The Association of Angiotensin-Converting Enzyme Gene Insertion/Deletion Polymorphisms with Acute Mountain Sickness Susceptibility: A Meta-Analysis

The effects of respiratory inhaled drugs on the prevention of acute mountain sickness

BACKGROUND

Acute mountain sickness (AMS) is common in high-altitude travelers, and may lead to life-threatening high-altitude cerebral edema (HACE) or high-altitude pulmonary edema (HAPE). The inhaled drugs have a much lower peak serum concentrations and a shorter half-life period than oral drugs, which give them a special character, greater local effects in the lung. Meanwhile, short-term administration of inhaled drugs results in almost no adverse reactions.

METHODS

We chose inhaled ipratropium bromide/salbutamol sulfate (combivent, COM), budesonide (pulmicortrespules, BUD), and salbutamol sulfate (ventolin, VEN) in our study to investigate their prophylactic efficacy against AMS. Since COM is a compound drug of ipratropium bromide and salbutamol sulfate, to verify which part of COM plays a role in the prevention of AMS, we also tested VEN in our experiment.

RESULTS

In our study, Lake Louise scores (LLS) in the COM (1.14 ± 0.89 vs 1.91 ± 1.23, P < .05) and BUD (1.35 ± 0.94 vs 1.91 ± 1.23, P < .05) groups were both significantly lower than the placebo group at 72 hours. There were no significant differences in LLS scores among the 4 groups at 120 hours. The incidence of AMS in the COM group was significantly reduced at 72 hours (16.7% in COM group vs 43.4% in placebo group, P < .05) after exposure to high-altitude. There were no significant differences in AMS incidences at 120 hours among the 4 groups.

CONCLUSION

The prophylactic use of COM could prevent AMS in young Chinese male at 72 hours after high-altitude exposure. BUD also could reduce LLS but not prevent AMS at 72 hours. Ipratropium bromide maybe the effective drug in COM work on the prevention of AMS alone.

Progress in Mass Spectrometry-Based Proteomics in Hypoxia-Related Diseases and High-Altitude Medicine

Human migration, influenced by social conflict and natural disasters as well as global climate change, has become recognized as a major "planetary force." It has also brought to the forefront, new specialties of integrative biology-such as high-altitude medicine-and the impact of hitherto understudied environmental factors on human pathophysiology in these new geographical settings. For people migrating to or living in high-altitude regions, environmental hypoxia is a primary challenge. Decreased partial pressure of oxygen in environmental air, caused by lower barometric pressure, puts living organisms in a hypoxic state. When there is a serious inability to adapt, death may ensue. Research efforts over the past few years have applied mass spectrometry-based proteomics analyses to uncover the mechanisms of hypoxia-related high-altitude pathophysiology. The differential proteomic profiles in plasma and tissues under high-altitude hypoxia conditions, as compared with sea level controls, and the multitudinous hypoxia-specific proteins identified elucidate mechanisms underlying high-altitude hypoxia acclimatization and diseases, and provide a foundation for development of new therapeutic, prophylactic, and diagnostic approaches. In this expert review and innovation analysis, we highlight the current proteomics findings on high-altitude hypoxia, and suggest paths forward toward effective interventions to address this key challenge in high-altitude medicine.

The association of angiotensin-converting enzyme gene insertion/deletion polymorphisms with adaptation to high altitude: A meta-analysis

Background:

Fluid retention is linked to the physiology and pathophysiology of humans at high altitude (HA). The angiotensin-converting enzyme (ACE) gene plays a role in the regulation of plasma volume and vascular tone.

Materials and methods:

In this meta-analysis, eligible studies published before 1 September 2015 that focused on the association between the ACE insertion/deletion (I/D) polymorphism and HA adaption were identified by searching the PubMed, Web of Science, Embase and Medline online databases. We used a fixed-effects model and assessed the study qualities multiple times.

Results:

The seven selected studies included a total of 582 HA-native individuals and 497 low-altitude controls, and these subjects were analyzed for the ACE I/D gene polymorphism. A significant association was found between the ACE DD genotype and HA maladaptation. The results for genotype DD versus ID + II were as follows: Odds ratio (OR) = 0.46; 95% CI 0.31–0.70; p = 0.0002. The results for genotype ID versus DD were as follows: OR = 1.97; 95% CI 1.27–3.06; p = 0.002.

Conclusions:

Our findings suggested that the DD genotype of ACE is a risk factor for HA maladaptation and that the presence of fewer ACE DD allele carriers in a population indicates a greater ability of that population to adapt to HA.

Association between smoking and the risk of acute mountain sickness: a meta-analysis of observational studies

BACKGROUND

People rapidly ascending to high altitudes (>2500 m) may suffer from acute mountain sickness (AMS). The association between smoking and AMS risk remains unclear. Therefore, we performed a meta-analysis to evaluate the association between smoking and AMS risk.

METHODS

The association between smoking and AMS risk was determined according to predefined criteria established by our team. Meta-analysis was conducted according to the PRISMA guidelines. We included all relevant studies listed in the PubMed and Embase databases as of September 2015 in this meta-analysis and performed systemic searches using the terms "smoking", "acute mountain sickness" and "risk factor". The included studies were required to provide clear explanations regarding their definitions of smoking, the final altitudes reached by their participants and the diagnostic criteria used to diagnose AMS. Odds ratios (ORs) were used to evaluate the association between smoking and AMS risk across the studies, and the Q statistic was used to test OR heterogeneity, which was considered significant when P < 0.05. We also computed 95% confidence intervals (CIs). Data extracted from the articles were analyzed with Review Manager 5.3 (Cochrane Collaboration, Oxford, UK).

RESULTS

We used seven case-control studies including 694 smoking patients and 1986 non-smoking controls to analyze the association between smoking and AMS risk. We observed a significant association between AMS and smoking (OR = 0.71, 95% CI 0.52-0.96, P = 0.03).

CONCLUSIONS

We determined that smoking may protect against AMS development. However, we do not advise smoking to prevent AMS. More studies are necessary to confirm the role of smoking in AMS risk.

Evaluation of the visual analog score (VAS) to assess acute mountain sickness (AMS) in a hypobaric chamber

OBJECTIVE

The visual analog score (VAS) is widely used in clinical medicine to evaluate the severity of subjective symptoms. There is substantial literature on the application of the VAS in medicine, especially in measuring pain, nausea, fatigue, and sleep quality. Hypobaric chambers are utilized to test and exercise the anaerobic endurance of athletes. To this end, we evaluated the degree of AMS using the visual analog scale (VAS) in a hypobaric chamber in which the equivalent altitude was increased from 300 to 3500 m.

METHODS

We observed 32 healthy young men in the hypobaric chamber (Guizhou, China) and increased the altitude from 300 to 3500 m. During the five hours of testing, we measured the resting blood oxygen saturation (SaO2) and heart rate (HR). Using the VAS, we recorded the subjects' ratings of their AMS symptom intensity that occurred throughout the phase of increasing altitude at 300 m, 1500 m, 2000 m, 2500 m, 3000 m, and 3500 m.

RESULTS

During the phase of increasing altitude in the hypobaric chamber, the patients' SaO2 was 96.8 ± 0.8% at 300 m and 87.5 ± 4.1% at 3500 m (P<0.05) and their HR was 79.0 ± 8.0 beats/minute at 300 m and 79.3 ± 11.3 beats/minute at 3500 m. The incidence of symptoms significantly increased from 21.9% at an altitude of 1000 m to 65.6% at an altitude of 3500 m (P<0.05). The composite VAS score, which rated the occurrence of four symptoms (headache, dizziness, fatigue, and gastrointestinal discomfort), was significantly correlated with elevation (P<0.01).

CONCLUSION

Based on the experimental data, the VAS can be used as an auxiliary diagnostic method of Lake Louise score to evaluate AMS and can show the changing severity of symptoms during the process of increased elevation in a hypobaric chamber; it also reflects a significant correlation with altitude.

‘Ome’ on the range: update on high-altitude acclimatization/adaptation and disease

The main physiological challenge in high-altitude plateau environments is hypoxia.

Strategies for the prevention of acute mountain sickness and treatment for large groups making a rapid ascent in China

Approximately 26.8% of China's land area has an elevation of 3000 m above sea level or higher. Because of recent demands for economic development and new construction in highland areas, many people have relocated from the plains to high plateau regions and have to face the possibility of contracting acute mountain sickness. Therefore, prevention and treatment strategies are necessary to reduce the incidence of acute mountain sickness in people who rapidly ascend to plateau areas. This paper describes the Chinese experience when large numbers of people moved to the plateau and the steps that were taken to deal with this illness. These steps included implementing basic prevention measures, increasing medical awareness among populations ascending to high altitudes, and installing standardized medical management systems to prevent and treat acute mountain sickness before, during, and after ascent. The incidence of acute mountain sickness can be reduced by improving prevention and treatment and by implementing the recommendations described in this manuscript.