Acute high-altitude illness: a clinically orientated review

Smedley, Thomas; Grocott, Michael P.W.

doi:10.1177/2049463713489539

Cited by 37 publications

(33 citation statements)

References 52 publications

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“…For example, long-term exposures to an altitude above 4 km could induce a loss of appetite, leading to nutrition deficiency and weight loss (Siesjö et al, 1996; Wasse et al, 2012). Collectively, these symptoms associated with acute mountain sickness are related to harsh environmental factors such as low oxygen, cold, and ultraviolet rays (Askew, 2002; Smedley and Grocott, 2013). Particularly, hypobaric hypoxia generates a large amount of ROS, resulting in the subsequent tissue injuries in mountaineers (Askew, 2002; Julian et al, 2014).…”

Section: Ros Generation In Various Types Of Exercisementioning

confidence: 99%

Redox Mechanism of Reactive Oxygen Species in Exercise

et al. 2016

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It is well known that regular exercise can benefit health by enhancing antioxidant defenses in the body. However, unaccustomed and/or exhaustive exercise can generate excessive reactive oxygen species (ROS), leading to oxidative stress-related tissue damages and impaired muscle contractility. ROS are produced in both aerobic and anaerobic exercise. Mitochondria, NADPH oxidases and xanthine oxidases have all been identified as potential contributors to ROS production, yet the exact redox mechanisms underlying exercise-induced oxidative stress remain elusive. Interestingly, moderate exposure to ROS is necessary to induce body's adaptive responses such as the activation of antioxidant defense mechanisms. Dietary antioxidant manipulation can also reduce ROS levels and muscle fatigue, as well as enhance exercise recovery. To elucidate the complex role of ROS in exercise, this review updates on new findings of ROS origins within skeletal muscles associated with various types of exercises such as endurance, sprint and mountain climbing. In addition, we will examine the corresponding antioxidant defense systems as well as dietary manipulation against damages caused by ROS.

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Section: Ros Generation In Various Types Of Exercisementioning

confidence: 99%

Redox Mechanism of Reactive Oxygen Species in Exercise

et al. 2016

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“…Cough that is dry at onset and expectorant with pink frothy sputum later is also very common accompaniment. Only 50 per cent of HAPE patients have concurrent AMS and 14 Per cent have concurrent HACE 18 , while 5 Per cent of autopsies of fatal HAPE have evidence of cerebral oedema 28 .…”

Section: Referencesmentioning

confidence: 99%

“…Maximum altitude gained too influences the likelihood of AHAI-AMS typically develops at altitudes>2,500, HAPO at > 3000 m and HACO between 4000 m -5000 m 18 . A large body of evidence points towards individual susceptibility as an interactive outcome between: genetic and environmental factors 18,19 . Studies on Tibetan and Andean populations have revealed different genetic phenotypes 20 .…”

Section: Epidemiology and Riskmentioning

confidence: 99%

Physiology and Medicine at High Altitude: The Exposure and the Stress

Gurtoo

2018

Def. Life. Sc. Jl.

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, it was sometimes in the mid-nineteenth century that, Bert first showed the association between hypobaria triggered lowering of PiO 2 and high altitude illness 2 . This relationship is best captured by the gas-law equation:PV = nRT where P = pressure, V = volume, n = number of gas molecules, R = universal gas constant, and T = absolute temperature. Since, the partial pressure of a gas, P = Fi x B, at sea level given a B of 760 mmHg (P B ), the partial pressure of inspired O 2 becomes = 20.9 x 760 =159 mm Hg. This fall is most dramatic at 5,486 meters, which is the upper level of functional acclimatisation where a PB of = 395 mm Hg yields a Pi O 2 of 82 mmHg (20.9 x 395), which is nearly half that at sea level. Even at 3000 m, the height of Leh, the barometric pressure (P B ) and inspired PO 2 (PiO 2 ) are only 70 per cent of the sea level values. On the summit of Mt. Everest, at 8848 m, the PiO 2 is less than 30 per cent of its sea level value. These values signify the stress and challenge to the physiology at high altitude. The ADApTATIONTaken suddenly to the top of Mt. Everest (8848 m), a person would lose consciousness in less than 3 min 3 . Taken slowly the same person remains alive and functional. In fact the lowest recorded P A O 2 in a healthy individual at 8400 m on Everest by the Caudwell Xtreme Everest expedition was 19 mmHg (2.55 KPa). The stark contrast between the two scenarios is accounted for by the adaptive process called acclimatisation that tends to increase the oxygen delivery (DO 2 ) to the tissues. The ClAssIC MODelThe classic model holds that this increase in DO 2 is affected by an optimisation between: (i) Pulmonary (ii) haematological and, (iii) cardiovascular processes. Pulmonary process optimisation is the first response to hypobaric hypoxia: hyperventilation is triggered by a combination of stimulation of peripheral chemoreceptor and inhibition of the central chemoreceptors that leads to an increased respiratory rate and depth. This hypoxic ventilator response (HVR) triggers in within a few hours of exposure to hypobaric hypoxia. This HVR tends to restore the falling oxygen gradient across the physiology and Medicine at high Altitude: The exposure and the stress Anil GurtooLady Hardinge Medical College, ABsTRACT Increase in altitude causes decrease in atmospheric barometric pressure that results in decrease of inspired partial pressure of oxygen, a source for stress and pose a challenge to climbers/trekkers or persons posted on high altitude areas. This review discusses about the high altitude sickness, their incidence rates, pathophysiology and the classic model of acclimatisation, which explains about how oxygen requirement in extreme environment is achieved by complex interplay among pulmonary, hematological and cardiovascular processes. The acute high altitude illness (AHAI) is basically composed of two syndromes: cerebral and pulmonary that can afflict un-acclimatised climbers/trekkers. The cerebral syndrome includes acute mountain sickness (AMS) and high altitude cerebral oedem...

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“…Textinn byggist á helstu heimildum sem fundust á PubMED, MEDLINE og í heimildaskrám nýlegra yfirlitsgreina. [5][6][7][8][9] Fyrst er fjallað um eðlilega haeðaraðlögun og lífeðlisfraeði hennar en síðan greint frá birtingarmyndum og meinlífeðlisfraeði þeirra sjúkdóma sem geta gert vart við sig í mikilli haeð. Loks er útskýrt hvernig fyrirbyggja má haeðarveiki og meðhöndla.…”

Section: á G R I Punclassified