# Technical question regarding hemodialysis

**URL:** <https://boards.straightdope.com/t/technical-question-regarding-hemodialysis/190812>\
**Category:** Factual Questions\
**Created:** [July 25, 2003, 5:26am UTC](https://boards.straightdope.com/t/technical-question-regarding-hemodialysis/190812 "2003-07-25T05:26:08Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\
**Post date:** [July 25, 2003, 5:26am UTC](https://boards.straightdope.com/t/technical-question-regarding-hemodialysis/190812/1 "2003-07-25T05:26:08Z")

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I have a friend who has recently gone on hemodialysis due to diabetes-related kidney failure. I know that in lieu of his kidneys functioning, his blood is being passed through the dialyzer, getting stripped of excess water and waste products, then returned, cleaned up, to his body. What I don’t know is:

_what is the approximate volume of blood that is in the dialyzer rather than in his body while the procedure is in full swing?_

IOW, should some emergency in the building require that he be immediately removed from the machine, and evacuated, how much of his blood would still be in the machine?