GE TuffSat, Руководство пользователя и сервисное руководство

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TuffSat User’s Guide and Service Manual
1-2
Relative Perfusion Index (PI
r
®)
pulsatile value
The PI
r
pulsatile value indicates the strength of the pulse signal at the sensor site:
the higher the PI
r
value, the stronger the pulse signal. A strong pulse signal
increases the validity of SpO
2
and pulse rate data.
PI
r
is a relative value that varies from patient to patient. Clinicians can use the PI
r
value to compare the strength of the pulse signal at different sites on a patient in
order to locate the best site for the sensor (the site with the strongest pulse signal).
TruTrak
®
data sampling system
The TruTrak data sampling system, patented by Datex-Ohmeda, enables the TuffSat
oximeter to calculate SpO
2
many times each second through advanced statistical
data processing. While other oximeters calculate only at the peak and trough of
each waveform, the TuffSat assesses SpO
2
continuously. The TruTrak data sampling
system provides reliable readings during times of low perfusion, motion, or
electrical interference.
The TuffSat oximeter employs an analog/digital (A/D) converter and maximized
digital signal processing techniques to produce samples for the TruTrak system to
process. The result is a highly reliable level of oximetry performance.
Theory of operation
The TuffSat oximeter uses a two-wavelength pulsatile system—red and infrared
light—to distinguish between oxygenated (O
2
Hb) and reduced (HHb) hemoglobin,
each of which absorbs different amounts of light emitted from the oximeter sensor.
The SpO
2
and pulse rate are determined by the oximeter through sensor signal
processing and microprocessor calculations.
Signal processing
Figure 1-1. Signal processing block diagram
The sensor contains a light source and a photodetector:
• The light source consists of red and infrared light-emitting diodes (LEDs).
• The photodetector is an electronic device that produces an electrical current
proportional to incident light intensity.
Photodetector
Sensor
Front End
Amplifier
A/D
Converter
Digital
Processing
Display
LED
Analog
Processing