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.

Nutrition in Women at High Altitude: A Scoping Review-UIAA Medical Commission Recommendations.

Andjelkovic, Marija, Peter Paal, Susi Kriemler, Kaste Mateikaite-Pipiriene, Alison Rosier, Beth Beidleman, Mia Derstine, Jacqueline Pichler Hefti, David Hillebrandt, Lenka Horakova, Dominique Jean, and Linda E. Keyes. Nutrition in women at high altitude: a scoping review-UIAA Medical Commission recommendations. High Alt Med Biol. 25:9-15, 2024. Background: Nutritional concerns such as food composition, energy intake, and nutrient absorption are essential for performance at high altitude and may differ between men and women. We performed a scoping review to summarize what is currently known on nutrition for women during short-term, high-altitude, physically active sojourns. Methods: The UIAA Medical Commission convened an international team to review women's health issues at high altitude and to publish updated recommendations. Pertinent literature from PubMed and Cochrane was identified by keyword search combinations (including nutrition, metabolism, energy composition, micronutrients) with additional publications found by hand search. Results: We found 7,165 articles, of which 13 original articles assessed nutritional aspects in physically active women on short-term high-altitude sojourns, with other articles found by hand search. We summarize the main findings. Conclusions: Data on women's nutrition at altitude are very limited. Reduction in energy intake plus increased energy expenditure at high altitude can lead to unbalanced nutrition, negatively influencing high-altitude adaptation and physical performance. Therefore, adequate dietary and fluid intake is essential to maintaining energy balance and hydration at high altitude in women as in men. Iron supplementation should be considered for women with iron depletion before travel.

Intermittent hypoxic exposure does not improve endurance performance at altitude.

PURPOSE: This study examined the effect of 1 wk of normobaric intermittent hypoxic exposure (IHE) combined with exercise training on endurance performance at a 4300-m altitude (HA). METHODS: Seventeen male lowlanders were divided into an IHE (n = 11) or SHAM (n = 6) group. Each completed cycle endurance testing consisting of two 20-min steady state (SS) exercise bouts (at 40% and 60% V O2peak) followed by a 10-min break and then a 720-kJ cycle time trial at HA before IHE or SHAM treatment (Pre-T). IHE treatment consisted of a 2-h rest at a PO2 of 90 mm Hg followed by two 25-min bouts of exercise at approximately 80% of peak HR at a PO2 of 110 mm Hg for 1 wk in a hypoxia room. SHAM treatment was identical except that the PO2 was 148 mm Hg for both rest and exercise. After IHE or SHAM treatment (Post-T), all completed a second cycle endurance test at HA. HR, arterial oxygen saturation (SaO2), and RPE were obtained from the 10th to the 15th minute during the two SS exercise bouts and every 5 min during the time trial. RESULTS: Seven volunteers in the IHE group could not finish the 720-kJ time trial either at Pre-T or at Post-T. Time trial analysis was limited, therefore, to the time to reach 360 kJ (halfway point) for all volunteers. From Pre-T to Post-T, there was no improvement in time trial performance (min +/- SE) in the IHE (62.0 +/- 4.8 to 63.7 +/- 5.2) or SHAM (60.9 +/- 6.3 to 54.2 +/- 6.8) group. There was no change from Pre-T to Post-T in HR, SaO2, and RPE during the two SS exercise bouts or time trial in either group. CONCLUSIONS: One week of IHE combined with exercise training does not improve endurance performance at a 4300-m altitude in male lowlanders.

Intermittent hypoxic exposure does not improve sleep at 4300 m.

The purpose of this study was to determine in sea-level residents if 6 to 7 consecutive days of normobaric intermittent hypoxic exposure (IHE) (hypoxia room: 2-h ambient PO2=90 mmHg sedentary and 1-h ambient PO2=110 mmHg exercising at 80+/-5% of maximum heart rate) improved sleep quality (awakenings per hour) and quantity at altitude (4300 m). We hypothesized that IHE would improve sleep arterial oxygen saturation (SaO2) levels and decrease desaturation events, thereby contributing to improvements in sleep quality and quantity during subsequent exposure to high altitude. Ten sea-level residents (mean+/-SE: 22+/-1 yr, 179+/-2 cm, 79+/-3 kg) were assigned to an IHE group and six to a SHAM group (20+/-0.5 yr, 180+/-3 cm, 77+/-4 kg). Sleep quantity, SaO2, and heart rate (HR) were monitored at sea level and during high altitude (i.e., 4300 m in a hypobaric chamber) before pretest (PRE-T) and 60 h after posttest (POST-T) for the last IHE or SHAM treatment. Over the 6 to 7 days of IHE, resting SaO2 increased from 75+/-1% to 81+/-3% in the IHE group, while the SHAM group remained at 98+/-1%. From PRE-T to POST-T at 4300-m exposure, both the IHE and SHAM groups had significantly higher sleep SaO2, fewer desaturation events per hour, and an increase in the percentage of time asleep while sleeping (sleep percent). The IHE group, but not the SHAM group, had significantly lower sleep HR and a trend to more awakenings during the POST-T 4300-m exposure. These results indicate that although IHE treatment induced significant ventilatory acclimatization, relative to the SHAM group, IHE did not further improve sleep SaO2 quality and quantity following rapid ascent to 4300 m. Rather, it is likely that the acquired ventilatory acclimatization was lost in the 60 h between the last IHE session and the POST-T altitude exposure.