Using a new plateau hyperbaric chamber to alleviate high altitude hypoxia: Rabbit and human studies.

OBJECTIVES: To validate the effects of the new plateau hyperbaric chamber on alleviating high altitude hypoxia on Mount Kun Lun. METHODS: A prospective, controlled study of rabbits and adult volunteers was conducted at altitudes of 355, 2880 and 4532m. We obtained arterial blood samples from rabbits and volunteers before and after hyperbaric treatment. The respiratory rate, heart rate, and blood pressure (BP) of adult volunteers were monitored during hyperbaric treatment. RESULTS: The mean PaO2 levels of experimental group rabbits and volunteers increased significantly after 60min of hyperbaric treatment at 350, 2880 and 4532m. The mean PaCO2 and pH levels of rabbits were not significant different before and after hyperbaric treatment at each altitude. The mean PaCO2 and pH levels were not significant different at 355m in the human study. However, at 2880 and 4532m, pH fell with increasing PaCO2 levels in humans before and after hyperbaric treatment. CONCLUSIONS: The new multiplace plateau hyperbaric chamber may be used to alleviate plateau hypoxia by increasing patient PaO2. However, its value in treating AMS must be confirmed in field conditions.

Development and preliminary test of a new plateau hyperbaric chamber.

OBJECTIVE: The objective of this study is to validate the performance, define its limits, and provide details on a new plateau hyperbaric chamber at 355-, 2880-, and 4532-m high altitude. METHODS: A new multiplace plateau hyperbaric chamber was designed to satisfy the needed of patients who have acute mountain sickness. Tests were conducted inside the chamber at 355-, 2880-, and 4532-m high altitude. The safely and conveniences of the new plateau hyperbaric chamber were estimated. RESULTS: Minimum pressures of the main compartment can reach up to 0.029, 0.022, and 0.02 MPa at 355-, 2880-, and 4532-m high altitude. During pressurization, there was no leak of air around the chamber. The time lag of pressure equilibration between main and buffer compartment varies from 30.3±2.01 to 200.5±5.44 seconds and between buffer compartment and ambient pressure varies from 60.2±4.13 to 215.9±6.76 seconds. CONCLUSIONS: The chamber can be applicated for acute mountain sickness treatment safety and convenience. However, further experience about animals and human within the chamber is needed to improve the hardware and establish conditions of effective utilization of this equipment in the high altitude.

Polymorphisms of hypoxia-related genes in subjects susceptible to acute mountain sickness.

BACKGROUND: The occurrence of acute mountain sickness (AMS), which develops in some individuals who ascend to altitudes above 2,500 m, may be associated with 4 hypoxia-related genes (HIF-1, VEGFA, HSP-70 and eNOS). OBJECTIVES: The aim of our study was to investigate the potential role of the 4 hypoxia-related genes in AMS pathogenesis. We therefore evaluated single-nucleotide polymorphisms (SNPs) of the genes in an association study using a case-control design. METHODS: At an altitude of 4,600 m, 64 male Chinese patients with AMS, defined according to the Lake Louise consensus criteria, were compared to 64 Chinese men free of symptoms of AMS. Clinical data, such as age, history of diseases, oxygen saturation (SpO(2)) and heart rate, were obtained. Genotypes of selected SNPs of these genes in patients were compared with those in controls. RESULTS: The mean SpO(2) and heart rate of the AMS and control groups were similar before ascent to high altitude (p = 0.79, p = 0.62) but, 24 h after ascent, the mean SpO(2) of the AMS group was significantly lower than that of the control group (p = 0.001), and the mean heart rate of the AMS group was significantly higher than that of the control group (p = 0.001). Twenty-eight of the 48 SNPs investigated were successfully genotyped, and SNP allele frequencies were obtained. The rs3025039 SNP and the haplotype (rs1413711, rs833070 and rs3025000) in the VEGFA gene were significantly associated with AMS (p = 0.0435 and 0.024, respectively). CONCLUSIONS: Our study demonstrates a possible association between the VEGFA gene and AMS. We conclude that VEGFA may have an important role in the AMS process.