Changes in blood pressure, oxygen saturation, hemoglobin concentration, and heart rate among low-altitude migrants living at high altitude (5380 m) for 360 days.

BACKGROUND: This article aimed to study the adjustment and adaptation of resting systolic blood pressure (SBP), diastolic blood pressure (DPB), oxygen saturation (SpO2 ), hemoglobin concentration ([Hb]), and heart rate (HR) in low-altitude migrants during a 1-year stay at high altitude. MATERIALS AND METHODS: Our study enrolled 35 young migrants who were exposed to a hypoxia environment at 5380 m altitude on the Qinghai Tibetan Plateau between June 21, 2017, and June 16, 2018. We set 14-time points (the 1st-10th, 20th, 30th, 180th, and 360th day after arriving at 5380 m) for obtaining the measurements of resting SBP, DBP, HR, SpO2, and [Hb] and compared them with the control values recorded prior to migration. Variables with continuous data were summarized as means (SD). One-way repeated measures ANOVA without assuming sphericity was carried out to test whether the mean values (SBP, DBP, HR, SpO2 , and [Hb]) on different days were different significantly. Furthermore, Dunnett's multiple comparisons test was carried out to determine the time points whose values were significantly different from the control values. RESULTS: SBP and DBP were continually increasing within d1-3 and peaked on the 3rd day, then steadily declined from d3 to d30. SBP fell back to the control values on d10 (p > 0.05), and DBP fell back to the control values on d20 (p > 0.05). A significant decline occurred on d180 (p < 0.05). Both SBP and DBP were lower than the control values on d180 (p < 0.05), and this trend was maintained to d360. There were similar characteristics of HR and BP in the time course at HA. HR on d1-3 was increasing (p < 0.05) compared to the control values, after which it fell back to the control values on d180 (p > 0.05), and this trend was maintained to d360. SpO2 was the lowest on d1 and lower than the control value throughout the study at HA (p < 0.05). [Hb] increased after long-term exposure (180 and 360 days) to HA (p < 0.05). CONCLUSIONS: Our study continuously monitored lowlanders at 5380 m in Tibet, and is perhaps the only longitudinal study of migrants conducted at an altitude above 5000 m during a 1-year period. Our study provides new information on the adjustment and adaptation of [Hb], SpO2 , SBP, DBP, and HR in high-altitude plateau migrants during a 360-day stay at an altitude of 5380 m.

[MtDNA haplogroup U4b is a genetic susceptibility factor for high altitude essential hypertension in the Chinese Tajik population].

Objective: To investigate the relationship between mitochondrial DNA (mtDNA) variation and high altitude essential hypertension(HAEH) in the Chinese Tajik population. Methods: Fifty-three patients with HAEH and 46 healthy subjects were enrolled from the Chinese Tajik population. The mtDNA fragments were amplificated by polymerase chain reaction, and products were sequenced to acquire full sequence of mtDNA. The mtDNA sequences of all subjects were compared to the Cambridge sequence to explore mtDNA variations and analyze difference between HAEH and healthy controls. Online softwares were applied to predict function changes caused by positive associated mtDNA variations. Results: Compared to the control group, the frequency of haplogroup U4b was significant higher in HAEH group(P=0.023,OR=7.062,CI(95%)=1.306-38.182), and the frequencies of 8 mutations from haplogroup U4b showed a significant difference between the HAEH group and control group (all with P values below 0.05). The mt DNA15693T＞C mutation was the only missense mutation, which affected amino acid 316 in mitochondrial cytochrome b (MTCYB) by changing it from methionine to threonine. Bioinformatics analysis indicated that the mutation in MTCYB may play a biological role through affecting the second structure of protein. Conclusion: MtDNA subhaplogroup U4b is a genetic factor for HAEH in the Chinese Tajik population, and mtDNA15693T＞C mutation may be an important molecular mechanism of HAEH.

[Prevalence and risk factors of chronic mountain sickness in Pamirs plateau].

OBJECTIVE: To investigate the prevalence of chronic mountain sickness (CMS) and its predisposing factors in Pamirs plateau and analysis clinical feature and risk factors. METHODS: Eight hundred and twenty-four individuals in Pamirs plateau were surveyed used Qinghai CMS scoring system. Demographics, BP, SaO2, heart rate and specified symptoms of CMS were recorded, Hb level was estimated. RESULTS: Overall CMS prevalence was 22.08%, including 21.84% mild and 0.24% moderate without severe patient. Gender, nation, age, immigration time, altitude, occupation and accommodation mode were risk factors for CMS (P<0.05 or P<0.01), CMS prevalence was higher than HAPC rate both in male and female (χ2=90.59 and 44.13, P<0.01). Multiple linear regression analysis showed age, BMI, SaO2 and systolic pressure correlated with CMS (P<0.01). CONCLUSIONS: Chronic mountain sickness prevalence in Pamirs plateau is rather high but high altitude polycythemia prevalence is low, so the disease type is high altitude deterioration. Work and exercise more reasonable to avoid overtiredness, oxygen inhalation to raise blood oxygen saturation, control blood pressure and resting therapy can improve CMS symptom and decrease prevalence.

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.

[The deacclimatization symptom scores of 159 youth returning to the same plain from different plateau].

OBJECTIVE: To analysis deacclimatization symptom scores of 159 youth from Karakoram and Tibet Ali area, and provide the basis for the development of relevant prevention and control measures. METHODS: Using the method of epidemiological symptoms questionnaire, 18 symptoms of 190 youth who returned to the plain area from the different plateau were investigated. The symptom scores of different altitude, age, the time of staying, different units, continuous or intermittent stage and education were surveyed. RESULTS: Deacclimatization symptom scores among 5,000 meter groups were significantly higher than those of 4,300 meter and 3,700 meter group (P < 0.05, P < 0.01). There was no significant difference between the 4,300 meter group and the 3,700 meter group (P > 0.05). There were significant differences among the stayed personnel (different age, position, unit, education, time, continuous or intermittent) (P < 0.01). There was significant difference between the continuous defended the group and intermittent group (P < 0.01). CONCLUSION: Deacclimatization symptom scores were related to the plateau exposure time, altitude, workload, plateau continued exposure. The older, the longer exposure, the higher altitude, the greater workload at plateau were showed higher deacclimatization symptom score.

Therapeutic intervention against deacclimatization to high altitude.

The incidence of deacclimatization to high altitude syndrome (DAHAS) prevailed up to 80% in highland troops, and 100% in manual workers, and severe DAHAS could significantly affects patients' health, work and life. So it is imperative to develop effective prevention and treatment measures for DAHAS. The present review analyzes effective prophylactic and therapeutic measures against DAHAS, implemented at our hospital.