Oxygen enrichment and its application to life support systems for workers in high-altitude areas

Background:

Workers coming from lowland regions are at risk of developing acute mountain sickness (AMS) when working in low oxygen high-altitude areas.

Objectives:

The aim of this study was to improve the conditions that lead to hypoxia and ensure the safety of the high-altitude workers. We analyzed the influence of low atmospheric pressure on the oxygen enrichment process in high-altitude areas using an engineering method called low-pressure swing adsorption (LPSA).

Methods:

Fourteen male subjects were screened and divided into three groups by type of oxygen supply system used: (1) oxygen cylinder group; (2) LPSA oxygen dispersal group; and (3) control group. These tests included arterial oxygen saturation (SaO₂), pulse rate (PR), breaths per minute (BPM), and blood pressure (BP).

Results:

The results showed that after supplying oxygen using the LPSA method at the tunnel face, the SaO₂ of workers increased; the incidence of acute mountain sickness, PR, and BPM significantly decreased.

Conclusions:

The LPSA life support system was found to be a simple, convenient, efficient, reliable, and applicable approach to ensure proper working conditions at construction sites in high-altitude areas.     

慢性高原病肾功能及血脂的变化

目的探讨慢性高原病(CMS)患者肾功能及血脂的变化。方法选择移居海拔4 300 m 3个月以上的汉族男性青年323名,其中CMS患者87名,为CMS组,其余236名为非CMS组。清晨抽取空腹静脉血检测尿素氮、肌酐、尿酸、三酰甘油、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇。以血红蛋白(18 g<血红蛋白<21 g,记0分,血红蛋白≥21 g,记3分)及动脉血氧饱和度(动脉血氧饱和度≤85%,记3分)记分。分别以1,2,3分表示轻、中、重度。无CMS总记分为0~5分,轻度为6~10分,中度为11~14分,重度为15分或更高。结果CMS组较非CMS组尿素氮、尿酸增高,有显著性差异(P<0.05);总胆固醇增高,三酰甘油、高密度脂蛋白胆固醇降低,有非常显著性差异(P<0.01),肌酐、低密度脂蛋白胆固醇无统计学意义(P>0.05)。结论CMS引起肾功能指标及血脂异常,提示CMS伴有多器官或组织受损。     

Non‐invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation

Background and objective: Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end‐expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. Methods: We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non‐invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. Results: We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO₂ was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusions: The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO₂. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.     

低山带疗养护理对老年高血压患者心身健康的影响

目的探讨低山带疗养护理对老年高血压患者心身健康的影响。方法 2012年7-9月,广州军区武汉疗养院对在鸡公山疗养地疗养的68名老年高血压患者疗养前后的血压、心率、血氧饱和度、体质指数及心理健康状况等进行了研究并比较。结果疗养后,老年高血压患者的收缩压及血氧饱和度均优于疗养前(均P0.01),舒张压、心率、BMI等与疗养前比较,差异均无统计学意义(均P0.05);躯体化、抑郁、焦虑、恐怖、睡眠饮食障碍等5项因子均分与疗养前的差异均有统计学意义(均P0.05),其余因子的评分与疗养前的差异均无统计学意义(均P0.05)。结论低山带气候疗养护理对老年高血压患者的血压及心身健康状况有积极的影响。     

Acute Mountain Sickness: Pathophysiology, Prevention, and Treatment

Barometric pressure falls with increasing altitude and consequently there is a reduction in the partial pressure of oxygen resulting in a hypoxic challenge to any individual ascending to altitude. A spectrum of high altitude illnesses can occur when the hypoxic stress outstrips the subject's ability to acclimatize. Acute altitude-related problems consist of the common syndrome of acute mountain sickness, which is relatively benign and usually self-limiting, and the rarer, more serious syndromes of high-altitude cerebral edema and high-altitude pulmonary edema. A common feature of acute altitude illness is rapid ascent by otherwise fit individuals to altitudes above 3000 m without sufficient time to acclimatize. The susceptibility of an individual to high-altitude syndromes is variable but generally reproducible. Prevention of altitude-related illness by slow ascent is the best approach, but this is not always practical. The immediate management of serious illness requires oxygen (if available) and descent of more than 300 m as soon as possible. In this article, we describe the setting and clinical features of acute mountain sickness and high-altitude cerebral edema, including an overview of the known pathophysiology, and explain contemporary practices for both prevention and treatment exploring the comprehensive evidence base for the various interventions.     

Prevention and Treatment of High-Altitude Pulmonary Edema

We distinguish two forms of high altitude illness, a cerebral form called acute mountain sickness and a pulmonary form called high-altitude pulmonary edema (HAPE). Individual susceptibility is the most important determinant for the occurrence of HAPE. The hallmark of HAPE is an excessively elevated pulmonary artery pressure (mean pressure 36-51 mm Hg), caused by an inhomogeneous hypoxic pulmonary vasoconstriction which leads to an elevated pulmonary capillary pressure and protein content as well as red blood cell-rich edema fluid. Furthermore, decreased fluid clearance from the alveoli may contribute to this noncardiogenic pulmonary edema. Immediate descent or supplemental oxygen and nifedipine or sildenafil are recommended until descent is possible. Susceptible individuals can prevent HAPE by slow ascent, average gain of altitude not exceeding 300 m/d above an altitude of 2500 m. If progressive high altitude acclimatization would not be possible, prophylaxis with nifedipine or tadalafil for long sojourns at high altitude or dexamethasone for a short stay of less then 5 days should be recommended.     

Budesonide Versus Acetazolamide for Prevention of Acute Mountain Sickness

Background

Inhaled 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.

Efficacy of Acetazolamide for the Prophylaxis of Acute Mountain Sickness: A Systematic Review,Meta-Analysis and Trial Sequential Analysis of Randomized Clinical Trials

BackgroundAcute mountain sickness (AMS) is a benign and self-limiting syndrome but can progress to life-threatening conditions if leave untreated. This study aimed to assess the efficacy of acetazolamide for the prophylaxis of AMS and disclose potential factors that affect the treatment effect of acetazolamide.Materials and MethodsRandomized controlled trials comparing the use of acetazolamide versus placebo for the prevention of AMS were included. The incidence of AMS was the primary endpoint. Meta-regression analysis was conducted to explore potential factors associated with acetazolamide efficacy. Trial sequential analysis (TSA) was conducted to estimate the statistical power of the available data.ResultsA total of 22 trials were included. Acetazolamide at 125, 250, and 375 mg/ twice daily (bid) significantly reduced incidence of AMS compared to placebo. TAS indicated that the current evidence was adequate confirming the efficacy of acetazolamide at 125, 250, and 375 mg/bid in lowering incidence of AMS. There was no evidence of an association between efficacy and dose of acetazolamide, timing at start of acetazolamide treatment, mode of ascent, AMS assessment score, timing of AMS assessment, baseline altitude, and endpoint altitude.ConclusionAcetazolamide is effective prophylaxis for the prevention of AMS in doses of 125, 250, and 375 mg/bid. Future investigations should focus on personal characteristics, disclosing the correlation between acetazolamide efficacy and body mass, height, degree of prior acclimatization, individual inborn susceptibility, and history of AMS.     

Long term neurologic sequelae in a Mexican rocky mountain spotted fever case

During the second half of the twentieth century, neurologic sequelae associated with central nervous system impairment caused by Rickettsia rickettsii were studied widely and exclusively in the United States. We present the case of a Mexican pediatric patient with neurologic sequelae 10 years after an acute infection by R. rickettsii.     

血管内皮功能不全与急性高原病相关性的研究进展

急性高原病(acute mountain sickness,AMS)是人群由平原快速进入海拔3000米以上的地区时常出现的疾病,轻者出现头痛、头晕、恶心、心慌、失眠等多种适应不良的症状,重者可发生急性高原肺水肿(high altitude pulmonary edema,HAPE)或急性高原脑水肿(high altitude cerebral edema,HACE),甚至威胁生命安全. 从机体暴露于高原缺氧环境到AMS发生,其过程及衍变的机制尚不清楚.目前大多数学者认为,AMS三种类型(轻型高原病、高原肺水肿、高原脑水肿)的发病机制有共同之处,其中体液潴留、体液重分配(脑、肺中水分较多)、运动、睡眠时低氧血症、通气反应降低、心功能不全及遗传等因素在其中起着重要的作用.且AMS的发生易感性与众多因素相关,如恶劣的环境因素、呼吸道炎症等.下面重点阐述AMS发病过程中血管内皮功能的变化,以及内皮功能不良与AMS发病相关性与易感性的研究进展.