Relative Decompression Risks of Spacecraft Cabin Atmospheres - Comparision of Gases Using Miniature Pigs Final Report

Using miniature pigs for analysis of altitude decompression sickness and relative decompression hazards of various cabin atmospheres of inert gase

Examination of novel diagnostic approaches and contemporary strategies for preventing acute mountain sickness

Introduction and purpose: Acute mountain sickness is caused by hypoxia, of which the brain is the most sensitive. The frequency of occurrence at altitudes above 2500 m above sea level may reach up to 75% of travelers. Prevention of altitude sickness mainly concerns the travel plan and pharmacology.  Our study aimed to assess the current literature on altitude sickness, and discuss the possible pathophysiology, epidemiology, and symptoms. Moreover, we underline new guidelines for the treatment, prevention, and diagnosis of altitude sickness in the context of the last guidelines and research.   We conducted a PubMed literature review using keywords like "mountaineering sickness" and "altitude sickness".  All article types were taken into account: clinical trial, meta-analysis, case report, case series, systematic review, randomized controlled trial, observational study, clinical study, books, and documents in the last 5 years.A brief description of the state of knowledge: In recent years, there has been a surge in the accessibility and popularity of high-altitude tourism, emphasizing the need to disseminate information about altitude sickness among travelers. This heightened accessibility has sparked a push for comprehensive research and viable solutions, aiming to address the ramifications of the increased risk associated with such endeavors. Furthermore, there's a growing call for additional research focusing on the unique medical demands posed by tourist excursions and extreme expeditions. Conclusions:It underscores the necessity for healthcare professionals equipped with specialized knowledge and expertise in both preventing and treating medical conditions arising in exceptional circumstances

High altitude sickness - review

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenHigh altitude sickness is a common name for illnesses that can occur at high altitude, usually above 3000 meters from sea level. The cause is hypoxia but the pathophysiology of the diseases is a complex mixture of multiple factors, involving the human response to hypoxia. The most common symptom is headache, but loss of appetite, nausea and sleep disturbances are also common complaints. With rapid or high ascent there is increased risk of acute mountain sickness, with severe headache that responds poorly to pain medications, nausea, vomiting and extreme fatigue as the most common symptoms. The most severe forms of high-altitude sickness are high altitude cerebral edema and high altitude pulmonary edema. High altitude sickness can be prevented by slow ascent and avoiding overexertion. Medications can also be used to reduce symptoms. In this overview high altitude physiology and acclimatisation are reviewed. The main types of high altitude sickness are described with special emphasis on symptoms and diagnosis, but treatment and prevention are also reviewed.Hæðarveiki* er samheiti yfir sjúkdóma sem gera vart við sig í mikilli hæð yfir sjávarmáli, oftast þegar komið er yfir 3000 metra hæð. Aðallega er um þrjár gerðir hæðarveiki að ræða, háfjallaveiki, háfjallaheilabjúg og háfjallalungnabjúg. Orsök hæðarveiki er almennt talin vera súrefnisskortur en meingerð sjúkdómanna er flókið samspil margra þátta sem til verða vegna viðbragða líkamans við súrefnisskorti. Höfuðverkur er algengastur en lystarleysi, ógleði og svefntruflanir eru einnig algengar kvartanir. Við hraða eða mikla hækkun er hætta á bráðri háfjallaveiki en helstu einkenni hennar eru svæsinn höfuðverkur sem svarar illa verkjalyfjum, ógleði, uppköst og mikil þreyta. Háfjallalungnabjúgur og háfjallaheilabjúgur eru alvarlegustu tegundir hæðarveiki. Hæðarveiki er helst hægt að fyrirbyggja með því að hækka sig rólega og stilla gönguhraða í hóf. Einnig má draga úr einkennum með lyfjum. Í þessari yfirlitsgrein er fjallað um háfjallalífeðlisfræði og hæðaraðlögun, mismunandi tegundir hæðarveiki, einkenni og greiningu, ásamt meðferð og fyrirbyggjandi aðgerðir

Inhaled Budesonide and Oral Dexamethasone Prevent Acute Mountain Sickness

AbstractBackgroundThis double-blind, randomized controlled trial aimed to investigate inhaled budesonide and oral dexamethasone compared with placebo for their prophylactic efficacy against acute mountain sickness after acute high-altitude exposure.MethodsThere were 138 healthy young male lowland residents recruited and randomly assigned to receive inhaled budesonide (200 μg, twice a day [bid]), oral dexamethasone (4 mg, bid), or placebo (46 in each group). They traveled to 3900 m altitude from 400 m by car. Medication started 1 day before high-altitude exposure and continued until the third day of exposure. Primary outcome measure was the incidence of acute mountain sickness after exposure.ResultsOne hundred twenty-four subjects completed the study (42, 39, and 43 in the budesonide, dexamethasone, and placebo groups, respectively). Demographic characteristics were comparable among the 3 groups. After high-altitude exposure, significantly fewer participants in the budesonide (23.81%) and dexamethasone (30.77%) groups developed acute mountain sickness compared with participants receiving placebo (60.46%) (P = .0006 and P = .0071, respectively). Both the budesonide and dexamethasone groups had lower heart rate and higher pulse oxygen saturation (SpO2) than the placebo group at altitude. Only the budesonide group demonstrated less deterioration in forced vital capacity and sleep quality than the placebo group. Four subjects in the dexamethasone group reported adverse reactions.ConclusionsBoth inhaled budesonide (200 μg, bid) and oral dexamethasone (4 mg, bid) were effective for the prevention of acute mountain sickness, especially its severe form, compared with placebo. Budesonide caused fewer adverse reactions than dexamethasone

Acute mountain sickness management: Case of Mount Kilimanjaro and review of literature

Background: High-altitude Illness is the collective term for all illnesses occurring at or during terrestrial elevations over 1500m, it encompasses acute mountain sickness (AMS), high-altitude cerebral oedema (HACE) and High-altitude Pulmonary Oedema (HAPE).High- altitude-related problems consist of the common syndrome of acute mountain sickness, which is relatively benign and usually self-limiting, and the rarer, more serious syndromes of high-altitude cerebral oedema and high-altitude pulmonary oedema. A common feature of acute altitude illness is rapid ascent by otherwise fit individuals to altitudes above 3000 m without sufficient time to acclimatize which is accompanies with many hypobaric hypoxia related complications which if not managed on time results into death, especially when ascending mountain with sharp ascent like Kilimanjaro Acute Mountain Sickness is the first manifestation of High-altitude illness, it can be easily prevented and managed but most of the time AMS symptoms are ignored or mismanaged hence resulting into death. The susceptibility of an individual to high-altitude syndromes is variable but generally reproducible. Prevention of altitude-related illness by slow ascent is the best approach, but this is not always practical, especially in Mountains like Kilimanjaro with very low medical resources. The immediate management of AMS requires oxygen and descent of more than 300 m as soon as possible, accompanied other pharmacological and non-pharmacological management from well-trained health care providers, tour guides, porters and mountain guards.Methods: A Systematic review of case studies, research articles and guidelines for prevention and treatment of Acute Mountain Sickness (AMS) in Mt. Kilimanjaro. Searches from PubMed, MEDLINE and EMBASE from inception to October 2018, a total of 247 peer reviewed articles and case studies, 2 international guidelines, 17 books and 1 conference proceeding were used to prepare this article.Results: Detailed review of Acute Mountain Sickness management and other High-altitude clinical complications in Kilimanjaro (HACE and HAPE). This review provides detailed information about each of these important clinical entities. After reviewing the clinical features, epidemiology and current understanding of the pathophysiology of each disorder, the article describe the current pharmacological and non-pharmacological approaches to the prevention and treatment of these diseases. A total of 247 articles and case studies, 2 international guidelines, 17 books and 1 conference proceeding were used for this review. All articles searches where from peer reviewed sources, majority were international though thorough searches and emphasis was for those written about AMS in Mt. Kilimanjaro. Majority authors were from were from the global north (Europeans and Americans)Conclusion: Currently there is an increase in number of cases of high-altitude illnesses and deaths reported in Mt. Kilimanjaro. Many of these travellers seek medical advice prior to expedition from inexperienced practitioners around world or under resourced and inexperienced health care providers in Tanzania. In this Review article, I describe the setting and clinical features of acute mountain sickness, an overview of the known pathophysiology, prevention, treatment and comprehensive evidence based recommendations for health care providers in Africa

Does This Patient Have Acute Mountain Sickness?: The Rational Clinical Examination Systematic Review.

Acute mountain sickness (AMS) affects more than 25% of individuals ascending to 3500 m (11 500 ft) and more than 50% of those above 6000 m (19 700 ft). AMS may progress from nonspecific symptoms to life-threatening high-altitude cerebral edema in less than 1% of patients. It is not clear how to best diagnose AMS. To systematically review studies assessing the accuracy of AMS diagnostic instruments, including the visual analog scale (VAS) score, which quantifies the overall feeling of sickness at altitude (VAS[O]; various thresholds), Acute Mountain Sickness-Cerebral score (AMS-C; ≥0.7 indicates AMS), and the clinical functional score (CFS; ≥2 indicates AMS) compared with the Lake Louise Questionnaire Score (LLQS; score of ≥5). Searches of MEDLINE and EMBASE from inception to May 2017 identified 1245 publications of which 91 were suitable for prevalence analysis (66 944 participants) and 14 compared at least 2 instruments (1858 participants) using a score of 5 or greater on the LLQS as a reference standard. To determine the prevalence of AMS for establishing the pretest probability of AMS, a random-effects meta-regression was performed based on the reported prevalence of AMS as a function of altitude. AMS prevalence, likelihood ratios (LRs), sensitivity, and specificity of screening instruments. The final analysis included 91 articles (comprising 66 944 study participants). Altitude predicted AMS and accounted for 28% of heterogeneity between studies. For each 1000-m (3300-ft) increase in altitude above 2500 m (8200 ft), AMS prevalence increased 13% (95% CI, 9.5%-17%). Testing characteristics were similar for VAS(O), AMS-C, and CFS vs a score of 5 or greater on the LLQS (positive LRs: range, 3.2-8.2; P = .22 for comparisons; specificity range, 67%-92%; negative LRs: range, 0.30-0.36; P = .50 for comparisons; sensitivity range, 67%-82%). The CFS asks a single question: "overall if you had any symptoms, how did they affect your activity (ordinal scale 0-3)?" For CFS, moderate to severe reduction in daily activities had a positive LR of 3.2 (95% CI, 1.4-7.2) and specificity of 67% (95% CI, 37%-97%); no reduction to mild reduction in activities had a negative LR of 0.30 (95% CI, 0.22-0.39) and sensitivity of 82% (95% CI, 77%-87%). The prevalence of acute mountain sickness increases with higher altitudes. The visual analog scale for the overall feeling of sickness at altitude, Acute Mountain Sickness-Cerebral, and clinical functional score perform similarly to the Lake Louise Questionnaire Score using a score of 5 or greater as a reference standard. In clinical and travel settings, the clinical functional score is the simplest instrument to use. Clinicians evaluating high-altitude travelers who report moderate to severe limitations in activities of daily living (clinical functional score ≥2) should use the Lake Louise Questionnaire Score to assess the severity of acute mountain sickness

Baseline Psychological Traits Contribute to Lake Louise Acute Mountain Sickness Score at High Altitude

Talks, Benjamin James, Catherine Campbell, Stephanie J. Larcombe, Lucy Marlow, Sarah L. Finnegan, Christopher T. Lewis, Samuel J.E. Lucas, Olivia K. Harrison, and Kyle T.S. Pattinson. Baseline psychological traits contribute to Lake Louise Acute Mountain Sickness score at high altitude. High Alt Med Biol. 23:69-77, 2022. Background: Interoception refers to an individual's ability to sense their internal bodily sensations. Acute mountain sickness (AMS) is a common feature of ascent to high altitude that is only partially explained by measures of peripheral physiology. We hypothesized that interoceptive ability may explain the disconnect between measures of physiology and symptom experience in AMS. Methods: Two groups of 18 participants were recruited to complete a respiratory interoceptive task three times at 2-week intervals. The control group remained in Birmingham (140 m altitude) for all three tests. The altitude group completed test 1 in Birmingham, test 2 the day after arrival at 2,624 m, and test 3 at 2,728 m after an 11-day trek at high altitude (up to 4,800 m). Results: By measuring changes to metacognitive performance, we showed that acute ascent to altitude neither presented an interoceptive challenge, nor acted as interoceptive training. However, AMS symptom burden throughout the trek was found to relate to sea level measures of anxiety, agoraphobia, and neuroticism. Conclusions: This suggests that the Lake Louise AMS score is not solely a reflection of physiological changes on ascent to high altitude, despite often being used as such by researchers and commercial trekking companies alike. Keywords: acute mountain sickness; altitude; breathlessness; exercise; filter detection task; interoceptio

Blood Coagulation Changes at High Altitude

The current concepts of blood coagulation changes in the pathogenesis of acute mountain sickness (AMS), high altitude pulmonary oedema (HAPO), high altitude pulmonary hypertension (HAPH) and chronic mountain sickness(CMS) which afflict the inductees and residents at high altitude have been reviewed. Hypercoagulable state which is more marked during the first few days of exposure is countered by enhanced fibrinolytic activity and accelerated cell mediated immunity. Magnesium levels are increased in normal residents at high altitudes and may be responsible for enhancing fibrinolytic activity and accelerating immune responses. Magnesium levels are significantly reduced in HAPO patients. Judicious use of furosemide in lower dosage is still the mainstay of treatment of HAPO and AMS

Physiology and Medicine at High Altitude: The Exposure and the Stress

Increase in altitude causes decrease in atmospheric barometric pressure that results in decrease of inspiredpartial pressure of oxygen, a source for stress and pose a challenge to climbers/trekkers or persons posted onhigh altitude areas. This review discusses about the high altitude sickness, their incidence rates, pathophysiologyand the classic model of acclimatisation, which explains about how oxygen requirement in extreme environmentis achieved by complex interplay among pulmonary, hematological and cardiovascular processes. The acutehigh altitude illness (AHAI) is basically composed of two syndromes: cerebral and pulmonary that can afflictun-acclimatised climbers/trekkers. The cerebral syndrome includes acute mountain sickness (AMS) and highaltitude cerebral oedema (HACO) and pulmonary syndrome typically refers to high altitude pulmonary oedema(HAPO). The core physiological purpose, according to the classic model is centered upon the optimisation ofincreased delivery of oxygen to the cells through a coherent response involving increased ventilation, cardiacoutput and hemoglobin concentration with aim to increase the oxygen flux across the oxygen cascade, whichwill help in preventing the development of majority of high altitude illness