Otro poco sobre medicina de las alturas

Fisiología y patofisiología de las grandes alturas: implicaciones y relevancia para la medicina intensiva High-altitude physiology and pathophysiology: implications and relevance for intensive care medicine. Grocott M, Montgomery H, Vercueil A. Centre for Altitude, Space and Extreme Environment Medicine (CASE Medicine), UCL Institute of Human Health and Performance, UCL Archway Campus, Highgate Hill, London, UK. mike.grocott@ucl.ac.uk Crit Care. 2007;11(1):203. Abstract Cellular hypoxia is a fundamental mechanism of injury in the critically ill. The study of human responses to hypoxia occurring as a consequence of hypobaria defines the fields of high-altitude medicine and physiology. A new paradigm suggests that the physiological and pathophysiological responses to extreme environmental challenges (for example, hypobaric hypoxia, hyperbaria, microgravity, cold, heat) may be similar to responses seen in critical illness. The present review explores the idea that human responses to the hypoxia of high altitude may be used as a means of exploring elements of the pathophysiology of critical illness  http://ccforum.com/content/pdf/cc5142.pdf   Papel del óxido de nitrógeno en la adaptación humana a la hipoxia The role of nitrogen oxides in human adaptation to hypoxia. Levett DZ, Fernandez BO, Riley HL, Martin DS, Mitchell K, Leckstrom CA, Ince C, Whipp BJ, Mythen MG, Montgomery HE, Grocott MP, Feelisch M; Caudwell Extreme Everest Research Group. Centre for Altitude Space and Extreme Environment Medicine, Portex Unit, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK. Sci Rep. 2011;1:109. Epub 2011 Oct 6. Abstract Lowland residents adapt to the reduced oxygen availability at high altitude through a process known as acclimatisation, but the molecular changes underpinning these functional alterations are not well understood. Using an integrated biochemical/whole-body physiology approach we here show that plasma biomarkers of NO production (nitrite, nitrate) and activity (cGMP) are elevated on acclimatisation to high altitude while S-nitrosothiols are initially consumed, suggesting multiple nitrogen oxides contribute to improve hypoxia tolerance by enhancing NO availability. Unexpectedly, oxygen cost of exercise and mechanical efficiency remain unchanged with ascent while microvascular blood flow correlates inversely with nitrite. Our results suggest that NO is an integral part of the human physiological response to hypoxia. These findings may be of relevance not only to healthy subjects exposed to high altitude but also to patients in whom oxygen availability is limited through disease affecting the heart, lung or vasculature, and to the field of developmental biology http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3219423/pdf/srep00109.pdf

Atentamente Anestesiología y Medicina del Dolor www.anestesia-dolor.org