Dexamethasone for prevention of AMS, HACE, and HAPE and for limiting impairment of performance after rapid ascent to high altitude: a narrative review.

Acute exposure to high altitude can cause acute altitude illnesses and is associated with impaired cognitive and physical performance. The most effective preventive strategies currently recommended include environmental acclimatization (slow ascent and/or pre-acclimatization) or pharmacological support of acclimatization using acetazolamide. However, these strategies are not practical for high-altitude exposures that require rapid and unplanned ascent, high physical and mental performance, such as rescue missions or military operations.

Effects of nocturnal periodic breathing on sympathetic nerve activity and ventilatory control at high altitude: a randomised, crossover study.

During acute exposure to the hypoxia of high altitude, activation of the peripheral chemoreflex increases sympathetic nerve activity (SNA) and pulmonary ventilation. If exposure extends over several days, SNA and ventilation further increase and we investigated whether nocturnal periodic breathing (nPB) - a form of sleep-disordered breathing that is common at high altitude - contributes to these further increases. In a randomised, placebo-controlled, crossover protocol, twelve healthy men completed two 3-day sojourns in hypobaric hypoxia equivalent to 4000 m altitude.

Xenon Inhalation for Expeditions to High Altitude: A Position Statement from the International Climbing and Mountaineering Federation (Union Internationale des Associations d'Alpinisme, UIAA) Medical Commission.

Hilty, Matthias P, Urs Hefti, Pierre Bouzat, Hannes Gatterer, Lenka Horakova, Linda E Keyes, Justin Lawley, Benjamin D Levine, George Rodway, Daniel Trevena, Eduardo Vinhaes, and Benoit Champigneulle. Xenon Inhalation for Expeditions to High Altitude: A Position Statement from the International Climbing and Mountaineering Federation (Union Internationale des Associations d'Alpinisme, UIAA) Medical Commission. 00:00-00, 2025.

Impact of Living in a Mountain Environment on Health and Mortality: Insights from the Alpine Population in Northern Italy.

Introduction: Residing at moderate altitudes has been associated with various health benefits also affecting mortality risk. This study investigates life expectancy and disease-specific mortality rates among populations in the Italian Alps and in northern Italian lowland regions. Additionally, cardiometabolic health and serum metabolite concentrations of residents in an Alpine province across three distinct elevation zones (<1,000 m, 1,000-1,500 m, and >1,500 m above sea level) are studied.

Lack of Altitude Medicine Knowledge Among Mountaineers in the Italian Alps.

Berendsen, Remco R., Dirk C A.A.

A new approach to haemoglobin oxygen affinity research at high altitude: Determination of haemoglobin oxygen dissociation curves and 2,3-bisphosphoglycerate in an experimental human crossover hypoxic chamber study.

Purpose: During rapid exposure to hypobaric hypoxia (HH), arterial oxygen tension and haemoglobin oxygen saturation decrease. The oxygen dissociation curve (ODC) describes the relationship of oxygen tension and haemoglobin oxygen saturation. Previous methods for ODC determination are mostly limited to standard conditions (40 mmHg PCO, 37 °C), and measurements of 2,3-bisphosphoglycerate (2,3-BPG) and adenosine triphosphate (ATP) are omitted.

Marked hemoglobin mass expansion and plasma volume contraction in Sherpas acclimatizing to 5,400 m altitude.

In lowlanders, high altitude (HA) acclimatization induces hemoconcentration by reducing plasma volume (PV) and increasing total hemoglobin mass (Hb). Conversely, Tibetan highlanders living at HA are reported to have a similar hemoglobin concentration ([Hb]) as lowlanders near sea level, and we investigated whether this reflects alterations in the PV or the Hb response to HA. Baseline assessment of PV and Hb was performed by carbon monoxide rebreathing at low altitudes (∼1,400 m) in Sherpas (an ethnic group of Tibetans living in Nepal) and native lowlanders.

Low-dose carbon monoxide inhalation to increase total hemoglobin mass and endurance performance: scientific evidence and implications.

Recently, chronic intermittent inhalation of low-dose carbon monoxide (CO) has been postulated as a practice to increase total hemoglobin mass with potential beneficial effects on endurance performance. In this perspective article, we discuss the potential performance enhancing capabilities as well as the safety concerns, which include individual variability in CO response, and acute and chronic health effects. It is also important to note that according to the World-Anti-Doping-Agency (WADA), CO inhalation could fall under "" and therefore could be considered a prohibited method if used as a non-diagnostic tool.

Cardiorespiratory Responses to Exercise in Hypobaric versus Normobaric Hypoxia: A Randomized, Single-Blind, Crossover Study.

Purpose: There is controversy whether there are meaningful physiological differences between hypobaric (HH) and normobaric hypoxia (NH). This study aimed to compare the cardiorespiratory responses to acute HH and NH under strictly controlled conditions. We hypothesized no differences at rest and during submaximal exercise, whereas during maximal exercise, a higher maximal ventilation (V̇ Emax ), peripheral oxygen saturation (SpO 2 ), and maximal oxygen consumption (V̇O 2max ) in HH than in NH.

Sport climbing performance determinants and functional testing methods: A systematic review.

Background: Sport climbing is becoming incredibly popular both in the general population and among athletes. No consensus exists regarding evidence-based sport-specific performance evaluation; therefore, this systematic review was aimed at analyzing determinants of sport climbing performance and evaluation methods by comparing climbers of different levels.

Methods: PubMed, Scopus, and Web of Science were searched up to December 20,2022.

Flying to high-altitude destinations.

Every year millions of people fly to high-altitude destinations. They thereby expose themselves to specific high-altitude conditions. The hypoxic environment (low ambient oxygen availability) constitutes a major factor affecting health and well-being at high altitude.

Altitude illnesses.

Millions of people visit high-altitude regions annually and more than 80 million live permanently above 2,500 m. Acute high-altitude exposure can trigger high-altitude illnesses (HAIs), including acute mountain sickness (AMS), high-altitude cerebral oedema (HACE) and high-altitude pulmonary oedema (HAPE). Chronic mountain sickness (CMS) can affect high-altitude resident populations worldwide.

Cerebral blood flow regulation in hypobaric hypoxia: role of haemoconcentration.

During acute hypoxic exposure, cerebral blood flow (CBF) increases to compensate for the reduced arterial oxygen content (CaO). Nevertheless, as exposure extends, both CaO and CBF progressively normalize. Haemoconcentration is the primary mechanism underlying the CaO restoration and may therefore explain, at least in part, the CBF normalization.

Effects of periodic breathing on sleep at high altitude: a randomized, placebo-controlled, crossover study using inspiratory CO.

Hypoxia at high altitude facilitates changes in ventilatory control that can lead to nocturnal periodic breathing (nPB). Here, we introduce a placebo-controlled approach to prevent nPB by increasing inspiratory CO and used it to assess whether nPB contributes to the adverse effects of hypoxia on sleep architecture. In a randomized, single-blinded, crossover design, 12 men underwent two sojourns (three days/nights each, separated by 4 weeks) in hypobaric hypoxia corresponding to 4000 m altitude, with polysomnography during the first and third night of each sojourn.

Hypoxia Sensing and Responses in Parkinson's Disease.

Parkinson's disease (PD) is associated with various deficits in sensing and responding to reductions in oxygen availability (hypoxia). Here we summarize the evidence pointing to a central role of hypoxia in PD, discuss the relation of hypoxia and oxygen dependence with pathological hallmarks of PD, including mitochondrial dysfunction, dopaminergic vulnerability, and alpha-synuclein-related pathology, and highlight the link with cellular and systemic oxygen sensing. We describe cases suggesting that hypoxia may trigger Parkinsonian symptoms but also emphasize that the endogenous systems that protect from hypoxia can be harnessed to protect from PD.

Mechanisms underlying the health benefits of intermittent hypoxia conditioning.

Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender.

Repeated Short-Term Bouts of Hyperoxia Improve Aerobic Performance in Acute Hypoxia.

Faulhaber, M, Schneider, S, Rausch, LK, Dünnwald, T, Menz, V, Gatterer, H, Kennedy, MD, and Schobersberger, W. Repeated short-term bouts of hyperoxia improve aerobic performance in acute hypoxia. J Strength Cond Res 37(10): 2016-2022, 2023-This study aimed to test the effects of repeated short-term bouts of hyperoxia on maximal 5-minute cycling performance under acute hypoxic conditions (3,200 m).

Isolated high altitude psychosis, delirium at high altitude, and high altitude cerebral edema: are these diagnoses valid?

Psychosis is a psychopathological syndrome that can be triggered or caused by exposure to high altitude (HA). Psychosis can occur alone as isolated HA psychosis or can be associated with other mental and often also somatic symptoms as a feature of delirium. Psychosis can also occur as a symptom of high altitude cerebral edema (HACE), a life-threatening condition.

Effects of Hypobaric Hypoxia on Coagulation in Healthy Subjects Exposed to 3,500 m Altitude.

Kammerer, Tobias, Anna Walzl, Thomas Müller, Philipp Groene, Giulia Roveri, Rachel Turner, Johanna Roche, Hannes Gatterer, Christoph Siebenmann, and Simon T. Schäfer. Effects of hypobaric hypoxia on coagulation in healthy subjects exposed to 3,500 m altitude.

Surgical masks and filtering facepiece class 2 respirators (FFP2) have no major physiological effects at rest and during moderate exercise at 3000-m altitude: a randomised controlled trial.

Background: During the COVID-19 pandemic, the use of face masks has been recommended or enforced in several situations; however, their effects on physiological parameters and cognitive performance at high altitude are unknown.

Methods: Eight healthy participants (four females) rested and exercised (cycling, 1 W/kg) while wearing no mask, a surgical mask or a filtering facepiece class 2 respirator (FFP2), both in normoxia and hypobaric hypoxia corresponding to an altitude of 3000 m. Arterialised oxygen saturation (SaO2), partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), heart and respiratory rate, pulse oximetry (SpO2), cerebral oxygenation, visual analogue scales for dyspnoea and mask's discomfort were systematically investigated.

Changes in body mass, appetite-related hormones, and appetite sensation in women during 4 days of hypobaric hypoxic exposure equivalent to 3,500-m altitude.

Altitude exposure may suppress appetite and hence provide a viable weight-loss strategy. While changes in food intake and availability as well as physical activity may contribute to altered appetite at altitude, herein we aimed to investigate the isolated effects of hypobaric hypoxia on appetite regulation and sensation. Twelve healthy women (age: 24.

Hypoxia briefly increases diuresis but reduces plasma volume by fluid redistribution in women.

We have recently reported that hypobaric hypoxia (HH) reduces plasma volume (PV) in men by decreasing total circulating plasma protein (TCPP). Here, we investigated whether this applies to women and whether an inflammatory response and/or endothelial glycocalyx shedding could facilitate the TCCP reduction. We further investigated whether acute HH induces a short-lived diuretic response that was overlooked in our recent study, where only 24-h urine volumes were evaluated.