Re: RE LifePak 12 NIBP

[Jerry Zion <jerryz@protocol.com>]

The problem is that the pressure pulsation in the cuff acts somewhat
like a sound wave.
The more compliant the material the more absorption of the signal,
the less compliant the material the more the reverberation (i.e. more
echoes of the pulsation, making more noise---small pressure
pulsations---) to which sensitive pressure transducers may react causing
less accurate readings.

What the manufacturer does is optimize the whole design so that it
provides the best possible performance given a specific set of material,
electronics, and software.  What the user sees is some level of
acceptable NIBP performance.  

When part of the materials are changed, the performance will also
change.  It is best to not change what works, unless it can be changed,
or approved by the manufacturer.

NIBP is one of, if not the most difficult vital sign parameter to make
accurate over the range of cuff sizes, physiologic scenarios, hose
material, and make it so that the user can rely on it.  

Jerry Zion

Ted Reesor wrote:
> 
> --- Jerry Zion <jerryz@protocol.com> wrote: > All:
> > Just a note of caution.  NIBP is dependant on the
> > physics of the
> > pressure pulsations in the cuff, coupled through the
> > tubing to the
> > monitor where they are actually transduced into the
> > information
> > displayed on your monitor.  It is highly recommended
> > that you do NOT
> > change the tubing supplied by the manufacturer of
> > the monitor for NIBP.
> > Your NIBP performance will suffer, and it's not all
> > that great to begin
> > with.  If you are having trouble with connectors,
> > get the manufacturer
> > to fix it.
> >
> > Jerry Zion
> > Welch Allyn Protocol
> > Makers of Propaq Brands and OEM NIBP Sub-Assemblies
> >
> 
> Interesting note, Jerry
> 
> How does the compliance of the tubing affect the
> actual reading?  One would think that you would want
> as non-compliant as possible tubing in order to
> prevent a dampening effect, like an art line.  Don't
> get me wrong, if I'm incorrect I actually like it when
> challenged (its a learning thing for me...).  An
> additional sleeve would decrease the compliance, would
> it not?
> 
> Cheers,
> 
> =====
> Ted Reesor, RRT/RRCP
> Joseph Brant Memorial Hospital
> Burlington, Ontario
> 
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