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Introduction: High altitude regions are characterized by harsh conditions (environmental, rough terrain, natural hazards, and limited hygiene and health care), which all may contribute to the risk of accidents/emergencies when trekking or climbing. Exposure to hypoxia, cold, wind, and solar radiation are typical features of the high altitude environment. Emergencies in these remote areas place high demands on the diagnostic and treatment skills of doctors and first-aiders. The aim of this review is to give insights on providing the best possible care for victims of emergencies at high altitude. Methods: Authors provide clinical recommendations based on their real-world experience, complemented by appropriate recent studies and internationally reputable guidelines. Results and Discussion: This review covers most of the emergencies/health issues that can occur when trekking or during high altitude climbing, that is, high altitude illnesses and hypothermia, freezing cold injuries, accidents, for example, with severe injuries due to falling, cardiovascular and respiratory illnesses, abdominal, musculoskeletal, eye, dental, and skin issues. We give a summary of current recommendations for emergency care and pain relief in case of these various incidents.

As a model of extreme conditions, eight healthy women, part of a 40-member Nepal mountain-climbing expedition, were monitored for dynamic endocrine adaptations. Endocrine measurements were made at frequent intervals over a 6-10-h period at four altitudes: 450 m, 4,800 m (base camp), 6,050 m, and again at 4,800 m (on descent) after an acclimatization (A) period (4,800 mA). Quantified hormones were growth hormone (GH), prolactin (PROL), cortisol (Cort), thyroid-stimulating hormone (TSH), and free thyroxine. These hormones are important to the anabolic/catabolic balance of the body, and are vital to growth, homeostasis, hypothalamic inhibition, regulation of stress, and metabolism. A key secondary question was the degree to which acclimatization can stabilize hormonal disruption. On the basis of statistical false discovery rates, the present analyses unveil marked adaptive changes in the thyroid axis at the level of pulsatile secretion of the pituitary hormone TSH and its downstream product, free thyroxine; strong effects on the mass of GH, TSH, Cort, and PROL secretion per burst; and prominent pulsatile frequency disruption and recovery for PROL and Cort. Because pulsatility changes reflect de facto perturbations in hypothalamo-pituitary control mechanisms, the present data introduce the concept of both frequency- and amplitude-dependent adaptive control of brain-pituitary neuroendocrine signals under conditions of extreme altitude exertion and exposure.

In vitro and animal studies revealed micro-RNAs (miRs) to be involved in modulation of hypoxia-induced pulmonary hypertension (HPH). However, knowledge of circulating miRs in humans in the context of HPH is very limited. Since symptoms of HPH are nonspecific and noninvasive diagnostic parameters do not exist, a disease-specific and hypoxemia-independent biomarker indicating HPH would be of clinical value. To examine whether plasma miR levels correlate with hypoxia-induced increase in pulmonary artery pressures, plasma miRs were assessed in a model of hypoxia-related pulmonary hypertension in humans exposed to extreme altitude. Forty healthy volunteers were repetitively examined during a high-altitude expedition up to an altitude of 7,050 m. Plasma levels of miR-17, -21, and -190 were measured by real-time quantitative PCR and correlated with systolic pulmonary artery pressure (SPAP), which was assessed by echocardiography. A significant altitude-dependent increase in circulating miR expression was found (all P values < 0.0001). Compared with baseline at 500 m, miR-17 changed by 4.72 ± 0.57-fold, miR-21 changed by 1.91 ± 0.33-fold, and miR-190 changed by 3.61 ± 0.54-fold at 7,050 m (means ± SD). Even after adjusting for hypoxemia, miR-17 and miR-190 were found to be independently correlated with increased SPAP. Progressive hypobaric hypoxia significantly affects levels of circulating miR-17, -21, and -190. Independently from the extent of hypoxemia, miR-17 and -190 significantly correlate with increased SPAP. These novel findings provide evidence for an epigenetic modulation of hypoxia-induced increase in pulmonary artery pressures by miR-17 and -190 and suggest the potential value of these miRs as biomarkers for HPH.