Incidence of High Altitude Illnesses among Unacclimatized Persons Who Acutely Ascended to Tibet

Abstract

Incidence of high altitude illnesses among unacclimatized persons who acutely ascended to Tibet. High Alt. Med. Biol. 11:39-42, 2010.-High altitude illnesses pose health threats to unwary travelers after their acute ascent to high altitude locations. The incidence of high altitude illnesses among unacclimatized persons who acutely ascend to Tibet has not been previously reported. In the present study, we surveyed the incidence of high altitude illness among 3628 unacclimatized persons who had no previous high altitude experience and who traveled to Tibet by air to an altitude of 3600 m. These subjects were asked to answer questions in a written questionnaire about symptoms associated with high altitude illnesses that occurred within 2 weeks of their first arrival, their severity, and possible contributing factors. Physical examination and appropriate laboratory tests were also performed for hospitalized subjects. We found that 2063 respondents had mild acute mountain sickness with an incidence of 57.2%, and 249 (12.07%) of them were hospitalized for treatment. The incidence of high altitude pulmonary edema was 1.9%, while no case of high altitude cerebral edema was found. Additionally, there was no report of death. Psychological stresses and excessive physical exertions possibly contributed to the onset of HAPE. Acute mountain sickness is common among unacclimatized persons after their acute ascent to Tibet. The incidence of HAPE and HACE, however, is very low among them.

Incidence of acute mountain sickness in young adults at 3200 meters: comparison of the Lake Louise Scoring and Chinese Scoring Systems

“…Using the AMS-CSS, the incidence of AMS in Chinese male soldiers at 3600 m was reported to be 57.2% (Ren et al, 2010), a value higher than that found in the present study (29.79%). Ren et al (2010) subjects traveled to Tibet (3600 m) by air, whereas our participants traveled by train and bus.…”

“…Ren et al (2010) subjects traveled to Tibet (3600 m) by air, whereas our participants traveled by train and bus. In addition, our camp was located at ~3200 m rather than at 3600 m. It is well known that the incidence of AMS is influenced by the method of travel and the rate of ascent to high altitude (Schneider et al, 2002).…”

“…In addition, our camp was located at ~3200 m rather than at 3600 m. It is well known that the incidence of AMS is influenced by the method of travel and the rate of ascent to high altitude (Schneider et al, 2002). Furthermore, the study by Ren et al (2010) included lip color ('bluish') as one of the parameters used to diagnose AMS, and this symptom was present in 95.31% of their participants. We did not use this parameter in our AMS-CSS, as we believe that this is not a specific sign of AMS at high altitude, based on the results of Ren et al Our decision not to use this parameter may have decreased the total AMS-CSS score, and hence the incidence of AMS, compared with observations of Ren et al…”

“…However, there was no vomiting case reported in our subjects in the present study. In Ren et al (2010), in which AMS was evaluated with a more rapid ascent and at higher altitude, only 12% of the subjects suffered vomiting symptoms. Therefore, vomiting might not be as relevant to AMS as previously thought, or at least not at a high altitude of 3200 m. Therefore, the role of vomiting in the AMS-CSS is worthy of further study.…”

Natural selection on EPAS1 ( HIF2α ) associated with low hemoglobin concentration in Tibetan highlanders

“…Indeed, it caused one group of investigators to observe in respect of the EPAS1 gain of function mutations that "it raises the possibility that polymorphic variation in HIF2α [EPAS1] contributes to the marked differential susceptibility to erythrocytosis, reduced plasma volume and pulmonary hypertension in humans at high altitude" (39). Chronic mountain sickness occurs among Tibetans at a lower prevalence than Han lowlanders (1.2% compared with 5.6%) living in the Tibet Autonomous Region (4,46). Chronic mountain sickness remains at that low level throughout adulthood among Tibetans but, in Peruvians, prevalence increases with age from approximately 13% in 20 to 39 y olds to approximately 36% in 55 to 69 y olds at 4,300 m (47).…”