GE HEALTHCARE B20, User'S Reference Manual

Page: 225 / 320

Pulse oximetry
13-9
Measurement limitations
•
The monitors are designed to minimize the interference of electrosurgery. Under some
circumstances electrosurgery may cause noise on the screen. Therefore, be careful in
interpreting the results, especially the plethysmographic pulse waveform, during
electrosurgery.
•
The saturation values may be somewhat higher for smokers. Special care should be taken
with patients who have burns or carbon monoxide (CO) intoxication. When carbon
monoxide intoxication is suspected, always confirm the pulse oximetry reading with a
blood sample measurement.
•
Intravascular dyes may cause erroneous readings. For example, methylene blue, indigo
carmine, indocyanine green or any substances that contain dyes, interfere with the SpO
2
measurement.
•
Vasoconstrictive drugs, such as phenylephrine hydrochloride and dopamine, may affect
the accuracy of the measurement.
•
The pulse oximeter cannot distinguish between oxyhemoglobin and dyshemoglobins.
•
Poor perfusion may affect the accuracy of measurement, especially when using an ear
sensor.
•
To avoid erroneous readings, do not use a blood pressure cuff or arterial blood pressure
measurement device, or NMT sensor in the same limb as the SpO
2
sensor.
•
For Masimo SpO
2
, loss of pulse signal can occur when:
− Sensor is too tight
− The patient has hypotension, severe vasoconstriction, severe anemia or
hypothermia.
− There is arterial occlusion proximal to the sensor.
Interference
These types of interference can influence the function of SpO
2
:
•
Incorrect sensor application, e.g., sensor placement on an extremity with a blood
pressure cuff, arterial catheter, or intravascular line, sensor applied too tightly.
•
Intravascular dyes, such as idocyanine or methylene blue.
•
Externally applied coloring agents with opaque materials in high ambient light conditions,
e.g., conditions created from one or more of the following sources:
−
Surgical lights, especially xenon light sources
− Bilirubin lamps
−
Fluorescent lights
− Infrared heating lamps
−
Direct sunlight
•
Excessive patient activity
•
Venous pulsation
•
Dysfunctional hemoglobin
•
Poor (low) peripheral perfusion
•
Arterial occlusion proximal to the sensor
•
Loss of pulse (cardiac arrest)