A Technical Details; How It Works - ADInstruments Human NIBP Nano Owner's Manual

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A P P E N D I X
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Technical
Details
This Appendix describes some important technical aspects of the
operation of the Human NIBP Nano. You do not need to know this
material to use the Human NIBP Nano, but it is likely to be of interest
to the technically-minded. In the Human NIBP soft ware, the periodic
interruption of a finger blood pressure measurement with constant cuff
pressure levels to apply the PhysioCal algorithm is simply referred to as
an Auto calibration or 'AutoCal'.
It should also be noted that the ADInstruments Human NIBP soft ware is
designed to support the connection of a single Human NIBP Nano unit
at any one time. It does not support connection of two (or more) Human
NIBP Nano devices.
This material is not intended in any way as a service guide. It should be
noted that any modification or attempt to service your Human NIBP
Nano Interface voids your rights under the warranty.

How it Works

In a manner similar to other Finapres® products (www.finapres.com),
the Human NIBP Nano uses the volume-clamp method, originally
described by the Czech physiologist Jan Peñáz [Peñáz 1969, Peñáz
1973], to measure blood pressure in the finger. In this method the
diameter of an artery under a cuff wrapped around the finger is kept
constant (clamped), in spite of the changes in arterial pressure during
each heart beat.
Changes in arterial diameter, detected by means of an infrared
photoplethysmograph built in the finger cuff , are opposed by a fast
pressure servo controller that changes pressure in an inflatable air
bladder, which is also mounted in the finger cuff . Based on the patented
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Human NIBP Nano Owner's Guide