Altitude Sickness

Original publisher: Houston, Tex. : National Aeronautics and Space Administration, Lyndon B. Johnson Space Center, [2008] OCLC Number: (OCoLC)672030344 Excerpt: ... Quality and Quantity of Research Data Any factor that could reduce crew health and performance should be minimized. There is not an abundance of data specific to that required for the spaceflight AMS risk assessment. There are only 4 reports about a P effect per se on the risk of AMS B induced by HH and 6 reports on the combined effects of HH and simulated μG adaptation that have some application here. So, all of the conclusions listed in this summary are based on extrapolation or interpolation from limited information. Although initial signs and symptoms of AMS in susceptible subjects are expected after acute exposure to between 2,000 m ( 6,600 ft at P O = 75 mmHg ) and 2,590 m A 2 ( 8,500 ft at P O = 67 mmHg ) while breathing air, it is likely that these would be A 2 self-limiting once acclimatization occurs. At 8.0 pounds per square inch, absolute ( psia ) ( 4,876 m or 16,000 ft ) with a nominal P O = 77 mmHg, it is likely that susceptible astronauts breathing O-enriched air A 2 2 and simultaneously undergoing adaptation to μG will experience signs and symptoms of AMS. No clinically significant increase in hematocrit or blood viscosity is expected as red blood cell mass, plasma, and total body water volumes adjust to the combined HH and μG environment. A transient increase to a mean hematocrit of about 50 %, possibly as high as 55 % in a particular crewperson, would be predicted based on the data for the combined effects of HH and adaptation to μG as envisioned for the CEV program. However, typical μG-adapted spaceflight hematocrit values are in the low normal range, from 36 to 40 % depending on gender. The repeatedly validated operational experience with the shuttle staged denitrogenation protocol at 10.2 psia ( 10,000 ft ) while breathing 26.5 % O ( P O = 2 A 2 85 mmHg ) in μG-adapted astronau...