| Mortalidad en el Monte Everest, 1921-2006: estudio descriptivo |
Mortality on Mount Everest, 1921-2006: descriptive study.
Firth PG, Zheng H, Windsor JS, Sutherland AI, Imray CH, Moore GW, Semple JL, Roach RC, Salisbury RA.
Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA. pfirth@partners.org
BMJ. 2008 Dec 11;337:a2654. doi: 10.1136/bmj.a2654.
Abstract
OBJECTIVE: To examine patterns of mortality among climbers on Mount Everest over an 86 year period. DESIGN: Descriptive study. SETTING: Climbing expeditions to Mount Everest, 1921-2006. PARTICIPANTS: 14,138 mountaineers; 8030 climbers and 6108 sherpas. MAIN OUTCOME MEASURE: Circumstances of deaths. RESULTS: The mortality rate among mountaineers above base camp was 1.3%. Deaths could be classified as involving trauma (objective hazards or falls, n=113), as non-traumatic (high altitude illness, hypothermia, or sudden death, n=52), or as a disappearance (body never found, n=27). During the spring climbing seasons from 1982 to 2006, 82.3% of deaths of climbers occurred during an attempt at reaching the summit. The death rate during all descents via standard routes was higher for climbers than for sherpas (2.7% (43/1585) v 0.4% (5/1231), P<0.001; all mountaineers 1.9%). Of 94 mountaineers who died after climbing above 8000 m, 53 (56%) died during descent from the summit, 16 (17%) after turning back, 9 (10%) during the ascent, 4 (5%) before leaving the final camp, and for 12 (13%) the stage of the summit bid was unknown. The median time to reach the summit via standard routes was earlier for survivors than for non-survivors (0900-0959 v 1300-1359, P<0.001). Profound fatigue (n=34), cognitive changes (n=21), and ataxia (n=12) were the commonest symptoms reported in non-survivors, whereas respiratory distress (n=5), headache (n=0), and nausea or vomiting (n=3) were rarely described. CONCLUSIONS: Debilitating symptoms consistent with high altitude cerebral oedema commonly present during descent from the summit of Mount Everest. Profound fatigue and late times in reaching the summit are early features associated with subsequent death.
http://www.bmj.com/highwire/filestream/394247/field_highwire_article_pdf/0.pdf
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| Renacimiento de los conceptos sobre hipoxia |
Concepts in hypoxia reborn.
Martin DS, Khosravi M, Grocott MP, Mythen MG.
Centre for Altitude, Space and Extreme Environment Medicine, Portex Unit, University College London Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK. dan.s.martin@gmail.com
Crit Care. 2010;14(4):315. Epub 2010 Jul 30.
Abstract
The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest. We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies.
http://ccforum.com/content/pdf/cc9078.pdf
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