NIBP Monitoring
11-6
11.3 Measurement Restrictions
Inaccurate SpO
2
readings may be caused by the following factors:
1) High-frequency radio interference, whether from the host system or from the electrosurgical equipment
connected to the host system. To minimize radio interference, other electrical equipment that emits radio
frequency transmissions should not be in close proximity to the instrument.
2) Do not use the oximeter or SpO
2
sensor in the MRI process, or the induced current may cause burns.
3) Intravenous dyes.
4) The patient moves frequently.
5) Ambient optical radiation.
6) The sensor is fixed improperly or to an improper position on the patient.
7) Improper sensor temperature (optimum temperature: 28℃~42℃).
8) The sensor is placed on a limb with a blood pressure cuff, ductus arteriosus or intravenous tube.
9) Concentration of the non-functional hemoglobin, like COHb or MetHb.
10) Low SpO
2
.
11) Poor circulation perfusion at the tested location.
12) The shock, anemia, hypothermia and application of vasoconstrictors may reduce the arterial blood flow to a
non-measurable level.
13) The SpO
2
measurement accuracy depends also on the absorption of the lights with special wavelength by
oxyhemoglobin and reduced hemoglobin. If any other substance also absorbs such lights, like COHb, MetHb,
methylene blue or indigo carmine, you may obtain a false or low SpO
2
value.
11.4 SpO
2
Display
(1) Plethysmographic (Pleth/Plethb) waveform: the amplitude of Pleth/Plethb waveform can directly reflect the
intensity of the patient's pulse signal.
(2) Saturation of pulse oxygen (SpO
2
/SpO
2
b) value (unit of %SpO
2
).
(3) Pie graph (for Nellcor SpO
2
): Fills in clockwise as the SatSeconds alarm management system detects a %SpO
2
reading outside of the limit setting. Empties in counterclockwise direction when %SpO
2
reading is within limits.
When the indicator is full, a medium priority alarm sounds.
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