low pressure effects on human body

[will_tekkie]

Hello Dr. Deco..

A time ago i read a paper related to deco procedures used in the space program..and some ideas there were very interesting......

they said that in shuttle cabin the pressure is reduced overnight to 0.694 atm in order to reduce the oxygen prebreathing time from 4 hours to 30 min...(i think a 30% O2 mix to reach a normoxic non explosive atmosphere???????) and then the pressure is futher reduced to the space suit working pressure of 0.293 atm. my question is..what is the lowest pressure that could keep a human being alive (in good shape at least) keeping fluids as fluids ..what´s atmosphere is required in such conditions for a long or shorther exposure in low and very low pressure... :11:...deco procedures in these cases looks quite tricky...

decompression related to low pressure seems to be very interesting as well..

thanks doc for your info...

 

[Dr Deco]

Hi tekkie:

The lowest pressures in a space suit are determined by the requirement for oxygen. The is actually some allowance made for the fact that the “dead band” in the measurement devices could result in too low an oxygen level if the bare minimum were selected. Thus, some additional pressure is used.

The problem with all of this is that you would really like a space suit with no decompression obligation (“prebreathe”) needed at all. This would require a suit with an internal pressure nearly that of the spacecraft cabin. This would result in a suit so stiff that the astronaut would soon become very fatigued in his fingers and wrists. Thus low pressures are the rule and the minimum is set by the requirement for a normoxic environment.

Dr Deco :doctor:

Please note the next class in Decompression Physiology :book3:
http://wrigley.usc.edu/hyperbaric/advdeco.htm