Prevalence Of Acute Mountain Sickness Research Articles

Reestablishing the Prevalence of Acute Mountain Sickness in Nepal: Surveying Manang and the Khumbu

Reestablishing the Prevalence of Acute Mountain Sickness in Nepal: Surveying Manang and the Khumbu

Effects of age on hypoxic tolerance in women

Effects of age on hypoxic tolerance in women

Prevalence and knowledge about acute mountain sickness in the Western Alps.

To assess the prevalence of acute mountain sickness (AMS) in 1370 mountaineers at four different altitudes in the Western Alps. We also examined the influence of potential risk factors and the knowledge about AMS on its prevalence. In this observational cross-sectional study AMS was assessed on the day of ascent by the Lake Louise score (LLS, cut-off ≥3, version 2018) and the AMS-Cerebral (AMS-C) score of the environmental symptom questionnaire (cut-off ≥0,70). The latter was also obtained in the next morning. Knowledge regarding AMS and high-altitude cerebral edema (HACE) and the potential risk factors for AMS were evaluated by questionnaires. On the day of ascent, the prevalence of AMS assessed by the LLS and AMS-C score was 5.8 and 3.9% at 2850 m, 2.1 and 3.1% at 3050 m, 14.8 and 10.1% at 3650 m, and 21.9 and 15% at 4559 m, respectively. The AMS prevalence increased overnight from 10.1 to 14.5% and from 15 to 25.2% at 3650 m and 4559 m, respectively, and was unchanged at 2850 m and 3050 m. A history of AMS, higher altitude, lower degree of pre-acclimatization, and younger age were identified as risk factors for developing AMS. Slow ascent was weakly associated with AMS prevalence, and sex and knowledge about AMS and HACE were indistinct. AMS is common at altitudes ≥ 3650 m and better knowledge about AMS and HACE was not associated with less AMS in mountaineers with on average little knowledge.

Is it time to revise the acclimatization schedule at high altitude? Evidence from a field trial in Western Himalayas

BackgroundIn Western Himalayas, Indian Army soldiers take 11 days (6 days of acclimatization and 5 days of travel) on a sea-level to high altitude road (SH road) to reach a high altitude location (HAL) situated at an altitude of 11,500 feet from sea-level location (SLL) at an altitude of 1150 feet while following acclimatization schedule (AS). AS has an extra safety margin over the conventional ‘mountaineering thumb rule’ of not exceeding 500m sleeping altitude above 3000m altitude. We carried out this randomised field trial to study the feasibility of moving large number of troops rapidly from SLL to HAL on SH road in western Himalayas in 4 days under pharmaco-prophylaxis. MethodsBased on the pharmaco-prophylaxis, at SLL 508 healthy lowland soldiers were divided into two groups: ‘A’ (n=256) with Acetazolamide+Dexamethasone and ‘B’ (n=252) with Acetazolamide+Placebo. They travelled rapidly by road to HAL in 4 days and prevalence of acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE) during the ascent was measured. ResultsPrevalence of AMS was found to be 1.56% and 1.59% in group ‘A’ and group ‘B’ respectively during the ascent with no cases of HAPE and HACE. ConclusionAt least on SH road, troops can be inducted rapidly to HAL from SLL in 4 days under pharmaco-prophylaxis with Acetazolamide with minimal occurrence of acute high altitude illnesses.

Budesonide Versus Acetazolamide for Prevention of Acute Mountain Sickness

BackgroundInhaled budesonide has been suggested as a novel prevention for acute mountain sickness. However, efficacy has not been compared with the standard acute mountain sickness prevention medication acetazolamide. MethodsThis double-blind, randomized, placebo-controlled trial compared inhaled budesonide versus oral acetazolamide versus placebo, starting the morning of ascent from 1240 m (4100 ft) to 3810 m (12,570 ft) over 4 hours. The primary outcome was acute mountain sickness incidence (headache and Lake Louise Questionnaire ≥3 and another symptom). ResultsA total of 103 participants were enrolled and completed the study; 33 (32%) received budesonide, 35 (34%) acetazolamide, and 35 (34%) placebo. Demographics were not different between the groups (P > .09). Acute mountain sickness prevalence was 73%, with severe acute mountain sickness of 47%. Fewer participants in the acetazolamide group (n = 15, 43%) developed acute mountain sickness compared with both budesonide (n = 24, 73%) (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.3-10.1) and placebo (n = 22, 63%) (OR 0.5, 95% CI 0.2-1.2). Severe acute mountain sickness was reduced with acetazolamide (n = 11, 31%) compared with both budesonide (n = 18, 55%) (OR 2.6, 95% CI 1-7.2) and placebo (n = 19, 54%) (OR 0.4, 95% CI 0.1-1), with a number needed to treat of 4. ConclusionBudesonide was ineffective for the prevention of acute mountain sickness, and acetazolamide was preventive of severe acute mountain sickness taken just before rapid ascent.

Prevalence of acute mountain sickness on Mount Fuji: A pilot study.

Few studies have investigated climbing-related acute mountain sickness (AMS) on Mt Fuji. Although several studies of AMS have been conducted elsewhere, Mt Fuji is unique because there are many mountain lodges between the fifth station (a common starting point for climbers at an altitude of 2305 m) and the summit (3776 m), and many climbers commonly sleep overnight at mountain lodges during their ascents. This study surveyed the prevalence of AMS among climbers on Mt Fuji to determine which factors, if any, were related to the risk of developing AMS. This study collected data from 345 participants who climbed Mt Fuji in August 2013, including information regarding age, sex, climbing experience and whether the climber stayed at a mountain lodge (n = 239). AMS was surveyed using the Lake Louise Score (LLS) questionnaire. The item on perceived sleep quality was excluded for those who did not stay at a mountain lodge (n = 106). The overall prevalence of AMS was 29.5% (≥ 3 LLS with headache). According to a univariate analysis, AMS was not associated with sex (male vs female), age group (20-29, 30-39, 40-49 or >50 years) or stay at a mountain lodge (single day vs overnight stay). Conversely, prior experience climbing Mt Fuji (no prior attempts vs one or more prior attempts) was related to the risk of AMS. In addition, there was a significant deviation in the number of participants reporting poor sleep, and total sleep time was significantly shorter in participants with AMS. These preliminary findings suggest that no single factor can explain the risk for developing AMS while climbing Mt Fuji. In addition, impaired perceived sleep quality was associated with the severity of AMS in climbers who stayed overnight at a mountain lodge.

Prevalence of Acute Mountain Sickness at 3500 m Within and Between Families: A Prospective Cohort Study

To investigate symptoms, prevalence and associated factors of acute mountain sickness (AMS) in families upon a fast ascent to 3450 m. 87 children, 70 adolescents, and 155 parents (n=312) were assessed for AMS 8-10 and 20-24 hours after fast passive ascent by the Lake Louise Score (LLS). Pain sensitivity and oxygen saturation (SO2) were measured and familial clustering was assessed. AMS prevalence was significantly lower in children (21%) compared to adolescents (34%) and adults (39%) on day 1 (p<0.05), but not on day 2 (18% vs. 19% and 25%). Cumulative prevalence of AMS was 30, 37, and 45% in children, adolescents, and adults, respectively (p<0.001). Familial clustering of AMS was consistent and explained 25%-50% of variability in AMS. Pain sensitivity significantly increased from low to high altitude and was higher at low altitude in those with compared to those without AMS. SO2 at high altitude was not related to the presence of AMS. After fast ascent to 3500 m, AMS prevalence was lower in children than in adolescents and adults on day 1, but not on day 2. Thus, children may travel at least as safely to an altitude of 3500 m as adolescents and adults, even if risk factors (pain sensitivity and heredity) are present.

A pilot study on the prevalence of acute mountain sickness at the sikh pilgrimage of hemkund sahib in the Indian Himalayas

Background:Hemkund Sahib is a popular pilgrimage located at 4,330 m in the Garhwal range of the Indian Himalayas. Many travelers to the region have observed pilgrims exhibiting Acute Mountain Sickness (AMS)-like symptoms. However, no systematic study on its prevalence at Hemkund has been conducted.Materials and Methods:We surveyed 25 adults. AMS rates were determined using a standard Lake Louise Score (LLS). Responses to questions related to awareness of AMS, the perceived difficulty of the trek, and physiological data including arterial oxygen saturation (SpO2) and pulse rate, amongst others, were collected.Results:Overall prevalence of AMS was 28% (mild AMS 20%, severe AMS 8%). Borg Rating of Perceived Exertion (RPE) was 3.9/10. Water consumption for the 4-5 hour trek to Hemkund was only 0.9 L and 20% of pilgrims consumed no water at all. Nine pilgrims claimed to be aware of AMS although only one had taken prophylactic medication. SpO2 was 82.2 ± 1.2% and pulse rate was 106.5 ± 2.9 bpm (mean ± SEM). There were no differences in non-LLS-related parameters when pilgrims were subdivided by presence or absence of AMS.Conclusion:This pilot study has, for the first time, documented the prevalence of AMS amongst pilgrims to Hemkund Sahib in the Indian Himalayas.

Effect of hypohydration and altitude exposure on aerobic exercise performance and acute mountain sickness

Hypoxia often causes body water deficits (hypohydration, HYPO); however, the effects of HYPO on aerobic exercise performance and prevalence of acute mountain sickness (AMS) at high altitude (ALT) have not been reported. We hypothesized that 1) HYPO and ALT would each degrade aerobic performance relative to sea level (SL)-euhydrated (EUH) conditions, and combining HYPO and ALT would further degrade performance more than one stressor alone; and 2) HYPO would increase the prevalence and severity of AMS symptoms. Seven lowlander men (25 ± 7 yr old; 82 ± 11 kg; mean ± SD) completed four separate experimental trials. Trials were 1) SL-EUH, 2) SL-HYPO, 3) ALT-EUH, and 4) ALT-HYPO. In HYPO, subjects were dehydrated by 4% of body mass. Subjects maintained hydration status overnight and the following morning entered a hypobaric chamber (at SL or 3,048 m, 27°C) where they completed 30 min of submaximal exercise immediately followed by a 30-min performance time trial (TT). AMS was measured with the Environmental Symptoms Questionnaire-Cerebral Score (AMS-C) and the Lake Louise Scoring System (LLS). The percent change in TT performance, relative to SL-EUH, was -19 ± 12% (334 ± 64 to 278 ± 87 kJ), -11 ± 10% (334 ± 64 to 293 ± 33 kJ), and -34 ± 22% (334 ± 64 to 227 ± 95 kJ), for SL-HYPO, ALT-EUH, and ALT-HYPO, respectively. AMS symptom prevalence was 2/7 subjects at ALT-EUH for AMS-C and LLS and 5/7 and 4/7 at ALT-HYPO for AMS-C and LLS, respectively. The AMS-C symptom severity score (AMS-C score) tended to increase from ALT-EUH to ALT-HYPO but was not significant (P = 0.07). In conclusion, hypohydration at 3,048 m 1) degrades aerobic performance in an additive manner with that induced by ALT; and 2) did not appear to increase the prevalence/severity of AMS symptoms.

Prevalence of Acute Mountain Sickness in the Eastern Alps

Little information is available on the prevalence of acute mountain sickness (AMS) in the Eastern Alps compared with the Western Alps. Because of differences regarding the populations of mountaineers, we hypothesized that the prevalence differs between the Eastern and Western Alps. Thus, we determined the prevalence and risk factors of AMS at four different altitudes in the Eastern Alps of Austria. Four hundred and thirty-one recreational hikers were studied using questionnaires on the morning of their first night at high altitude. A diagnosis of AMS was based on a Lake Louise Score > or =4, the presence of headache, and at least one additional symptom. Overall 16.2% of the subjects met the criteria for AMS, and the prevalence of AMS increased significantly with altitude (2200 m: 6.9%; 2500 m: 9.1%; 2800 m: 17.4%; 3500 m: 38.0%). Heavy perceived exertion, a history of migraine, the absolute altitude reached, little mountaineering experience, and inadequate water intake (< or =2 L) were independent AMS risk factors. The reported altitude-related AMS prevalence in the Western Alps is 4% to 8% lower compared with that found in this study for the Eastern Alps. In conclusion, the prevalence of AMS is higher in the tourist population of the Eastern Alps compared to the more experienced mountaineers of the Western Alps. Consideration of easily modifiable risk factors such as individual exertion and water intake could markedly reduce AMS and contribute to the enjoyment of mountaineering.

Prevalence and Time Course of Acute Mountain Sickness in Older Children and Adolescents After Rapid Ascent to 3450 Meters

Acute mountain sickness is a frequent and debilitating complication of high-altitude exposure, but there is little information on the prevalence and time course of acute mountain sickness in children and adolescents after rapid ascent by mechanical transportation to 3500 m, an altitude at which major tourist destinations are located throughout the world. We performed serial assessments of acute mountain sickness (Lake Louise scores) in 48 healthy nonacclimatized children and adolescents (mean +/- SD age: 13.7 +/- 0.3 years; 20 girls and 28 boys), with no previous high-altitude experience, 6, 18, and 42 hours after arrival at the Jungfraujoch high-altitude research station (3450 m), which was reached through a 2.5-hour train ascent. We found that the overall prevalence of acute mountain sickness during the first 3 days at high altitude was 37.5%. Rates were similar for the 2 genders and decreased progressively during the stay (25% at 6 hours, 21% at 18 hours, and 8% at 42 hours). None of the subjects needed to be evacuated to lower altitude. Five subjects needed symptomatic treatment and responded well. After rapid ascent to high altitude, the prevalence of acute mountain sickness in children and adolescents was relatively low; the clinical manifestations were benign and resolved rapidly. These findings suggest that, for the majority of healthy nonacclimatized children and adolescents, travel to 3500 m is safe and pharmacologic prophylaxis for acute mountain sickness is not needed.

Prevalence of Acute Mountain Sickness among Finnish Trekkers on Mount Kilimanjaro, Tanzania: An Observational Study

The aim of this study was to evaluate the prevalence of acute mountain sickness (AMS) among trekkers on Mount Kilimanjaro during the winter season of 2006-2007. A A total of 130 Finnish trekkers at Marungu route were asked to complete daily a Lake Louise self-report and clinical assessment score questionnaire with the help of a trainee Finnish guide during their trek to Kilimanjaro. A Lake Louise questionnaire score>or=3 indicated AMS. Altogether 112 mountaineers or travelers [54 men, 58 women, mean age 51+/-10 (SD) years] were studied. Fifty-nine travelers (53%) reached Gillman's Point or Uhuru Peak. The incidence of AMS among Finnish Kilimanjaro trekkers was 75%. The most common high altitude symptoms were headache, followed by sleeping problems and fatigue or weakness. The incidence of AMS is high among trekkers climbing Mount Kilimanjaro.The main reason for this seems to be rapid ascent. Kilimanjaro treks normally have a fixed timetable, and for commercial reasons there is little opportunity to spend extra days for acclimatization in the camps. Some contributing factors are preventable, so we recommend an educational program for all the trekking agencies that guide on this peak and, in particular, the Tanzania-based guiding agencies, which, typically, are driving these very fast ascent rates.

Very low prevalence of acute mountain sickness in teenagers after rapid ascent to 3454 m

Acute mountain sickness (AMS) is a frequent and debilitating complication of high‐altitude exposure. After a rapid ascent to tourist destinations located above 3000 m, as many as 60% of an adult population are affected. Circumstantial evidence suggests that children and teenagers may be even more susceptible to AMS than adults, but direct evidence is lacking. We, therefore, performed serial assessments of AMS (Lake Louise Score, LLS) in 48 teenagers (mean±SD age, 13.7±0.3 yrs; 20 girls and 28 boys) 6, 24, 48 hrs after arrival at the Jungfraujoch high‐altitude research station (3454 m) reached after a 2 hr ascent by train. The major new finding was that 6 hrs after arrival, AMS (LLS≥3) was present in only 22% of the subjects (mean score 4.1±0.4, range 3–7). The incidence of AMS was similar in both genders and steadily declined during the stay (17% at 24 hrs, 8% at 48 hrs). None of the subjects needed pharmacological treatment other than paracetamol. In conclusion, in teenagers the incidence of AMS after rapid arrival at an altitude where major high‐altitude tourist destinations are located world‐wide, is surprisingly low, benign, and resolves rapidly. These findings challenge the notion that teenagers are more susceptible to AMS than adults. They suggest that for the vast majority of teenagers, travel to these altitudes is safe and does not necessitate pharmacological prophylaxis for AMS.Grant support: Swiss National Science Foundation.

Mountain Sickness Knowledge Among Foreign Travelers in Cuzco, Peru

Cuzco, Peru, is host to a dangerous mix of high altitude and rapid access from low elevation, which results in a high prevalence of acute mountain sickness (AMS). Thus, it is important that travelers entering Cuzco understand the basics of AMS. To this end, we assessed travelers' awareness of AMS, especially the resources used to obtain this knowledge. With this information we make recommendations with regard to better avenues for distribution of AMS information. One hundred foreign travelers, representing an international population, completed a 45-item written questionnaire that was subsequently analyzed. Over half of the respondents (51%) rated their knowledge of AMS as "low" or "none." Furthermore, very few respondents knew about acetazolamide (Diamox) as prophylaxis for (9%) or treatment of AMS (5%). People who consulted physicians for AMS information were more likely to know about the utility of acetazolamide than those who depended on a guidebook (P = .0266) but were less likely to correctly identify the symptomatology of AMS (P = .047). While AMS knowledge was poor, the majority of travelers (90%) indicated compliance with recommended pretravel vaccinations. This survey adds to the body of knowledge that indicates a lack of AMS knowledge among travelers. In addition, this survey identifies 2 potential avenues for improved dispersal of information: 1) guidebooks for countries of concern and 2) national health agency Web sites linked to information on pretravel vaccinations. Recommendations are made to utilize these commonly accessed resources to increase AMS information distribution to the general populous.

Self-Assessment of Acute Mountain Sickness in Adolescents: A Pilot Study☆

To perform a pilot study exploring the prevalence of acute mountain sickness (AMS) in adolescents on ascent to altitude and evaluating whether this age group is capable of self-assessment of AMS using the Lake Louise scoring system. Twelve teenagers aged 15 to 18 years old (5 girls) traveled for 21 days between 2400 and 5500 m. Each member of the expedition completed a Lake Louise self-assessment questionnaire on a daily basis. Group leaders (nonmedical) were informed about any subject with a score of 3 or more. Appropriate treatments were then initiated. Detailed analysis of data was undertaken on return to the UK. There was 100% completion of 252 questionnaires. Eleven of the 12 subjects (91.7%) had symptom scores greater than or equal to 3, consistent with a diagnosis of AMS, on at least one day (range, 0-8). Symptoms of AMS were more common in the female group members (P = .041). AMS is a common problem among adolescents. There are increasing numbers of adolescents traveling to high altitudes, and there appears to be a lack of information about the prevalence of AMS in this age group. Motivated adolescents seemed capable of self-monitoring for AMS using the Lake Louise questionnaire. Combined with an appropriate ascent profile and support, we feel this approach may contribute to safety in the mountains and merits further study.

Prevalence of acute mountain sickness in the Swiss Alps.

To assess the prevalence of symptoms and signs of acute mountain sickness of the Swiss Alps. A study using an interview and clinical examination in a representative population of mountaineers. Positive symptoms and signs were assigned scores to quantify the severity of acute mountain sickness. Four huts in the Swiss Alps at 2850 m, 3050 m, 3650 m, and 4559 m. 466 Climbers, mostly recreational: 47 at 2850 m, 128 at 3050 m, 82 at 3650, and 209 at 4559 m. In all, 117 of the subjects were entirely free of symptoms and clinical signs of acute mountain sickness; 191 had one or two symptoms and signs; and 158 had more than two. Those with more than two symptoms and signs were defined as suffering from acute mountain sickness. At 4559 m 11 climbers presented with high altitude pulmonary oedema or cerebral oedema, or both. Men and women were equally affected. The prevalence of acute mountain sickness correlated with altitude: it was 9% at 2850 m, 13% at 3050 m, 34% at 3650 m, and 53% at 4559 m. The most frequent symptoms and signs were insomnia, headache, peripheral oedema, and scanty pulmonary rales. Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales were associated with other symptoms and signs and therefore characteristic of acute mountain sickness. Acute mountain sickness is not an uncommon disease at moderately high altitude--that is, above 2800 m. Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales indicate severe acute mountain sickness, and subjects who suffer these should immediately descend to lower altitudes.