Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update

To provide guidance to clinicians about best practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention, diagnosis, and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches for managing each form of acute altitude illness that incorporate these recommendations as well as recommendations on how to approach high altitude travel following COVID-19 infection. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine in 2010 and the subsequently updated WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2014 and 2019.

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. It is unclear how psychotic symptoms at HA should be classified into existing diagnostic categories of the most widely used classification systems of mental disorders, including the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and the International Statistical Classification of Diseases and Related Health Problems (ICD-11). We provide a diagnostic framework for classifying symptoms using the existing diagnostic categories: psychotic condition due to a general medical condition, brief psychotic disorder, delirium, and HACE. We also discuss the potential classification of isolated HA psychosis into those categories. A valid and reproducible classification of symptoms is essential for communication among professionals, ensuring that patients receive optimal treatment, planning further trips to HA for individuals who have experienced psychosis at HA, and advancing research in the field.

Progress in the Treatment of High Altitude Cerebral Edema: Targeting REDOX Homeostasis

With the increasing of altitude activities from low-altitude people, the study of high altitude cerebral edema (HACE) has been revived. HACE is a severe acute mountain sickness associated with exposure to hypobaric hypoxia at high altitude, often characterized by disturbance of consciousness and ataxia. As for the pathogenesis of HACE, previous studies suggested that it might be related to the disorder of cerebral blood flow, the destruction of blood-brain barrier and the injury of brain parenchyma cells caused by inflammatory factors. In recent years, studies have confirmed that the imbalance of REDOX homeostasis is also involved in the pathogenesis of HACE, which mainly leads to abnormal activation of microglia and destruction of tight junction of vascular endothelial cells through the excessive production of mitochondrial-related reactive oxygen species. Therefore, this review summarizes the role of REDOX homeostasis and the potential of the treatment of REDOX homeostasis in HACE, which is of great significance to expand the understanding of the pathogenesis of HACE. Moreover, it will also be helpful to further study the possible therapy of HACE related to the key link of REDOX homeostasis.

Hiccups and Slurring of Speech: Atypical Presentation of High-Altitude Cerebral Edema

High-altitude cerebral edema (HACE) is one of the rare and severe form of high-altitude mountain sickness. Usually it presents as headache, altered mental status, ataxia in un-acclimatized person with rapid ascent to high altitude. Here we report a case of a 62-year-old male patient who had history of rapid ascent to high altitude and presented to the department of emergency after descent from high altitude with an atypical presentation as hiccups and slurring of speech. Magnetic resonance imaging (MRI) of brain showed white matter edema suggestive of HACE. The patient improved after treatment with supplemental oxygen, dexamethasone, and acetazolamide. He was discharged after three days of hospital stay with complete resolution of symptoms.

High Altitude Cerebral Edema: Improving Treatment Options

High altitude illness in its most severe form can lead to high altitude cerebral edema (HACE). Current strategies have focused on prevention with graduated ascents, pharmacologic prophylaxis, and descent at first signs of symptoms. Little is understood regarding treatment with steroids and oxygenation being commonly utilized. Pre-clinical studies with turmeric derivatives have offered promise due to its anti-inflammatory and antioxidant properties, but they warrant validation clinically. Ongoing work is focused on better understanding the disease pathophysiology with an emphasis on the glymphatic system and venous outflow obstruction. This review highlights what is known regarding diagnosis, treatment, and prevention, while also introducing novel pathophysiology mechanisms warranting further investigation.

Assessment of Psychotic Symptoms in Individuals Exposed to Very High or Extreme Altitude: A Field Study

Hüfner, Katharina, Fabio Caramazza, Agnieszka E. Stawinoga, Evelyn R. Pircher Nöckler, Paolo Fusar-Poli, Sanjeeb S. Bhandari, Buddha Basnyat, Monika Brodmann Maeder, Giacomo Strapazzon, Iztok Tomazin, Barbara Sperner-Unterweger, and Hermann Brugger. Assessment of psychotic symptoms in individuals exposed to very high or extreme altitude: A field study. High Alt Med Biol. xx:xxx-xxx, 2021. Background: Symptoms of psychosis such as hallucinations can occur at high or extreme altitude and have been linked to accidents on the mountain. No data are available on how to assess such symptoms in the field and what their prevalence or predisposing factors might be. Methods: In this field study at Everest Base Camp (5,365 m) in Nepal, 99 participants of organized expeditions underwent 279 assessments: The High Altitude Psychosis Questionnaire (HAPSY-Q), the Prodromal Questionnaire, 16-items (PQ-16), and the Mini International Neuropsychiatric Interview (M.I.N.I., psychosis section) were collected together with further clinical data. Statistical analysis was done for each phase, that is, altitude range of the climb, and overall data. Results: One of 97 climbers fulfilled the M.I.N.I. diagnostic criteria for psychosis during one acclimatization climb. At least one endorsed item on the HAPSY-Q and the PQ-16, indicating the presence of symptoms of psychosis in the absence of a psychotic disorders, were identified in 10/97 (10.3%) and 18/87 (20.7%) participants respectively. The scores of the HAPSY-Q and the PQ-16 were correlated (r = 0.268, p < 0.001). Odds ratio analysis identified an increased risk for accidents in individuals with endorsed items on the HAPSY-Q. Conclusions: The diagnosis of high altitude psychosis is rare in climbers during organized expeditions. Nevertheless, subdiagnostic symptoms of psychosis occurred in a significant proportion of climbers. Future research is needed to validate these pilot findings.

Altitude-Related Disorders on Mount Kilimanjaro, Tanzania: Two-Year Survey in a Local Referral Center

INTRODUCTION

A significant number of climbers on Mount Kilimanjaro are affected by altitude-related disorders. The aim of this study was to determine the main causes of morbidity and mortality in a representative cohort of climbers based on local hospital records.

METHODS

We conducted a 2-y retrospective chart review of all patients presenting to the main referral hospital in the region after a climb on Mount Kilimanjaro, including all relevant records and referrals for postmortem studies.

RESULTS

We identified 62 climbers who presented to the hospital: 47 inpatients and 15 outpatients. Fifty-six presented with high altitude illness, which included acute mountain sickness (n=8; 14%), high altitude pulmonary edema (HAPE) (n=30; 54%), high altitude cerebral edema (HACE) (n=7; 12%), and combined HAPE/HACE (n=11; 20%). The mean altitude of symptom onset ranged from 4600±750 m for HAPE to 5000±430 m for HAPE/HACE. The vast majority of inpatients (n=41; 87%) were improved on discharge. Twenty-one deceased climbers, most having died while climbing (n=17; 81%), underwent postmortem evaluation. Causes of death were HAPE (n=16; 76%), HAPE/HACE (n=3; 14%), trauma (1), and cardiopulmonary (1).

CONCLUSIONS

HAPE was the main cause of death during climbing as well as for hospital admissions. The vast majority of climbers who presented to hospital made a full recovery.

[High altitude illness and related diseases - a review]

Upon reaching a height over 2500 m above seal level symptoms of altitude illness can develop over 1 - 5 days. The risk is mainly -determined by the altitude and rate of ascent and the symptoms vary. Most common are symptoms of acute mountain illness (AMS) but more dangerous high altitude cerebral edema (HACE) and high altitude pulmonary edema (HAPE) can also develop. The causes of AMS, HACE and HAPE are lack of oxygen and insufficient acclimatization, but the presenting form is determined by the responses of the body to the lack of oxygen. The most common symptoms of AMS include headache, fatique and nausea, but insomnia and nausea are also common. The most common symptoms of HAPE are breathlessness and lassitude whereas the cardinal sign of HACE is ataxia, but confusion and loss of consciousness can also develop. In this article all three main forms of altitude illness are reviewed. The emphasis is on preventive measures and treatment but new knowledge on pathogenesis is also addressed.

Polysaccharide extracted from Potentilla anserina L ameliorate acute hypobaric hypoxia-induced brain impairment in rats

High altitude cerebral edema (HACE) is a high altitude malady caused by acute hypobaric hypoxia (AHH), in which pathogenesis is associated with oxidative stress and inflammatory cytokines. Potentilla anserina L is mainly distributed in Tibetan Plateau, and its polysaccharide possesses many physiological and pharmacological properties. In the present study, the protective effect and potential treatment mechanism of Potentilla anserina L polysaccharide (PAP) in HACE were explored. First, we measured the brain water content and observed the pathological changes in brain tissues, furthermore, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione (GSH) were evaluated by kits. Finally, the protein contents and mRNA expressions of pro-inflammatory (IL-1β, IL-6, TNF-α, vascular endothelial cell growth factor [VEGF], NF-κB, and hypoxia inducible factor-1 α [HIF-1α]) were detected by ELISA kits, RT-PCR, and western blotting. The results demonstrated that PAP reduced the brain water content, alleviated brain tissue injury, reduce the levels of MDA and NO, and increased the activity of SOD and GSH level. In addition, PAP blocking the NF-κB and HIF-1α signaling pathway activation inhibited the generation of downstream pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and VEGF). Therefore, PAP has a potential to treat and prevent of HACE by suppression of oxidative stress and inflammatory response.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2019 Update

To provide guidance to clinicians about best preventive and therapeutic practices, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. Recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each form of acute altitude illness that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in 2010 and subsequently updated as the WMS Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness in 2014.

Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update

To provide guidance to clinicians about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for prevention and treatment of acute mountain sickness, high altitude cerebral edema, and high altitude pulmonary edema. These guidelines present the main prophylactic and therapeutic modalities for each disorder and provide recommendations about their role in disease management. Recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens according to criteria put forth by the American College of Chest Physicians. The guidelines also provide suggested approaches to prevention and management of each disorder that incorporate these recommendations. This is an updated version of the original WMS Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness published in Wilderness & Environmental Medicine 2010;21(2):146-155.