Impact of Sleeping Altitude on Symptoms of Acute Mountain Sickness on Mt. Fuji

Influence of Smoking and Alcohol Habits on Symptoms of Acute Mountain Sickness on Mount Fuji: A Questionnaire Survey-Based Pilot Study

Horiuchi, Masahiro, Satomi Mitsui, and Tadashi Uno. Influence of smoking and alcohol habits on symptoms of acute mountain sickness on Mount Fuji: a questionnaire survey-based pilot study. High Alt Med Biol 00:000-000, 2024. Background: Acute cigarette smoking or alcohol intake would cause opposing vasculature effects that may influence acute mountain sickness (AMS). The present study aimed to investigate the effects of smoking and alcohol consumption behaviors, and acute smoking and consuming alcohol during ascent on AMS on Mount Fuji. Methods: This questionnaire survey study included 887 participants who climbed Mount Fuji and obtained information regarding sex, age, and smoking and alcohol habits, including behavior during ascent. Results: AMS prevalence was 45% for all participants. A univariate analysis revealed that younger participants (20-29 years) were associated with increased AMS prevalence (effect size [ES] = 0.102, p = 0.057) and severity (ES = 0.18, p = 0.01). A prediction model using multiple logistic regression indicated that several factors influenced AMS risk: younger age (p = 0.001), daily smoking habits (p = 0.021), no smoking (p = 0.033), or alcohol consumption during ascent (p = 0.096). Alcohol consumption during ascent had no effect on the increased AMS risk in younger participants (20-29 years), while alcohol consumption during ascent increased AMS risk for middle-age participants (50-59 years). Conclusion: Younger individuals are more likely to experience AMS. Smoking habits are associated with an increased AMS risk. It may be recommended that middle-aged climbers should ascend without consuming alcohol.

Association between high cardiac output at altitude and acute mountain sickness: preliminary study on Mt. Fuji

BACKGROUND

Acute mountain sickness (AMS) affects around 30% of people climbing Mt. Fuji, but its pathogenesis is incompletely understood. The influence of a rapid ascent to high altitude by climbing and summiting Mt. Fuji on cardiac function in the general population is unknown, and its association with altitude sickness has not been clarified.

METHODS

Subjects climbing Mt. Fuji were included. Heart rate, oxygen saturation, systolic blood pressure, cardiac index (CI) and stroke volume index were measured multiple times at 120 m as baseline values and at Mt. Fuji Research Station (MFRS) at 3,775 m. Each value and its difference from the baseline value (Δ) of subjects with AMS (defined as Lake Louise Score [LLS] ≥ 3 with headache after sleeping at 3,775 m) were compared with those of non-AMS subjects.

RESULTS

Eleven volunteers who climbed from 2,380 m to MFRS within 8 h and stayed overnight at MFRS were included. Four suffered AMS. Compared with the non-AMS subjects, CI in the AMS subjects was significantly higher than that before sleeping (median [interquartile range]: 4.9 [4.5, 5.0] vs. 3.8 [3.4, 3.9] mL/min/m²; p = 0.04), and their ΔCI was significantly higher before sleeping (1.6 [1.4, 2.1] vs. 0.2 [0.0, 0.7] mL/min/m²; p < 0.01) and after sleeping (0.7 [0.3, 1.7] vs. -0.2 [-0.5, 0.0] mL/min/m²; p < 0.01). ΔCI in the AMS subjects dropped significantly after sleeping versus before sleeping (3.8 [3.6, 4.5] vs. 4.9 [4.5, 5.0] mL/min/m²; p = 0.04).

CONCLUSIONS

Higher values of CI and ΔCI were observed at high altitude in the AMS subjects. A high cardiac output might be associated with the development of AMS.

Risk factors for acute mountain sickness in travellers to Cusco, Peru: coca leaves, obesity and sex

BACKGROUND

Acute mountain sickness (AMS) may occur after rapid ascents to altitudes >2500 m. Cusco (3350 m) in Peru is a popular destination for altitude inexperienced travellers. This study aimed at evaluating the incidence and risk factors for AMS among a cohort of foreign Spanish language students in Cusco.

METHODS

We performed a cohort study among young healthy foreign Spanish language students arriving to Cusco between 2012 and 2016. Consenting students answered an enrollment questionnaire on demographics, travel history and intended AMS preventive behaviour within 48 h of arrival. At 4-5 days after enrollment participants answered a second questionnaire about actual preventive behaviour before symptoms and the development of symptoms compatible with AMS during their first 48 h in Cusco. We used the 2018 Lake Louise Scoring System for AMS diagnosis. Participants with headache and a score ≥ 3 were considered to have AMS.

RESULTS

We enrolled 142 language students, the median age was 21 years (interquartile range 20-25) and 57% were female. Participants decreased physical activity (38%), increased fluid intake (34%), drank coca leaf tea (34%), took acetazolamide (16%) and acclimatized at a lower altitude (6%) to prevent AMS. Thirty-nine percent had AMS. In the multivariate analysis, obesity [odds ratio (OR) 14.45 (2.33-89.6)] and female sex [OR 4.32 (1.81-10.28)] were associated with increased risk of AMS. Taking acetazolamide [OR 0.13 (0.03-0.56)] was associated with decreased AMS risk. Consumption of coca leaf tea was not associated with decreased risk of AMS.

CONCLUSIONS

In our cohort, AMS affected two out of five travellers. Obesity and female sex were associated with increased risk. Drinking coca leaf tea for prevention did not decrease the risk of AMS. Acetazolamide prophylaxis was associated with decreased risk of AMS.

Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis

BACKGROUND

When lowlanders rapidly ascend to altitudes > 2500 m, they may develop acute mountain sickness (AMS). The individual susceptibility, ascending velocity, time spent at altitude, activity levels and altitude reached are considered risk factors for AMS. However, it is not clear whether sex is a risk factor. The results have been inconclusive. We conducted a meta-analysis to test whether there were sex-based differences in the prevalence of AMS using Lake Louise Scoring System.

METHODS

Systematic searches were performed in August 2019 in EMBASE, PubMed, and Web of Science for prospective studies with AMS data for men and women. The titles and abstracts were independently checked in the primary screening step, and the selected full-text articles were independently assessed in the secondary screening step by the two authors (YPH and JLW) based on pre-defined inclusion criteria. The meta-analysis was performed using by the STATA 14.1 software program. A random-effects model was employed.

RESULTS

Eighteen eligible prospective studies were included. A total of 7669 participants (2639 [34.4%] women) were tested. The results showed that there was a statistically significant higher prevalence rate of AMS in women than in men (RR = 1.24, 95%CI 1.09-1.41), regardless of age or race. Howerver, the heterogeneity was significant in the analysis (Tau² = 0.0403, Chi² = 50.15, df = 17; I² = 66.1%, P = 0.000), it was main caused by different numbers of subjects among the studies (coefficient = - 2.17, P = 0.049). Besides, the results showed that there was no evidence of significant publication bias in the combined studies on the basis of Egger's test (bias coefficient = 1.48, P = 0.052) and Begg's test (P = 0.130).

CONCLUSIONS

According to this study, the statistically significant finding emerging from this study was that women have a higher prevalence of AMS. However, the authors could not exclude studies where patients were on acetazolamide. Our analysis provided a direction for future studies of the relationship of sex and the risk of AMS, such as the pathological mechanism and prevention research.

Prevalence of Falls on Mount Fuji and Associated with Risk Factors: A Questionnaire Survey Study

Since little is known about the detailed situations of falls on Mount Fuji, the aim of this study was to clarify the risk factors of falls on Mount Fuji in Japan. We conducted a questionnaire survey of 556 participants who had climbed Mount Fuji and collected the following information: fall situation, mental status, fatigue feeling, sex, age, climbing experience on Mount Fuji and other mountains, summit success, whether staying at a lodge, use of a tour guide, and symptoms of acute mountain sickness. Among the 556 participants, 167 had a fall (30%). Among 167 participants who had experienced a fall, 30 had fallen more than three times (18%). The main cause (>60%) of fall were slips. The most optimal model using multiple logistic regression (no fall = 0, and fall = 1) found eight significant risk factors, including sex, prior climbing experience on Mount Fuji, staying overnight at a lodge, subjective feeling of relaxation, sleepiness, emotional stability, dullness, and eyestrain. These results suggest that females, people who have no prior climbing experience on Mount Fuji, and people who did not stay at a lodge should pay attention to an increased risk of falls on Mount Fuji.

Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

The importance of arterial oxygen saturation for the prediction of acute mountain sickness (AMS) is still a matter of debate. Reasons for discrepancies may result from varying laboratory or field conditions and their interactions. Thus, we analyzed data from our prior high-altitude studies, including participants of a broad range of age of both sexes (20 males and 20 females, aged between 20 and 67 years) under strictly standardized conditions of pre-exposure and acute exposure to real high altitude (3480 m). A set of resting cardiovascular, respiratory, hematological, and metabolic variables were recorded at high altitude (Testa Grigia, Plateau Rosa, 3480 m; Swiss-Italian boarder) after performing pretests at low altitude (Innsbruck, 600 m, Austria). Our analyses indicate that (1) smaller changes in resting minute ventilation (VE) and a larger decrease of peripheral oxygen saturation (SpO₂) during the first 3 hours of acute exposure to high altitude were independent predictors for subsequent development of AMS (90% correct prediction), (2) there are no differences of responses between sexes, and (3) there is no association of responses with age. Considering the independent effects of both responses (VE and SpO₂) may be of clinical/practical relevance. Moreover, the presented data derived from a broad age range of both sexes might be of interest for comparative purposes.

Combined effects of exposure to hypoxia and cool on walking economy and muscle oxygenation profiles at tibialis anterior

We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O₂ or 13%O₂) on energy cost of walking (C_w: J·kg^-1·km^-1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s^-1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O₂) = NN; 23°C (N) with hypoxia (H: 13%O₂) = NH; cool (C: 13°C) with 21%O₂ (N) = CN, and 13°C (C) with 13%O₂ (H) = CH. Muscle deoxygenation (HHb) and tissue O₂ saturation (StO₂) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s^-1) and CH (1.275 ± 0.099 m s^-1) than in NN (1.334 ± 0.112 m s^-1) and CN (1.332 ± 0.104 m s^-1). Changes in HHb and StO₂ were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO₂ may partly account for an individual ES.