GE TruSat, User Manual

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TruSat User’s Guide
1–2
TruSat pulse oximetry
TruSignal Enhanced SpO
2
TruSignal Enhanced SpO
2
offers improved performance, especially during challenging
conditions of clinical motion and low perfusion. With ultra-low-noise technology,
TruSignal selects the appropriate clinically-developed algorithm to compensate for
weak or motion-induced signals and generate reliable saturation readings.
PI
r
pulsatile value
The perfusion index measurement—the PI
r
pulsatile value—is a quick and easy-to-use
clinical tool that provides a dynamic numeric reflection of perfusion at the sensor site.
PI
r
is a relative value that varies from patient to patient.
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. 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.
Measurement characteristics
The pulse oximetry measurement uses a two-wavelength pulsatile system—red and
infrared light—to distinguish between oxyhemoglobin (O
2
Hb) and reduced hemoglobin
(HHb). The light is emitted from the oximeter sensor, which contains the 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.
The two light wavelengths generated by the LEDs are transmitted through the tissue at
the sensor site and are modulated by arterial blood pulsation. Since other fluids and
tissues present generally don’t pulsate, they don’t modulate the light. The pulsatile
portion of the incoming signal is used to detect and isolate the attenuation of light
energy due to arterial blood flow.
Absorption
Time
Figure 1-1. Comparative light absorption
Variable absorption
(due to arterial pulse)
Arterial blood absorption
Venous blood absorption
Other tissue absorption