blinded to the transducer read-out. A clinical field test was then conducted on a variable data set of 42 volunteer trekkers and climbers scaling Mt. Everest, Nepal. Mean ICPs were estimated at several altitudes on the ascent both across and within subjects. RESULTS Portable vODM measurements increased directly and linearly with ICP resulting in good predictability (r = 0.85). We also found that estimated ICP increases normally with altitude (10 ± 3 mm Hg; sea level to 20 ± 2 mm Hg; 6553 m) and that AMS symptoms did not correlate with raised ICP. CONCLUSION vODM technology has potential to reliably estimate absolute ICP and is portable. Physiologic increases in ICP and mild-mod AMS are separate responses to high altitude, possibly reflecting swelling and vasoactive instability, respectively.
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Affiliation(s)
- Henry W Querfurth
- Dept of Neurology, Rhode Island Hospital, Warren Alpert Medical School, Brown University Providence, RI 02903, USA.
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Bailey DM, Bärtsch P, Knauth M, Baumgartner RW. Emerging concepts in acute mountain sickness and high-altitude cerebral edema: from the molecular to the morphological. Cell Mol Life Sci 2009; 66:3583-94. [PMID: 19763397 PMCID: PMC3085779 DOI: 10.1007/s00018-009-0145-9] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 08/20/2009] [Indexed: 01/09/2023]
Abstract
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.
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Affiliation(s)
- Damian Miles Bailey
- Neurovascular Research Laboratory, Faculty of Health, Science and Sport, University of Glamorgan, Pontypridd, CF37 1DL, South Wales, UK.
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Baillie JK, Thompson AAR, Irving JB, Bates MGD, Sutherland AI, Macnee W, Maxwell SRJ, Webb DJ. Oral antioxidant supplementation does not prevent acute mountain sickness: double blind, randomized placebo-controlled trial. QJM 2009; 102:341-8. [PMID: 19273551 DOI: 10.1093/qjmed/hcp026] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Acute mountain sickness may be caused by cerebrovascular fluid leakage due to oxidative damage to the endothelium. This may be reduced by oral antioxidant supplementation. AIM To assess the effectiveness of antioxidant supplementation for the prevention of acute mountain sickness (AMS). DESIGN A parallel-group double blind, randomized placebo-controlled trial. METHODS The study was conducted in a university clinical research facility and a high altitude research laboratory. Eighty-three healthy lowland volunteers ascended to 5200 m on the Apex 2 high altitude research expedition. The treatment group received a daily dose of 1 g l-ascorbic acid, 400 IU of alpha-tocopherol acetate and 600 mg of alpha-lipoic acid (Cultech Ltd., Wales, UK) in four divided doses. Prevalence of AMS was measured using the Lake Louise Consensus score sheet (LLS). Secondary outcomes were AMS severity measured using a novel visual analogue scale, arterial oxygen saturation and pulmonary artery systolic pressure (PASP). RESULTS Forty-one subjects were allocated to the antioxidant group, and 42 to the placebo group. There was no difference in AMS incidence or severity between the antioxidant and placebo groups using the LLS at any time at high altitude. At the pre-determined comparison point at Day 2 at 5200 m, 69% of the antioxidant group (25/36) and 66% of the placebo group (23/35) had AMS using the LLS criteria (P = 0.74). No differences were observed between the groups for PASP, oxygen saturation, presence of a pericardial effusion or AMS assessed by VAS. CONCLUSION This trial found no evidence of benefit from antioxidant supplementation at high altitude. TRIAL REGISTRATION NUMBER NCT00664001.
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Affiliation(s)
- J K Baillie
- Department of Anaesthesia, Critical Care and Pain Medicine, University of Edinburgh, Royal Infirmary of Edinburgh, Edinburgh, UK.
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Abstract
Cellular hypoxia is the common final pathway of brain injury that occurs not just after asphyxia, but also when cerebral perfusion is impaired directly (eg, embolic stroke) or indirectly (eg, raised intracranial pressure after head injury). We Review recent advances in the understanding of neurological clinical syndromes that occur on exposure to high altitudes, including high altitude headache (HAH), acute mountain sickness (AMS), and high altitude cerebral oedema (HACE), and the genetics, molecular mechanisms, and physiology that underpin them. We also present the vasogenic and cytotoxic bases for HACE and explore venous hypertension as a possible contributory factor. Although the factors that control susceptibility to HACE are poorly understood, the effects of exposure to altitude (and thus hypobaric hypoxia) might provide a reproducible model for the study of cerebral cellular hypoxia in healthy individuals. The effects of hypobaric hypoxia might also provide new insights into the understanding of hypoxia in the clinical setting.
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Affiliation(s)
- Mark H Wilson
- Centre for Altitude, Space and Extreme Environment Medicine, University College London, London, UK.
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Abstract
OBJECTIVE To examine patterns of mortality among climbers on Mount Everest over an 86 year period. DESIGN Descriptive study. SETTING Climbing expeditions to Mount Everest, 1921-2006. PARTICIPANTS 14,138 mountaineers; 8030 climbers and 6108 sherpas. MAIN OUTCOME MEASURE Circumstances of deaths. RESULTS The mortality rate among mountaineers above base camp was 1.3%. Deaths could be classified as involving trauma (objective hazards or falls, n=113), as non-traumatic (high altitude illness, hypothermia, or sudden death, n=52), or as a disappearance (body never found, n=27). During the spring climbing seasons from 1982 to 2006, 82.3% of deaths of climbers occurred during an attempt at reaching the summit. The death rate during all descents via standard routes was higher for climbers than for sherpas (2.7% (43/1585) v 0.4% (5/1231), P<0.001; all mountaineers 1.9%). Of 94 mountaineers who died after climbing above 8000 m, 53 (56%) died during descent from the summit, 16 (17%) after turning back, 9 (10%) during the ascent, 4 (5%) before leaving the final camp, and for 12 (13%) the stage of the summit bid was unknown. The median time to reach the summit via standard routes was earlier for survivors than for non-survivors (0900-0959 v 1300-1359, P<0.001). Profound fatigue (n=34), cognitive changes (n=21), and ataxia (n=12) were the commonest symptoms reported in non-survivors, whereas respiratory distress (n=5), headache (n=0), and nausea or vomiting (n=3) were rarely described. CONCLUSIONS Debilitating symptoms consistent with high altitude cerebral oedema commonly present during descent from the summit of Mount Everest. Profound fatigue and late times in reaching the summit are early features associated with subsequent death.
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Affiliation(s)
- Paul G Firth
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA.
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