Accession Number : ADA482503


Title :   Hemoglobin P50 During a Simulated Ascent of Mt. Everest, Operation Everest II


Descriptive Note : Journal article


Corporate Author : ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA MILITARY NUTRITION DIV


Personal Author(s) : Wagner, Peter D ; Wagner, Harrieth E ; Groves, Bertron M ; Cymerman, Allen ; Houston, Charles S


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a482503.pdf


Report Date : Jan 2007


Pagination or Media Count : 12


Abstract : The amount of O2 available to tissues is essentially the product of cardiac output, [Hb], and O2 saturation. Saturation depends on P(O2) and the O2Hb dissociation curve. With altitude, increased [2,3-DPG] shifts the dissociation curve rightward, but hypocapnia and alkalosis move it leftward. We determined both standard and in vivo P(50) in 5 fit subjects decompressed over 42 days in an altitude chamber to the equivalent of the Mt. Everest summit (Operation Everest II). Arterial and venous blood was sampled at five altitudes (P(B) 760, 429, 347, 282, 253 mmHg), and P0(2), Pco2, pH , O2 saturation, [Hb] and [2,3-DPG] were measured. As reported previously, 2,3-DPG levels increased from 1.7 (P(B) 760) to 3.8 mmol/L (P(B) 282). Standard P(50) also increased (from 28.2 mmHg at sea level to 33.1 on the summit, p 0.001). Alone, this would have lowered saturation by 12 percentage points at a summit arterial P(O2) of approx. 30 mmHg. However, in vivo P(50) remained between 26 and 27 mmHg throughout due to progressive hypocapnia and alkalosis. Calculations suggest that the increase in standard P(50) did not affect summit V(O2MAX), alveolar, arterial and venous P(O2's), but reduced arterial and venous O2 saturations by 8.4 and 17.4 points, respectively, and increased O2 extraction by 7.9 percentage points. Reduced saturation was balanced by increased extraction, resulting in no significant overall O2 transport benefit, thus leaving unanswered the question of the purpose of increased [2,3- DPC] concentrations at altitude.


Descriptors :   *SIMULATION , *MOUNTAINS , *CLIMBING , *OXYGEN , *HEMOGLOBIN , ALTITUDE CHAMBERS , EXERCISE(PHYSIOLOGY) , METABOLIC DISEASES , CARDIAC GLYCOSIDES , GLYCERIDES , DECOMPRESSION , DISSOCIATION , IN VIVO ANALYSIS , SATURATION , HYPOCAPNIA , REPRINTS


Subject Categories : Biochemistry
      Medicine and Medical Research
      Inorganic Chemistry


Distribution Statement : APPROVED FOR PUBLIC RELEASE