Perfusion fixation:How pres is deter.

elbert at elbert at
Tue Mar 15 20:22:25 EST 1994

I'm concerned about how pressures for perfusion fixations are reported.  It
seems that most researchers convert the height of their bottles to
mm Hg, a number which is absolutely meaningless due to severe friction
losses in this type of piping (ie. sudden contraction from a large tube
to a small canulla).  A more meaningful measurement would be volumetric
flow rate, which yields pressure exactly if the diameter at the exit
is known.  Besides, once flow is begun and some vein is cut, the 
pressure at the cut is atmospheric, the pressure in the IV bottle is
some function of height and friction losses in the piping (determinable
only through volumetric flow rate or pressure transducers), and the
pressure at the organ is indeterminate.

My question is: The pressures that are reported for perfusion fixations,
are those actually measured, or are they calculated from the height
of the IV bottles.  I'm trying to get a feel for the percentage of 
researchers who determine pressure by a given method.

Thanks,    Don Elbert    Dept. of Chem. Eng.   Univ. of Texas at Austin

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