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WatchPAT
™
ONE System
11
Operation Manual
Figure 3
–
A zzzPAT Analysis Program typical screen
2.2
Finger Probe Description
The WatchPAT Finger Probe is an electro-opto-pneumatic finger-mounted probe. Its
role is to continuously measure the relative state of the vasomotor activity in the
distal part of the finger based on a plethysmographic method. The Finger Probe is
designed to cover the distal part of the finger with a uniform predetermined pressure
field extending to the tip of the finger, at all fingers’ sizes. This design prevents
venous blood pooling, engorgement and stasis, which inhibits retrograde venous
shock wave propagation, and allows partial unloading of arterial wall tension that
significantly improves the dynamic range of the measured signal. The optic
component of the probe measures the optical density related changes of the arterial
blood volume in the digital arteries, associated with each heartbeat. Peripheral
arterial constrictions, when present, are shown by attenuation in the PAT signal
amplitude, a marker of sympathetic activation.
The Finger Probe also measures the changes in absorbance of the finger at both red
and infrared light at peak wavelengths of approximately 660nm and 910nm
respectively. The maximum optical output power is 65mW. These measurements are
used to calculate the oximetry signal in an offline program according to the pulse
oximetry principles.
The Finger probe is an integral part of the WatchPAT™ device and is to be used
only with the WatchPAT device.