High altitude medicine & biology最新文献

González-García, Mauricio and Luis Ernesto Téllez. Adaptation to living at high altitude in patients with COPD. Comparative study of exercise capacity and ventilatory variables between patients residing at high and low altitudes in the Andes. High Alt Med Biol. 00:000-000, 2024. Introduction: Although some variables related to oxygen transport and utilization such as ventilation, pulmonary vascular responses to hypoxia, heart rate (HR), cardiac output, hemoglobin (Hb), and oxygen saturation (SpO₂) are used to compare adaptation to altitude between populations, peak oxygen consumption (VO₂) constitutes an integrative measure of total oxygen transport that may reflect successful adaptation to altitude. We designed this study to make a direct comparison of VO₂ in a cardiopulmonary exercise test (CPET) between chronic obstructive pulmonary disease (COPD) patients residing at high altitude (Bogotá, Colombia: 2,640 m) (COPD-HA) and those living at low altitude (Bucaramanga, Colombia: 959 m) (COPD-LA). Methods: All patients performed a CPET with measurements of VO₂, minute ventilation (V_E), HR, oxygen pulse (VO₂/HR), ventilatory equivalents (V_E/VCO₂), and SpO₂. Unpaired T-test or Mann-Whitney U test were used for comparisons between COPD-HA and COPD-LA. Results: We included 71 patients with COPD, 53 COPD-HA, and 18 COPD-LA. There were no differences between groups in age, sex, or forced expiratory volume in 1 second. The means ± SD of Hb, g/dl was slightly higher in COPD-HA (15.9 ± 1.9 vs. 14.7 ± 1.8, p = 0.048), without differences in VO₂, % pred (71.6 ± 17.9 vs. 69.0 ± 17.0, p = 0.584), VO₂/HR, % pred (92.1 ± 22.0 vs. 89.7 ± 19.8, p = 0.733) or V_E/MVV, % (75.5 ± 14.1 vs. 76.5 ± 14.3, p = 0.790) at peak exercise between groups. Median (IQR) of V_E/VCO₂ nadir [38.0 (37.0-42.0) vs. 32.5 (31.0-39.0), p = 0.005] was significantly higher, and SpO₂, % at rest [88.0 (86.0-91.0) vs. 95.0 (94.0-96.0), p < 0.001] and at peak exercise [84.0 (77.0-90.0) vs. 93.0 (92.0-95.0), p < 0.001] were significantly lower in COPD-HA. Conclusions: Despite higher desaturation at rest and during exercise in COPD-HA, there were no differences in VO₂ peak between COPD-HA and COPD-LA, suggesting a potential altitude adaptation in those patients chronically exposed to hypoxia.

Poudel, Sangeeta, Sandesh Gautam, Purushottam Adhikari, and Ken Zafren. Physiological effects of sildenafil versus placebo at high altitude: a systematic review. High Alt Med Biol. 25:16-25, 2024. Introduction: High altitude pulmonary edema (HAPE), a life-threatening condition that affects individuals ascending to high altitude, requires the development of pulmonary hypertension. Sildenafil can be used to prevent and treat HAPE, presumably by decreasing pulmonary artery pressure (PaP). We compared the physiological effects of sildenafil versus placebo at high altitude (above 2,500 m), including the effects on PaP. Methods: We performed a systematic search of PubMed, EMBASE, and Cochrane CENTRAL for randomized controlled studies of the physiological effects of sildenafil in hypoxia in healthy individuals. We conducted a systematic review of all studies meeting our criteria. Results: Of the 14 studies that met the inclusion criteria, 8 were hypobaric hypoxia studies. Six studies reported data at rest at altitudes from 3,650 to 5,245 m. Two were simulations reporting exercise data at equivalent altitudes of 2,750-5,000 m. Nine studies used normobaric hypoxia corresponding to altitudes between 2,500 and 6,400 m. One reported only rest data, two reported rest and exercise data, and the others reported only exercise data. Sildenafil significantly reduced PaP at rest and exercise in hypobaric or normobaric hypoxia. There were no significant differences between arterial oxygen saturation (SpO₂) with sildenafil in hypobaric or normobaric hypoxia at rest or exercise. There were no significant differences in heart rate or mean arterial pressure (MAP) at rest or exercise and cardiac output during exercise in hypobaric or normobaric hypoxia. Conclusions: Sildenafil significantly reduces PaP at rest and exercise in normobaric or hypobaric hypoxia. Sildenafil has no significant effects on SpO₂, heart rate, cardiac output (during exercise), or MAP at rest or exercise in hypobaric or normobaric hypoxia.

Westwood, Jessica, India Mayhook-Walker, Ciaran Simpkins, Andrew Darby-Smith, Dan Morris, and Eduardo Normando. Retinal vascular changes in response to hypoxia: a high-altitude expedition study. High Alt Med Biol. 25:49-59, 2024. Background: Increased tortuosity and engorgement of retinal vasculature are recognized physiological responses to hypoxia. This can lead to high-altitude retinopathy (HAR), but incidence reports are highly variable, and our understanding of the etiological mechanisms remains incomplete. This study quantitatively evaluated retinal vascular changes during an expedition to 4,167 m. Methods: Ten healthy participants summited Mount Toubkal, Morocco. Fundus images were taken predeparture, daily throughout the expedition, and 1 month postreturn. Diameter and tortuosity of four vessels were assessed, in addition to vessel density and features of HAR. Results: Significant (p ≤ 0.05) increases in tortuosity and diameter were observed in several vessels on high-altitude exposure days. There was a strong correlation between altitude and supratemporal retinal artery diameter on days 2, 3, and 6 of the expedition (r = 0.7707, 0.7951, 0.7401, respectively; p < 0.05). There was a significant increase in median vessel density from 6.7% at baseline to 10.0% on summit day. Notably there were no incidences of HAR. Conclusion: Physiological but not pathological changes were seen in this cohort, which gives insight into the state of the cerebral vasculature throughout this expedition. These results are likely attributable to relatively low altitude exposure, a conservative ascent profile, and the cohort's demographic. Future study must include daily retinal images at higher altitudes and take steps to mitigate environmental confounders. This study is relevant to altitude tourists, patients with diabetic retinopathy or retinal vein occlusion, and critically ill patients.

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.

Background: Acute altitude has a relevant impact on exercise physiology and performance. Therefore, the positive impact on the performance level is utilized as a training strategy in professional as well as recreational athletes. However, ventilatory thresholds (VTs) and lactate thresholds (LTs), as established performance measures, cannot be easily assessed at high altitudes. Therefore, a noninvasive, reliable, and cost-effective method is needed to facilitate and monitor training management at high altitudes. High Alt Med Biol. 25:94-99, 2024. Methods: In a cross-sectional setting, a total of 14 healthy recreational athletes performed a graded cycling exercise test at sea level (Munich, Germany: 512 m/949 mbar) and high altitude (Zugspitze: 2,650 m/715 mbar). Anaerobic thresholds (ATs) were assessed using a novel method based on beat-to-beat repolarization instability (dT) detected by Frank-lead electrocardiogram (ECG) monitoring. The ECG-based ATs (ATdT°) were compared to routine LTs assessed according to Dickhuth and Mader. Results: After acute altitude exposure, a decrease in AT was detected using a novel ECG-based method (ATdT°: 159.80 ± 52.21 W vs. 134.66 ± 34.91 W). AtdT° levels correlated significantly with LT_Dickhuth and LT_Mader, at baseline (r_{Dickhuth/AtdT°} = 0.979; p < 0.001) (r_Mader/AtdT° = 0.943; p < 0.001), and at high altitude (r_{Dickhuth/AtdT°} = 0.969; p < 0.001) (r_Mader/AtdT° = 0.942; p < 0.001). Conclusion: Assessment of ATdT is a reliable method to detect performance alterations at altitude. This novel method may facilitate the training management of athletes at high altitudes.

Tanaka, Shota, Koshi Nakagawa, Yosuke Kanagawa, Takashi Katsurahara, Kazuki Kozakai, Ken Tsuhako, Fumitaka Yoshikawa, Soh Gotoh, Kensuke Osanai, Madoka Sono, Hironori Inoue, Shuji Sakanashi, Hiroyuki Takahashi, and Hideharu Tanaka. Quality of cardiopulmonary resuscitation in avalanche victims with a single rescuer: a prospective, crossover, manikin pilot study. High Alt Med Biol. 25:60-67, 2024. Background: Winter outdoor recreational activities such as off-piste skiing have gained popularity and, as a result, the number of avalanche-related deaths has increased. However, the quality of cardiopulmonary resuscitation (CPR) at avalanche sites remains unclear. Our study compared the quality of CPR performed in a simulated avalanche burial on a snowy mountain with that performed indoors. Methods: Ten prehospital health care providers participated in the crossover pilot study. Various methods, including over-the-head CPR (OTH-CPR) and standard CPR, were used to perform avalanche resuscitation, with five rescue breaths, followed by 30 chest compressions and two breaths. The quality CPR was judged by four variables of chest compression and ventilation. Results: The OTH-CPR performed indoors was better in quality: 5.33% [95% confidence interval (CI) -14.2 to 3.5] higher in adequate compression depth (94.3 ± 10.6% on the snow vs. 99.3 ± 1.1% indoors), 3.4% [95% CI -16.1 to 22.9] higher in adequate compression rate (70.4 ± 38.0% vs. 76.1 ± 35.7%), and 2.3% [95% CI -6.4 to 1.72] higher in adequate recoil (96.9 ± 4.8% vs. 99.2 ± 1.6%) than OTH-CPR on the snow. In terms of ventilation quality, OTH-CPR performed indoors had a 50% higher ventilation score [95% CI -73.0 to -27.0] than OTH-CPR on the snow (1.4 ± 4.3% vs. 45.9 ± 32.6%, Cohen's d = -1.81). Conclusions: Chest compression quality was slightly impaired in the avalanche scenarios on the snow than in indoor settings. Asphyxiation is the main cause of avalanche-related deaths; however, low ventilation quality was observed on snow compared with the indoor setting.